NUMERICAL INVESTIGATIONS OF THE ACCURACY OF THE REMOTE SENSING OF NON-LTE ATMOSPHERE BY SPACE-BORNE SPECTRAL MEASUREMENTS OF LIMB IR RADIATION - 15 MU-M CO2 BANDS, 9.6 MU-M O-3 BANDS AND 10 MU-M CO2 LASER BANDS

摘要

Inverse problems of the remote sensing of the atmosphere are formulated for the general case of an optically thick atmosphere under non-local thermodynamic equilibrium condition for the space-borne spectral measurements of the limb i.r. radiation. A feasibility study of the retrieval of the vertical profiles of different atmospheric parameters [vibrational (T-v) and kinetic (T-kin) temperatures, concentration of the absorbing gases, pressure] has been carried out by means of the error matrix calculations (optimal estimation method) for different spectral intervals of measurements (15 mu m CO2 bands, 9.6 mu m O-3 bands and 10 mu m CO2 laser bands), different spectral resolutions Delta nu and wide range of noise equivalent radiance (NER) values. It has been shown that limb radiation spectral measurements, for example, in 15 mu m CO2 band (Delta nu = 1 cm(-1), NER corresponding to MIPAS interferometer) enable the retrieval of T-v for CO2 states 01(1)0, 02(0)0, 02(2)0, 10(0)0 with an error less than half of the a priori uncertainty up to 112.5, 100, 102.5 and 100 km, respectively. Limb radiation measurements in the 9.6 mu m O-3 band make it possible to retrieve, with an accuracy about 10-30% of the a priori uncertainty, the vertical profile of the ozone concentration up to 65-90 km depending on the NER value, Delta nu and atmospheric model. The lower limit retrieval errors for O-3 vibrational temperatures strongly depend on NER, Delta nu and the vibrational state under consideration, especially in the layers higher than 65 km. More than 50% decrease of a priori uncertainties (an error less than 25 K) is observed for the states of O-3 molecule 001, 100, 011, 003, 012 up to 102, 94, 93, 92, 90 km, respectively (for Delta nu = 2.5 cm(-1) and NER 10 times lower than one for MIPAS). Limb radiation measurements yield a considerable decrease (50-80%) of the a priori uncertainty of the pressure profile in the height range 30-60 km. If T-kin is considered as an independent unknown variable, the considerable amount of information on T-kin (up to 90-95 km) can be obtained only when NER is low, which is characteristic, for example, for CLAES instrument. Different ideas concerning the improvement of the retrieval accuracy are discussed. [References: 59]