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Impacts of climate change on reference evapotranspiration in the Qilian Mountains of China: Historical trends and projected changes
Author(s) -
Lin Pengfei,
He Zhibin,
Du Jun,
Chen Longfei,
Zhu Xi,
Li Jing
Publication year - 2018
Publication title -
international journal of climatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.58
H-Index - 166
eISSN - 1097-0088
pISSN - 0899-8418
DOI - 10.1002/joc.5477
Subject(s) - evapotranspiration , downscaling , environmental science , climate change , climatology , pan evaporation , wind speed , vegetation (pathology) , mean radiant temperature , penman–monteith equation , potential evaporation , representative concentration pathways , physical geography , atmospheric sciences , climate model , meteorology , geography , geology , medicine , ecology , pathology , biology , oceanography
Global climate change is likely to affect reference evapotranspiration (ET 0 ) and the use of water resources for vegetation management. Our goals were to identify spatio‐temporal characteristics of ET 0 and factors controlling the change in ET 0 and to project spatio‐temporal changes in the Qilian Mountains of China under the future climate conditions. Changes in ET 0 were estimated by the Penman–Monteith method for 22 meteorological stations from 1960 to 2015. We quantified the attributions of climatic factors with the differentiation equation method. Then, we assessed the spatio‐temporal changes in projected ET 0 with CanESM2 model outputs and statistical downscaling model for three representative concentration pathways (RCP) scenarios for years 2016–2100. We found that annual ET 0 averaged across the region was 1001.5 mm, with an insignificant decrease of −0.43 mm/year during 1960–2015. The lowest values were present in the alpine region in the central area, while the highest ET 0 was detected in the western region. An annual and seasonal “evaporation paradox” existed in the Qilian Mountains during the past few decades. Mean daily air temperature measured ( T mean ) and wind speed ( U 2 ) were the dominant factors in ET 0 change. However, the decreasing trend in ET 0 may be due to a diminished effect of T mean triggered by short‐wave radiation ( R s ), actual vapour pressure ( e a ), and wind speed ( U 2 ), but especially by the substantial reduction in U 2 at most stations. Compared with the baseline, ET 0 is likely to increase by 6.31–7.20, 6.11–10.41, and 6.58–17.66%, respectively, under RCP scenarios of 2.6 (very low forcing scenario), 4.5 (medium stabilization scenario), and 8.5 (very high emission scenario), but RCP2.6 ET 0 rates level off and even decline after 2050 while RCP4.5 rates climb only marginally after 2050. Thus, ET 0 projected with the CanESM2 model displayed an upwards trend in the Qilian Mountains, especially the central alpine region.