Response of Potential Evapotranspiration to Warming and Wetting in Northwest China

Abstract

In the last few decades, the climate in Northwest China has exhibited a warming–wetting tendency, which has been particularly prominent since the beginning of the 21st century. In this context, we analyzed the change in potential evapotranspiration (PET)in the corresponding period and its response to warming and wetting, which revealed clear periodic changes. The most significant changes occurred in the 1970s and 1980s, when PET decreased in the humid climate zone and increased in the semi-arid climate zone. Factor effect analysis showed that PET had a positive response to temperature; the highest and lowest temperatures in the region continued to rise. Relative humidity reduced the overall PET in the region, especially in the humid zone. Sunshine duration has continued to decrease rapidly since the 1980s, especially in humid and arid zones, resulting in a corresponding decrease in PET. Similarly, corresponding to the consistent wind speed decrease, there has also been a significant decrease in PET, with the largest decrease in the arid zone, followed by the humid zone. In general, PET in the central and eastern parts of Northwest China has mainly been affected by the temperature, whereas wind speed has been the main factor in the western part of the region. Relative humidity and sunshine duration have had relatively little effect on the PET (below 20% in most places). The reasons and processes that affect PET are very complicated. Owing to the unique climate characteristics and underlying surface energy mechanisms in Northwest China, it is still difficult to offer a scientific explanation for its warming and wetting. Therefore, the extent to which PET impacts climate change in this region is currently unclear, and systematic and scientific research on this is needed.

Climate Change in the Eastern Xinjiang of China and Its Connection to Northwestern Warm Humidification

“…At the beginning of the 21st century, Shi et al proposed that since the 1980s, the climate in the arid areas of Northwest China has gradually transformed from "warm and dry" to "warm and wet" [6]. Since then, scholars have conducted extensive research on the characteristics, formation mechanism, and future trends of climate warming and humidification in Northwest China [7][8][9][10][11][12][13]. Chen et al showed that the temperature and Atmosphere 2023, 14, 1421 2 of 12 precipitation in the arid region of Northwest China had "sharply" increased in the past 50 years.…”

Characteristics of Evapotranspiration and Crop Coefficient Correction at a Permafrost Swamp Meadow in Dongkemadi Watershed, the Source of Yangtze River in Interior Qinghai–Tibet Plateau

“…Therefore, evapotranspiration is not only an important part of the land water cycle, but also an important part of the land surface energy balance [3]. Moreover, both potential evapotranspiration (ET p ) and actual evapotranspiration (ET a ) had positive responses to temperature [4,5] and water vapor, which returns to the atmosphere through evapotranspiration and is also a major greenhouse gas capable of warming the climate [6]. Reasonable estimation of evapotranspiration is of great significance to regional climate change research [7], the rational utilization of water resources, agricultural irrigation, and water conservation projects [8].…”