Projected increase of the East Asian summer monsoon (Meiyu) in Taiwan by climate models with variable performance

Abstract

The active phase of the East Asian summer monsoon (EASM) in Taiwan during May and June, known as Meiyu, produces substantial precipitation for water uses in all sectors of society. Following a companion study that analysed the historical increase in the Meiyu precipitation, the present study conducted model evaluation and diagnosis based on the EASM lifecycle over Taiwan. Higher and lower skill groups were identified from 17 Couple Model Intercomparison Project Phase 5 (CMIP5) models, with five models in each group. Despite the difference in model performance, both groups projected a substantial increase in the Meiyu precipitation over Taiwan. In the higher skill group, weak circulation changes and reduced low‐level convergence point to a synoptically unfavourable condition for precipitation. In the lower skill group, intensified low‐level southwesterly winds associated with a deepened upper level trough enhance moisture pooling. Thus, the projected increase in Meiyu precipitation will likely occur through the combined effects of (1) the extension of a strengthened North Pacific anticyclone enhancing southwesterlies; and (2) more systematically, the Clausius–Clapeyron relationship that increases precipitation intensity in a warmer climate. The overall increase in the Meiyu precipitation projected by climate models of variable performance supports the observed tendency toward more intense rainfall in Taiwan and puts its early June 2017 extreme precipitation events into perspective.

Three-Dimensional Simulations of Wind Effects on Green Island Wake

“…From the figure, it is obvious that SW winds dominate in September 2010 and the average wind speed is about 3~7 m/s. This is consistent with the previous study [31] that showed SW winds dominating from July to September in Taiwan. In addition to wind data on a specific location, the wind field in the computational domain at 01:00 UTC on 9 September 2010 is obtained from the observation of the satellite scatterometer ASCAT [58].…”

“…From the figure, it is obvious that SW winds dominate in September 2010 and the average wind speed is about 3~7 m/s. This is consistent with the previous study [31] that showed SW winds dominating from July to September in Taiwan. [58].…”

“…The previous studies [29,30] remarked that the path of the Kuroshio current changes seasonally. In Taiwan, northeasterly (NE) winds prevail from November to February and southwesterly (SW) winds appear from July to September [31]. Therefore, the Ekman transport is to push the main axis of the Kuroshio current farther from the eastern coast of Taiwan in the summer when compared with that in the winter [21].…”

Climate Change Impact on Spatiotemporal Hotspots of Hydrologic Ecosystem Services: A Case Study of Chinan Catchment, Taiwan

“…Numerous GCMs have been found to possess insufficient features to simulate regional climate characteristics [64]. For example, mountains are a problem that has not been solved in all models [65] such that some studies have not considered the effects of local terrains [66] on water yield. These insufficiencies increase the number of discrepancies between simulation and observation results.…”

Nonstationary Analyses of the Maximum and Minimum Streamflow in Tamsui River Basin, Taiwan

“…Focusing on Taiwan, evidence of altering rainfall regime induced by climate change was indicated by several recent studies [32][33][34][35][36][37][38]. However, little research has examined the changes in streamflow regime in Taiwan, with the exception of Yeh et al [39] who investigated the long-term streamflow trend in northern Taiwan using the Mann-Kendall test.…”