Droughts over Pakistan: possible cycles, precursors and associated mechanisms

Abstract

In the recent few decades, climate variability had severely affected the socio-economic and environmental conditions worldwide. Frequent shifts in the atmospheric circulation patterns affect large parts of the globe, predominantly the arid and semi-arid regions facing severe to moderate droughts. Therefore, precursors of drought events and their associated mechanisms are important to understand. This study explores the possible cycles and precursor conditions that might be employed for predicting upcoming droughts in Pakistan. Standardize precipitation index and the single Z-index are used to detect and rank the drought years. Moreover, composite analysis is carried out to explore the largescale circulation anomalies related to extreme drought events. Results demonstrate that extreme drought events are highly correlated with wind patterns and intrinsic weather system in the Pacific and Indian Oceans. This study analyzed air temperature, sea level pressure and geopotential height in the average timeperiod of January to March, sea surface temperature from October to December, and wind vectors in March to May as precursors that could be employed to predict the occurrence of droughts in Pakistan. This information is of significance for policymakers to plan climate change adaptive measures accordingly.

Spatio-Temporal Characteristics and Trend Analysis of Grassland Ecosystem Drought in Asia From 2010 to 2018

“…The drought degree has increased or decreased in varying degrees from 2010 to 2018, mainly in South Asia and East Asia with wetter dry conditions had become drier and drier, changing to drier conditions, while severe dry conditions in certain areas had changed to wetter conditions. Other relevant studies have also confirmed the accuracy of this result (Ummenhofer et al, 2013;Manolache et al, 2020;Chandrasekara et al, 2021;Hina et al, 2021). In addition, the study of Manolache et al (2020) explored the obstacles of different grassland management measures and the uniqueness to be considered in the selection, which was of great significance to provide different grassland management schemes for grassland ecosystems with different drought degrees.…”

“…Therefore, the assessment results of trends in drought conditions by the annual data used in this study require further calibration. In addition, several studies showed that drought is caused by a combination of factors such as precipitation, water resources in rivers and lakes, soil moisture content, and soil potential evapotranspiration (Zhang X. Y. et al, 2020;Hina et al, 2021;Su et al, 2021). The TVDI calculated from LST and EVI data in this study could represent the drought of AGE to some extent.…”

Observed changes in seasonal drought characteristics and their possible potential drivers over Pakistan

“…Overall, the results inferred that most of the stations across Pakistan exhibited a rise in drought severity during Kharif season and annual timescale, especially those located in arid southeastern and northern parts of the region. The increase/decrease in these seasons and overall variability is somehow agreed with the findings of regional studies (Adnan et al ., 2016; Gao et al ., 2017; Ahmed et al ., 2018; Ain et al ., 2020; Hina et al ., 2021). The drought severity and frequency appeared to be shifting from the arid/semiarid regions towards the country's western humid region.…”

Spatio-Temporal Analysis of Drought Variability in Myanmar Based on the Standardized Precipitation Evapotranspiration Index (SPEI) and Its Impact on Crop Production

“…In addition, to understand possible climate changes implications on crop production, we conducted two separate analyses; the composite and correlational analysis. Reasons for selecting these two analyses is well articulated in [4,77]. Here, the study explored how to combined historical observations of crop production and weather and climate variables to explains crop production.…”