بررسی توزیع زمانی بارش‌های روزانه با روش منحنی‌های بارش نرمال (NRC) (مطالعه موردی: ایستگاه تبریز)

نوع مقاله: مقاله پژوهشی

چکیده

در این مطالعه، با استفاده از آمار روزانه ایستگاه هواشناسی تبریز به­بررسی منحنی­های بارش نرمال (NRC) پرداخته شد. برای این منظور، مقدار بارش روزانه به­ همراه تعداد روزهای بارانی به­صورت تراکمی در نظر گرفته شد و به­ترتیب، با  و  نشان داده شد، آنگاه منحنی­های NRC براساس معادله­های   و   بسط داده شد، این­ روش هم برای تمامی روزهای دوره آماری و هم برای هر ماه، به­طور جداگانه، در طول دوره آماری به­کار گرفته شد. مقادیر پارامترهای مدل­ها با روش بهینه­سازی و با گزینه solver در نرم­افزار اکسل تخمین زده شدند. افزون بر این، چند مدل دیگر ریاضی (از جمله، مدل چندجمله­ای درجه nام، توانی، توانی اصلاح شده، نمایی، نمایی پیوسته و ...) نیز برای داده­های  و  توسط نرم افزار Curve Expert 1.3 بسط داده شد. در نهایت، مدل با کمترین مقدار RMSE و بیشترین مقدار  به­عنوان مناسب­ترین مدل معرفی گردید. نتایج نشان داد که تقریبأ در همه موارد، مدل  کمترین مقدار RMSE (4858/0 میلی­متر) و بیشترین مقدار  (9996/0) را دارا بود. بنابراین، مدل مذکور به­عنوان مناسب­ترین مدل برای بسط منحنی­های NRC تبریز انتخاب شد. در مقیاس ماهانه، معیار RMSE از کمینه 22/0 میلی­متر (در ماه سپتامبر) تا بیشینه 67/0 میلی­متر (در ماه آوریل) تغییر می­کند. در حالی­که مقادیر  این دو ماه، به­ترتیب، 9999/0 و 9993/0 به­دست آمد.

کلیدواژه‌ها


عنوان مقاله [English]

Investigation of Temporal Distribution of Daily Rainfall Using the Normalized Rainfall Curves (NRC) (Case Study: Tabriz Station)

چکیده [English]

In this study, by use of the daily rainfalls of Tabriz weather station the normalized rainfall curves (NRC) were investigated. For this purpose, the cumulative amount of daily rainfalls with the cumulative number of rainy days were considered and shown by and , respectively. Then, the NRCs were extracted according to the equations of  and . This approach was applied to all days and every months of the data recording time period, separately. The parameters of models were estimated using the solver option in Excel software by the optimization method. Moreover, some of the other mathematical models (including the n-th degree polynomial, power, modified power, exponential, continuous exponential, etc.) were derived for and data by the Curve Expert 1.3 software. Among the all extracted models, a model having the lowest RMSE and highest  was introduced as the most appropriate one. The results showed that, approximately, in the all cases the  model with the lowest RMSE value (0.4858 mm) and the largest amount of  (0.9996) was known as the most appropriate model to derive the NRCs of Tabriz station. Furthermore, in monthly time scale the amount of RMSE varied from 0.22 mm (in September) up to 0.67 mm (in April). The  values for these two months obtained as 0.9999 and 0.9993, respectively.

کلیدواژه‌ها [English]

  • Daily rainfall
  • Experimental model
  • Normalized rainfall curves
  • Tabriz
  • Temporal distribution
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