@article { author = {Khodamorad Pour, M. and Irannejad, P.}, title = {Evaluation of simulated river discharge by NOAH land surface scheme coupled in WRF by entering the effect of topographic index and groundwater model}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {1-18}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Introduction Land Surface parameterization Schemes (LSS) play an important role in both general circulation models and regional weather prediction models. A Land surface scheme generally solves the surface energy balance equation to compute the partitioning of the available surface net radiation into sensible and latent heat fluxes, and the surface water balance equation to compute the partitioning of precipitation into evaporation, runoff and the change in the soil moisture storage. Runoff is an important component of the water cycle whose estimation is very difficult because of its strong spatial and temporal variability. In land surface schemes, runoff is usually represented as the sum of the surface runoff and subsurface runoff. Surface runoff occurs due to saturation excess (Dunn Mechanism) and infiltration excess (Horton Mechanism) flows. Subsurface runoff occurs when water enters into the soil and reaches to an impermeable layer or a layer with low permeability. Then, the water flows along the slope under the surface. A coarse-resolution land surface scheme cannot explicitly model the complexities of runoff generation in the model grid square. Instead, it represents the major processes via sub-grid scale parameterizations. A popular solution involves the use of probability distribution functions (pdf) to represent sub-grid scale variability.   Materials and Methods In this paper, two types of runoff parameterizations in NOAH land surface scheme coupled in the Weather and Research Forecasting model (WRF) are examined. The default WRF-NOAH parameterizes surface runoff based on the pdf of soil infiltration and subsurface runoff based on the gravity drainage from the lowest layer of the soil model. We have modified the runoff parameterization of NOAH by following the philosophy used in the simplified TOPMODEL, in which surface runoff is parameterized using the pdf of the topographic index and subsurface runoff is defined by applying a simple groundwater model to the lowest layer of the soil model. To obtain low resolution topographic index, the downscaling method of Pradhan et al. is used. To calculate the river discharge the Total Runoff Integrating Pathway (TRIP) is coupled with the land surface scheme. In this study, only the treatment of runoff in the model is considered, hence some of the errors in simulations can be the result of deficiencies in the parameterization of other process, such as precipitation. In this paper, the Karoon River is divided into three sub-basins including Farsiat, Harmaleh and Soosan located in the south, west and east of the Karoon respectively by using ARCGIS and ARCHYDRO softwares. The WRF model was run in a one-way method, consisted of two domains. The simulations are conducted for the winter 2006 with 5×5 km grid spacing over an internal domain having 108×114 grid points along latitude and longitude, respectively, and with 15×15 km grid spacing over the parent domain having 69×69 grid points along latitude and longitude and centered at 50◦E and 32◦N. The initial and boundary conditions are derived from the GFS data. The river discharge calculated from WRF-NOAH and WRF-NOAHSIM simulated runoff and routed using TRIP model for three sub-basins of Karoon River is compared with the observed discharge in the winter 2006.   Results and discussion The comparison between the simulated discharge of WRF-NOAH and observed discharge shows that the model generally underestimates total runoff during winter 2006, and that there is large model bias and Mean Absolute Error (MAE) in all the three sub-basins, particularly in Farsiat and Harmaleh. This is due to the great differences between the mean discharge of the coupled model and what observed. The negative efficiency of the model at Harmale shows that NOAH is not successful in simulating runoff; however, the efficiency of the model is positive, but small in the other sub-basins. The daily simulated runoff shows that the modeled peaks that occur due to precipitation were generally too low, and there was little flow during the recession in the studied sub-basins. The evaluation of stimulated discharge by the two land surface schemes (NOAHSIM, NOAH) coupled in WRF, with observed discharge proves improved runoff simulation by NOAHSIM in all the three sub-basins in the winter 2006. Compared to NOAH, NOAH-SIM simulated discharge has lower bias, smaller mean absolute error, higher model efficiency, higher correlation coefficient and the standard deviation closer to that observed. The daily study of simulated and observed discharge shows that NOAHSIM improves surface runoff parameterization by decreasing the differences from observed peaks of discharge. As the subsurface runoff dominates in most of the study period, improved subsurface runoff parameterization of NOHASIM has greatly reduced errors (bias and MAE) in estimating total runoff. The comparison of water balance in these land surface schemes coupled in WRF shows that NOAHSIM has been able to balance the water budget better than what NOAH does in winter 2006.   Conclusion  The results of the comparison between two types of sub-grid scale surface runoff parameterization in NOAH land surface scheme coupled in WRF represent the superiority of runoff parameterization based on the topographic index to that based on soil infiltration, probably because of the availability of topographic data and the use of objective function for estimating its pdf. The subsurface runoff parameterization by using groundwater model, instead of gravity drainage, has a great impact on the improvement of total runoff simulation. Lower uncertainties in runoff parameterization of NOAH-SIM not only lead to improve discharge simulation but also lead to better water budget balance.}, keywords = {Land surface parameterization scaheme,runoff,Discharge river,Efficiency model}, title_fa = {ارزیابی دبی شبیه سازی شده رودخانه توسط طرحواره سطح NOAH جفت‌شده در مدل WRF با وارد کردن تاثیر شاخص توپوگرافی و مدل آب زیرزمینی}, abstract_fa = {   رواناب از مهم‌ترین مولفه‌های طرحواره‌های سطح است که برآورد آن به دلیل وابستگی به بارندگی، رطوبت خاک و توپوگرافی، که به شدت با زمان و مکان متغیر هستند، مشکل است. در این بررسی دو روش مختلف پارامتره‌سازی زیرشبکه‌ای رواناب در طرحواره‌ سطح NOAH جفت‌شده در مدل پیش‌بینی عددی WRF در سه زیرحوضه رودخانه ‌کارون (زیرحوضه‌های سوسن، حرمله و فارسیات) در زمستان 2006 مقایسه می‌شوند. رواناب سطحی در طرحواره NOAH براساس تابع توزیع احتمال بیشینه ظرفیت نفوذ خاک و رواناب زیرسطحی براساس نفوذ گرانشی کف مدل خاک پارامتره می‌شود. مدل WRF-NOAH با مدل روندیابی رودخانه TRIP در حوضه رودخانه کارون، دبی را به‌ شدت فرو-برآورد می‌کند که این  می‌تواند ناشی از عدم قطعیت در پارامتره‌سازی رواناب سطحی، به‌دلیل در دسترس نبودن داده‌های نفوذ خاک و بکار بردن تابع ذهنی در برآورد تابع چگالی احتمال آن، و رواناب زیرسطحی، به‌دلیل برآورد نادرست رطوبت لایه کف مدل خاک، باشد. لذا در این مقاله طرحواره جدید NOAH-SIM، بر مبنای روش تاپ‌مدل ساده‌شده ارائه می‌شود که رواناب سطحی بر اساس شاخص توپوگرافی، به‌دلیل در دسترس بودن داده‌های شاخص توپوگرافی، رواناب زیرسطحی با واردکردن عمق ایستابی و مدل آب زیرزمینی پارامتره می‌شود. ارزیابی دبی شبیه‌سازی شده توسط طرحواره‌های‌ سطح NOAH و NOAH-SIM به‌طور جفت‌شده در مدل WRF در حوضه رودخانه کارون، بیانگر ضریب کارایی بالاتر، اریبی پایین‌تر، خطاهای مدل کوچک‌تر، ضریب همبستگی بالاتر و انحراف‌معیار نرمال‌شده نزدیک به یک طرحواره‌ SIM-NOAH است که برتری پارامتره‌سازی رواناب بر اساس تاپ‌مدل ساده شده، به‌ویژه رواناب زیرسطحی به‌دلیلی حاکم بودن آن در اکثر زمان‌های مورد مطالعه، را نشان می‌دهد. هم‌چنین تاثیر پارامتره‌سازی رواناب بر توازن بودجه آبی در هر دو طرحواره‌ سطح،  بیانگر توازن بهتر بودجه آبی توسط طرحواره NOAH-SIM است.