Analysis of Instability Indices during severe weathers, in Mashhad Metropolis

جغرافیا و مخاطرات محیطی

Article 6, Volume 3, Issue 1 - Serial Number 9, January 2014, Pages 113-123   

Document Type: Research Article

DOI: 10.22067/geo.v3i1.27409

Authors

Hassan Salehi^* ; Hossein Saneinejad; Mohammad Mousavi Baygi

Ferdowsi University of Mashhad

Abstract

1. Introduction
Increasing of extreme events such as flood, hailstorm, drought, thermal waves, dust storm and other dangerous climatological events, especially in local scale, could be the result of the climatic change over the globe. The characteristics and impacts of severe weather are function of place and time of occurrence. Severe weathers are usually accompanied by strong winds and heavy hailstones, which are very destructive. They develop and then downfalls very fast. This is the reason that makes forecasting of these phenomena difficult. It is very important to study severe weathers from both thermodynamic and dynamic points of views. The aim of this study was to improve forecasting by investigating the relationship between upper atmosphere conditions and surface weather conditions in Mashhad, Iran.
Showalter (1953) introduced an index named SI for determining the amount of instability and prediction of the thunderstorm and hailstorm. Galway (1956) extracted the lifting index of LI among his studies over convective events. His index is more or less similar to that of SI index and their thresholds amount for occurring the thunderstorm and hail are same. George (1960) developed a simple formula for calculating K index using dry bulb and dew point temperatures in different atmospheric level. Miller (1972) introduced the SWEAT and TT indices by combining some different indices. Miller and Mancriff (1976) have been finally developed a strong index of CAPE for evaluating the potential activity of the thunderstorm.
2. Study Area
In this research, Mashhad synoptic and upper atmosphere station, is located in the northeast of Iran with 36° 16´ N latitude and 59° 38´ W longitude, was selected as the study area, and severe instabilities that occur during 1980-2009 were used for analysis.
3. Material and Methods
In this research, we try to introduce the parameters and instability indices and try to prepare the summary of their thresholds to anticipate the kinds of instabilities. Therefore, set of parameters and indices is calculated specifically for Mashhad station as follows: showalter index, lifted index (LI), SWEAT, K index (KI), total totals (TT), convective available potential energy (CAPE), CIN, and equilibrium level pressure(EL), precipitable water (PW), Bulck Richardson number (BRN). Severe instabilities which occurred during 1980- 2009 are used in this analysis. The severe instability reports were obtained from the METAR, SYNOP, and Special meteorological reports, and also from synoptical notebooks. The international criteria for severe instabilities [winds greater than 50 knot (25 m/s), all kind of hail reports, all kind of thunderstorms, lightnings, squalls, funnel clouds, and tornado or waterspout] were used. All of these reports have been classified in three categories: Lightning, thunderstorm, and hail. The days with no of these criteria are called no-instability. Instability Indices were derived from radiosonding data of Mashhad upper air synoptic station that collected in Wyoming University database.
4. Results and Discussion
For most indices, the threshold that gives the best prediction was determined using statistical methods, box plots, and scatter plot diagrams.
For achievement to better results, relationship between two different indices in forecasting of phenomena was analysed, and complex of each pair of indices such as CAPE with lifted index (LI), and lifted index with equilibrium level pressure (EL), that had a strong relationship, introduced as the best combination indices.

Table 1 Lower and upper thresholds for instability indices during various severe weathers in Mashhad.

Lightning threshold Thunderstorm threshold Hail threshold Indices & Units

-

CAPE (J/Kg)
-

SWEAT



SI(°C)



LI(°C)



KI(°C)



TT(°C)
- -
PLCL (hPa)



TLCL (°K)
-

LFC (hPa)



EL (hPa)



(g/Kg)

The threshold of most individual indices, which gives the best prediction for different kinds of phenomena was determined and introduced, that are summarized in table 1. Then upper and lower thresholds of different indices in forecasting of severe weathers were showed in box plots, and scatter plot diagrams. Finally, relationship between two different indices in forecasting of phenomena was discussed, and complex of CAPE with lifted index (LI-CAPE), and lifted index with equilibrium level pressure (LI-EL), had a power relationship and introduced as the best combination indices.
5. Conclusion
A set of sounding data was carried out in Mashhad station, in the period 1980-2009 were analyzed and the result is that using instability indices, has very good performance in predicting and warning of severe weathers. In this study, 12UTC sounding has better result than 00UTC for severe weather forecasting. For some indices such as Richardson number (BRN), convective inhibition (CIN), and thickness results were not favorable. Using these parameters individually may result in error for prediction, and it is necessary that all indices are used in combination with each other and, synoptical methods of forecasting.

Keywords

Severe weather; forecasting; Radiosonde; Atmospheric dynamic; Mashhad

References

امینی، ل؛ 1379 . بررسی انرژی پتانسیل در دسترس در یک سیستم همرفتی. پایان نامه کارشناسی ارشد، دانشگاه تربیت مدرس، دانشکده منابع طبیعی و علوم دریایی نور. به راهنمایی هوشنگ قائمی.

امیدوار، کمال، و همکاران؛ 1392. واکاوی ترمودینامیکی بارشهای سنگین ناشی از پدیده سردچال در نواحی مرکزی و جنوب غرب ایران (مطالعه موردی: رخداد بارش 11 آذر 1387)؛ جغرافیا و مخاطرات محیطی، شماره 5: صص 1- 19.

