Intra‐annual differences of 3‐month Standardized Precipitation‐Evapotranspiration Index dryness/wetness sensitivity over southwest China

Abstract

The monthly 3-month Standardized Precipitation-Evapotranspiration Index (SPEI-3) over southwest China (SWC) shows obvious inter-annual and inter-decadal variability during 1961-2012. By examining the isolated contributions of precipitation and reference evapotranspiration (ET 0 ) alone to the monthly SPEI-3 anomalies, we find out that although anomalous precipitation plays a predominant role, ET 0 impacts cannot be neglected, particularly during February-May. The monthly dryness/wetness sensitivity to precipitation (S p ; S et0 for ET 0 ), that is, SPEI-3 changes by per millimetre of precipitation (ET 0 ) anomalies, is quantified as the slope of a linear regression, which has precipitation (ET 0 ) contributions and anomalies during 1961-2012 as the dependent and the independent variables, respectively. Both SWC S p and S et0 have evident intra-annual differences, decreasing during February-August and increasing afterwards. Moreover, their magnitudes are dependent on climatological precipitation and generally decrease with precipitation increase. To sum up, the estimated respective contributions of monthly precipitation and ET 0 anomalies are favourable for thoroughly understanding SWC dry/wet condition evolutions during the past 52 years. More importantly, S p and S et0 are of significance for drought forecasting and emergency system over SWC.

Altitudinal differentiation of forest resilience to drought in a dryland mountain

“…It encompasses multiscale effects and is more sensitive to changes in the water and heat conditions (Bachmair et al, 2015;Blauhut et al, 2016;. We chose the SPEI with the time scale of three months for reflecting short-term and medium-term moisture conditions to study the seasonal characteristics and harshness of drought events, and reveal the drought effects on ecosystems (Beguería et al, 2014;Li et al, 2019;Sun et al, 2018;.…”

Altitudinal Differentiation of Forest Resilience to Drought in a Dryland Mountain

“…It encompasses multiscale effects and is more sensitive to changes in the water and heat conditions [45][46][47]. Considering the seasonal characteristics of forest growth, we chose the SPEI with the time scale of three months (SPEI-3) that reflects short-term and medium-term moisture conditions, allowing us to study the characteristics of seasonal drought events and reveal the drought effects on ecosystems [41,[48][49][50]. The potential evapotranspiration (PET) was calculated through using the Thornthwaite method [51].…”