Journal of Spatial Analysis Environmental Hazards
تحلیل فضایی مخاطرات محیطی
Journal of Spatial Analysis Environmental Hazards
Literature & Humanities
http://jsaeh.khu.ac.ir
1
admin
2423-7892
2588-5146
10.61186/jsaeh
fa
jalali
1400
6
1
gregorian
2021
9
1
8
2
online
1
fulltext
fa
عوامل مؤثر در اغتشاشات عمق لایه مرزی غرب ایران در فصول تابستان و زمستان(مورد مطالعه: ایستگاه جو بالای کرمانشاه)
Factors affecting the depth of the boundary layer turbulence West of Iran in the summer and winter seasons (Case Study: Kermanshah Upper Air Station)
تخصصي
Special
پژوهشي
Research
<div style="text-align: justify;">در این تحقیق با استفاده از مدل پیشنهادی هافتر عمق لایه آمیخته و ارتفاع لایه مرزی ایستگاه کرمانشاه برای دو ماه آگوست و فوریه سال 2012 بررسی شد. در این راستا از دادههای مربوط به پیمایش قائم جو در موقعیت ایستگاه کرمانشاه از پایگاه دادههای اقلیمی <span dir="LTR">Wyoming</span> استفاده گردید. با ترسیم و تحلیل گرافهای <span dir="LTR">Skew-T</span> و براساس روش وارونگی بحرانی <span dir="LTR">Heffter</span>، دو ماه فوریه و آگوست بعنوان نماینده های فصل زمستان و تابستان انتخاب و سقف وارونگی به عنوان سقف لایه مرزی اتمسفری در نظر گرفته شد. سپس عوامل موثر در کمینه و بیشینه شدن لایه آمیخته این دو ماه (آگوست و فوریه) شامل وضعیت همدیدی موجود در منطقه مورد مطالعه، فرارفت گرما، رطوبت، چینش قائم و سرعت باد مورد بررسی قرار گرفت. نتایج نشان داد که در ماه آگوست عمق لایه در طول ماه بین 3680 تا 10292 متر بوده است. در این ماه فرارفت دما، نوع سامانه های همدید و چینش قائم باد به طور مستقیم در رشد یا تضعیف لایه نقش داشته اند. در ماه فوریه نوسانات چشمگیری در مقادیر عمق لایه آمیخته در طول ماه مشاهده شده که بین 2273 تا 7017 متر بوده است. در این ماه نیز فرارفت دما، چینش قائم باد و سامانه های همدیدی در تغییرات عمق لایه آمیخته موثر بوده اند. با مقایسه نتایج بدست آمده از هردو ماه می توان گفت که مقدار شار سطحی در فصل تابستان بیشتر از فصل زمستان است؛ بنابراین عمق متوسط لایه در ماه آگوست تقریباً به دو برابر ماه فوریه رسیده است. در کل نوسانات عمق لایه آمیخته در فصل زمستان بدلیل عبور سامانه های مختلف و ناپایداری های جوی، تغییرات بیشتری نسبت به فصل تابستان داشته است.</div>
<div style="text-align: justify;"><strong>Introduction</strong><br>
The daily cycle of radiant heating from sunrise and sunset leads to the daily cycle of tangible and hidden heat fluxes between the earth's surface and the atmosphere. These fluxes, which cannot directly reach the whole atmosphere, are confined to the shallow layer near the surface, called the boundary layer of the atmosphere. . The processes that take place in this layer are important in various aspects such as the dynamics of fluxes and atmospheric systems, surface radiation, the hydrological cycle, and air pollution research. The thickness of the boundary layer of the atmosphere varies with time and place, and its size varies from a few hundred meters to several kilometers on land under different conditions. This thickness depends on various factors such as the type of atmospheric systems and their structure, surface fluxes, steep vertical arrangement and wind direction and surface cover. The depth of the boundary layer can be calculated by different methods. This depth, which indicates the thickness of the turbulence zone near the surface, is usually called the depth of the mixed layer or the depth of the mixture. The methods used to determine the boundary layer of the atmosphere or the depth of the mixed layer are commonly used to investigate air pollution. Estimating the depth of the mixed layer is one of the most important parameters in the pollutant diffusion model. Therefore, the purpose of this study is to investigate the causes of monthly fluctuations in the height of the western border layer of the country with respect to the barley station above Kermanshah.<span dir="RTL"></span><br>
<br>
<strong>Materials and methods</strong><br>
