博碩士論文 976201005 完整後設資料紀錄

DC 欄位 語言
DC.contributor大氣物理研究所zh_TW
DC.creator蔡國榮zh_TW
DC.creatorKuo-jung Tsaien_US
dc.date.accessioned2010-7-26T07:39:07Z
dc.date.available2010-7-26T07:39:07Z
dc.date.issued2010
dc.identifier.urihttp://ir.lib.ncu.edu.tw:88/thesis/view_etd.asp?URN=976201005
dc.contributor.department大氣物理研究所zh_TW
DC.description國立中央大學zh_TW
DC.descriptionNational Central Universityen_US
dc.description.abstract由於熱帶降雨觀測計畫 TRMM (Tropical Rainfall Measuring mission)已成功執行長達十餘年,現在已有能力在定量上提供地基式雷達與星載雷達之間較具確定性的比較。因此本研究選取 2008 年西南部地區較顯著的降雨事件作為研究對象,並且使用同時間所通過的降雨雷達 (PR)及七股雷達掃描資料,再以地面雨量站的資料作驗證,以期能夠增進七股雷達的降雨估計能力。另一方面,也透過與美國NCAR S-POL 雷達之間的資料比對,評估降雨雷達在台灣地區的降水觀測能力。 研究結果顯示,高度小於五公里的區域,PR 與七股雷達的回波分佈相當接近;但在五公里以上的高度,地面雷達的回波則有高估的情形。分析回波與高度的機率密度函數,發現兩者在三公里高度的分佈較一致,因此後續研究統一使用位於三公里高度的回波作分析。 比較兩種雷達所辨識的降雨類型,在針對大於 18dBZ 的回波時,兩者的分類一致性相當高。此外,對於不同降雨型態及不同下表面(陸地及海洋)時的分佈情形也相當一致,顯示 PR 所觀測的回波在台灣西南部地區具有相當高的可信度。 值得一提的是,兩種雷達的回波差異量會隨著回波值的大小而呈現線性相關,並非單一的常數。 在估計降雨能力的部份,過去使用 Z-R 關係式估算降雨率時,時常會低估強降雨事件的降雨率。利用 PR 所修正後的七股雷達回波重新估算降雨,並且利用 2008 年和雨量站資料的線性回歸式調整高降雨率的部份,能有效改進地基式雷達的降雨估計能力。而針對不同年份的強降雨個案所作的估計累計降雨,也比使用傳統 Z-R 關係式所估計的降雨來得準確許多。 zh_TW
dc.description.abstractBase on the decade-long and highly successful Tropical Rainfall Measuring Mission(TRMM),it is now possible to provide more quantitative comparisons between ground-based radar and the spaceborne TRMM precipitation radar (PR) with greater certainty. Therefore, this research select the significant precipitation events in the southwestern area of Taiwan in 2008, and compare the PR reflectivity data with simultaneous RCCG plan position indicator reflectivity data. In addition, rain gauge data are used to compare the rainfall derived from PR and RCCG separately, and try to improve the rainfall estimation ability of RCCG. In the aspect of accuracy for PR reflectivity, we introduce the NCAR SPOL data as a ground truth to validate the performance of PR retrieval algorithm. Comparison results suggest that the reflectivity distribution of PR and RCCG are quite close at lower levels (<5km), but the RCCG’s reflectivity is overestimated at higher levels (>5km). Analyzing the probability distribution frequency of reflectivity at different height, it reveals that the distribution pattern of reflectivity is more closer at three kilometer height. Therefore, the data at 3km will be used to analyze and intercompare in this research. The results of identifying precipitation type for the reflectivity larger than 18 dBZ agree well between PR and RCCG, the average agreement can reach 83%. Besides, for the different type of rainfall over different surface,such as convective,stratiform rain over land and ocean, the PDF of reflectivity at 3km height is quite close between PR and RCCG. It’s worth mentioning,the offset between RCCG and PR is linear-correlated with the reflectivity magnitude,and not a constant traditionally. In the part of rainfall estimation,using Z-R relationship to estimate rainfall often underestimate the heavy rainfall rate in the past. In this research, we first tune the reflectivity distribution by PR-RCCG statistical relationship. Second, using the PR-tuned RCCG reflectivity estimate rainfall again, and adjust the heavy rainfall part by linear regression with rain gauge in 2008. After the upper two steps, we use two significant precipitation events in different years to verify the method. The results show that it indeed improve the ground-based radar’s ability in rainfall estimation. en_US
DC.subject七股雷達zh_TW
DC.subject降雨雷達zh_TW
DC.subjectCigu radaren_US
DC.subjectprecipitation radaren_US
DC.title2008年台灣西南部地區TRMM降雨雷達與七股雷達回波觀測比較分析及降雨估計應用研究zh_TW
dc.language.isozh-TWzh-TW
DC.titleComparisons of Reflectivity and Rain Rate Derived from the TRMM Precipitation Radar and the CWB Cigu Radar over the Southwestern Area of Taiwan in 2008en_US
DC.type博碩士論文zh_TW
DC.typethesisen_US
DC.publisherNational Central Universityen_US

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