KAUFMAN, YJ, GAO, BC (1992). REMOTE-SENSING OF WATER-VAPOR IN THE NEAR IR FROM EOS/MODIS. IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 30(5), 871-884.
Remote sensing of the total column water vapor (in cloud free conditions) from the proposed MODIS instrument on the NASA's Earth Observing System requires special water vapor channels in the near infrared (IR). By using 2 near-IR water vapor channels (0.905 mum and 0.940 mum) in addition to existing window channels (0.865 mum and 1.24 mum), it will be possible to derive the total column water vapor amount from MODIS data. A ratio of the measured radiance in an absorbing channel at 0.940+/-0.025 mum or 0.905+/-0.015 mum to that in a nonabsorbing channel at 0.865+/-0.020 mum is proposed to retrieve the column water vapor over land. LOWTRAN-7 code was used to simulate remote sensing of water vapor over 20 different surface covers. The simulation was used to optimize the water vapor channel selection and to test the accuracy of the remote sensing method. The channel selection minimizes the uncertainty in the derived water vapor due to variations in the spectral dependence of the surface reflectance. The selection also minimizes the sensitivity of the selected channels to possible drift in the channel position. In a sensitivity analysis it is shown that the error in the directly derived water vapor amount is +/-13%. The use of additional MODIS channels reduces the errors due to the effect of haze, subpixel clouds and uncertainties in the temperature profile to +/-7%. Remote sensing of the variation of water vapor from day to day will be more accurate, because the surface reflectances vary slowly with time. The method was applied to Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data acquired from the NASA-ER2 aircraft and compared with other measurements.