Investigating the Relationship between Change of Tropopause Pressure's level (TPL) and Cyclones Associated with Widespread Precipitation (WP) in Iran

Document Type : Research Paper


1 Professor, Department of Geography, Faculty of Humanities, University of Zanjan, Zanjan, Iran

2 Professor, Department of Physical Geography, Faculty of Natural Resources, University of Kurdistan, Sanandaj, Iran

3 Ph.D. Graduated, Department of Geography, Faculty of Humanities, University of Zanjan, Zanjan, Iran


The study of the simultaneous occurrence of cyclones and the changes of Tropopause Pressure's level (TPL) can provide useful insights into the characteristics of the precipitation, especially the widespread precipitation (WP) over Iran; as mid-latitude cyclones are one of the most critical factors associated with WP in Iran. Understanding the mechanisms and the features associated with the cyclones can be crucial for estimating and predicting cyclones and their consequences with precision. To this end, in the current study, we underlined the relationship between tropopause and cyclones affecting WP in the country.
In the current study, two data sets were adopted. These data sets include daily precipitation data of Asfazary national data set (version 3) and atmospheric data (including temperature and geopotential height (GH) data of ERA-Interim base from the European Centre for Medium-Range Weather Forecasts (ECMWF)) with spatial resolution of 0.25 degrees for an area comprised 0 to 80° N and -10 to 120° E. The main aim of selecting the aforementioned area and the data was to identify all the cyclones which are originated from or pass through the Mediterranean Sea and are associated with WP over Iran. Accordingly, the associated pressure levels of the tropopause were examined.
The Asfazary database from 1979 to 2015 was adopted to identify days with WP based on precipitation anomalies covering more than 10% of the country. Accordingly, a total of about 1189 days with WP was extracted for the intended period.
In this study, regional variations of GH at the level of 1000 hPa have been used to identify cyclone centers. To this end, the GH of the pixel was evaluated in relation to the eight neighboring pixels; when the GH was lower than the neighboring ones, and the gradient of the GH was at least 100 geopotential meters per thousand kilometers, the pixel was considered as the center of the cyclone. Cyclones were tracked with respect to the days with WP, and their characteristics were investigated based on the day of cyclone activity and the day of WP.
Using the thermal criterion defined by the World Meteorological Organization (WMO, 1957)), the tropopause was identified.
The 1189 days with WP have been studied visually. Since it is not feasible to present all the days in this brief paper, a few samples were selected to identify the association of tropopause with cyclones on days with WP. The days were selected based on the highest percentage of the area covered for different months. Accordingly, for the entire period, 8 days were selected to represent January, February, March, April, June, October, November, and December. In May, July, August, and September, days with WP were not observed. In the present study, to investigate the relationship between tropopause and cyclones in eight WP samples, the features of tropopause and cyclones on the starting days and on the days with WP were considered.
The spatial distribution of the TPL on the day of cyclone activity and the day with WP showed that on the day of cyclone activity, tropopause had certain characteristics; at this time, the tropopause pressure level showed larger values than those in the surrounding areas. Even on days when WP was observed in Iran and within the cyclone activity range, this anomaly was observed in the TPL. The tropospheric condition of the country compared to the day of the cyclone activity had significant differences; at the time of precipitation, tropopause level showed a larger numerical value in most areas compared to the beginning of the cyclone, especially in areas with heavy precipitation intensity. Tropopause at the time of the formation of the cyclone with WP on April 7, 2013, was different from other under study cases. In this case, at the beginning of the cyclone activity on the cyclone formation area, the tropopause did not have a significant anomaly; while on the day of WP in the south of Iran, the anomaly was significantly prominent. It seems that this difference can be due to the differences in the origin and the mechanism of cyclones in different areas. This probably explains the difference in the characteristics of tropopause on the day of cyclone activity. In the whole area under study, at latitudes above 30 degrees, in geographic locations where the cyclones emerged at the 1000 hPa, tropopause was broken. At this time, tropopause pressure levels showed larger values than the surrounding areas. Given this fact, it seems that there is a relationship between the two phenomena, cyclones and TPL.
Based on the findings, in all eight samples of WP days, tropopause had special characteristics in the same area of cyclone; in addition, tropopause pressure levels in these areas were higher than their counterparts at the same geographical situation.