}, keywords_fa = {طرحواره‌های پارامتره سازی سطح,رواناب,دبی رودخانه,شاخص توپوگرافی,کارایی مدل}, url = {https://clima.irimo.ir/article_15072.html}, eprint = {https://clima.irimo.ir/article_15072_c65f514398460b9a515dd4c2ec85d596.pdf} } @article { author = {Esmaili, R.}, title = {Human Bioclimatic Zoning of Iran}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {19-32}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Introduction Human bioclimatology science expresses complex effects of meteorology variables on the human’s body in a simple way throughout the bioclimatic indices. So far, over 200 bioclimatic indices are presented which the thermo physiological indices derived from human body’s heat balance equations have more acceptability. Physiological Equivalent Temperature (PET) index are using widely in bioclimatology studies.  In this regard, zoning of human bioclimatic conditions of Greece was performed with PET index in monthly scale (Matzarakis, 2001). Also, zoning of bioclimatic conditions of Hungary with PET index (Gulyasa and Matzarakis, 2009) and of the world with PET and PMV indices (Jendritzky and Tinz, 2009) were another studies of this matter. There are few limited and local studies on PET index in Iran, so the subject of this research was zoning of bioclimatic condition in this country. Materials and Methods In this research, the daily data of 101 synoptic stations were used. Data includes: temperature (oC), relative humidity (%), wind speed (m/s), cloudiness (octa), water vapor pressure (hpa) in the years of 1988 to 2007 (20 years period). The PET index was calculated for each station with using Rayman 1.2 software model. The multivariable regression model was used to derive relations of PET index and latitude, longitude and altitude. ArcGIS 9.3 were used to zoning PET index in Iran. Results and discussions There are very different bioclimatic conditions in month of April, in which there is heat stress in over the 36o latitude and cold stress under this region. The 19 percents of the Iran’s area were in the comfort region. In the month of May, cold stress was limited to the mountainous regions on north and northwest and heat stress to the southern seashore. There are no cold stress in June and July. There is decrease of heat stressed regions in month of august with relation to the July. The comfort regions were at the maximum level in mount of September (32.2%) and the October is the mount which cold stress starts. Based on November’s PET map, there is no heat stress in Iran and only the southeastern seashore (5% of area) has the comfort situation. In the month of December, there is most severe and vast cold stress situation which extended to the 57.6% of whole area. There are more comfort conditions in month of March relation to the prior months (10.6% of area) and in which extended parallel to the seashore regions, from the Chabahar (south east) to the Ahwaz (south west). According to the Spatial variation coefficient of PET it can be concluded that the month of July and Day has the lowest and highest variation coefficient (4.9 and 185%) respectively. Also there are two separate time periods of comfort conditions. 1: start of warm period and 2: start of cold period of the year. Conclusion The result showed altitude role in shaping the bioclimatic conditions is much more latitude and longitude. The result of the monthly bioclimatic maps showed in terms of the comfort zone is an area October (32 percent of the area) is ranked in first and bioclimatic condition has the best desirable. In January ,93 percent of  country  area is cold stress and then  heat stress  in July  that  there  has the 85 percent  of the country , worst  bioclimatic conditions. The highest rate of the bioclimatic spatial coefficient variation in January and lowest is in July. Based on mean of 365 daily bioclimatic maps, mean annual of physiologic equivalent temperature is 18.2 centigrade. The annual trend of PET showed that climate comfort time frame is short and located from two distinct period times, the first period after the cold season and second period occurs at the end warm season. Result from  this research can be used in environmental panning , tourism and recreations , health and medical , construction and housing , energy efficiency ,sport  and  etc .}, keywords = {Physiologic equivalent temperature (PET),Iran bioclimatic,Climate Comfort,GIS,Zoning}, title_fa = {پهنه بندی زیست اقلیم انسانی ایران}, abstract_fa = {در تحقیق حاضر با استفاده از شاخص دمای معادل فیزیولوژیک (PET)، که جزء جامع‌ترین و پرکاربردترین شاخص های زیست اقلیم انسانی است، سطح کشور در مقیاس ماهانه پهنه‌بندی شد. با استفاده از سیستم اطلاعات جغرافیایی[1] (GIS)، مقادیر محاسبه شده PET برای101 ایستگاه کشور با داده های محیطی(ارتفاع، طول و عرض جغرافیایی) ترکیب و نقشه های زیست اقلیم انسانی تهیه شد. براساس نقشه های ترسیم شده مقادیر شاخص PET از شمال به جنوب و از غرب به شرق کشور افزایش می یابد اما نقش ارتفاعات در شکل دهی شرایط زیست اقلیمی بسیار پررنگتر از طول و عرض جغرافیایی است. از حیث مساحتی که در منطقه آسایش اقلیمی قرار دارد مهر ماه با32 درصد از مساحت در رتبه اول قرار گرفته است و مطلوبترین شرایط زیست اقلیمی را داراست. در همین ارتباط در دی ماه 93 درصد از سطح کشور دارای تنش های سرمایی است و بعد از آن تیر ماه با تنش های گرمایی که در85 درصد از سطح کشور وجود دارد، بدترین شرایط زیست اقلیمی را دارا است. بیشترین و کمترین ضریب تغییرات مکانی زیست اقلیمی کشور بترتیب مربوط به دی و تیر ماه است. بر اساس365 نقشه روزانه زیست اقلیم انسانی، متوسط دمای معادل فیزیولوژیک سالانه کشور 2/18 درجه سانتیگراد است. روند تغییرات سالانه PET  نشان داد بازه زمانی آسایش اقلیمی در کشور کوتاه و به صورت دو دوره مجزا در ابتدا و انتهای فصل سرد سال واقع شده است. نتایج حاصل از این تحقیق می تواند در برنامه ریزی های محیطی، امور گردشگری و تورگردانی، ساخت و ساز و مسکن، بهینه سازی مصرف انرژی، پزشکی و سلامت، ورزشی و ... به کار گرفته شود. [1]. Geographical Information System}, keywords_fa = {دمای معادل فیزیولوژیک (PET),زیست اقلیم انسانی ایران,آسایش اقلیمی,سیستم اطلاعات}, url = {https://clima.irimo.ir/article_15073.html}, eprint = {https://clima.irimo.ir/article_15073_781a9bc49c88a4f544437e969698a4c0.pdf} } @article { author = {Moradi, M. and Rezazadeh, P. and Vazifeh, A.}, title = {A case study on low level vertical wind shear in Mehrabad Airport}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {33-46}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Abstract Every two second Radio sound data of Mehrabad airport upper air station in Tehran for January and July 2010 is used in this research to investigate low level vertical wind shear (LLVWS) in the station. Results show in January non-convective LLVWS were caused by temperature inversion and front transitions. Vertical shear occurred in different layers and its weak vertical shear frequency is significant in this month. The highest shear values were observed on 4th and 23rd January at 0000UTC. Survey of the LLVWS on different days of the month show the phenomenon mainly caused by inversion and is greater in the layer 10 to 71m above the ground with different intensities. Frequency of moderate intensities in July is more than January. In this month 35% of cases had LLVWS, within those cases 22% are weak, 11% moderate and 2% are intense.  