Dominance of climate warming effects on recent drying trends over wet monsoon regions

Chang-Eui Park,Shilong Piao,Hoonyoung Park,Chang-Hoi Ho,Jinwon Kim,Song Feng,Su-Jong Jeong

doi:10.5194/acp-17-10467-2017

Abstract

Abstract. Understanding changes in background dryness over land is key information for adapting to climate change because of its critical socioeconomic consequences. However, causes of continental dryness changes remain uncertain because various climate parameters control dryness. Here, we verify dominant climate variables determining dryness trends over continental eastern Asia, which is characterized by diverse hydroclimate regimes ranging from arid to humid, by quantifying the relative effects of changes in precipitation, solar radiation, wind speed, surface air temperature, and relative humidity on trends in the aridity index based on observed data from 189 weather stations for the period of 1961–2010. Before the early 1980s (1961–1983), change in precipitation is a primary condition for determining aridity trends. In the later period (1984–2010), the dominant climate parameter for aridity trends varies according to the hydroclimate regime. Drying trends in arid regions are mostly explained by reduced precipitation. In contrast, the increase in potential evapotranspiration due to increased atmospheric water-holding capacity, a secondary impact of warming, works to increase aridity over the humid monsoon region despite an enhanced water supply and relatively less warming. Our results show significant drying effects of warming over the humid monsoon region in recent decades; this also supports the drying trends over warm and water-sufficient regions in future climate.

Highlights

The background dryness over land varies as climate changes, but the major climate parameter driving dryness changes remains unclear in many regions (Sherwood and Fu, 2014; Hegerl et al, 2015)
The present study suggests that trends in surface dryness reverse from wetting to drying around the early 1980s over both arid and humid monsoon regions
Large influences of P and Rn on dryness trends are consistent with the results of previous studies on trends in aridity and potential evapotranspiration (PET) using daily observations of weather (Wu et al, 2006; Han et al, 2012)

Summary

Introduction

The background dryness over land varies as climate changes, but the major climate parameter driving dryness changes remains unclear in many regions (Sherwood and Fu, 2014; Hegerl et al, 2015). Precipitation (P ), the amount of water supply, is regarded as a key variable for understanding variations in dryness, in humid regions such as Asian monsoon regions (Wang et al, 2012; Kitoh et al, 2013; Liu and Allan, 2013). Park et al.: Dominance of climate warming effects on recent drying trends of India, part of the southern Asian monsoon region (Zhou et al, 2008; Roxy et al, 2015). PET variations largely affect dryness trends that are in turn closely related to the occurrence of droughts, water scarcity, and tree mortality (Westerling et al, 2006; Park Williams et al, 2013; Dai, 2013). The processes involved in the variability in dryness need to be examined in various hydroclimate regimes to better understand continental dryness changes

Objectives

Methods

Results

Conclusion