İstanbul’da 8-9 Eylül 2009’da Meydana Gelen Aşırı Yağışın HARMONIE, HIRLAM ve WRF-ARW ile Simülasyonu

Öz

Türkiye'nin kuzeybatısında farklı yerlere birkaç saat içinde büyük miktarda yağış meydana gelmiştir. Sinoptik duruma bakıldığında Akdeniz üzerinde bir kaç günlük tipik bir sonbahar konvektif durum görülmektedir. Bu çalışmada, 8–9 Eylül 2009 tarihlerinde meydana gelen aşırı yağışın üç farklı sayısal hava modeli (HARMONIE, Yüksek Çözünürlük Sınırlı Alan Modeli (HIRLAM) ve WRF) kullanarak tahmin yeteneklerini değerllendirmektedir. Her bir model yağış tahminleri bölgedeki 28 yağış gözlemleriyle karşılaştırılmıştır. Sel felaketine sebep olan bu tehlikeli durumu farklı sayısal hava tahmin modelleri ile derinlemesine incelemek önemlidir. Hidrometeorolojik olay olan aşırı yağış ve ani selin tahmini özellikle çok kalabalık bölgelerde çok zordur. Ani seller yağış süre ve miktarı, topografya yer yürüzü kullanımı gibi çeşitli faktörlere bağlıdır. Tüm modeller İstanbul batısı baz alınarak çalıştırılmıştır. Her üç modelde bölgede yoğun yağış tahmin etmektedir, ancak, en yoğun yağış alanlarının yerleri onlarca kilometer uzaklıktadır. Modeller, aşırı yağışların sinyallerini iyi tahmin etmektedir, ancak maksimumların konumları, gözlenen yerlere göre farklıdır.

Anahtar Kelimeler

• Yağış,doğal felaketler,tahmin,modelleme

Simulating Heavy Precipitation with HARMONIE, HIRLAM and WRF-ARW: A Flash Flood Case Study in İstanbul, Turkey

Abstract

A big amount of precipitation was recorded in a few hours over different places in northwest Turkey. The synoptic situation covers a couple of days in a typical convective situation in autumn over the Mediterranean. The paper discusses the ability of three different NWP models (HARMONIE, High Resolution Limited Area Model (HIRLAM) and WRF) to forecast a heavy precipitation event that occurred on 8–9 September 2009. The precipitation forecast for each model is compared against rainfall observations from 28 meteorological stations in the region. This event was a destructive flood, and for that reason, it is important to study in depth the skill of different NWP models in such hazardous cases. Flash flood is a hydro meteorological phenomenon, and its forecast is a very difficult task, especially in very populated areas. Flash floods depend on several factors; the outstanding one, of course, is the amount of precipitation, but also the rate of precipitation, topography, etc. All models are performed on domains centred on the Thracian region (north-western Turkey). All three models forecast heavy rainfall in the area; however, the locations of the most intense rainfall are off by several tens of kilometres. The models forecast good signals of heavy precipitation, but locations of the forecasted maxima are shifted with respect to the observed locations.

Keywords

• Rainfall,natural hazards,forecasting,modelling

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