Introduction. Vertical wind shear is a complicated problem in aviation meteorology and tropical cyclone and has been on the center of attention of researchers. Based on the recommendation of WMO since 1960s; it was considered more drastically and publication No. 230 of WMO published in 1969 which is mainly devoted to results of investigations of world researchers. Among the researchers in the publication which investigated vertical wind shear in boundary layer are Kosano, Robert and Pettitt (1969). Later there have been many specialized studies on the subject which we can name Sinclier (1991), Arkell (2000). Sinklier et.al in a paper investigated wind shear in low level flights to reveal the phenomenon and for use in warnings. Arkell investigated types of wind shear and its forecast procedures from aeronautical meteorology view. The purpose of this study is to determine different layers LLVWS in the Mehrabad airport in July and January as a representative to warm and cold months to ease landing and take off operations.            Materials and methods. The Mehrabad airport station is located at the geographical position of 51.31° E and 35.69° N  and height of 1191m above mean sea level.  It is an aviation met station with twice daily soundings. To investigate wind shear, every 2 second wind data of the station at 0000 and 1200UTC is used. LLVWS is defined when the vertical wind speed difference is at least 5mps/100ft and is dominant from surface to 2000ft aloft[18],[11]. The surface wind speed is measured at 10m above the ground, so the height 0f 2030 is divided to 20 sub-layers of 100ft. Then, through routine meteorology procedures, data related to the base and top of the shallow layers is obtained. Typically the data is presented in Table 3. We computed vertical wind shear using the equation (1). The phenomenon is considered significant when. Results and discussion.The data Survey shows non convective vertical wind shear in January results from frontal movements and inversions. During the month, the phenomena occurred in different layers above the station with higher frequencies of weak LLVWS cases. The maxima of the phenomena were at 0000UTC on 4th and 23rd of January. The data Survey in July show inversions are the main reason for vertical wind shear and it occurred with different intensities and more frequent within the 10 to71 m layer above the ground. The survey indicate within July 35% of cases were LLVWS, 63% of them of weak intensity, 31% moderate and 6% severe.   Conclusion. January and July 2010 wind profile data in a 2030ft layer divided to 100ft sub-layers show that atmospheric fronts in January and inversions in July are the main reason for of LLVWSin the Mehrabad meteorology station. The maximum cold season wind shear occurs at 0000UTC and warm season at 1200UTC. Since in warm seasons the dominant heat low on Iran diminishes at 0000UTC and gets its maxima in 1800UTC, thus intensified afternoon easterly winds dominates Iranian plateau and transfers desert warm air toward Mehrabad airport. This mechanism causes low level convection in Mehrabad in mid-day.   }, keywords = {Low Level Vertical Wind Shear,Velocity shear,Directional shear,Mehrabad Airport,radio sound}, title_fa = {بررسی موردی چینش قائم باد سطوح پایین در فرودگاه مهرآباد}, abstract_fa = {یکی از پدیده‌های هواشناسی که بویژه در هواشناسی هوانوردی مورد توجه پژوهشگران قرار می‌گیرد چینش قائم باد سطوح پایین است.‌این کمیت در نزدیکی سطح زمین در اثر اختلاف برداری باد افقی در یک لایه کم عمق در راستای افقی یا قائم‌ایجاد می‌شود.‌این اختلاف می‌تواند در اثر تغییر سمت یا سرعت و یا تفاوت همزمان هر دو کمیت‌ایجاد گردد. در‌این پژوهش با بکارگیری داده‌های دو ثانیه‌ای‌ایستگاه کاوش جو فرودگاه مهرآباد تهران در ماه‌های ژانویه و ژولای سال2010 میلادی، چینش قائم باد سطوح پایین در فرودگاه مهرآباد بررسی شد.‌این داده ها که برای اولین بار در‌ایران مورد استفاده قرار گرفت، از مرکز فن آوری اطلاعات سازمان هواشناسی گرفته شده است. برای محاسبه چینش قائم باد سطوح پایین در‌این پژوهش، ابتدا فاصله 620 متری از سطح آنمومتر(سطح 10 متری) به بازه‌های 30 متری(100 پائی) تقسیم شد و سپس. داده‌های سمت و سرعت باد در لایه‌های‌ایجاد شده بدست آمد. در ادامه چینش قائم بادسطوح پایین  محاسبه و بررسی شد. نتایج نشان داد که در ماه ژانویه چینش قائم باد سطوح پایین غیر همرفتی در اثر عبور جبهه‌های جوی و وارونگی دما‌ایجاد شده است. چینش قائم باد سطوح پایین در‌این ماه در‌ایستگاه مهرآباد، در لایه‌های مختلفی رخ داده است و فراوانی چینش قائم باد ضعیف در‌این ماه بیشتر می‌باشد. بیشترین مقدار‌این کمیت در‌این ماه به ساعت 0000 گرینویچ مربوط می‌شود که در روزهای چهارم و بیست و سوم ژانویه در لایه 71-10 متری با مقادیر به ترتیب 14.2 و 12.3 بر حسب2-10 بر ثانیه رخ داده است. از بررسی چینش قائم باد سطوح پایین در روزهای مختلف ماه ژولای دیده می‌شود که چینش قائم باد در‌این ماه در اثر وارونگی دما‌ایجاد شده است. در‌این ماه فراوانی رخداد چینش قائم باد در لایه 10-71 متری بیشتراست. . بیشترین مقدار‌این کمیت در‌این ماه در ساعت 1200 گرینویچ روز چهادهم ژولای در لایه 71-10 متری با مقدار 16.7 بر حسب2-10 بر ثانیه برآورد شده است. بررسی چینش قائم باد در ماه ژولای‌این سال نشان می‌دهد که در 35 درصد موارد، چینش قائم باد سطوح پایین رخ داده است که 22 درصد آن از نوع ضعیف، 11 درصد از نوع متوسط و 2 درصد از نوع شدید بوده است. شایان ذکر است که فراوانی چینش قائم باد متوسط در ماه ژولای  نسبت به ماه ژانویه بیشتر می‌باشد.}, keywords_fa = {چینش قائم باد سطوح پایین,چینش سرعتی باد,چینش سمتی باد,فرودگاه مهرآباد,رادیو گمانه}, url = {https://clima.irimo.ir/article_15075.html}, eprint = {https://clima.irimo.ir/article_15075_4bdc61e32ecd929a9f6f54ddfb750735.pdf} } @article { author = {Hejazi, A. and Mobasheri, M. R. and Majidi, D.}, title = {Using satellite images to calculate atmospheric visibility}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {47-56}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Introduction Atmospheric visibility distance is a crucial information for transport safety as well as a good evidence of air pollution. Electro-optical sensors such as transmitometers or scatterometers have been developed to measure this environmental parameter. Transmitometers are reliable but are very expensive, which explains why they are deployed at critical places like major airports. The recent development of satellite meteorology has allowed us to estimate spatially and frequently number of basic meteorological parameters. This paper presents the proposed methodology for retrieving visibility values based on the application of aerosol optical thickness algorithm on satellite image data. To calculate the atmospheric visibility, computing Blur atmosphere parameter will be beneficial. Aerosols as the most important factor Blur the atmosphere and absorb sunlight, reducing visibility in the atmosphere. In this study, by Using remote sensing data (aerosol optical thickness), atmospheric blur parameter is calculated.   Methodology  A number of data from various sources were collected for this research, including the historical air quality data sets, MODIS aerosol imagery, and ground-based meteorological measurements. In this work, using the relationship between the optical thickness and atmospheric blur, atmospheric blur parameter calculated evenly. For this, the corrected values of Aerosol Optical Depth (AOD) retrieved from MODIS images are used. Hence the AODs were corrected for the effects of air humidity and the air mixing height.   Results and discussion Atmospheric visibility distance is a property of the atmosphere, which can be remotely sensed by satellite data. In this aim, a linear mapping function between the atmospheric visibility distance and atmospheric blur parameter was planned. In used model, with the help regression analysis, the relationships were detected between atmospheric blur parameter and the atmospheric visibility. According to this study, it is found that there are relatively good correlation between atmospheric blur parameter and atmospheric visibility (R= 0.77). However, in the procedure of atmospheric blur and AOD correction, limitations such as insufficient number of ground-based weather stations and approximate determination of the air mixing height may cause some uncertainties in the proposed method.     