Main Subjects

برهانی، ر. و احمدی گیوی، ف.، 1397، تحلیل آماری-دینامیکی تاشدگی‌های وردایست منطقه جنوب‌غرب آسیا در سال‌های 2000 تا 2015، م. ژئوفیزیک ایران، 7، 127-146.
برهانی، ر.، احمدی گیوی، ف.، قادر، س. و محب‌الحجه، ع.، 1397، مطالعه فراوانی و توزیع تاشدگی‌ وردایست و تغییرات فصلی آن در سال‌های 2013-2015 با تأکید بر منطقه جنوب‌غرب آسیا، م. فیزیک زمین و فضا، 9، 607-624.
حیدری، م. ا. و خوش‌اخلاق، ف.، 1394، واکاوی و مدل‌سازی ناهنجاری‌های فراگیر بارش غرب ایران در ارتباط با عملکرد مراکز فشار دریای مدیترانه. تحقیقات کاربردی علوم جغرافیایی (علوم جغرافیایی).
عبداللهی، م.، احمدی گیوی، ف. و میرزائی، م.، 1398، بررسی دینامیکی اثر تاشدگی وردایست بر جبهه‌زایی سطوح زبرین و زیرین، م. فیزیک زمین و فضا، 45 (2)، 401-421.
عزیزی، ق. و علیزاده، ت.، 1393، ارتباط بین تیپ الگوهای گردشی تراز دریا، با بارش‌های فراگیر در ایران، م.پژوهش‌های جغرافیای طبیعی (پژوهش‌های جغرافیایی)، 46(3)، 297-310.
عساکره، ح.، 1387، کاربرد روش کریجینگ در میان‌یابی بارش مطالعه موردی: میان‌یابی بارش 26/12/1376 درایران‌زمین، جغرافیا و توسعه، 12، 25-42.
عساکره، ح. و خجسته، آ.، 1400، فراوانی ورود چرخندهای مدیترانه‌ای به ایران و اثر آنها بر بارش های فراگیر، مخاطرات محیط طبیعی، 10 (27)، 159-176.
عساکره، ح.، دارند، م. و زندکریمی، س.، 1399، ویژگی‌های توصیفی وردایست بر روی جو ایران در فصول گذار، پژوهش‌های جغرافیای طبیعی، 52 (2)، 333-350.
علیجانی، ب.، 1374، آب­وهوای ایران، تهران، انتشارات دانشگاه پیام نور.
علیزاده، ت.، عزیزی، ق. و روستا، ا.، 1391، واکاوی الگوهای گردشی تراز 500 هکتوپاسکال جو هنگام رخداد بارش‌های فراگیر و غیر‌فراگیر در ایران، 4، 1-24.
فاروقی، آ.، زرین، آ. و مفیدی، ع.، 1397، بررسی بارش حاصل از سامانه های کم فشار عبوری از جنوب غرب آسیا فصل زمستان 2014-2010، دومین کنفرانس ملی آب‌وهواشناسی ایران، مشهد،
کیخسروی، ق.،. 1394، تحلیل همدیدی – آماری تغییرات ارتفاع لایه تروپوپاوز به‌عنوان نمایه‌ای از تغییر اقلیم در خراسان رضوی، آب‌وهواشناسی کاربردی، 2(2)، 33-48.
لشکری، ح.، 1381، مسیریابی سامانه های کم فشار سودانی ورودی به ایران، مدرس علوم انسانی، 6(2)،133-156.
مسعودیان، س. ا.، 1398، گزارش بارش‌های اسفند 1397 و فروردین 1398 حوضه‌های سیل‌زده ایران، هیأت ویژه گزارش ملی سیلاب. کارگروه اقلیم‌شناسی و هواشناسی. منتشر نشده.
مسعودیان، س. ا.، رعیت‌پیشه، ف. و کیخسروی‌کیانی، م. ص.، 1393، معرفی و مقایسه پایگاه داده بارشی TRMM3B43 و پایگاه داده بارش اسفزاری، م. ژئوفیزیک ایران، 4، 15-31.
مصطفایی، ح.، علیجانی، ب. و سلیقه، م.، 1394، تحلیل سینوپتیکی بارش های شدید و فراگیر در ایران، تحلیل فضایی مخاطرات محیطی، 4، 65-76.
مفیدی، ع. و زرین، آ.، 1385، تحلیلی بر ماهیت و ساختار مراکز پرفشار و کم فشار، رشد آموزش زمین‌شناسی، 46، 54-61.
Babu, S. R., Ratnam, M. V., Basha, G., Krishnamurthy, B. V. and Venkateswararao, B., 2015, Effect of tropical cyclones on the tropical tropopause parameters observed using COSMIC GPS RO data. Atmospheric Chemistry and Physics, 15(18), 10239.
Bengtsson, L., Hodges, K. I. and Keenlyside, N., 2009, Will extratropical storms intensify in a warmer climate?, Journal of Climate, 22, 2276-2301.
Bethan, S., Vaughan, G. and Reid, S. J., 1996, A comparison of ozone and thermal tropopause heights and the impact of tropopause definition on quantifying the ozone content of the troposphere, Quarterly Journal of the Royal Meteorological Society, 122, 929-944.
Bleck, R. and Mattocks., C., 1984, A preliminary analysis of the role of potential vorticity in Alpine lee cyclogenesis, Beitr. Phys. Atmos, 57, 357-368.
Blender, R. and Schubert, M., 2000, Cyclone tracking in different spatial and temporal resolutions, Monthly Weather Review, 128, 377-384.
Boyle, J. S. and Bosart, L. F., 1983, A cyclone/anticyclone couplet over North America: An example of anticyclone evolution. Mon, 111, 1025-1045.
Browning, K. A., Thorpe, A. J., Montani, A., Parsons, D., Griffiths, M., Panagi, P. and Dicks, E. M., 2000, Interactions of tropopause depressions with an ex–tropical cyclone and sensitivity of forecasts to analysis errors, Monthly weather review, 128, 2734-2755.
