Atmospheric Trace Molecule Spectroscopy (ATMOS) Experiment Version 3 data retrievals

Abstract

Version 3 of the Atmospheric Trace Molecule Spectroscopy ͑ATMOS͒ experiment data set for some 30 trace and minor gas profiles is available. From the IR solar-absorption spectra measured during four Space Shuttle missions ͑in 1985, 1992, 1993, and 1994͒, profiles from more than 350 occultations were retrieved from the upper troposphere to the lower mesosphere. Previous results were unreliable for tropospheric retrievals, but with a new global-fitting algorithm profiles are reliably returned down to altitudes as low as 6.5 km ͑clouds permitting͒ and include notably improved retrievals of H 2 O, CO, and other species. Results for stratospheric water are more consistent across the ATMOS spectral filters and do not indicate a net consumption of H 2 in the upper stratosphere. A new sulfuric-acid aerosol product is described. An overview of ATMOS Version 3 processing is presented with a discussion of estimated uncertainties. Differences between these Version 3 and previously reported Version 2 ATMOS results are discussed. Retrievals are available at http:͞͞atmos.jpl.nasa.gov͞atmos.

Long‐term trends of inorganic chlorine from ground‐based infrared solar spectra: Past increases and evidence for stabilization

“…[39] The ClONO 2 a priori profile was adopted from ATMOS version 3 measurements of the SS72 occultation at 31.5°N latitude during the November 1994 mission [Irion et al, 2002], with a smoothed extension above 38 km and to mixing ratios decreasing to 10 À12 ppv at 12.5 km and 10 À13 ppv below 10 km. Profiles of ClONO 2 and H 2 O were both retrieved.…”

“…[46] Retrievals of ClONO 2 columns were performed using SFIT2, with an a priori profile from a November 1994 ATMOS version 3 retrieval [Irion et al, 2002] at 45°N latitude and 6°E longitude. The two-step sequential wide/ narrow microwindow retrieval approach [Reisinger et al, 1995] was implemented for use with SFIT2.…”

“…The modified version of the two-step wide/narrow microwindow retrieval method [Reisinger et al, 1995] adopted for the Jungfraujoch analysis was used in combination with the pseudolines described in section 2. The ClONO 2 a priori profile from ATMOS version 3 measurements [Irion et al, 2002] from March 1992 at 45°S latitude was adopted and smoothly connected to a standard reference file above the range of the ATMOS measurements and to negligibly small mixing ratios below the tropopause. Individual ClONO 2 total columns have an estimated precision of 25% [Reisinger et al, 1995], corresponding to about ±4% uncertainty after monthly averaging.…”

“…Line parameters for analysis of the R(1) HCl line were adopted from the 1996 HITRAN compilation [Rothman et al, 1998]. The ClONO 2 a priori profile adopted at Zugspitze has been constructed using volume mixing ratios of for levels between 0 and 12 km altitude, a linear interpolation of ATMOS original data [Irion et al, 2002] to levels between 12.5 and 31.5 km, and a standard profile between 32 and 100 km. The two-step retrieval method [Reisinger et al, 1995;Rinsland et al, 1996] and the pseudolines described in section 2 were used.…”

“…A zero-level shift was applied based on measurements of fully saturated absorptions in the interval. The a priori vertical distribution was adopted from ATMOS occultation SS89 recorded near the same latitude during November 1994 [Irion et al, 2002] with extensions to both lower and higher altitudes. A signal-to-noise ratio of 500 was assumed, consistent with the noise level in typical spectra.…”