Conclusion This paper has proposed model for the estimate of atmospheric visibility. Remotely sensed MODIS AOD, and ground-based measurements of surface temperature and surface relative humidity have been found to be highly significant in the prediction atmospheric visibility. Although MODIS extracted AOD may contain valuable information about atmospheric blur parameter but this parameter is highly affected by the atmospheric conditions where usually it is hard to acquire the weather data during many satellite overpasses.  }, keywords = {Atmospheric blur,Aerosol Optical Depth (AOD),Atmospheric visibility}, title_fa = {استفاده از تصویر ماهواره‌ای در محاسبه قابلیت دید افقی جو}, abstract_fa = {کاهش قابلیت دید از اولین اثرات قابل ملاحظه آلودگی هوا بر پدیده‌های جوی بشمار می‌آید. در توصیفات هواشناسی قابلیت دید عبارتست از معیار استاندارد شفافیت اتمسفر در طیف مرئی. کاهش دید موجب مخاطرات ایمنی می‌شود و از لحاظ ظاهر نیز ناخواسته است. برای بررسی قدرت دید، محاسبه تیرگی جو مفید خواهد بود. هواویزها به عنوان مهمترین عامل تیرگی جو، با جذب و پراکنده‌سازی نور خورشید موجب کاهش قابلیت دید در جو می‌شوند.در این پژوهش با استفاده از روش سنجش از دوری تیرگی جو محاسبه شده است. به این منظور از تصاویر سنجنده MODIS مستقر بر سکوی Aqua ضخامت نوری هواویز استخراج شده و تصحیحاتی از قبیل رطوبت نسبی و ارتفاع اختلاط بر روی این پارامتر انجام می‌شود و با استفاده از روابط موجود بین ضخامت نوری هواویز و تیرگی جو، پارامتر تیرگی جو محاسبه می‌شود.در نهایت بررسی‌ها در این تحقیق نشان می‌دهد که بین پارامتر تیرگی جو و کاهش قدرت دید  جو، یک رابطه خطی با میزان همبستگی 77/0، وجود دارد که در مجموع این همبستگی نشان می‌دهد که برای سنجنده‌ای با دقت در حد سنجنده MODIS و قدرت تفکیک مکانی آن، قابل قبول می‌باشد از مزایای روش سنجش از دوری در محاسبه تیرگی جو نسبت به سایر روش‌ها، عدم محدودیت مکانی آن می‌باشد. با این حساب در هر روز در نوبت زمانی می‌توان قدرت دید مناطق مختلف را مورد ارزیابی قرار داد. موردی که باید به آن اشاره کرد فرضی است که در این پژوهش از آن استفاده شدو آن در نظر گرفتن توزیع همگن برای عوامل به وجود آورنده تیرگی جو در محیط تحت پوشش یک پیکسل می‌باشد که تا حدودی ممکن است خلاف واقع باشد.}, keywords_fa = {تیرگی جو,ضخامت نوری هواویز,نمای انگستروم,قدرت دید}, url = {https://clima.irimo.ir/article_15077.html}, eprint = {https://clima.irimo.ir/article_15077_4daf0f1bbfe7c88cd32b1ded5997c03d.pdf} } @article { author = {Khosravi, M. and Alijani, B. and Almasi, F.}, title = {Synoptic Analysis of Sultry Phenomena in Khuzestan Province}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {57-72}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Introduction Composition of temperature and humidity is a climate phenomenon in southern coast of Iran. Humidity and hot weather create sultry sense. Human are very sensitive and vulnerable against climate change. Iran has a significant temperature and humidity change, therefore during a year, the comfort conditions are limited. A sultry phenomenon is a basic factor in limitation comfort statues in the coastal zone. So the control of humidity and temperature is very important. Severity of this condition is increased with increasing temperature and humidity. The south coast of Iran has a varied climate that is affected by its widespread, variation in topography and location of Persian Gulf in southern boundaries. Because of high temperature and humidity in Khuzestan province, Sultry is seen in more than a half year and create an uncomfortable bioclimatic conditions in human population. Unfavorable climatic conditions, lack of suitable knowledge of the special features of the formation and development of localized climate in Khuzestan province has caused that many of Khuzestan climate characters are unrecognized. The main purpose of this study was to identify the structure and nature of the synoptic scale circulation components in the lower and middle levels of the troposphere, which control the sultry phenomenon. The identifying sultry weather in this region is of considerable importance in order to better plan and find better ways for decreasing environmental problems. Finally recognizing this phenomenon allows us to decrease their harmful effects.   Material and methods In this paper, to identify the formation structure of sultry phenomena in Khuzestan province, 10 synoptic stations which had a suitable spread and without a gap in climate variables were selected. Daily data of mean temperature and humidity from 1994/01/01 till 2008/12/30 were used. Sultry days were extracted by using lancaster-karston index. Because of spatial distribution and temporal changes, the days with simultaneity in 5 stations were selected. This research has done after extracting 14 distinct sultry waves and dividing them to both warm and cold periods of the year. Finally synoptical analysis has been done by using Geopotential height in level of 500hpa and sea level pressure through compositional maps, streamline in two levels of 500hpa and sea level and the map of surface level  humidity advection in the range of 10 to 50 north degrees and 10 to 70 east degrees for two distinct sultry waves.   Result and discussion The study of Geopotential height in level of 500hpa and sea level pressure through compositional maps, streamline in two levels of 500hpa and sea level and the map of surface level humidity advection showed that subtropical high pressure have moved to the 45 degrees south of the circuit in the warm period of the year. Air dynamic subsidence of the subtropical high pressure's eastern section causes a warm and dry weather in the study area. Earth's surface thermal low pressure systems, especially Iraq low-pressure system would be one of the sultry creating factors. Meridional flows were southern. Subtropical high pressure's axis moving, backing on its two southern latitudes and dominate of the high pressure ridge in the study area are the main factors of creating south advections in the cold period of the year. The humidity advection maps showed that the most important humidity resources entered into Khuzestan province include Arabian Sea and Persian Gulf. Moisture of Arabian Sea was strengthened in the Persian Gulf, entered to study area. Humidity advections were south and southeast.   Conclusion The results of synoptic analysis were shown that the distinct waves with complete hegemony of subtropical high pressure in 500hpa level, its meridional extension and support causing the stability atmosphere support and continues over the region. The impact of harmonizing heat low pressure, especially Arabia low pressure, provides a suitable condition for humidity transferring to the region. Domination of subtropical high pressure and the settled manner of its axis during the cold period of the year is the most important trends in south stream from warm southern seas to the study area. The main resources of humidity and sultry conditions of Khuzestan province include Arabian Sea, Gulf of Oman, and Persian Gulf that the moisture contents of currents strengthened over the Persian Gulf. Humidity entry routes are mainly from the south and southeast.