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
1396
10
1
gregorian
2018
1
1
4
4
online
1
fulltext
fa
تحلیل شاخص های ناپایداری توفان های تندری در ایران با استفاده از داده های بازتحلیل
Analysis of Thunderstorm Instability Indexes in Iran using Reanalysis Data
تخصصي
Special
پژوهشي
Research
<div style="text-align: justify;"><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">مطالعۀ</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> توفان­تندر به­عنوان یک پدیدۀ مخاطره­آمیز جوی</span></span></strong> <strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">با استفاده از شاخص</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">­</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">های ناپایداری به­دلیل کمبود ایستگاه­های مشاهداتی در ایران</span></span></strong> <strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">کمتر مورد توجه قرارگرفته است. </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">این پژوهش با استفاده از داده­های بازتحلیل به ارزیابی توفان­های تندری در ایران با دو شاخص </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">CAPE</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> و </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">VWS</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> می­پردازد. ابتدا فراوانی، روند و ساعات وقوع توفان­های تندری در ایران </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">طی یک دورۀ 37ساله (1980 تا 201</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">6</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">) </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">بررسی شد. سپس</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> برای تحلیل توفان­ها،</span></span></strong> <strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">از داده­های <span style="color:black;">بازتحلیل </span></span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">شبکه­ای </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">ERA-Interim</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> متعلق به «</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">مرکز اروپایی پیش­بینی­های جوی میان­مدت» (</span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">ECMWF</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">) </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">استفاده شد. </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">داده­های </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">ERA</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> با استفاده از داده­های مشاهداتی80 رخداد توفان در 14 ایستگاه جو بالای کشور با نرم­افزار </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">RAOB</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> ارزیابی شد</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">. پس از تأیید صحت داده­های </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">ERA</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">، مقادیر دو شاخص </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">CAPE</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> و </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">VWS</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> مربوط به 4542 رخداد توفان­تندری برای ساعت­های صفر و 12</span></span></strong> <strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">گرینویچ در 42 ایستگاه سینوپتیک به­دست آمد. </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">سپس برای تمایز محیط­های رخداد توفان­تندری بسیارشدید از شدید و ملایم، از تحلیل ممیزی استفاده شد.</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> در نهایت، معادلۀ خط تشخیص برای هرکدام از گروه­های شدت توفان به­دست آمد</span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">. </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">نتایج نشان داد که روند توفان­های تندری در ایران رو به افزایش است. بیشترین فراوانی رخداد مربوط به ماه می و ساعت 21:30 است. داده­های </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">ERA</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> تخمین بسیار نزدیکی برای </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">VWS</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> ارائه می­دهند؛ اما تخمین­ها برای شاخص </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">CAPE</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> اندکی بیش از مقادیر مشاهداتی است. بیشترین میزان شاخص </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">CAPE</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> در استان­های جنوبی و جنوب­غرب سواحل خزر، و بیشترین مقادیر شاخص </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">VWS</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> در سواحل خلیج فارس مشاهده می­شود. بین مقادیر میانگین </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">CAPE</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> و </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">VWS</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> در سه گروه شدت توفان، اختلاف معناداری وجود ندارد. </span></span></strong><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;">نقش شاخص </span></span></strong><span dir="LTR"><span style="font-family:times new roman,serif;"><span style="font-size:10.0pt;">VWS</span></span></span><strong><span style="font-family:b nazanin;"><span style="font-size:10.0pt;"> در تعیین نوع توفان بیشتر بوده است.</span></span></strong></div>
<div style="text-align: justify;"></div>
