Productions of Initial and Boundary Condition for Mesoscale Model - Construction of Taiwan Surface Roughness Dateset and the Soil Moisture from Remote Sensing Data

Abstract

Land is the major component of the climate system, but it inclusion in climate models isstill relatively simplistic. More realistic treatments of land processes and a fuller appropriatedataset are current research objectives. Some Land surface scheme (LSS) parameters, such asalbedo, fraction of vegetated cover, leaf area index, etc., can be measured (estimated) at boththe patch scale and the large scale (via remote sensing), and the relationship between theirarea-averaged values at patch and large scales is linear. However, other parameters such assoil hydraulic conductivity, stomatal resistance, aerodynamic resistance, etc., are not easilymeasured at the relevant scales, and their relationship at different scales is less simple.The main work in this project will be divided into five items and completed within threeyears: 1) Construction of NCHU flux tower over urban areas to observe the fluxes betweenthe atmosphere and the underlying surface and the meteorological data , 2) Derivation of landcharacteristics, including roughness length for heat, albedo, surface emissivity, area heatcapacity, canopy resistance and Bowen ratio using the observed data of N. Tongyen Mt.,NHCU and TFRI, 3) Development of a 1-km resolution dataset of roughness length formomentum and heat based on observations and its relationship to landuse types, andImplementation the roughness dataset for use in WRF under the cooperation with CWB, 4)Construction of long-term observation sites for soil moisture and development of hydrologicalrunoff model applied to the complex terrain in Taiwan, and 5) Development of a localizedland surface scheme (LSS) for use in WRF based on observation in Taiwan.地表真實值的觀測(例如各能量通量與土壤函水率等)及地表參數的表現在氣候及氣象模式中極為重要。在國外所提供之氣動粗糙度一般過小，造成風速模擬過快(Tsuang etal., 2003; Tsai and Tsuang, 2005)。計畫申請人過去5 年，已發表了相關研究期刊論文達3篇，利用繫留氣球、渦流協變性系統等觀測資料，或反演等方法求取中部地區等參數(Tsaiand Tsuang 2005; Tsai et al., 2007; Tsuang et al., 2008; Tsuang et al., 2009; Tsai et al.,2010a)。本計畫主要目的是希望能建立全台灣之動量粗糙度及熱粗糙度資料庫和台灣地區地表阻抗及土壤含水率在時間、空間上的分布，進而整合入WRF 區域氣象模式。此研究計畫將有以下四個工作方向。第一、收集地面觀測氣象資料並推導不同地貌的動量粗糙度(z0m)，並搭配過去成果(Tsuang et al., 2003; Tsai and Tsuang, 2005; Tsai etal., 2010a)及本計畫資料建立台灣地區動量粗糙度資料庫。第二、利用水稻田及森林地觀測資料推導熱粗糙度。第三、利用遙測資料推導台灣地區地表阻抗及土壤含水率時間、空間上的分布，以提供初始及邊界場予中尺度氣象模式使用。第四、將所得之初始及邊界資料應用於WRF 模式比較其是否改善地面風場及各能量通量模擬的模式表現。本計畫預定主要工作人力為計畫申請人本人，並搭配共同主持人所提供之地面觀測資料及衛星遙測資料來進行研究。希望三年內可以完整建立台灣地區重要大氣陸地下邊界之參數化過程包含觀測，並整合入WRF 之模式中，方便台灣之研究團隊及氣象單位使用