A Global Dataset of Palmer Drought Severity Index for 1870–2002: Relationship with Soil Moisture and Effects of Surface Warming

Abstract

A monthly dataset of Palmer Drought Severity Index (PDSI) from 1870 to 2002 is derived using historical precipitation and temperature data for global land areas on a 2.5Њ grid. Over Illinois, Mongolia, and parts of China and the former Soviet Union, where soil moisture data are available, the PDSI is significantly correlated (r ϭ 0.5 to 0.7) with observed soil moisture content within the top 1-m depth during warm-season months. The strongest correlation is in late summer and autumn, and the weakest correlation is in spring, when snowmelt plays an important role. Basin-averaged annual PDSI covary closely (r ϭ 0.6 to 0.8) with streamflow for seven of world's largest rivers and several smaller rivers examined. The results suggest that the PDSI is a good proxy of both surface moisture conditions and streamflow. An empirical orthogonal function (EOF) analysis of the PDSI reveals a fairly linear trend resulting from trends in precipitation and surface temperature and an El Niño-Southern Oscillation (ENSO)-induced mode of mostly interannual variations as the two leading patterns. The global very dry areas, defined as PDSI Ͻ Ϫ3.0, have more than doubled since the 1970s, with a large jump in the early 1980s due to an ENSO-induced precipitation decrease and a subsequent expansion primarily due to surface warming, while global very wet areas (PDSI Ͼ ϩ3.0) declined slightly during the 1980s. Together, the global land areas in either very dry or very wet conditions have increased from ϳ20% to 38% since 1972, with surface warming as the primary cause after the mid-1980s. These results provide observational evidence for the increasing risk of droughts as anthropogenic global warming progresses and produces both increased temperatures and increased drying.

Future discharge drought across climate regions around the world modelled with a synthetic hydrological modelling approach forced by three general circulation models

“…Other research has focused on soil moisture droughts on the global scale (e.g. Dai et al, 2004;Sheffield and Wood, 2007;Sheffield et al, 2009;Dai, 2011;Orlowsky and Seneviratne, 2013). Global soil moisture droughts have been often examined (e.g.…”

“…Global soil moisture droughts have been often examined (e.g. Dai et al, 2004;Dai, 2011;Sheffield et al, 2012) with the Palmer Drought Severity Index (PDSI Palmer, 1965), which is calculated from a simple soil water balance, with the threshold method in combination with a more comprehensive model (e.g. Sheffield and Wood, 2007;Sheffield et al, 2009) or through anomalies (e.g.…”

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

“…Numerous drought indices have been developed to quantify the complicated drought processes [Heim, 2002]. Among them, the Palmer Drought Severity Index (PDSI) [Palmer, 1965] has been widely used to measure cumulative departure in surface water balance and to quantify dry and wet periodicity at regional to global scales [Heim, 2002;Dai et al, 2004;Dai, 2011;van der Schrier et al, 2013;Sheffield et al, 2012]. PDSI takes antecedent precipitation, moisture supply, and moisture demand into account by using a two-layered soil-water balance model.…”

“…Evaluation with observed soil moisture and river flow has demonstrated PDSI's potential in drought monitoring [Dai et al, 2004]. The simple structure of model enables wide applications [Heim, 2002].…”

Spatio-temporal variations in soil moisture and physicochemical properties of a typical semiarid sand-meadow-desert landscape as influenced by land use

“…1), usually has fragile hydrologic conditions that are very sensitive to land cover alteration from human activities (e.g., cultivation; Ma and Fu, 2005; Correspondence to: T. Liu (txliu1966@163.com) 2006). The fragility is characterized by measurable spatial and/or temporal changes in soil hydrologic (e.g., soil moisture) and physicochemical (e.g., soil fine particles, organic matter, and nutrients) properties (Nicolson et al, 1998;Dai et al, 2004;Held et al, 2005;Fu and Ma, 2008). These changes usually result in land desertification and environmental degradation (Hennessy and Kies, 1986;Okin et al, 2001;Fu et al, 2006), which in turn is likely to reduce grassland agricultural productivity, reduce usable water resources, and intensify sandstorms in terms of both occurrence and magnitude (Kertész and Mika, 1999;Ma and Fu, 2007;Monger, 2010).…”