Thunderstorm is a destructive atmospheric phenomenon, which annually causes a lot of damage to various parts of human activities. Due to the accompaniment of thunderstorm with rainstorm and hail and its effective role in creating sudden floods, the analysis of the behavior of this hazard has been widely studied both in terms of agriculture and in terms of financial and life damages throughout the world. The study of thunderstorm as a hazardous atmospheric phenomenon using instability indexes in Iran has been less considered due to lack of observation stations. Convective Available Potential Energy (CAPE) and Vertical Wind Shear (VWS) are two indexes that are often used to describe and detect thunderstorm environments. This study evaluates the thunderstorms in Iran with reanalysis data using CAPE and VWS indexes.<br>
Thunderstorm data in 7 different conditions at 8 times a day for 42 synoptic and upper air stations during a 37-year common period (1980-2016) was received from the Iranian Meteorological Organization. At first, frequency, trend and time of occurrence of thunderstorms in Iran were investigated during the statistical period. Then, the ERA-Interim reanalysis dataset of the European Centre for Medium-Range Weather Forecasts (ECMWF) with spatial resolution of 0.5 ° was used for the analysis of thunderstorms. To evaluate the ERA-Interim dataset, the CAPE and VWS values for the 80 selected thunderstorm events that were calculated using the RAOB software were compared with ERA data and their accuracy was confirmed. After confirming the accuracy of ERA data, the average values of CAPE and VWS indexes in 42 stations of the country were calculated based on 4,542 thunderstorm events at 00 and 12 GMT during the study period, and the maps of these two indexes were drawn up using the IDW method. Then, using an equation, the thunderstorm severity thresholds across the country were determined using ERA data with 4,542 thunderstorm events to distinguish between mild, severe and very severe storms. To ensure the selection of important storms, storms with CAPE values of less than 50 were removed to exclude poor environments for convection occurrence. As a result, out of 4,542 thunderstorms, 535 events were eliminated and 4007 events remained. On this basis, a "2 x 2 contingency table" was prepared that compares thunderstorm events and forecasts. This table provides the information required to compute warning performance statistics including POD (Probability of Detection), FAR (False Alarm Ratio) and CSI (Critical Success Index). But the results of these statistics did not match well with the conditions of thunderstorm events in Iran. Therefore, the discriminant analysis was used to differentiate the intensity of thunderstorms and to discriminate mild, severe and extremely severe thunderstorms.
<div style="text-align: justify;">The results of the study showed that thunderstorms in Iran are increasing during the statistical period with a regression slope of 0.23 events per year (8.5 events in the statistical period). The highest frequency of thunderstorms was observed in the month of May with an annual number of 111, and the lowest was observed in January with 12 events. Most thunderstorms occur around 21:30. The highest average frequency of annual events at stations was related to the stations of Urmia, Tabriz, Khorramabad and Bushehr respectively. The proper capability of ERA data to estimate instability indexes in Iran was proved. ERA data provides a very near estimate for VWS, but estimates for the CAPE index are slightly more than observational values. The highest values of the CAPE index are observed in southern provinces, as well as in the southwest of the Caspian Sea coasts, and the highest values of the VWS index are found on the Persian Gulf coasts. When the storm severity breakdown equation for the 400 selected storm events was obtained and the "2 x 2 contingency table" was prepared, it was found that this equation was not satisfactory with respect to the POD, FAR, and CSI indexes. Hence, using the discriminant analysis, the storm severity breakdown relationships and their discriminant equations were obtained. These equations categorized 60% of the surveyed thunderstorms correctly. There is no significant difference between the mean values of CAPE and VWS in the three storm intensity groups. The role of the VWS index was higher in determining the type of storm.</div>
توفان تندر, ایران,ECMWF , داده های بازتحلیل ERA-Interim, شاخص CAPE, شاخص VWS
Thunderstorm, Iran, ECMWF, ERA-Interim Reanalysis Data, CAPE Index, VWS Index
33
48
http://jsaeh.khu.ac.ir/browse.php?a_code=A-10-547-1&slc_lang=fa&sid=1
Firouz
Mojarrad
فیروز
مجرد
f_mojarrad@yahoo.com
10031947532846003100
10031947532846003100
Yes
Geography Dept., Faculty of Literature and Humanities, Razi Univ., Kermanshah
گروه جغرافیا، دانشگاه رازی، کرمانشاه
Samira
Koshki
سمیرا
کوشکی
koshkys@yahoo.com
10031947532846003101
10031947532846003101
No
Geography Dept., Faculty of Literature and Humanities, Razi Univ., Kermanshah
گروه جغرافیا، دانشگاه رازی، کرمانشاه
Jafar
Masompour
جعفر
معصومپور
J_masompour27@yahoo.com
10031947532846003102
10031947532846003102
No
Geography Dept., Faculty of Literature and Humanities, Razi Univ., Kermanshah
گروه جغرافیا، دانشگاه رازی، کرمانشاه
Morteza
Miri
مرتضی
میری
mmiri@alumni.ut.ac.ir
10031947532846003103
10031947532846003103
No
Clhmatology Dept., Geography Faculty, Tehran Univ., Tehran
گروه اقلیم شناسی، دانشکده جغرافیا، دانشگاه تهران