}, keywords = {Synoptic Analysis,sultry,subtropical high pressure,Khuzestan Province}, title_fa = {تحلیل همدیدی سامانه‌های شرجی در استان خوزستان}, abstract_fa = {   پدیده‌ی شرجی یکی از ویژگی‌های اقلیمی بارز در استان خوزستان بوده که در اثر افزایش هم‌زمان رطوبت و دمای روزانه حادث می‌شود. هدف اصلی این پژوهش تحلیل همدید شرجی‌های استان خوزستان است. در این پژوهش پس از استخراج موج‌های شرجی طی دورۀ آماری (2008-1994)، موج‌های شرجی شاخص به دو دورۀ گرم (بهار و تابستان)  و سرد (پائیز و زمستان) تفکیک‌شده برای هر دوره موج‌هایی که بیشترین شدت و فراگیری را داشته انتخاب شدند. سپس با استفاده از نقشه‌های ترکیبی ارتفاع ژئوپتانسیل تراز 500 هکتوپاسکال و سطح متوسط تراز دریا، نقشه وزش جریان رطوبتی تراز دریا و جریان هوا در دو سطح 500 هکتوپاسکال و سطح متوسط دریا در محدودۀ 10 تا 50 درجه شمالی و 10 تا 70 درجه شرقی برای دو سامانه شرجی شاخص انجام‌شده است. نتایج تحقیق نشان می‌دهد که در دورۀ گرم سال در تراز 500 هکتوپاسکال استیلای کامل پرفشار دینامیکی جنب حاره، گسترش و تقویت نصف‌النهاری آن موجب تقویت و تداوم پایداری بر فراز جو منطقه شده است. تأثیر هماهنگ  کم‌فشارهای حرارتی سطح زمین بخصوص کم‌فشار شبه‌جزیره عربستان زمینه مناسب را برای انتقال رطوبت به منطقه فراهم می‌آورد. در دورۀ سرد نیز تسلط مرکز فشار زیاد جنب‌حاره‌ای بر جنوب‌غربی ایران و استقرار محور پرفشار منطبق بر آن، مهم‌ترین عامل در هدایت جریان‌های نصف‌النهاری مثبت (جنوبی) و انتقال رطوبت از دریاهای گرم جنوب به سمت استان محسوب می‌شود. مهم‌ترین منابع رطوبتی مؤثر بر پدیده شرجی استان خوزستان، دریای عرب،دریای عمان و خلیج‌فارس بوده که محتوی رطوبتی جریانات درگذر از خلیج‌فارس تقویت می‌شود.. مسیرهای ورودی رطوبت نیز عمدتاً جنوبی و جنوب شرقی می‌باشد. }, keywords_fa = {تحلیل همدیدی,شرجی,پرفشار جنب‌حاره‌ای,استان خوزستان}, url = {https://clima.irimo.ir/article_15087.html}, eprint = {https://clima.irimo.ir/article_15087_eb78adfa75daf9b835c77755d6c81bff.pdf} } @article { author = {Meshkatee, A. H. and Shojaei, M. and Mazraeh Farahani, M.}, title = {Atmospheric circulation structure during heavy precipitation of 21th December 1992 over the City of Shiraz}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {73-90}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Introduction Heavy precipitation are among those natural events that may lead to disasters like flood and landslides or both simultaneously. One of the occasions that these types of precipitations occur is after a prolonged drought. Heavy precipitation normally  occur during transient seasons like autumn and spring. However, they may occur in winter or even in summer. Considering the atmospheric circulations diversity at different times of year, it does not seem wrong if suppose there must be significant differences between weather conditions that led to such precipitations would be of great assistance to weather forecasters to issue weather warnings that may help to prevent or reduce the impacts of those precipitations. To identify heavy precipitations, Brook’s statistical method has been used. In the course of the study upon the structure of atmospheric circulations during heavy precipitations over the city of Shiraz during autumns of 1371 to 1378(1992 and 2000), we came across with an interesting situation on 21th of December 1992, that is the subject of this article. Its atmospheric circulation structure examined by means of the meteorological quantities such as sea level pressure, geopotential height, relative humidity, horizontal wind divergence, vertical­ motion at 850 and 500 hPa surfaces, temperature at 850 hPa surface and horizontal wind speed at 300 hPa  surface. Required data have been acquired from  NCEP(National Center for Environmental Prediction (website and maps have been plotted by means of Grads software. Results showed that a low pressure system that was formed over the Saudi Arabia and Red Sea some times before 21th of December 1992, entered Iran on that day. During its course towards the northeast of the country, it met with a high pressure system entering the country from Europe. This situation created a suitable condition for development of instability over the southwest of Iran. At 500 hPa surface intensive divergence area was located over west and southwest of Iran, supporting the vertical motion and the intensification of surface low pressure system. Subtropical Jet relative location to surface low pressure played important role in the development and intensification of the instability. In day after precipitation event the pressure system exits from northeast of Iran and high pressure system with moving in direction of northeast to southeast locates over the Mediterranean Sea.   Materials and methods The data related to daily precipitation on 1371 to 1378 (1992-2000) of Shiraz station is received from IRIMO, the country meteorological organization. The data related to meteorological parameters is extracted from National Center for Environmental Prediction site (NCEP). In this research the heavy precipitations of shiraz on 1371 to 1378 are determined by the Brooks statistical method. In this method the precipitation are divided to different groups according to the relations of (1) , (2) that the first group precipitation as known as heavy precipitation.   The number of groups = 5Log N                     (1) The space of groups = maximum precipitation – minimum precipitation / number of groups                                                          (2) That N is the number of days with precipitation on autumn. According to the first group results that only have 75 mm precipitation, this number is known as heavy precipitation on autumn. This amount of precipitation occurs on the 30 day of Azar (21 December 1992). To determine dominant atmospheric circulation of them, distribution of temperature, pressure and moisture quantities and their changes on the earth surface, levels of 850, 500 and 300 hPa on an area between the longitude of 20 degree of west to 90 degree of east and the latitude of 10 to 70 degree of north were investigated. In the dynamical analysis the distribution of pressure, temperature, wind and moisture fields and the relation between them were investigated by using quantities like geopotential height, horizontal wind divergence and vertical­ motion. Distribution of above quantities will clear the atmospheric conditions that change of them by passing of time shows the way of forming, strengthening and weakness of systems and atmospheric circulations. The maps were prepare one day before to the day after the heavy precipitation on the time of 00UTC and 12UTC. The maps were prepared by programming on the GRADS of studied geographical area.   Results and Discussion The atmospheric pattern of 21 December shows that a low pressure system that is formed on Arabia and Red Sea some days ago, has moved toward the north of Iran and penetrate inside of Iran. Then by encountering to a high pressure system entering the country from Europe moving toward the southwest, the system has made a proper condition on the southwest of Iran for instability and causes the value of    -2*10-5 S-1 convergence on low levels of the area. On the 500 hPa level of area intensive divergence area (1*10-5 S-1) has located on the west and southwest of Iran that causes the strengthening of vertical motions about -0.4 PaS-1 and intensification of low pressure. Subtropical Jet also according to its position relative to surface low pressure played important role in the development and intensification of the instability. According to the high relative humidity on both levels (90 %and 75%), we will see heavy precipitation on this day. In the next day of heavy precipitation, the low pressure system is going out of Iran from the northeast side and the high pressure system is still on the Mediterranean Sea and its effect has increased on the northwest of Iran. Since the convergence on the low levels is less than divergence on the high levels on last day, the vertical motion on this day is weaken. The temperature at the beginning of day has increased as compared with the last day and regarding that weakening of vertical motions on this day there will be less precipitation.   