Long‐term change of potential evapotranspiration over southwest China and teleconnections with large‐scale climate anomalies

Abstract

Potential evapotranspiration (PET) is a sensitive factor for atmospheric and ecological systems over southwest China which is characterized by intensive karst geomorphology and fragile environment. Based on daily meteorological data of 94 stations during 1961–2013, the spatiotemporal characteristics of PET are analysed. The changing characteristics of local meteorological factors and large‐scale climatic features are also investigated to explain the potential reasons for changing PET. Study results are as follows: (1) The high‐value centre of PET with a mean value of 1097 mm a−1 locates in the south mainly resulted from the regional climatic features of higher air temperature (TEM), sunshine duration (SSD) and lower relative humidity (RHU), and the low‐value centre of PET with a mean value of 831 mm a−1 is in the northeast primarily attributed to higher RHU and weaker SSD. (2) Annual PET decreases at −10.04 mm decade−1 before the year 2000 but increases at 50.65 mm decade−1 thereafter, and the dominant factors of PET change are SSD, RHU and wind speed (WIN), with the relative contributions of 33.29, 25.42 and 22.16%, respectively. (3) The abrupt change of PET in 2000 is strongly dominated by large‐scale climatic anomalies. The strengthened 850 hPa geostrophic wind (0.51 m s−1 decade−1), weakened total cloud cover (−2.25% decade−1) and 500 hPa water vapour flux (−2.85% decade−1) have provided advantageous dynamic, thermal and dry conditions for PET over southwest China since the 21st century.

Spatial‐temporal evaluation of different reference evapotranspiration methods based on the climate forecast system reanalysis data

“…Different trend magnitudes of rainfall and input climatic parameters for PET or ETo have manifested in the lower, middle and upper regions of the Omo‐Gibe basin. Spatially heterogeneous changes of temperatures, wind speed, relative humidity, and solar radiation which resulted in varying PET have been observed in different parts of the world (Celik & Cengiz, 2014; B. Liu et al, 2017; Shan et al, 2016; Sherwood et al, 2010). Wind speed in Africa is generally decreasing (Wu et al, 2018).…”

“…upper regions of the Omo-Gibe basin. Spatially heterogeneous changes of temperatures, wind speed, relative humidity, and solar radiation which resulted in varying PET have been observed in different parts of the world (Celik & Cengiz, 2014;B. Liu et al, 2017;Shan et al, 2016;Sherwood et al, 2010).…”

Influence of mature El Niño‐Southern Oscillation phase on seasonal precipitation and streamflow in the Yangtze River Basin, China

“…As a strong ocean–atmosphere coupling, a powerful climatic and oceanic oscillation, ENSO behaviour can impact hydrological regimes since the atmospheric variables are the crucial elements that form streamflow (Niedzielski, ). The anomalous hydrological behaviours are associated with persistent climate anomalies (She et al ., ; Wang et al ., ; Xing et al ., ; Zhang et al ., ; ; Liu et al ., ). Meanwhile, streamflow variations are often linked with anomalous atmospheric conditions on seasonal time scales (Ionita et al ., ; Wang et al ., ).…”