- 學位論文
GPS大氣可降水量之測定及年變化分析
GPS determination on precipitable water vapor and analysis on its yearly variation
摘要
台灣近年來因季節或颱風等因素而帶來大量雨水，形成某些區域發生土石流或水災等天然災害，不僅造成某些區域人員傷亡，進而影響經濟層面上的重大損失。西太平洋國家如台灣、日本以及中國大陸等，每年約5~6月期間是梅雨發生的時段，經常形成連續的降雨。而雨水來自大氣對流層中之水氣，其屬於一種不穩定的狀態，於氣候上的變遷，更扮演一種能量傳遞角色，形成真實降雨量也有延遲的可能性，本文採用中央氣象局提供的觀測資料，討論大氣中之可降水量(precipitable water vapor, PWV)與實際降雨量的趨勢分析。 因全球定位系統(Global Positioning System, GPS)觀測站與雨量站彼此不共站，故以95個衛星追蹤站找出和氣象局的最短距離的測站，共有92個雨量站，藉此縮小環境誤差影響，且利用GPS訊號以Bernese 5.0求解對流層濕延遲量及反演可降水量資料與真實降雨量互相做比對，表現出台灣各區在2006-2011年期間之年週期變化趨勢，且真實反映對流層延遲變化情形。 成果顯示，各區可降水量的年週期呈現一致的趨勢，因對流層水氣含量屬於範圍性籠罩台灣上空，其每年數據之線性關係有上升趨勢，年增量介於0.67-0.83 mm之間，但卻與實際降雨量不一致。實際降雨量較高的情況下，通常即有氣流影響或颱風事件因素，使累積雨量增加，吾人藉由數據的統計分析得知6年期間的實際降雨量變化之情形與天氣事件較為相關。
並列摘要
In Taiwan, heavy rainfalls due to plum rain season or typhoons bring some serious natural disasters in recent years. Not only result casualties of human, but also affect significant loss of economy. Some continuous rainfall often happen to the countries of western pacific such as Taiwan, Japan and China during plum rain season on May or June every year. The rainfalls come from the troposphere of atmosphere is an unstable state and the role of an energy transfer on climate change. This study applied the observational data of the Central Weather Bureau in Taiwan and discussed the trend of the rainfall and the precipitable water vapor (PWV) of the atmosphere. Because the Global Positioning System (GPS) stations and the rainfall stations are not co-location, the 95 GPS tracking stations identify the shortest distance of 92 rainfall stations as to reduce the influence of the different environment. Moreover, the Bernese 5.0 software is used to calculate the zenithal wet delay (ZWD), and the experience formula is adopted to transfer the ZWD to PWV. In this study, we compared the PWV and rainfall data to show the trend and yearly variation during the period of 2006-2011, and reflected the variation of the ZWD. The results show that the PWV of annual variation is a consistent trend in different dis-tricts, because the water vapor in the atmosphere is a large scale phenomenon in Taiwan. There is an upward trend of the PVV data, and the annual increment is between 0.67 and 0.83 mm per year, which is inconsistent with the rainfall data. When the rainfall is higher, it usually has the airstream or typhoon events. According to the statistical analysis in this study, the changes of the rainfall are more relevant with the weather events in the past six years.