MODIS

MODIS, or Moderate Resolution Imaging Spectroradiometer, is a key optical instrument for observing Earth's land, oceans, and atmosphere. It operates as part of NASA's Earth Observing System and is carried on two polar-orbiting satellites, Terra and Aqua. The instrument was developed by NASA's Goddard Space Flight Center in collaboration with international partners and began collecting data in 1999 (Terra) and 2002 (Aqua). MODIS collects radiance in 36 spectral bands spanning visible to thermal infrared wavelengths, providing a wide swath of about 2330 kilometers and spatial resolutions of 250 meters, 500 meters, and 1 kilometer depending on the spectral band.

MODIS data are organized into global science data products for land, ocean, and atmosphere. The instrument delivers near-daily global coverage, with the Terra and Aqua platforms complementing each other to increase temporal sampling. The data are used to monitor vegetation and land cover change, fires, aerosols, snow and ice, ocean color, and atmospheric properties such as aerosol optical depth and cloud characteristics, supporting applications in climate research, weather forecasting assistance, agriculture, forestry, and disaster response.

Data products include Level-1 radiances and higher-level geophysical products (Level-2 and Level-3). Examples of products include land surface reflectance and vegetation indices (e.g., NDVI, EVI), land cover maps, ocean chlorophyll concentration, sea surface temperature, aerosol optical depth, and cloud properties. Data are archived and distributed by NASA civil space agency centers and are publicly accessible.

MODIS has contributed to long-running climate data records and continues to serve as a foundational data source for Earth observation. Its mission continuity is supported by successor instruments such as VIIRS on the Suomi NPP and JPSS satellites, which provide similar measurements to maintain uninterrupted global monitoring.