Satellite‐Observed Vegetation Responses to Intraseasonal Precipitation Variability

Abstract

There is limited understanding of how vegetation responds to intraseasonal modes of rainfall variability despite their importance in many tropical regions. We use observations of precipitation and X-band Vegetation Optical Depth (VOD) from 2000 to 2018 to assess the relationships between rainfall and vegetation water content on 25–60-day timescales. Cross-spectral analysis identifies coherent intraseasonal relationships between precipitation and VOD, mostly in arid or semi-arid regions where vegetation is water-limited. Changes in VOD tend to lag anomalous rainfall, usually within 7 days. The fastest vegetation response is observed in sparsely vegetated areas (median 3 days). Following strong intraseasonal wet events, anomalously high VOD can persist for 2 months after the rainfall peak. This vegetation response can feed back onto the atmosphere, so improved representation of vegetation responses in models has the potential to improve subseasonal-to-seasonal forecasts.