Data on inversions of Kermanshah meteorological station during February and August 2012; Obtained from the Meteorological Organization of the country. Also, the data related to the vertical barley survey in this station, which were collected by radio sound, were used and the statistics of daily vertical barley survey above the Kermanshah synoptic station were obtained from the climatic database of the University of Wyoming. After obtaining information about vertical barley survey in Kermanshah station, Skew-T diagram, indicators and profile information of atmospheric conditions were drawn to recognize the dynamic and thermodynamic status of the atmosphere during the selected days in RAOB software environment. Then, in order to study the lower atmosphere more accurately, the changes in the vertical index of potential temperature, using daily radiosound data, the curves of potential temperature changes in terms of altitude were plotted. Then, using Huffer's computational method, days with critical inversion at potential temperature were found. Then, using geopotential height, wind and vertical ascent (omega) data, the synoptic causes of boundary layer depth fluctuations (mixed) and the effective factors were investigated.<br>
<br>
<strong>Results and discussion</strong><br>
The main purpose of this study is to implement Hafter's proposed model to investigate the monthly fluctuations of the height of the boundary layer of Kermanshah station. The results of using Hafter method in estimating the depth of the mixed layer of the city and its daily changes for Kermanshah station in August and February 2012. In this regard, the effective factors in minimizing and maximizing the mixed layer in every two months (August and February), including: the synoptic situation in the study area on selected days, heat transfer, humidity, vertical arrangement and wind speed were investigated.<br>
<br>
<strong>Conclusion</strong><br>
The results showed that in August, the depth of the layer during the month was between 3680 to 10292 meters. In this month, temperature subsidence, type of synoptic systems and vertical wind arrangement have directly played a significant role in the growth or weakening of the layer. Considering the comparison of the role of effective factors in maximizing and minimizing the depth of the boundary layer in August, it can be concluded that all factors have a positive role in maximizing the depth of the mixed layer; while the vertical wind arrangement plays an essential role in minimizing the layer depth in this month. In February, the depth of the mixed layer was about 2273 to 7017 meters and significant fluctuations in the values of the depth of the mixed layer were observed during the month. In this month, temperature subsidence, vertical wind arrangement and synoptic systems have been effective in changing the depth of the mixed layer. Comparing the results obtained from both months, it can be said that the amount of surface flux is higher in summer than in winter; thus, the average depth of the mixed layer in August has almost doubled to February. In general, it can be concluded that the depth fluctuations of the mixed layer in winter due to the passage of different systems and the occurrence of atmospheric instabilities, have more changes than in summer<span dir="RTL">.</span><br>
</div>
لایه آمیخته, مدل هافتر, چینش باد, فرارفت دما, کرمانشاه
the mixed layer, Hafter model, arrangement of wind, temperature advection, Kermanshah
83
100
http://jsaeh.khu.ac.ir/browse.php?a_code=A-10-1183-1&slc_lang=fa&sid=1
Hossein
jahan tigh
حسین
جهان تیغ
h.jahantigh@saravan.ac.ir
10031947532846009123
10031947532846009123
No
assistant professor, Saravan Higher Education Complex, Saravan,Iran.
استادیار جغرافیای طبیعی مجتمع آموزش عالی سراوان
zeynab
Dolatshahi
زینب
دولتشاهی
i@gmail.com
10031947532846009124
10031947532846009124
No
PhD in climatology Kharazmi University
دانشجوی دکتری اقلیم شناسی دانشگاه خوارزمی تهران
zahra
zarei cheghabalaki
زهرا
زارعی چغابلکی
zarei@yahoo.com
10031947532846009125
10031947532846009125
No
PhD in climatology, Lorestan University
دکتری اقلیم شناسی دانشگاه لرستان
meysam
toulabi nejad
میثم
طولابی نژاد
Meysam.toulabi@gmail.com
10031947532846009126
10031947532846009126
Yes
PhD in climatology Kharazmi University
دکتری اقلیم شناسی دانشگاه خوارزمی تهران