The Analysis of Climatological Characteristics of Non-typhoon Rainfall in Taiwan
Date Issued
2006
Date
2006
Author(s)
Li, Ya-Chuan
DOI
zh-TW
Abstract
The main rainfall type of Taiwan can be divided into a typhoon rain and monsoon rain. The overall rainfall that typhoon brings yearly depends on the actual times of invasion. This research mainly discussed the ' non-typhoon rainfall ' , and expected to analyze the relation among the variations of the change of geopotential height in the entire environment, the corresponding change of airflow surrounding Taiwan, and the transition of rainfall type of Taiwan caused by he variation of airflow.
We use the 85 stations of daily rainfall observation in Taiwan, the data of 850 hpa airflow surrounding Taiwan (117.5°-125°E、20°-27.5°N), and the data of 850 hpa geopotential height within this area (90°-170°E、0°-60°N) from 1980 to 2004 in this research. Four methods are used in this research. First, we extracted the typhoon rainfall. Second, the Principle Components Analysis. Third, the analysis of cumulation anomaly. Finally, we tried to find the relation among three climatology and anomalies, the geopotential height, the airflow and the rainfall of the duration of moist-rain or drought.
This research reveals three important results. First, the yearly arithmetic mean of rainfall in Taiwan is about 2400mm. The typhoon rainfall accounts for around 23 %, 38% at most (in 2004) and 3 % at least (1983). This means a huge variation over years. Consequently, when analyzing the long-term characteristics of rainfall, it is suggested to discuss these two types separately. Second, three principle components of rainfall are derived by using the principle components analysis. The first one displays a positive coefficient in Taiwan, especially in South-east. The second one is a positive coefficient in North-west with a negative value in South-east, and the third is a positive value in West with a negative value in East. Finally, there is a considerately good relation between geopotential height and rainfall from the duration of moist-rain or drought, e.g., the geopotential height varies with the positive coefficients of different principle components to show a positive anomaly during the drought. This research has explored the relation among geopotential height, airflow in the entire environment and rainfall. In the future, we expect to use this index as an estimation criteria of yearly or seasonal change of non-typhoon rainfall in Taiwan after development and examination.
Subjects
主成份分析
非颱風降雨
累計距平分析
PCA
non-typhoon rainfall
cumulative index
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-95-R92521323-1.pdf
Size
23.31 KB
Format
Adobe PDF
Checksum
(MD5):5991b5e29de6038c36a87311dfd59032