Interannual variability in North American grassland biomass/productivity detected by SeaWinds scatterometer backscatter

We analyzed 2000–2004 growing‐season SeaWinds Ku‐band microwave backscatter and MODIS leaf area index (LAI) data over North America. Large anomalies in mid‐growing‐season mean backscatter and LAI, relative to 5‐year mean values, occurred primarily in the western Great Plains; backscatter and LAI anomalies had similar spatial patterns across this region. Backscatter and LAI time series data for three ∼10 3 km 2 regions in the western Great Plains were strongly correlated (r 2 ∼ 0.6–0.8), and variability in mid‐growing season values was well‐correlated with annual precipitation (October through September). The results indicate that SeaWinds backscatter is sensitive to interannual variability in grassland biomass/productivity, and can provide an assessment that is completely independent of optical/near‐infrared remote sensing instruments.