Validation of ACE-FTS v2.2 methane profiles from the upper troposphere to the lower mesosphere

Abstract

Abstract. The ACE-FTS (Atmospheric Chemistry Experiment -Fourier Transform Spectrometer) solar occultation instrument that was launched onboard the Canadian SCISAT-1 satellite in August 2003 is measuring vertical profiles from the upper troposphere to the lower mesosphere for a large number of atmospheric constituents. Methane is one of the key species. The version v2.2 data of the ACE-FTS CH 4 data have been compared to correlative satellite, balloonborne and ground-based Fourier transform infrared remote sensing data to assess their quality. The comparison results indicate that the accuracy of the data is within 10% in the upper troposphere -lower stratosphere, and within 25% in the middle and higher stratosphere up to the lower mesosphere (<60 km). The observed differences are generally consistent with reported systematic uncertainties. ACE-FTS is also shown to reproduce the variability of methane in the stratosphere and lower mesosphere.

Validation of revised methane and nitrous oxide profiles from MIPAS–ENVISAT

“…We compared MIPAS profiles to HALOE data version v19. This version has already been compared to ACE-FTS v2.2 profiles by De Mazière et al (2008), where HALOE data were shown to have mixing ratios about 5-10 % lower than ACE-FTS. Waymark et al (2013) found the CH 4 ACE-FTS version 3.0 mixing ratios to be reduced at some altitudes compared to version 2.2.…”

“…Waymark et al (2013) found the CH 4 ACE-FTS version 3.0 mixing ratios to be reduced at some altitudes compared to version 2.2. And since the version 3.5 research CH 4 data have even lower mixing ratios than version 3.0, the difference between HALOE v19 and the latest ACE-FTS version (3.5 research) should be smaller than those in the earlier versions found by De Mazière et al (2008). The typical vertical resolution of the profiles is given as 3-5 km ).…”

Satellite observations of atmospheric methane and their value for quantifying methane emissions

“…These include balloons , TCCON stratospheric retrievals (Saad et al, 2014), and satellite observations by solar occultation and in the limb (de Mazière et al, 2008;von Clarmann et al, 2009;Minschwaner and Manney, 2014). Bergamaschi et al (2013) presented a detailed evaluation of their CTM with balloon observations as a prelude to inversion of SCIAMACHY data, and this led them to limit their inversion to the 50 • S-50 • N latitudinal range where model bias was small.…”

Seasonal variability of stratospheric methane: implications for constraining tropospheric methane budgets using total column observations

“…Tropospheric columns have been shown to represent the magnitude and seasonality of in situ measurements (Saad et al, 2014;Washenfelder et al, 2003;Wang et al, 2014). The tropospheric CH 4 column-averaged DMFs (X t CH 4 ) are derived by the hydrogen fluoride (HF) proxy method described in Saad et al (2014), which uses the relationship between CH 4 and HF in the stratosphere, derived from ACE-FTS satellite measurements (Bernath, 2005;De Mazière et al, 2008;Mahieu et al, 2008;Waymark et al, 2014), to calculate and remove the stratospheric contribution to X CH 4 . The X t CH 4 used in this analysis have been processed consistently with the GGG2014 TCCON products, with air-mass dependence and calibration factors calculated for and applied to X t CH 4 .…”