Atmospheric column-averaged mole fractions of carbon dioxide at 53 aircraft measurement sites

Y Miyamoto,M Inoue,A E Andrews,Y Sawa,T Machida,I Morino,T Yokota,P P Tans,O Uchino,C Sweeney,H Matsueda,P K Patra

doi:10.5194/acp-13-5265-2013

Abstract

Abstract. Atmospheric column-averaged mole fractions of carbon dioxide (XCO2) at 53 locations around the world were derived from aircraft measurements covering the altitude range of about 1–10 km. We used CO2 vertical profile measurements from three major carbon cycle programs, a global climatological data set of air number density profiles and tropopause height for calculating XCO2 for the period of 2007–2009. Vertical profiles of the CO2 mixing ratio are complemented by tall tower data up to 400 m from the earth's surface and by simulated profiles in the stratosphere from a chemistry-transport model. The amplitude of the seasonal cycle of calculated XCO2 values shows clear latitudinal dependence, and the amplitude decreases from about 10 ppm at high latitudes in the Northern Hemisphere to at most 2 ppm in the tropics and the Southern Hemisphere. The uncertainties of XCO2 were estimated from assumptions about CO2 profiles for each flight. Typically, uncertainties were less than 1 ppm; thus, this data set is within the level of uncertainty needed for primary validation of XCO2 measurements by the Greenhouse gases Observing SATellite (GOSAT) and by future satellite missions for monitoring greenhouse gases.

Highlights

We report the results of XCO2 calculations carried out with data provided by CONTRAIL, measurements made by the US National Oceanic and Atmospheric Administration (NOAA) and Japan’s National Institute for Environmental Studies (NIES) at 53 sites between 2007 and 2009
XCO2 at 53 sites in the world was calculated from aircraft measurement data obtained by CONTRAIL, NOAA, and NIES between 2007 and 2009 along with tower data obtained at the surface and the ACTM simulated age of air to estimate profiles in the stratosphere
XCO2 has been derived from data obtained by satellites, such as gases Observing SATellite (GOSAT) (Yokota et al, 2009), the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY; Bovensmann et al, 1999) on board ENVISAT, and the Atmospheric Infrared Sounder (AIRS; Crevoisier et al, 2004) on board NASA’s Aqua platform

Summary

Introduction

To calculate XCO2, additional information is needed: (1) supplemental vertical profiles of CO2 in the altitude range where observation data are not available, and (2) vertical profiles of the dry air number density above the sites. The modeled age of air was compared with ages estimated by using several vertical profiles of sulfur hexafluoride (SF6) in the upper troposphere and stratosphere in the latitude range of 17–70◦ N, based on measurements made by balloon-borne instruments (Harnisch et al, 1996; Patra et al, 1997), to obtain correction factors at each profile location.

Results

Conclusion