بررسي موردي عملكرد مدل WRF جهت پيش‌يابي ميدان باد تراز 10 متر و دماي تراز دومتر با استفاده از داده‌هاي ماهواره‌اي و ايستگاه‌هاي همديدي در منطقه درياي عمان و درياي عرب

A Case study of WRF model performance to hindcast of 10-m wind and 2-m temperature against the satellite and synoptic stations data over the Gulf of Oman and The Arabian Sea

در پژوهش حاضر شبيه‌سازي پيش‌يابي و ارزيابي ميدان‌ باد تراز 10 متر و همچنين دماي تراز دومتر با مدل ميان‌مقياس WRF نسخه 1. 7. 3 در منطقه درياي عمان و درياي عرب انجام شده است. تمامي شبيه‌سازي‌ها براي دو پيكربندي متفاوت از ديدگاه پارامترسازي فيزيكي كه به نام‌هاي Phys1 و Phys2 معرفي شده‌اند، انجام شده است. ارزيابي نتايج شبيه‌سازي با استفاده از داده‌هاي ايستگاه‌هاي همديدي در دسترس و همچنين داده‌هاي دو سنجنده ماهواره‌اي ASCAT و OSCAT انجام شده است. براي بررسي عملكرد مدل عددي از سنجه‌هاي آماري مانند ضريب همبستگي پيرسون، ريشه ميانگين مربعات خطاها و نمودار آماري تيلور استفاده شده است. نتايج نشان مي‌دهند كه در بخش ارزيابي با داده‌هاي ماهواره‌اي باد تراز 10 متر نتايج عملكرد مدل، قابل قبول و مناسب بوده است. در اين بخش شبيه‌سازي‌هاي براي مناطق دور از ساحل كه به‌كمك داده‌هاي ماهواره‌اي ارزيابي شده‌اند، نسبت به داده‌هاي ايستگاه‌هاي همديدي ساحلي و نزديك ساحل، به مقادير مشاهدات نزديك‌ترند. نتايج حاصل از ارزيابي دماي تراز دو متر نيز گواه عملكرد مناسب مدل در اين بخش است.

Reliable and sufficient information of 10-m wind and temperature fields over open seas and near coastlines is a necessary and important data that has impact on many marine activities. Assimilation of NWP models can be used to assess an estimation of these fields. This study reports the performance of the weather research and forecasting (WRF) model to hindcast 10-mwind and temperature fields that were evaluated under two different physical options of planetary boundary layer (PBL) and surface layer (SL) for an area over the Gulf of Oman and the Arabian Sea. The case study includes 16 simulations of 8 different days from WRF model version 3.7.1. The WRF model is configured with two nests. Parent nest has 0.3 degree and the inner nest has 0.1 degree horizontal grid resolution. The grid spacing of the inner domain is almost 11-km. The Lat-Lon (latitude-longitude) method is used as the map projection method. For all domains and all runs 39 terrain following vertical levels are set. The validation of the simulated fields is done considering two observational datasets (the weather stations for 10-m wind and 2-m temperature and satellite instruments just for 10-m wind). Near-surface observations of 2-m temperature and 10-m wind speed and direction are collected from 55 weather stations, located within the chosen area. The measurements from satellite instruments have become an important source of data in the regions that in-situ observations are sparse like seas and oceans, hence observations from two different scatterometers (ASCAT and OSCAT) are also used to evaluate 10-m wind simulations. Moreover, in order to better understand the model performance for different choices of the physical schemes, sensitivity of the model has been investigated. There is plenty of choices for the combination of parameterization schemes available for WRF model; for the current study two configurations are taken from other’s previous published research works. The physical parameterization that used in this study are Revised MM5 and Monin-Obukhov for surface layer and MRF and MYJ for planetary boundary layer. These choices are used to create two different configurations called Phys1 and Phys2. Comparison between winds from satellite scatterometer and simulated winds show very little difference and hence good agreement with observations. Acceptable accuracy has been obtained from statistical analyses. These analyses demonstrate that the maximum average RMSE of wind field is 2.39 m/s, based on results of comparing with ASCAT data and it is 2.37 m/s, based on results of comparing with OSCAT data. The analyses also show that simulation of wind fields have better results over offshore regions than coastlines weather stations. The outcome shows that the simulated 10-m wind present acceptable general skills over the sea. The validation of 2-m temperature presents that the model has a proper estimation about temperature field over the coasts and near coastal station within the simulation domain. The maximum average RMSE of temperature field is 2.6 degrees of centigrade. Finally, without any justification to run WRF for longer periods from a quantitative and qualitative assessment of the results, it can be concluded that for the WRF model has an acceptable performance to simulate 10-m wind and 2-m temperature over the Gulf of Oman and the Arabian Sea. It should be noted that to verify these results for longer periods more similar experiments must be tested.