ثنایی‌نژاد، ح؛ صالحی، ح؛ بابائیان؛ 1389. تحلیل سینوپتیکی و دینامیکی پدیده‌های همرفتی محلی به منظور بهبود پیش‌بینی آن‌ها. چهاردهمین کنفرانس ژئوفیزیک ایران، تهران اردیبهشت 89، صص 234-237.

صادقی حسینی، ع؛ رضائیان، م؛ 1385. بررسی تعدادی از شاخص‌های ناپایداری و پتانسیل بارورسازی ابرهای همرفتی منطقه اصفهان؛ مجلة فیزیک زمین و فضا، 32 (2): 83 تا 98.

عبدمنافی، د؛ 1383. بررسی شاخص‌های ناپایداری، برش قائم باد و وضعیت‌های رطوبتی در هنگام نزول تگرگ در تهران. پایان‌نامه کارشناسی ارشد، دانشگاه آزاد واحد تهران شمال. به راهنمایی حسن عسکری شیرازی و مشاوره حسن خالقی زواره.

Abdemanafi, D., 2002. Analysis of instability indices, vertical wind shear and humidity conditions during hail in Tehran. M.Sc. Thesis, Islamic Azad University of Tehran shomal. Supervisor: H., Askari Shirazi.

Amini, L., 2000. Analysis of available potential energy in a convective system, M.Sc. Thesis, Tarbiat Modares University. Supervisor: H., Ghaemi.

Costa, S., Mezzasalam, P., Levizzani, V., Alberoni, P., and Nanni, S., 2001. Deep convection over Northern Italy: synoptic and thermodynamic analysis. Atmospheric Research 56, 73- 88

Craven, J.P., H.E. Brooks, 2004. Baseline Climatology of Sounding Derived Parameters Associated with Deep, Moist Convection. National Weather Digest, 28: 13-24.

Dahl, J. M. L., 2006. Supercells, Their Dynamics and Prediction. M.sc. Thesis, Institute of Meteorology, Free University of Berlin, Germany.

Galway, J. G., 1956. The lifted index as a predictor of latent instability. Bulletin of the American Meteorological Society 37, 528–529.

Gottlieb, R. J., 2009. Analysis of Stability Indices for Severe Thunderstorms in the Northeastern United States. M.Sc. Thesis, Cornell University, Ithaca, USA

Groenemeijer, P., 2005. Sounding-derived parameters associated with severe convective storms in the Netherlands. M.Sc. thesis, Institute of Marine and Atmospheric research Utrecht (IMAU), The Netherlands

Haklander, A. J., A. Van Delden, 2003. Thunderstorm predictors and their forecast skill for the Netherlands. Atmospheric Research 67-68: 273-299.

Huntrieser, H., H.H. Schiesser, W. Schmid, and A. Waldvogel, 1997. Comparison of traditional and newly developed thunderstorm indices for Switzerland. Weather Forecasting 12, 108-125.

Krauss, T. W., Santos, J. R., 2004. exploratory analysis of the effect of hail suppression operations on precipitation in Alberta: Atmospheric Research, 71, 35-50.

LaPenta, K.D., G.J. Malagras, J.W. Center, S.A. Munafo, and C.J. Alonge, 2002. An updated look at some severe weather forecast parameters. Eastern Region Technical Attachment No. 1.

Manzato, A., and Morgan Jr. G., 2003. Evaluating the sounding instability with the lifted parcel theory: Atmospheric Research 67-68, 455-473.

Marinaki, A., M. Spiliotopoulos, and H. Michalopoulou, 2006. Evaluation of Atmospheric Instability Indices in Greece. Advances in Geosciences 7, 131–135.

Moncrieff, M.W. M.J. Miller, 1976. The dynamics and simulation of tropical cumulonimbus and squall lines. Royal Meteorological Society 102: 373-394.

Sadeghi Hosseini, A., Rezaeian, M., 2004. Analysis of some instability indices and convective cloud seeding potential in Isfahan. Earth and space physics. 32(2): pp 83-98.

SanaeiNejad, H., Salehi, H., Babaeian, I., 2009. Dynamic and Synoptic Analysis of convective local phenomena. 14th Geophysics Conference of Iran. Tehran. pp 234-237.

Showalter, A. K., 1953. A stability index for thunderstorm forecasting. Bulletin of the American Meteorological Society 34: 250-252.

Simoenov, P., and Georgiev, C. G., 2001. A case study of tornado-producing storm south of Rhodopes Mountain in the Eastern Mediterranean: Atmospheric Research, 57: 187-199.

Sioutas, M. V. and Flocas, H. A., 2003. Hailstorms in Northern Greece: synoptic patterns and thermodynamic environment. Theoretical and Applied Climatology 75: 189–202.

Thompson, R. L., R. Edwards, J. A. Hart, K. L. Elmore, and P. Markowski, 2003. Close proximity soundings within supercell environments obtained from the Rapid Update Cycle. Weather Forecasting 18: 1243-1261.

Tuschy, H., 2009. Examination of severe thunderstorm outbreaks in Central Europe. M.sc. Thesis, University of Innsbruck, Austria.