2012/05/14 by Xavier Calbet, Calbet, Xavier
Earth and Planetary Sciences · Engineering · Environmental Science · #Atmospheric Ozone and Climate #Atmospheric and Environmental Gas Dynamics #Atmospheric and Oceanic Physics (physics.ao-ph) #Calibration and Measurement Techniques #FOS: Physical sciences #Meteorological Phenomena and Simulations
paper · pdf · doi:10.48550/arxiv.1205.3012
openalex publication_date 2012/05/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The availability of hyperspectral infrared remote sensing instruments, like\nAIRS and IASI, on board of Earth observing satellites opens the possibility of\nobtaining high vertical resolution atmospheric profiles. We present an\nobjective and simple technique to derive the parameters used in the optimal\nestimation method that retrieve atmospheric states from the spectra. The\nretrievals obtained in this way are optimal in the sense of providing the best\npossible validation statistics obtained from the difference between retrievals\nand a chosen calibration/validation dataset of atmospheric states. This is\ndemonstrated analytically. To illustrate this result several real world\nexamples using IASI retrievals fine tuned to ECMWF analyses are shown. The\nanalytical equations obtained give further insight into the various\ncontributions to the biases and errors of the retrievals and the consequences\nof using other types of fine tuning. Retrievals using IASI show an error of 0.9\nto 1.9 K in temperature and below 6.5 K in humidity dew point temperature in\nthe troposphere on the vertical radiative transfer model pressure grid\n(RTIASI-4.1), which has a vertical spacing between 300 and 400 m. The more\naccurately the calibration dataset represents the true state of the atmosphere,\nthe better the retrievals will be when compared to the true states.\n