Development of a remotely sensing seasonal vegetation‐based Palmer Drought Severity Index and its application of global drought monitoring over 1982–2011

Abstract

Vegetation effects are currently disregarded in Palmer Drought Severity Index (PDSI), and the sensitivity of PDSI to the choice of potential evaporation (E P ) parameterization is often a concern. We developed a revised self-calibrating PDSI model that replaces E P with leaf area index-based total evapotranspiration (ARTS E 0 ). It also included a simple snowmelt module. Using a unique satellite leaf area index data set and climate data, we calculated and compared ARTS E 0 , three other types of E P (i.e., Thornthwaite E P_Th , Allen E P_Al , and Penman-Monteith E P_PM ), and corresponding PDSI values (i.e., PDSI_ARTS, PDSI_Th, PDSI_Al, and PDSI_PM) for the period 1982-2011. The results of PDSI_ARTS, PDSI_Al, and PDSI_PM show that global land became wetter mainly due to increased precipitation and El Niño-Southern Oscillation (ENSO) effect for the period, which confirms the ongoing intensification of global hydrologic cycle with global temperature increase. However, only PDSI_Th gave a trend of global drying, which confirms that PDSI_Th overestimates the global drying in response to global warming; i.e., PDSI values are sensitive to the parameterizations for E p . Thus, ARTS E 0 , E P_Al , and E P_PM are preferred to E P_Th in global drought monitoring. In short, global warming affects global drought condition in two opposite ways. One is to contribute to the increases of E P and hence drought; the other is to increase global precipitation that contributes to global wetting. These results suggest that precipitation trend and its interaction with global warming and ENSO should be given much attention to correctly quantify past and future trends of drought.

Assessing spatiotemporal variation of drought in China and its impact on agriculture during 1982–2011 by using PDSI indices and agriculture drought survey data

“…The nonsignificant change of PDSI ARTS drought in China can be attributed to its two driving forces, i.e., P r (Figure b) and ARTS E 0 (Figure c), which also showed no significant change during 1982–2011. This agrees with the statistically nonsignificant drying trend in the midlatitudes (23°N–48°N) of the Northern Hemisphere due to weak variation of ARTS E 0 and P r , but it contrasted with the global wetting trend due to increased precipitation and El Niño–Southern Oscillation (ENSO) effect for the same period [ Yan et al ., ]. However, the wetting trend of PDSI ARTS during 2000–2011 (Figure a) primarily resulted from a decreasing trend of ARTS E 0 ( P < 0.01, see Figure c and Table ).…”

“…From the view of physical parameters and PDSI model complexity, the key driving force of potential evaporation E P should be explored because PDSI is sensitive to E P [ Sheffield et al ., ; Yan et al ., ]. E P_Th includes only one parameter of temperature and E P_PM considers temperature, radiation, wind speed, and vapor pressure deficit.…”

“…[] to point out a lack of consistency when making comparisons between different climatological regions. To solve this shortcoming, a self‐calibrating PDSI model has been developed [ Wells et al ., ] and considered prior in global drought monitoring [ Dai , ; Van der Schrier et al ., ; Yan et al ., ].…”

“…The PDSI ARTS model has been applied to global drought study and its detailed description can be found in Yan et al . [].…”

Use of the Standardized Precipitation Evapotranspiration Index (SPEI) to Characterize the Drying Trend in Southwest China from 1982–2012

“…These characteristics are useful for providing an objective and quantitative assessment of drought severity, and are commonly presented by use of the drought indices, which are constructed based on different climatic and hydrological variables that can reflect different aspects of drought [2,[10][11][12]. In the past decades, scientists have made great efforts to develop different drought indices, and their advantages and disadvantages have been extensively discussed [1,[6][7][8][13][14][15]. The Palmer Drought Severity Index (PDSI) [16] was a landmark in the development of drought indices.…”