The MACC reanalysis: An 8 yr data set of atmospheric composition
An eight-year long reanalysis of atmospheric composition data covering\nthe period 2003-2010 was constructed as part of the FP7-funded\nMonitoring Atmospheric Composition and Climate project by assimilating\nsatellite data into a global model and data assimilation system. This\nreanalysis provides fields of chemically reactive gases, namely carbon\nmonoxide, ozone, nitrogen oxides, and formaldehyde, as well as aerosols\nand greenhouse gases globally at a horizontal resolution of about 80 km\nfor both the troposphere and the stratosphere. This paper describes the\nassimilation system for the reactive gases and presents validation\nresults for the reactive gas analysis fields to document the data set\nand to give a first indication of its quality.\nTropospheric CO values from the MACC reanalysis are on average 10-20%\nlower than routine observations from commercial aircrafts over airports\nthrough most of the troposphere, and have larger negative biases in the\nboundary layer at urban sites affected by air pollution, possibly due to\nan underestimation of CO or precursor emissions.\nStratospheric ozone fields from the MACC reanalysis agree with\nozonesondes and ACE-FTS data to within +/-10% in most seasons and\nregions. In the troposphere the reanalysis shows biases of -5% to +10%\nwith respect to ozonesondes and aircraft data in the extratropics, but\nhas larger negative biases in the tropics. Area-averaged total column\nozone agrees with ozone fields from a multi-sensor reanalysis data set\nto within a few percent.\nNO2 fields from the reanalysis show the right seasonality over polluted\nurban areas of the NH and over tropical biomass burning areas, but\nunderestimate wintertime NO2 maxima over anthropogenic pollution regions\nand overestimate NO2 in northern and southern Africa during the tropical\nbiomass burning seasons.\nTropospheric HCHO is well simulated in the MACC re-analysis even though\nno satellite data are assimilated. It shows good agreement with\nindependent SCIAMACHY retrievals over regions dominated by biogenic\nemissions with some anthropogenic input, such as the eastern US and\nChina, and also over African regions influenced by biogenic sources and\nbiomass burning.