Corti, T., Luo, B. P., De Reus, M., Brunner, D., Cairo, F., Mahoney, M. J., Martucci, G., Matthey, R., Mitev, V., dos Santos, F. H., Schiller, C., Shur, G., Sitnikov, N. M., Spelten, N., Vössing, H. J., Borrmann, S. and Peter, T., 2008, Unprecedented evidence for deep convection hydrating the tropical stratosphere. Geophysical Research Letters, 35(10).
Dee, D. P., Uppala, S. M., Simmons, A. J., Berrisford, P., Poli, P., Kobayashi, S. and Vitart, F., 2011, The ERA‐Interim reanalysis: Configuration and performance of the data assimilation system, Quarterly Journal of the royal meteorological society, 137, 553-597.
Emanuel, K., 2010, Tropical cyclone activity downscaled from NOAA‐CIRES reanalysis, 1908–1958, Journal of Advances in Modeling Earth Systems, 2.
Emanuel, K., Solomon, S., Folini, D., Davis, S. and Cagnazzo, C., 2013, Influence of tropical tropopause layer cooling on Atlantic hurricane activity. Journal of Climate, 26, 2288-2301.
Hakim, G. J. and Canavan, A. K., 2005, Observed cyclone–anticyclone tropopause vortex asymmetries, Journal of the atmospheric sciences, 62, 231-240.
Hawcroft, M., Walsh, E., Hodges, K. and Zappa, G., 2018, Significantly increased extreme precipitation expected in Europe and North America from extratropical cyclones. Environmental research letters, 13, 124006.
Hirschberg, P. A. and Fritsch, J. M,. 1991, Tropopause undulations and the development of extratropical cyclones. Part I. Overview and observations from a cyclone event. Monthly weather review, 119, 496-517.
Hu, D., Tian, W., Guan, Z., Guo, Y. and Dhomse, S,. 2016, Longitudinal asymmetric trends of tropical cold-point tropopause temperature and their link to strengthened Walker circulation, Journal of Climate, 29, 7755-7771.
Lin, D., Huang, W., Yang, Z., He, X., Qiu, T., Wang, B. and Wright, J. S., 2019, Impacts of wintertime extratropical cyclones on temperature and precipitation over northeastern China during 1979–2016, Journal of Geophysical Research: Atmospheres, 124, 1514-1536.
Masoodian, S. A., 2008, On Precipitation Mapping in Iran, Journal of Humanities, 30, 69-80.
Mohanakumar, K., 2008, Stratosphere troposphere interactions: an introduction: Springer Science & Business Media.
Newton, C. and Holopainen, E. O. (Eds.), 2018, Extratropical Cyclones: The Erik Palmen Memorial Volume, Springer.
Pfahl, S. and Wernli, H., 2012, Quantifying the relevance of cyclones for precipitation extremes. Journal of Climate, 25, 6770-6780.
Pinto, J. G., Spangehl, T., Ulbrich, U. and Speth, P., 2005, Sensitivities of a cyclone detection and tracking algorithm: individual tracks and climatology. Meteorologische Zeitschrift, 14, 823-838.
Raveh‐Rubin, S. and Wernli, H., 2016, Large‐scale wind and precipitation extremes in the Mediterranean: dynamical aspects of five selected cyclone events, Quarterly Journal of the Royal Meteorological Society, 14, 3097-3114.
Schneider, T., 2004, The tropopause and the thermal stratification in the extratropics of a dry atmosphere, Journal of the atmospheric sciences, 61, 1317-1340.
Staley, D. O., 1960, Evaluation of potential-vorticity changes near the tropopause and related vertical motions, vertical advection of vorticity, and transfer of radioactive debris from stratosphere to troposphere, 17, 591-620.
Vecchi, G. A., Fueglistaler, S., Held, I. M., Knutson, T. R. and Zhao, M,. 2013, Impacts of atmospheric temperature trends on tropical cyclone activity, Journal of Climate, 26, 3877-3891.
Wang, S., Camargo, S.J., Sobel, A.H. and Polvani, L. M., 2014, Impact of the tropopause temperature on the intensity of tropical cyclones: An idealized study using a mesoscale model. Journal of Atmospheric Sciences, 71, 4333-4348.
Wirth, V., 2001, Cyclone–anticyclone asymmetry concerning the height of the thermal and the dynamical tropopause. Journal of the atmospheric sciences, 58, 26-37.
WMO Bulletin, Volume VI, No. 4: October 1957-WMO Library.