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題名 | 地面微波遙測資料在大氣水汽含量估算上之研究=Applying Ground based Microwave Radiometer Data in Estimating Atmospheric Water Vapor Content |
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作者 | 劉振榮; 高而正; 林唐煌; | 書刊名 | 大氣科學 |
卷期 | 24:3/4 民85.09-12 |
頁次 | 頁165-188 |
分類號 | 328.2 |
關鍵詞 | 水汽吸收頻道; 總水汽含量; 微波輻射儀; Water vapor absorption channels; Total water vapor content; Microwave radiometer; |
語文 | 中文(Chinese) |
中文摘要 | 利用微波水汽吸收頻道可偵測到水汽放射的特性,由此放射訊號經由估算模式,更可推求大氣中的總水汽含量。本研究所應用的地面微波輻射儀為22.235GHZ之被動式微波輻射儀,由此輻射儀之天線所接收的大氣輻射值可用來進行大氣水汽含量之分析。本研究主要為求取不同型態大氣之總水汽含量和其輻射值間之關係,而利用地面徵波輻射儀之量測資料,將可建立大氣輻射值和其總水汽含量之關係。此外本研究亦以輻射儀對大氣之量測,推求大氣水汽含量剖面和露點剖面預以及不同土壤含水量之放射強度變化情形。 研究結果顯示,就晴空天氣狀況而言,若大氣中之總水汽含量越多,則由地面微波輻射儀所量取之亮度溫度值會相對增大,此乃因水汽放射之結果。就有雲的天氣狀況而言,輻射儀所接收到的亮度溫度值會比晴天狀況下高,一般而言,雲層愈厚,則輻射儀所接收到的輻射值也就愈大。在資料分析誤差方面,晴天、薄雲和厚雲資料的總水汽含量之均方根誤差分別為0.4891cm 、0.4097cm和0.3866cm。在本研究中另使用連續性微波輻射儀觀測資料推估總水汽含量並比較探空資料所觀測的總水汽含量,其檢驗結果顯示其相關性與推估結果均甚合理,特別是對於晴空的天況下。在水汽含量剖面誤差分析上,均方根誤差百分比大都小於百分之三十,但高層則遠大於百分之三十。而就露點溫度均方根誤差剖面而言,最大時高達演4.5℃。對於量測土培含水量之結果顯示,土壤含水量多寡會澶響輻射值,且土壤含水量較多,輻射值會相對減小。 |
英文摘要 | Using microwave water vapor absorption channels to sense the properties of water vapor emission signals and analyze by the water vapor estimation model, the total water vapor content could be estimated. The methodology of this research is to apply the ground-based 22.235 GHZ passive microwave radiometer to detect the atmospheric radiation and assess the water vapor content, and to investigate and establish the relationships between the atmospheric radiation and water vapor for various weather patterns. Another aim of this research is to study the atmospheric water vapor profile, dew point profile and the emission density variation related to the soil moisture. The result of this research showed that the brightness temperature measured by microwave radiometer is proportional to the total water vapor content in Cleary sky cases. It is contributed by the water vapor emission. For the cloudy sky cases, the brightness temperature is higher than the clear sky cases. Generally, the radiation value is proportional to cloud thickness. The error analysis of this study showed that the RMSE of total water vapor content for clear sky, thin cloud and thick cloud case is 0.4891、0.4097 and 0.3886 cm, respectively. In this study, also the continuous observated data of microwave radiometer was used to estimate total water vapor and compare the radiosonde total water vapor. The examined result shows the correlationships and estimated results were reasonable, especially for the clear sky cases. The RMSE percentage of water vapor content profile is smaller than 30% in the most cases, but is much larger than 30% in higher levels. The RMSE of dew point profile is 4.5℃ in the worst cases. The analysis of this study showed that the radiation density is influenced by the soil moisture and the radiation value is inverse proportional to the measured soil moisture. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。