Conclusion Results showed that a low pressure system that was formed over the Saudi Arabia and Red Sea some times before 21th of December 1992, entered Iran on that day. During its course towards the northeast of the country, it met with a high pressure system entering the country from Europe. This situation created a suitable condition for development of instability over the southwest of Iran. At 500 hPa surface intensive divergence area was located over west and southwest of Iran, supporting the vertical motion and the intensification of surface low pressure system. Subtropical Jet relative location to surface low pressure played important role in the development and intensification of the instability. In day after precipitation event the pressure system exits from northeast of Iran and high pressure system with moving in direction of northeast to southeast locates over the Mediterranean Sea.}, keywords = {Atmospheric circulation,Heavy precipitation,Shiraz,NCEP}, title_fa = {ساختار گردش جوی در طی بارش سنگین 21 دسامبر 1992 برروی شیراز (30 آذر 1371)}, abstract_fa = {در طی بررسی الگوی گردش جوی در زمان وقوع بارش‌های سنگین برروی شهر شیراز در فصول پاییز سال‌های 1371 تا 1378 به موردی برخوردیم که با دیگر موارد تفاوت‌هایی داشت و ما را به بررسی جداگانه آن واداشت. در این مطالعه برای تعیین بارش‌های سنگین از روش آماری بروکس استفاده گردید. جهت تعیین ساختار گردشی جو در زمان وقوع بارش سنگین در این تاریخ کمیت‌های هواشناختی از قبیل فشار تراز دریا، ارتفاع ژئوپتانسیل، رطوبت‌نسبی، واگرایی، و سرعت‌قائم در ترازهای 850 و500 هکتوپاسکال، دما در تراز 850 هکتوپاسکال و سرعت باد افقی در تراز 300 هکتوپاسکال مورد بررسی قرار گرفته‌اند. نقشه‌های مورد نیاز با استفاده از نرم‌افزار GRADS و داده‌های مرکز ملی پیش‌بینی‌های محیطی (NCEP) امریکا ترسیم گردید. الگوی جوی روز 21 دسامبر نشان می‌دهد یک سامانه کم‌فشار که از روزهای قبل برروی عربستان و دریای سرخ شکل گرفته با حرکت به سمت شمال‌شرق در این روز به داخل ایران نفوذ کرده و در برخورد با پرفشار مستقر برروی اروپا که به سمت جنو‌ب‌غرب حرکت می‌کند شرایط مناسب برای ناپایداری را برروی جنوب غرب ایران ایجاد کرده و منجر به همگرایی در سطوح پایین برروی منطقه به میزان S-1 5-10*2- شده است . در سطح 500 هکتوپاسکال منطقه واگرایی شدید ناوه (S-1 5-10*1) برروی غرب و جنوب‌غرب ایران قرار دارد که باعث تقویت حرکات صعودی به میزان PaS-1 4/0- و تشدید کم‌فشار سطحی می‌شود. جت جنب‌حاره نیز با توجه به نحوه قرارگیریش نسبت به کم‌فشار سطحی نقش مهمی در توسعه ناپایداری ایفا کرده‌ است. در روز بعد از وقوع بارش سنگین سامانه کم‌فشار در حال خارج شدن از سمت شمال‌شرق ایران است و سامانه پرفشار با طی مسیر شمال‌شرق- جنوب‌غرب برروی دریای مدیترانه مستقر می‌شود.}, keywords_fa = {گردش جوی,بارش سنگین,شیراز,مرکز ملی پیش‌بینی‌های محیطی}, url = {https://clima.irimo.ir/article_15088.html}, eprint = {https://clima.irimo.ir/article_15088_e278eba22596057ca3111c239936b7f3.pdf} } @article { author = {Ranjbar SaadatAbadi, A. and Panahi, A. and Fatahi, E.}, title = {Influence of Monthly Atmospheric Circulation Patterns Anomalies on with Wet/Dry conditions in the West and Northwest of IRAN}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {91-109}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Introduction  In the recent years, the West and Northwest regions of Iran, have faced severe and elongated drought problems due to pressure pattern anomalies. The rainy season in the West and North West (WNW) regions normally lasts from October to April. In the summer months, rainfall is a small occurrence in the region due to the predominance of the quasi-permanent subtropical high system. The relationship between precipitation totals and pressure patterns in the regions close to Iran has been recently published. According to a very recent study (Kutiel et al. 2001), the relationship between regional sea-level pressure (SLP) patterns and dry or wet monthly precipitation conditions over Turkey is significant in winter and non-existent in summer. Pressure patterns associated with dry conditions usually show positive SLP departures, and vice versa. There is a strong relationship between pressure patterns associated with wet air. Similar atmospheric variations and relationships have been found for precipitation over the eastern Mediterranean Basin and Greece, especially during winter. In a study done by Maheras et al. 1999, Xoplaki et al. 2000, the influence of the large-scale winter mid-tropospheric circulation on Greek precipitation were investigated. They concluded that the spatial distribution of winter precipitation over Greece was related to the eastern North Atlantic-European mid-tropospheric circulation fields. Materials and methods Rainfall data including monthly totals for the period from 1981 to 2010 (thirty years) in ten stations across the West and Northwest of Iran, were studied (Table 1). It consists of monthly precipitation totals (mm) for October to April in the 30-year period from the meteorological synoptic stations. Also, the grid point data (Sea level Pressure and 500mb) were extracted from the National Center for Environmental Prediction and National Center for Atmospheric Research (NCEP-NCAR) reanalysis dataset. The grid data with 2.5°×2.5° resolution was selected for the area between 20°W -110°E and 10-80°N for seven months (October-April) over a 30-year period (1981-2010). Based on standard score criterion (Z), dry and wet conditions in each month were defined independently for each station (Table 3). For each month the data were standardized as follows:     where: Pi is the monthly rainfall in the year i; P is the long-term(30 years) monthly rainfall average and SD is its standard deviation. Furthermore, for each month and each year, monthly mean standard score (Z) was calculated for the region (Table 4). Then, the synoptical maps of every months having higher (lower) Z profile than the monthly average were investigated and analyzed SLP and 500hPa anomalies as a dry or wet criterion month. Although in this regarding, the monthly mean SLP, 850 and 500hPa geopotential heights (but not presented here) and their anomalies were investigated for a dry or wet criterion month, but in this paper were emphasized on monthly mean SLP and 500hPa anomalies for extreme dry/wet conditions.    Results and Conclusion The data presented in Table 5 are used for selection of the months with extreme precipitation regimes over the WNW area. The SLP and 500 geopotential height composite anomalies are determined for the dry and wet periods (Figures 2-8). Each of these patterns (Figures 2-8) for only two months with extremely high or low Z determined according Table 5 strengthening high pressure on Europe and deepening trough on Mediterranean follows rainfall increase of west and northwest regions in Iran.  High height strengthening in central and eastern regions of Iran and tilting western waves in a northeast to southwest axis, cause rainfall increase in Iran's west and north west regions. Strengthening Sudanese and Mediterranean low pressure, their integration and strengthening high pressure in Europe cause rainfall increase of the region under study. Through strengthening each of Siberian and north Atlantic high pressures in a way affecting the under study region, follows rainfall decrease there. The derived results indicate a decreasing trend for Z index in October-March months through a long term consideration (1981-2010), that confirms expansion of drought over the study area. We have different abnormalities in the pressure cells of sea level (SLP) and 500hPa level through dry and wet periods as following 3 forms: 1. Zonal abnormality extension mostly results in the extreme dry and wet spells over the region. In this condition the abnormalities of pressure and height are mostly extended zonal and based on the position of negative/positive abnormalities. The extreme drought and wet spells usually are occurred. Establishment of the negative/(positive) abnormalities over a zone between 25ºN-45ºN/(20ºN-45ºN) associated with positive/ (negative) abnormalities caused severe dry periods (Jan 1987/(Feb 2002) for example) in the region. Occurrence of the positive/(negative) pressure abnormalities over a zone between  45ºN-75ºN as well as 10ºE-100ºE/(20ºN-45ºN (Apr 2002 and Oct 1987 for example)) caused severe wet periods over the region. 