An Upgraded FLDAS-Forecast System for Continental Africa and the Middle East for Food Insecurity Early Warning

The hydrological predictions generated by the FLDAS-Forecast system plays an important role in supporting early warning efforts aimed at addressing food insecurity in vulnerable areas across Continental Africa and the Middle East. These forecasts have been particularly useful to the U.S. Agency for International Development's (USAID) Famine Early Warning System Network (FEWS NET) since 2018. This study compares two versions of the FEWS NET Land Data Assimilation System (FLDAS)-Forecast. This system is a custom instance of NASA's Hydrologic Forecasting and Analysis System (NHyFAS), designed to provide hydrological forecasts for the Continental Africa and Middle East regions.

FLDAS-Forecast version 1 (FF1) utilizes meteorological forecasts from the North American Multi-Model Ensemble (NMME) for precipitation, while non-precipitation meteorological predictions are from the Goddard Earth Observing System (GEOS). These meteorological forecast are used to drive NASA's Land Information System Framework (LISF) and produce hydrological forecasts within the sub-seasonal-to-seasonal (S2S) time frame. FLDAS-Forecast version 2 (FF2) integrates non-precipitation meteorological forecasts from the National Centers for Environmental Prediction's (NCEP's) Climate Forecast System version 2 (CFSv2), replacing GEOS, which is anticipated to cease providing daily forecasts beyond three-month lead period in future iterations. This development spurred us to devise an alternative input capability in our system. This update also introduces a new sub-daily temporal-disaggregation method to improve the realism captured in the forecasts.

To assess the impact of this upgrade, a comprehensive assessment of both FLDAS-Forecast versions is executed. This examination covers both probabilistic and deterministic validation against an array of remotely sensed observations such as IMERG precipitation, SMAP soil moisture, and VIIRS NDVI. The findings of this study will illustrate the strength and constraints of the upgraded FLDAS-Forecast version. This effort is directed at maintaining a cutting-edge system, capable of consistently guiding decision-makers and humanitarian efforts in effectively mitigating the impacts of hydrologic extremes in susceptible areas.