واکاوی اثر عوامل محلی در الگوی جریان باد در منطقه دریاچه ارومیه

نوع مقاله: مقاله پژوهشی

نویسندگان

1 هیات علمی دانشگاه تهران

2 استادیار اقلیم شناسی، گروه جغرافیای طبیعی، دانشکده جغرافیای دانشگاه تهران،

3 دانشیار اقلیم شناسی، د گروه جغرافیای طبیعی، انشکده جغرافیای دانشگاه تهران

4 دانشجوی دکترای اقلیم شناسی، گروه جغرافیای دانشگاه لرستان

چکیده

وزش باد در هر منطقه­ای تابع عوامل مختلفی در مقیاس­های سیاره­ای، منطقه­ای و محلی است و عامل اصلی انتقال جرم (رطوبت، ذرات جامد و .. ) و سایر ویژگی­های هوا از منطقه‌ای به منطقه دیگر است. در این مطالعه، با بهره­گیری از داده­های سه ساعتی جهت و سرعت باد در ایستگاه­های همدید اطراف دریاچه ارومیه و با استفاده از مدل میان­مقیاس آلودگی هوا TAPM به واکاوی اثر عوامل محلی در شکل­گیری بادها در این منطقه پرداخته شد. به این منظور، با انتخاب روزهای با شرایط بادهای محلی از داده­های سه ساعتی ایستگاه‌های هواشناسی (ارومیه، تبریز، خوی، مراغه و مهاباد، در 6 روز) با تأکید بر تغییر جهت وزش در طول شبانه روز، سرعت باد، دما و رطوبت برای بادهای محلی انتخاب شد. نتایج نشان داد که در 4 نمونه مورد بررسی ناوه کم عمقی با حاکمیت بادهای غربی در منطقه حاکم بوده که موجب ورود باد با سرعت­های کم و سرعت تقریبی حدود 4 متربرثانیه به منطقه گردیده است. بادهای حوضۀ دریاچه ارومیه تحت­تأثیر عوامل مختلف دارای پیچیدگی زیاد و تغییرات مکانی و زمانی شدید در جهت و شدت وزش است. خروجی های مدل گویای این است که امتداد کوهستان­ها بیشتر از هر عامل دیگر همچون دریاچه ارومیه در شکل­گیری بادهای محلی مؤثر هستند و چاله دریاچه در کانالیزه کردن بادهای شمالی یا جنوبی منطقه در رابطه با بادهای محلی نقش دارد. این شرایط باعث شکل­گیری هسته­های متعدد واگرایی و همگرایی مطابق با راستای ارتفاعات در منطقه مطالعاتی می­شود. همچنین شیب ارتفاعی به سمت دریاچه و اختلاف ارتفاع زیاد با کوهستان­های پیرامون مهمترین عامل مؤثر در شکل­گیری بادها در زمان­های مورد مطالعه است.

کلیدواژه‌ها


عنوان مقاله [English]

Analysis of Local Factors in Wind Pattern in Urmia Lake basin

نویسندگان [English]

  • Mostafa Karimi 1
  • Ali Akbar Shamsi Poor 2
  • Faramaz Asllani 3
  • Zahra Zarei 4
1 Assistant Professor of Climatology of University of Tehran
2 Assistant Professor, Department of Physical Geography, University of Tehran
3 Associate Professor, Department of Physical Geography, University of Tehran
4 PhD Students of climatology, Department of Geography, University of Tehran
چکیده [English]

Introduction
The effective factors in formation of atmospheric elements in local and regional scales usually have been trimming and smoothing roles. The identification of wind formation patterns in Uremia lake basin is an important issue for many management and regional planning affairs. In this context: Steven et al. (1992), Neil et al (2003), Zawarreza (2004), Luhar& Hurley (2004) and Kardane et al (2009) can be referred. Various studies have been done related to Urmia basin in generally, but there isn't almost any research about the formation mechanism of regional winds and the effect of local factor on it. In the study we tend to investigate the mechanism of local wind formation in Urmia basin using mesoscale climatic models.
Materials and Methods
Urmia Lake is a salt lake in the northwestern of Iran. The lake is between the provinces of and West Azerbaijan in Iran, and the southwest of the portion of Caspian Sea. At its full size, it is the largest lake in the Middle East and the sixth largest saltwater lake on earth with a surface area of approximately 5,200 km² (2,000 mile²), 140 km (87 mi) length, 55 km (34 mi) width, and 16 m (52 ft.) depth it is located in high of 1275 meters above sea level
Firstly, the data of daily wind of Stations around Lake Urmia has processed in Excel and then the hourly Wind Rose is designed for them. Then using network reanalysis databases of NCEP/NCAR for recognize and analysis atmospheric pressure systems and air masses interring to the basin of Lake Urmia were done. So have been selected 21 typical samples for warm season and 18 typical samples for cool season. The synoptic analysis for selected typical samples were done and finally using the air pollution model (TAPM) as a mesoscale atmospheric model for analyzing these samples.
Results and Discussion
The selected samples presented in table 4. Also using climatic model for analyzing of atmospheric situation in the days which the local factors are dominance. Finally using synoptic and statistical methods to analysis the results.
14 February. 2003: In this day the statistical investigation of wind data in particular speed and direction of wind indicated that the local factors are main component which control the winds characteristics. The atmospheric barotropic condition and regular fluctuations in daily temperature is the main signal of this local factors dominance. The slope of isobars in our study region is very small.
28 July 2006: The wind situation of the stations which located around the Urmia Lake is homogeny so that 4 meteorological station namely, Tabriz, Khoy, Urmia and Maraghe have strong Morning wind. The high pressure from the north can be seen in the area in this day which cause increase the slope of isobars in this region. Mountainous chain directions and topographic situation play an important role in the patterns of wind blowing.
1August 2003: The condition of wind blowing in surrounding stations of Urmia Lake are not homogeny in this day. Two stations from three investigated stations with names Tabriz and Urmia, have strong morning wind from north and east while Maraghe station has southeastern weak wind and Mahabad and Khoy stations have calm air conditions.
8 October 2006: In this day according the table 6 the condition of wind blowing in surrounding station of Urmia Lake is not homogeny. Two stations form 5 investigated weather stations namely Tabriz and Urmia, have strong morning wind from north and two stations of them namely Maraghe and Khoy weather stations are calm air in morning and in midday have southeastern direction winds. And in Mahabad weather station calm air condition was recorded. This heterogenic condition indicated the influent of local factors.
Conclusion
In this paper we intend to detect the effects of local factors in formation of local and regional winds in Urmia Lake basin. For this propose have been investigated four typical days that the local winds were observed. Our funding indicated that in all four typical samples days the weak trough that associated westerly is dominance in our study region due to it the low speed wind entering to our study region. Also using TAPM and its numerical and graphical outputs show the topographical condition in our study region can affect the direction of these entrance winds. Also we observed the north south channeled wind in our study region and formation of divergence core according to direction of topography is very attractive. The lake ward slopes of mountain and the height difference between Lake Surface and mountains is very important in formation of local winds.

کلیدواژه‌ها [English]

  • Urmia Lake
  • Local wind
  • Climate modeling
  • TAPM