2. Meridional abnormality extension also results in extreme dry and wet periods over the region, as following:  - increase of positive/(negative) pressure and height abnormalities from north side of the Red Sea, eastern parts of the Mediterranean, Iran up to north of Europe/(western parts of the Mediterranean, some parts of northern Atlantic cause the sever dry periods. - establishment of negative/ (positive) abnormalities from northeast of Africa and eastern side of the Mediterranean up to Iran and a zone around 80ºN / (over the west of the mentioned zones) caused extreme rainfalls in the region (December 1991 and March 1998 for example). 3. But we found another situation which shows that the extension of abnormalities is not similar to the both aforementioned status. In this situation the extension of abnormalities is Zonal-Meridional (a composite status). In this composite status the pressure-height abnormalities are not sufficiently extended and correlated, as this situation results in the weak dry/wet periods or normal conditions. In this situation mostly the positive/ (negative) abnormalities are established over eastern side of the Mediterranean Sea, in turn, increase occurrence of the weak dry/ (wet) or normal periods. Regarding the high resolution in the seasonal forecasting of pressure cells in contrast to the precipitation forecasting- the results obtained from this investigation have a potential to enhance the quality of the seasonal forecasting.    }, keywords = {The abnormalities of pressure and height,Dry month,Wet month,The West and North West}, title_fa = {تأثیر نابهنجاری‌های ماهانه الگوهای گردشی جو در رخداد دوره‌های خشک وتردر غرب و شمال غرب ایران}, abstract_fa = {طی سال‌های اخیر، رخداد دوره‌های خشک و طولانی در مناطق مختلف کشور، بویژه منطقه غرب و شمال غرب، سبب تنش‌هایی در بخش‌های مختلف از جمله منابع آب شده و خسارات قابل توجهی را به بخش کشاورزی و منابع طبیعی وارد نموده است. لذا مطالعه عوامل مؤثر بر رخداد دوره‌های خشک و تر، از جمله نابهنجاری‌های ماهانه الگوهای همدیدی از اهمیت زیادی می‌تواند برخوردار باشد. بر این اساس در این تحقیق جهت بررسی تأثیر الگوهای گردشی جو بر دوره‌های خشک وتر ماه‌های سرد سال در غرب و شمال غرب ایران، داده‌های بارش بارندگی ده ایستگاه همدیدی در یک دوره 30 ساله(2010-1981) برای ماه‌های اکتبر تا آوریل استفاده شد. آنگاه ماه‌های خشک و تر، بر اساس شاخص نمره استاندارد(Z) تعیین گردید، سپس در طول دوره 30 ساله، ماه‌هایی که میانگین نمایهZ  دارای مقادیر بیشینه و یا کمینه بود نقشه‌های همدیدی آنها در سه تراز، فشار سطح دریا (SLP)، 850 و 500 هکتوپاسکالی بررسی و تحلیل شد، در نهایت الگوهای ماهانه و نابهنجاری‌های میدان فشار تراز سطح دریا و میدان ارتفاع ژئوپتانسیل تراز 500 هکتوپاسکال(H500) تعیین گردید. نتایج حاصل نشان داد که: 1- تقویت پرفشار بر روی اروپا وتعمیق ناوه در روی مدیترانه، افزایش بارندگی در غرب و شمال غرب ایران را به دنبال دارد. 2- تقویت پرارتفاع در نواحی مرکزی و شرقی ایران و کج شدن ناوه موج غربی به حالت شمال شرقی- جنوب غربی، سبب افزایش بارش در غرب و شمال غرب ایران می‌گردد. 3- تقویت کم فشار در روی مدیترانه و سودان و ادغام آنها و تقویت پرفشار در روی اروپا با افزایش بارش در منطقه مورد مطالعه همراه خواهد بود. 4- افزایش نابهنجاری مثبت SLP و H500 از شمال دریای سرخ و روی نیمه شرقی مدیترانه تا شمال اروپا همراه با نابهنجاری‌های منفی در نیمه غربی مدیترانه سبب دوره‌های خشک شدید می‌شود. }, keywords_fa = {نابهنجاری‌ میدان‌های فشار و ارتفاع,ماه خشک,ماه تر,غرب و شمال غرب}, url = {https://clima.irimo.ir/article_15089.html}, eprint = {https://clima.irimo.ir/article_15089_3fd7a17eadbe7da3fc5fa345997fd876.pdf} } @article { author = {Farzandi, M. and Rezayie-pazhand, H. and Sanaei Nejad, H.}, title = {Reconstruction and extending of 127 years monthly temperature of Mashhad}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {111-123}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {  Introduction The length of data is very important in forecast and analysis of annual temperature. The long term data may have fluctuations.  The time series of temperature as a trend, can show seasonality and cyclical changes and will appear better and frequency analysis result could be improved. Maximum Statistical period of temperatures data in the stations of Iran is about 60 years that is a short-term. Mashhad has 127 years long-term monthly temperatures (2011-1885). The recent 60 years (2011-1951) have been observed by The Mashhad Synoptic Station and the remaining 67 years (1940-1885) observed by the America's consulate  which was located in Mashhad. These 127-years long-term data have missing values that should be repaired. There are some stations that have long-term temperatures data and have a good correlation with temperatures of Mashhad. This station consists of Jask (Iran, founded in 1893), Serakhs and Kyzyl (Turkmenistan, founded in 1900 and 1893 respectively), Turkestan (Kazakhstan, founded in 1885) and Baghdad (Iraq, founded 1893).  Materials and methods Mashhad a city in the center of Khorasan Razavi Province, is located in the northeast part of Iran at a latitude of , longitude of and an altitude of 946 MSL. Mashhad has 127 years long-term monthly temperatures (2011-1885). The recent 60 years (2011-1951) have been observed by The Mashhad Synoptic Station and the remaining 67 years (1940-1885) by the America's embassy which has been located in Mashhad observed. In linear regression, the model specification is that the dependent variable,   is a linear combination of the parameters (but need not be linear in the independent variables). For example, in simple linear regression for modeling n data points there is one independent variable: , and two parameters,   and  : according to equation (1).                                                                                                                   (1) In multiple linear regressions, there are several independent variables or functions of independent variables, according to equation (2).                                                                                 (2) Results and discussion Multiple linear and nonlinear patterns were used for estimating missing data in this paper. Three Linear models finally accepted and were used for this purpose. Multiple linear models for restoration of data in years 1904-1895, 1949-1941, January, February and July 1905, December 1910, January and February 1914, January 1913, May 1932, September to December 1933 and February and March 1937, by two base stations: Jask and Turkestan, according to equation (3).                                         (3) Univariate linear pattern according to equation (4) using data from the years 1885-1890 by using Turkistan stations to extending data and reconstruction of June, July and August 1892, October 1894 and March 1951 were used.                                                                     (4) Univariate linear pattern by using the temperature of Jask station to reconstruct July 1918 to December 1919 were used. This pattern is according to equation (5).                                                                     (5)  The coefficients of determination of these models are 0.98, 0.96 and 0.93 respectively. Classical tests and diagnostic of models showed acceptance of them. F-statistics of these models are 23160, 31080 and 14480, respectively. The P-value for all tests is closed to zero. VIF for all models are less than 10. Durbin-Watson statistic located in accepted regions. Conclusion Multiple linear and nonlinear models were used for estimating missing data in this paper. Three Linear models finally accepted and were used for this purpose. The coefficients of determination of these models are 0.98, 0.96 and 0.93 respectively. Classical tests and diagnostic of models showed acceptance of them. F-statistics of these models are 23160, 31080 and 14480, respectively. The P-value for all tests is closed to zero. VIF for all models are less than 10. Durbin-Watson statistic located in accepted regions .Therefore 127 years of monthly temperature for Mashhad (1885 to 2011) was completed. The test of homogeneity, independence, randomness and outliers were done and accepted. The analyzing of 127 Mashhad annual temperatures showed that there is a change point and an increasing trend from 1986.}, keywords = {127 years of monthly temperature of Mashhad,linear and nonlinear regression,Diagnostic,Trend,Homogeneity}, title_fa = {ترمیم و گسترش 127 سال آمار دمای ماهانه مشهد}, abstract_fa = {طول دوره‌ آماربرداری اهمیت زیادی در تحلیل و پیش‌بینی دمای سالانه دارد. آمار طولانی مدت می تواند نوسانات سری‌زمانی دما شامل روند، تغییرات فصلی و تغییرات دوره‌ای را بهتر نمایان کند یا دقت تحلیل‌فراوانی را افزایش دهد. حداکثر طول دوره آماربرداری دمای هوا در ایستگاه‌های کشور حدود 60 سال است که آمار کوتاه مدتی محسوب می شود. این آمار نمی تواند روند خطی یا غیر خطی و نوسانات دوره‌ای را به‌خوبی نشان دهد. مشهد دارای 127سال آمار بلندمدت دمای ماهانه است (2011- 1885). 60 سال اخیر آن توسط ایستگاه همدید مشهد (2011-1951) و 67 سال باقی مانده (1940-1885) توسط کنسولگری آمریکا واقع در مشهد آماربرداری شده است. این آمار دارای ماه‌های مفقود است (حدود 20%) که باید ترمیم شود. هدف این مقاله تکمیل آمار 127 سالانه دمای ماهانه مشهد است. چند ایستگاه با آمار طولانی مدت وجود دارد که همبستگی خوبی با دمای مشهد دارند که شامل جاسک (ایران، تاسیس 1893)، سرخس و کیزیل (ترکمنستان، تاسیس به ترتیب 1900 و 1893)، ترکستان (قزاقستان، تاسیس 1885) و بغداد (عراق، تاسیس 1893) است. الگوهای خطی و غیرخطی چندگانه متنوعی برای ترمیم آمارهای مفقود به‌کار رفت. سه الگوی خطی در نهایت پذیرفته و استفاده شد. ضریب‌تعیین این الگوهابه ترتیب 98/0، 96/0و 93/0که نشان از  قدرت خوب آنهاست. آزمون‌های کلاسیک و  آسیب‌شناسی الگوها نشان از قبول آنهاست. آماره F برای این سه به‌ترتیب 23160، 31080 و 14480 است. P-value برای تمام آزمون ها نزدیک به صفر است. VIF برای هرسه الگو کمتر از 10 است. همچنین آماره دوربین-واتسن نیز در ناحیه قبول قرار می‌گیرد. لذا 127سال دمای ماهانه (1885 تا 2011) ایستگاه مشهد به این ترتیب کامل شد. آزمون همگنی، استقلال، تصادفی بودن و نبود داده‌پرت انجام شد که نتایج رضایت بخش است. بررسی 127سال دمای سالانه مشهد نشان داد که یک نقطه شکست و ایجاد روند صعودی از 1986 به‌وجود آمده‌است. }, keywords_fa = {127 سال دمای ماهانه مشهد,رگرسیون خطی و غیرخطی,آسیب شناسی,روند,همگنی}, url = {https://clima.irimo.ir/article_15090.html}, eprint = {https://clima.irimo.ir/article_15090_40a4215a1a226f4e9e0edf9e81ed7686.pdf} } @article { author = {Javadi, Z. and Fallah-Ghalhari, G. and Entezari, Alireza}, title = {The role of climatic parameters on yield of almond Case Study: Sabzevar}, journal = {Journal of Climate Research}, volume = {1393}, number = {17}, pages = {125-141}, year = {2014}, publisher = {https://www.irimo.ir/}, issn = {2228-5040}, eissn = {2783-395X}, doi = {}, abstract = {Introduction       Climate is one of the basic elements of the environment that controls all aspects of life. Among the elements of climate, air temperature and precipitation play a crucial role. Temperature as an indicator of the severity of heat is one of the essential elements of knowledge about climate. Solar energy received by the earth is undergoing many changes in climate system. Effect of climatic factors on the performance of agricultural production is extremely important. If the knowledge on the climatic factors is not existed, much success could not be achieved. Material and methods       In this study, the mean temperature, wet bulb temperature, dry bulb temperature, relative humidity, rainfall, sunshine and wind speed is applied. We got variable values in the period between 1982-2011 from the city of Sabzevar weather office. Data quality control is done and wrong values of the time series of climatic elements is removed. Then, the correlation coefficient were calculated from parameters at various time intervals of a month, two months, three months, six months and a year were calculated. The date of phonological stages of almond is used from Golmakan agrometeorological station and the value of mentioned above variables are obtained in the different phonological stages. In the next step, trend analysis is applied on the time series of climatic variables. Then, factor analysis was applied on the variables that have correlation coefficient with almond yield. In the final step, the clustering analysis is used to gouping the main variables.   Results and discussion       Results show that the main factors affecting the performance of almonds can be placed in 3 separate clusters as follows: 1- The first cluster consists of dry bulb temperature in Feb- March, wet bulb temperature in February - May, dry bulb temperature in March, wet bulb temperature in February –March, minimum temperature in March and minimum temperature in February - March. 2- The second cluster consists of Maximum temperature in December, dry bulb temperature in winter, Maximum temperature in February -March, Maximum temperature in March and air temperature range in Oct. 3- The third cluster consists of Maximum temperature in April, dry bulb temperature in July and minimum temperature in July.   Conclusion       In this study, using Pearson correlation, the relation between almond crop yield and the climatic elements was evaluated. The results showed that the maximum temperature has the most significant negative correlation with performance of almonds. The results also showed that the start date of phonological stages is significant decreasing trend. In other words, the phonological stages are started earlier.}, keywords = {Pearson's correlation,Trend,mann-kendall test,t-test,almond}, title_fa = {نقش پارامتر های آب هوایی بر عملکرد محصول بادام مطالعه موردی: سبزوار}, abstract_fa = {در حال حاضر کشاورزی یکی از مهمترین بخشهای اقتصادی یک کشور به شمار  می آید. بازده تولید محصولات کشاورزی تا حدود زیادی با شرایط اقلیمی در ارتباط است. بررسی اثرات شرایط اقلیمی بر میزان تولید محصولات کشاورزی‌ می‌تواند کمک موثری به انتخاب مناسب‌ترین گیاه برای کشت محصول بنماید. امروزه بزرگترین مسأله در هواشناسی کشاورزی، اثر عوامل آب و هوایی بر روی محصولات کشاورزی است. در این تحقیق، برای بررسی اثر پارامترهای آب و هوایی بر عملکرد محصول بادام در سطح شهرستان سبزوار، از پارامتر های هواشناسی میانگین حداقل دما، میانگین حداکثر دما، میانگین دما، بارش، ساعات آفتابی، دمای تر، دمای خشک، رطوبت نسبی و سرعت باد ایستگاه همدید سبزوار در بازه‌ی زمانی 1390-1361 استفاده شده است. در این تحقیق برای بررسی ارتباط بین پارامترهای هواشناسی و عملکرد بادام از روش همبستگی پیرسون  در بازه های زمانی مختلف استفاده شده است. نتایج نشان می دهد  که از بین پارامتر آب هوایی دمای بیشینه بیشترین همبستگی منفی معنی دار را با تولید و عملکرد محصول بادام  داشته است. در این تحقیق روند تغییرات آغاز مراحل فنولوژی محصول  با استفاده از آزمون ناپارامتری  من کندال و آزمون پارامتری تی تست  مورد ارزیابی قرار گرفته است. نتایج تحلیل نشان می دهد زمان آغاز مراحل فنولوژی در پاسخ به گرمایش جهانی در هر دو روش دارای روند کاهشی معنی دار می باشد.}, keywords_fa = {همبستگی پیرسون,آزمون من کندال,آزمون تی تست,محصول بادام}, url = {https://clima.irimo.ir/article_15091.html}, eprint = {https://clima.irimo.ir/article_15091_2b8e95db8e97274ba45bf44055043d41.pdf} }