Evaluation of Terra/MODIS atmospheric profiles product (MOD07) over the Iberian Peninsula: a comparison with radiosonde stations

Abstract

Remote sensing techniques are a useful tool for continuous observation of the Earth at global scale. However, products derived from remote sensing data require a rigorous validation using in situ data. Moderate Resolution Imaging Spectroradiometer (MODIS) is not really a sounding instrument, but it does have 16 infrared bands (bands 20-36 covering the spectral range from 3 mu m to 14 mu m) that allow the retrieval of temperature and moisture profiles as well as total column integrated magnitudes. In this paper we show the results obtained in the evaluation of MOD07 daytime and nighttime products over the Iberian Peninsula during the decade from 2000 to 2010 using nine radiosonde stations. Although MODIS limitations in comparison with other sounding instruments, the validation provided satisfactory results, with bias (MOD07 minus radiosonde) < 0.3 cm and a standard deviation of 0.5 cm for the total column water vapor, and bias around 1 K on average with standard deviations between 2 K and 3 K for air temperature at different pressure levels. On average, bias was positive and below 2 K with standard deviations around 5 K for the dew point temperature case. Large errors were found in this case for pressure levels higher than 50 hPa.