صحت سنجي خروجي مدل SWAN با فراسنج هاي اقليمي شاهد

Verification of SWAN model outputs with buoy data on wave height and period

پيش بيني وضع دريا و نقش آن در حمل و نقل دريايي، كشتيراني، شيلات ، صيادي  و نيز در امور تخصصي بر همگان روشن است. با بهره گيري بهينه از مدلهاي مختلف و شناخت از ميزان صحت و دقت آنها، مي توان گام هايي موثر در جهت تحقق اين مهم برداشت . يكي از مدلهايي كه مطالعه تحقيقاتي در مورد آن مفيد مي باشد، مدل SWAN است و براي ارزيابي عملكرد اين مدل از نظر اجرايي و علمي، مطالعه در خصوص راستي آزمايي محصولات آن لازم است. در اين مطالعه ، خروجي ارتفاع و تناوب موج حاصل از اجراي مدل مذكور با داده هاي شاهد موجود براي بوشهر و عسلويه مورد راستي آزمايي قرار گرفته است. با انجام اين تحقيق سعي بر آن است كه ميزان دقت و صحت خروجي اين مدل با مقادير متناظر موجود از فراسنج هاي شاهد و كارايي آن در پيش بيني هاي12، 24، و 48 ساعت و بيشتر مورد بررسي و ارزيابي قرار گيرد. در فرايند راستي آزمايي با تشكيل جدول توافقي به دنبال بررسي انطباق  داده هاي اقليمي شاهد با خروجي مدل  براي دو فراسنج ارتفاع و تناوب موج هستيم. بدين منظور درصد صحت مدل را به ازاي مقادير مدل و داده هاي شاهد در بازه هاي زماني T<=2s،s   2s 5 sبراي تناوب و h<=25cm،  25 cm50cmبراي ارتفاع موج به مدت 12، 24، 48 ، 72 و 99 ساعت در نظر گرفتيم. در اين تحقيق همچنين امتيازهاي مهارتي مدل براي پيش بيني ارتفاع و تناوب موج محاسبه گرديده اند. ميانگين خطاي مطلق و نسبي مدل با داده هاي شاهد براي  پيش بيني 24 تا 99 ساعت محاسبه و در جدول11 فقط مقادير مربوط به 48 ساعت كه در مجموع از دقت بالاتري برخوردار بوده اند درج شده است. نمودارهاي سري زماني ارتفاع و تناوب موج مدل وديدباني ناشي از بويه ترسيم شده اند. نتايج نهايي از جمع بندي  تحليل ها بدست آمده اند.

Introduction Forecasting sea state and its role in marine transportation, shipping, fishery, fishing and professional affairs, is clear. By Using different models and identifying accuracy and precision of them can effectively achieve to these. One of the useful models is SWAN. For evaluating the performance of this model in aspect of executive and scientific both, study on verification of its products is required. In this study, the model outputs of wave height and period in the case of Bushehr and assaluyeh have been verified. With this study it is tried on the accuracy of the model outputs with the corresponding values of Buoy and its performance on predictions 12, 24, 48, 72 and 96 hours studied and assessed. Materials and methods In the verification process by using the adaptive table we want to control climatic data with the model output for both wave height and period parameters. For this purpose, threshold values smaller than or equivalent with 2 seconds and smaller than 5 seconds and the values between two mentioned thresholds for wave period also values h<=25cm،, 25 cm50cm for wave height were calculated. Moreover the skill scores of models for predicting wave height and period were calculated. Mean absolute and relative errors with the SWAN model and Buoy data for 48 hours forecasting were calculated and listed in Table. As a sle graphs of the measured wave period and measured height wave by Buoy, with the predicted value of them are plotted. Summarized findings results of the analysis are obtained. By examining the output values ​​from the model and observation data for two regions of Bushehr and Assaluyeh and setting minimum and maximum values ​​for the two parameters, the mention ranges are defined. Results and discussion In Assaluyeh region more than 60 percent of cases, the wave height was between 25 cmT >5s and less than 22 percent wave’s frequency was 5s T> s2 and more than 72 percent frequency waves was T>5 s. Values ​​obtained from the skill scores for forecasts 12, 24, 48, 72 and 99 hours shows that the model predictions for the both parameters   in 48 hours forecasting  in any two regions of Bushehr and Assaluyeh has high accuracy. Proportion Correction (PC) Values ​​ shows that more than of 94 percent, predicting the occurrence or nonoccurrence waves frequency and more than 86 percent for the wave height performed correctly and in Assaluyeh this value for the wave frequency of more than 64 percent for wave height of more than 88 percent of cases have been performed correctly. Overall results of SWAN model verification on wave height and frequency have acceptable accuracy. The mean absolute errors of observation data show that the model accuracy for wave height is greater than its accuracy for the wave frequency.