Improved seasonal drought forecasts using reference evapotranspiration anomalies

Abstract

A novel contiguous United States (CONUS) wide evaluation of reference evapotranspiration (ET0; a formulation of evaporative demand) anomalies is performed using the Climate Forecast System version 2 (CFSv2) reforecast data for 1982–2009. This evaluation was motivated by recent research showing ET0 anomalies can accurately represent drought through exploitation of the complementary relationship between actual evapotranspiration and ET0. Moderate forecast skill of ET0 was found up to leads of 5 months and was consistently better than precipitation skill over most of CONUS. Forecasts of ET0 during drought events revealed high categorical skill for notable warm‐season droughts of 1988 and 1999 in the central and northeast CONUS, with precipitation skill being much lower or absent. Increased ET0 skill was found in several climate regions when CFSv2 forecasts were initialized during moderate‐to‐strong El Niño–Southern Oscillation events. Our findings suggest that ET0 anomaly forecasts can improve and complement existing seasonal drought forecasts.

Forecasting Rapid Drought Intensification Using the Climate Forecast System (CFS)

“…The PET, dew point depression, and soil moisture weights are largest from lag 0 to lag +1, and all these predictors have almost no weight from past lags (−3 to −1). The fact that the peak weight is shifted toward positive lags compared to the precipitation suggests that CFS forecasts of these variables are more skillful, which is consistent with McEvoy et al ().…”

Seasonal Drought Prediction: Advances, Challenges, and Future Prospects

“…One challenge of the climate forecast from coupled GCMs is that the precipitation forecast quickly loses skill after 2 weeks because of the inherent chaotic nature of the atmosphere (Lavers et al, ; Smith et al, ; Yuan et al, ). There are large uncertainties in the precipitation forecast, and skillful climate forecast beyond the 1 month lead is still a prevailing challenge (Mcevoy et al, ; Saha et al, ; Weisheimer et al, ; Wood et al, ; Yuan et al, ). This leads to limitations of reliable drought prediction of long lead time, especially in midlatitude (or extratropics) regions in which the climate predictability is low (Sohn & Tam, ).…”

Changes in reference evapotranspiration over China during 1960–2012: Attributions and relationships with atmospheric circulation

“…For example, Hu and Willson () and Sun et al (), Sun, Chen, Ju, et al () have reported that the impact of ET 0 on drought could be equivalent to or even higher than that from precipitation. Consequently, understanding the spatial and temporal variations in ET 0 is a vital component for comprehensively understanding hydrometeorological changes and is helpful for better monitoring and predicting drought (Beguería, Vicente‐Serrano, Reig, & Latorre, ; Li, He, Quan, Liao, & Bai, ; McEvoy, Huntington, Mejia, & Hobbins, ; Sun et al, ; Sun, Chen, Sun, et al, ; Vicente‐Serrano, Beguería, & Lópezmoreno, ; Zhang et al, ).…”

“…As a result, this provides an efficient tool to more accurately and comprehensively understand the underlying mechanisms of changed ET 0 across China. Furthermore, by considering the importance of ET 0 for the estimation of crop water demand and drought forecasting systems (McEvoy et al, 2016), obtaining detailed information about ET 0 is critical before developing countermeasures for policy makers. Large-scale atmospheric or coupled atmosphere-ocean modes of climate variability (usually referred to as teleconnections due to their long-distance range of influence) can provide a useful framework for linking ET 0 to climate fluctuations via influencing climate variables (e.g., wind speed, solar radiation, temperature, and relative humidity; Chen, Li, & Pryor, 2013;Li & Chen, 2014;Yu, Zhong, Bian, & Heilman, 2015;Zhu et al, 2017).…”