• Microwave/radar remote sensing established quantitative links between backscatter, emissivity, soil moisture, surface roughness, and vegetation cover, driving retrieval algorithms for soil moisture mapping and soil-background separation from bare soil to vegetation-covered surfaces [8], [9], [3], [13], [18], [14].

• Vegetation dynamics and phenology are studied via NDVI-like indices and temporal AVHRR composites, enabling global and regional monitoring of green vegetation tied to rainfall and seasonal cycles with methods that map phenology and vegetation density [1], [7], [15], [5], [17], [6].

• Sensor technology development and multi-sensor data fusion enable richer surface characterization, with imaging spectrometry, radar polarimetry, and microwave radiometry advancing land/ocean surface retrievals [12], [10], [16], [4].

• Operational land-cover and biomass mapping in Africa/Sahel demonstrates practical satellite-based vegetation monitoring and productivity assessment using Landsat/NOAA-era sensors [5], [17], [6].