<title>Temperature and pressure retrievals from O2 A-band absorption measurements made by ILAS: retrieval algorithm and error analyses</title>

Abstract

A visible grating spectrometer of the Improved Limb Atmospheric Spectrometer (ILAS) aboard the Advanced Earth Observing Satellite (ADEOS) measured atmospheric absorption spectra at a wavelength region from 753 nm to 784 nm, including the molecular oxygen (O 2 ) A-band centered at 762 nm, with a spectral resolution of 0.17 nm. Temperature and pressure profiles throughout the stratosphere were retrieved from the satellite solar occultation measurements of the O 2 Aband absorption spectra. Based on simulation studies, root-sum-square errors associated with several systematic uncertainties in spectroscopic databases and instrument functions were estimated to be 4 K for temperature and 4% for pressure in the stratosphere. Current problems in this retrieval are also presented through comparisons with correlative temperature measurements.

Isolated line shapes of molecular oxygen: Requantized classical molecular dynamics calculations versus measurements

“…Commonly probed absorption features include the γ -(0.63 μm), B-(0.69 μm), and A-(0.76 μm) rovibronic bands of O 2 , which have been used for wind measurements [1], in the determination of surface pressure [2][3][4] and aerosol and cloud properties [5][6][7][8], and for the retrieval of vertical profiles of pressure and temperature [9,10]. Among the various remote sensing experiments, those targeting the quantification of greenhouse gas concentrations (e.g., GOSAT [11], OCO-2 [12,13], CarbonSat [14]) are the most demanding because they require a relative standard uncertainty of less than 0.3% [12] in the atmospheric pressure profile retrieved from the O 2 A band.…”

A comparative study of stratospheric temperatures between ILAS-II and other data

“…Actually, the instrument functions determined by the same method as given by Sugita et al 9 revealed some variation, which is anti-correlated with the instrument temperatures, as shown in Figure 1. The shifted value of the wavelength center is estimated to be 0.03 nm (1-pixel) per 10 degrees Celsius, which is the same value as was found from the ILAS measurement.…”

“…9 This is explained by the high dispersion of the spectrometer and its optical layout, as given in Sugita et al 9 Sugita et al 9 have also developed a calibration method for changing the wavelength center as a function of the two optical parameters using well determined solar line database.…”

“…It is almost the same as the ILAS temperature and pressure profiling. A detailed description for the ILAS measurement is given by Sugita et al 9 .…”

“…For this purpose, the visible/near-infrared channel measured atmospheric absorption spectra of the b 1 Σ + g −X 3 Σ -radiometer. For the first time, Sugita et al 9 This paper describes the current status of the ILAS-II retrieval scheme, error analyses, and some sensitivity tests. Preliminary comparisons with other correlative temperature measurements using the CO 2 bands and the meteorological analyses data are also performed.…”