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題名 | 紫外線指數的分析與預報=Analysis and Forecast of Ultra-Violet Index |
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作者 | 馮欽賜; 楊明仁; | 書刊名 | 氣象學報 |
卷期 | 43:1 1999.12[民88.12] |
頁次 | 頁11-26 |
分類號 | 328.481 |
關鍵詞 | 紫外線指數; UVI預報; Ultra-violet index; |
語文 | 中文(Chinese) |
中文摘要 | 成功的紫外線指數(UVI)預報,有賴於對雲衰減作用的正確預估。鑑於雲量將會成為氣象局每日預報的對象,本研究分析臺北和臺東成功兩測站自1994年至1996年的紫外線指數資料與對應時間目測的雲量之關係,希望由此進一步提出根據雲量預報資料從事紫外線指數預報的方法。在研究方法上,首先從紫外線指數分離出雲效應的影響,由觀測資料的分析取得各測站晴天時UVI的估計值,再以觀測UVI與晴天UVI之比值定義一個雲衰減因子,並歸納雲量為四個類別(1)晴天(2)疏雲(3)多雲(4)陰天,將雲衰減因子與雲量的相關性定量化。根據這些統計特性,提出本研究以雲量為基礎的紫外線預報法。預報技術的測試顯示,本研究之預報法的表現在臺北和成功兩測站的誤差均方根分別為1.72及1.85,其中絕對誤差在1以內的準確個案占60% 左右。此外,無論對應的UVI觀測值是大或小,UVI預報值的絕對誤差範圍表現都相當平均,顯示本預報法在各種條件下都能保持一定的預報水準。 |
英文摘要 | A successful forecast of the Ultra-Violet Index (UVI) mainly depends on the correct estimation of cloud attenuation effect. Since the cloud amount may become one of daily forecast items at the Central Weather Bureau in the future. this research conducted analysis of UVI and observed cloud-amount data at Taipei and Cheng-Kung stations from 1994 to 1996, in order to provide a UVI prognostic method based on cloud amount information. We first isolated the cloud effect on the UVI. The clear-sky UVI value of each station was determined from the UVI observations, and a Cloud Attenuation Factor (CAF) was defined as the ratio between the observed UVI and the clearsky UVI. The corresponding relations between CAF and cloud amount were quantified by four categories of cloud amount: (1) clear, (2) scattered, (3) broken, and (4) overcast. A UVI forecast method was proposed based on the statistical characteristics of CAF and cloud amount. The predicted UVI by this forecast method has root-mean-square errors of 1.72 and 1.85 at Taipei and Cheng-Kung stations, respectively; 60% of the forecast events have absolute errors less than 1.The standard deviation of predicted UVI is very small regardless of the value of observed UVI, which indicated that this UVI prediction method can maintain certain forecast performance under different sky conditions. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。