查詢結果分析
來源資料
頁籤選單縮合
題名 | 地面雙頻微波輻射計觀測濕遲延之空間變化=Spatial Variation in Atmospheric Wet Delay Observed by a Ground-Based Dual-Channel Radiometer |
---|---|
作者姓名(中文) | 劉說安; | 書刊名 | 航測及遙測學刊 |
卷期 | 4:3 1999.09[民88.09] |
頁次 | 頁31-41 |
分類號 | 328.6 |
關鍵詞 | 濕遲延; 亮溫; 光程; Wet delay; Brightness temperature; Optical depth; |
語文 | 中文(Chinese) |
中文摘要 | 本研究應用水汽微波輻射儀(Water Vapor Radiometer; WVR) 觀測大氣水汽 對全球定位系統(Global Positioning System; GPS)訊號延遲之影響,該影響量即所謂濕 遲延(Wet Delay, WD)。首先,使用了民國七十七年到八十六年三月間在臺北氣象站氣球 探空觀測資料做分析,推導亮溫 (brightness temperature)及光程估算濕遲延之迴歸公 式。其次,於民國八十七年三月十八日到二十五日間在臺北氣象站進行實驗,蒐集23.8 及31.4GHz 兩頻率的亮溫觀測,觀測時水平角設定在東西及南北走向兩方向轉換,仰角則 設定在15° 及165°間,每15°做一次觀測。最後,分析WVR觀測資料,在天頂方向時, 濕遲延變化範圍約介於晴天的14.8cm 到陰雨天的40.8cm間。此外,成層化大氣之假設, 隨著仰角偏離天頂方向而逐漸失真,在仰角165°時誤差可達8.3cm。 |
英文摘要 | A ground-based water vapor radiometer (WVR) was utilized to investigate the influence of water vapor on the propagation of Global Positioning System (GPS) signals through the atmosphere. The influence is in general characterized as so-called "wet delay" (WD). WD were inferred from brightness temperatures at 23.8 and 31.4GHz observed by WVR installed at Taipei weather station from March 18 to 25,1998, and the corresponding opacity depths. During the field campaign, the WVR was initially installed due east, while it was turned to north periodically. An elevation mirror is used to guide atmospheric emission to the antenna. It is designed to rotate perpendicularly to the WVR itself so that elevation angles can be automatically adjusted to scan the atmosphere every 15° at angles between 15 ° and 165°. In order to derive retrieval coefficients, radiosonde data collected at Taipei weather station in each March starting from 1988 to 1997 were used. WD from WVR measurements varies from 14.8cm for clear sky to 40.8cm for rainy/cloudy conditions at zenith. WD observations at angles from 15° to 165° indicate that stratified atmosphere becomes an less appropriate assumption with viewing angles departing from zenith. The deviation is increased to as much as 8.3cm at angle of 165°. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。