23.04.2024 Timo H. Virtanen, Finnish Meteorological Institute (FMI) (timo.h.virtanen@fmi.fi) Access right: Open Access License: CC-BY (http://creativecommons.org/licenses/by/4.0/) Work supported by Research Council of Finland (projects 331829, 337552, 353082, and 359196). --- These data are described and used in the manuscript "A global perspective on CO 2 satellite observations in high AOD conditions" by Timo H. Virtanen, Anu-Maija Sundström, Elli Suhonen , Antti Lipponen, Antti Arola, Christopher O’Dell, Robert R. Nelson, and Hannakaisa Lindqvist, submitted to Atmospheric Measurement Techniques in 2024. --- This is a collocated dataset of the OCO2_L2_Lite_FP.10r data with MODIS Aqua Dark Target 10 km Aerosol product. We use the OCO-2 daily Lite files (V10r) (OCO-2 Science Team et al., 2020), produced by the OCO-2 project at the Jet Propulsion Laboratory, California Institute of Technology, and obtained from the OCO-2 data archive maintained at the NASA Goddard Earth Science Data and Information Services Center (O’Dell et al., 2018; Wunch et al., 2017; Taylor et al., 2023). We use the level-2 (L2) Moderate Resolution Imaging Spectro-radiometer (MODIS) Collection 6 atmospheric aerosol product from the Aqua platform (MYD04_L2) (Levy and Hsu, 2015). MODIS Dark Target (Levy et al., 2013) and Deep Blue (Hsu et al., 2004) products are used. The MODIS data used in this study were obtained from the NASA Level-1 and Atmosphere Archive & Distribution System Distributed Active Archive Center (LAADS DAAC) https://ladsweb.modaps.eosdis.nasa.gov/. We use dense human habitation data from naturalearthdata.com (Ver. 4.1.0), https://www.naturalearthdata.com/http//www.naturalearthdata.com/download/50m/cultural/ne_50m_urban_areas.zip, see e.g. Schneider et al (2009). MODIS data was downloaded and preprocessed by Antti Lipponen. --- Collocation: for each OCO-2 pixel the nearest MODIS pixel is selected. For a match it is required that the MODIS pixel is within a 0.2 deg*0.2 deg box, and the overpass times are within one hour. Not all data fields available in the source data are included, but new fields can be added on request. Each data field is in a separate netcdf file. Data is in 'vector form'. Data points in each file are in corresponding order. Five years (2015-2019) have been included. Data fields are: Orig. index, DATAFIELD NAME NC FILE NAME (time stamp '2019' may vary): 1) OCO-2 longitude, OCOMOD_DTland_2019_lon.nc 2) OCO-2 latitude, OCOMOD_DTland_2019_lat.nc MODIS data: 3) 'Optical_Depth_Land_And_Ocean' OCOMOD_DTland_2019_aod.nc 4) 'Land_sea_Flag', OCOMOD_DTland_2019_LSF.nc 5) 'Scan_Start_Time', OCOMOD_DTland_2019_time.nc 8) AOD 660, OCOMOD_DTland_2019_aod2.nc 9) AOD 2.1, OCOMOD_DTland_2019_aod3.nc 10) aerosol type OCOMOD_DTland_2019_atyp.nc 17) Land_Ocean_Quality_Flag OCOMOD_DTland_2019_MQF.nc COMBINED data: 19) AOD difference OCOMOD_DTland_2019_dAOD.nc ('oco-2 tot AOD' - 'MOD 550 AOD') OCO-2 data: 20) 'xco2' OCOMOD_DTland_2019_XCO2.nc 21) 'xco2 unc' OCOMOD_DTland_2019_UNC.nc 22) 'aod_total' OCOMOD_DTland_2019_AOD2.nc 23) 'aod_bc' OCOMOD_DTland_2019_AOD3.nc 24) 'aod_oc' OCOMOD_DTland_2019_AOD4.nc 25) 'aod_seasalt' OCOMOD_DTland_2019_AOD5.nc 26) 'aod_sulfate', OCOMOD_DTland_2019_AOD6.nc 27) 'aod_strataer', OCOMOD_DTland_2019_AOD7.nc 28) 'aod_water', OCOMOD_DTland_2019_AOD8.nc 29) 'aod_ice', OCOMOD_DTland_2019_AOD9.nc 30) time OCOMOD_DTland_2019_tim2.nc 33) 'xco2_quality_flag' OCOMOD_DTland_2019_QFL.nc 39) sounding id OCOMOD_DTland_2019_sid.nc 44) operation mode OCOMOD_DTland_2019_op.nc 61) urban mask OCOMOD_DTland_2019_URB.nc Time stamps are in Matlab daynumber format (days since January 0, 0000). ---------------------- References: Hsu, N., Tsay, S.-C., King, M., and Herman, J.: Aerosol properties over bright-reflecting source regions, IEEE Transactions on Geoscience and Remote Sensing, 42, 557–569, https://doi.org/10.1109/TGRS.2004.824067, 2004. 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