Performance analysis of the SWAN model results forced with the ERA5 and ERA-Interim winds

Abstract

This study investigated whether a new re-analysis of ECMWF contributes to wave hindcast performance in the Black Sea. For this purpose, ERA5 and ERA-Interim winds presented by ECMWF were downloaded in order to have an inter-comparison of ECMWF datasets. For performance evaluation of wave hindcasts, third generation wave hindcast model SWAN was run with a default setting. Wave hindcast outputs such as significant wave height (Hm0), mean wave period (Tm02) and mean wave direction were obtained as a result of default setting SWAN run. These hindcasts were compared with wave measurements at three buoys (Gelendzhik, Hopa, Sinop) installed in the Black Sea in 1996 as part of NATO TU-WAVES project. During performance evaluation, error statistics, time series, scatter plots, quantile graphics and wave roses were examined. In error statistics, for example bias observed for Hm0 compared to measurement and model data at Hopa was 0.317 m for ERA-Interim forcing and 0.261 m for ERA5 forcing. As a result of this all evaluation process, it was revealed that in the Black Sea ERA5 produced in the recent years by ECMWF presents a more advanced wind data set in comparison to the ERA-Interim winds because default setting SWAN model performs better in the case of ERA5 winds.

Keywords

• ERA5,ERA-Interim,SWAN model,Black Sea

ERA5 ve ERA-INTERİM RÜZGARLARI İLE ÇALIŞTIRILAN SWAN MODEL SONUÇLARININ PERFORMANS ANALİZİ

Abstract

Bu çalışmada, Avrupa Orta Vadeli Hava Tahmin Merkezi (ECMWF)’nin yeni yeniden değerlendirme (reanaliz) veri setinin Karadeniz bölgesi dalga tahminine katkı yapıp yapmadığı araştırılmıştır. Bu maksatla, ECMWF’in veri tabanından hem ERA5 hem de mukayese yapmak maksadıyla ERA-Interim veri setlerinin rüzgar verileri indirilmiştir. Performans değerlendirilmesi için dalga tahminlerini gerçekleştirmek maksadı ile bu rüzgar verisini kullanan üçüncü nesil dalga tahmin modeli olan SWAN varsayılan ayarlamalı olarak çalıştırılmıştır. Varsayılan ayarlamalı SWAN simülasyonu sonucunda belirgin dalga yüksekliği (Hm0), ortalama dalga periyodu (Tm02) ve ortalama dalga yönü gibi dalga parametreleri elde edilmiştir. Bu tahminler 1996 yılında NATO TU-WAVES projesi kapsamında Karadeniz’e kurulan şamandıra ölçüm istasyonlarından üçünün (Gelendzhik, Hopa, Sinop) dalga ölçümleri ile kıyaslanarak performansları irdelenmiştir. Performans değerlendirmesi sırasında hata istatistiği parametreleri, zaman serisi grafikleri, saçılım diyagramları, kuantil grafikleri ve dalga gülleri incelenmiştir. Hata istatistiği parametrelerinde örneğin Hopa şamandıra ölçüm verisi ile model veri setleri kıyaslandığında, belirgin dalga yüksekliğinde gözlenen ortalamaların farkı (bias) ERA-Interim veri setinde 0,317 m iken ERA5 veri setinde 0,261 m değerini almıştır. Tüm bu değerlendirme süreci sonucunda ise, Karadeniz özelinde ECMWF tarafından son yıllarda üretilmiş ERA5 model rüzgarlarının dalga modellerine girdi olarak tanımlandığında ERA-Interim rüzgarlarına kıyasla daha doğru dalga tahmini sağladığı sonucuna varılmıştır.

Keywords

• ERA5,ERA-Interim,SWAN model,Karadeniz

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