# MIDAS Dataset ## Structure of the repository The files are provided in [netCDF4 format](https://www.unidata.ucar.edu/software/netcdf/docs/netcdf_introduction.html). The folders are organized in years and grid resolution (i.e., `/{year}/grid_resolution)`. There are two versions of the MIDAS dataset. -MODIS-Aqua Collection 6.1 (C061) files have been processed at 0.1 x 0.1 spatial resolution. -MODIS-Terra Collection 6.1 (C061) files have been processed at 0.1 x 0.1 spatial resolution. ## Filename format **Example file**: `MODIS-AQUA-C061_AOD-and-DOD-V1-GRID_RESOLUTION_0.1-20030101.nc` **Full length of the filename**: [62] - `MODIS-AQUA` --> MODIS satellite platform [0:10] - `C061` --> MODIS Collection [11:15] - `AOD-and-DOD` --> Aerosol and Dust optical depths [16:27] - `V1` --> MIDAS dataset version [28:30] - `GRID_RESOLUTION_0.1` --> Spatial resolution [31:50] - `20070101` --> Date (YYYYMMDD) [51:59] - `.nc` --> File format [59:62] **Example file**: `MODIS-TERRA-C061_AOD-and-DOD-V1-GRID_RESOLUTION_0.1-20030101.nc` **Full length of the filename**: [63] - `MODIS-TERRA` --> MODIS satellite platform [0:11] - `C061` --> MODIS Collection [12:16] - `AOD-and-DOD` --> Aerosol and Dust optical depths [17:28] - `V1` --> MIDAS dataset version [29:31] - `GRID_RESOLUTION_0.1` --> Spatial resolution [32:51] - `20070101` --> Date (YYYYMMDD) [52:60] - `.nc` --> File format [60:63] ## Datasets - `Angstrom_exponent_1_ocean` ["Calculated Angstrom Exponent for 0.55 vs 0.86 micron for Average Solution"] - It is advised to use this parameter with caution (see Levy et al., 2013; https://doi.org/10.5194/amt-6-2989-2013) - `Angstrom_exponent_2_ocean` ["Calculated Angstrom Exponent for 0.86 vs 2.13 micron for Average Solution"] - It is advised to use this parameter with caution (see Levy et al., 2013; https://doi.org/10.5194/amt-6-2989-2013) - `Aod_550_dark_target_deep_blue_combined` ["AOD_550_Dark_Target_Deep_Blue_Combined_(masked_CF>0.8_and_isolated_retrievals)"] - `Aod_550_dark_target_deep_blue_combined_algorithm_flag` ["Combined Dark Target, Deep Blue AOT at 0.55 micron Algorithm Flag (0=Dark Target, 1=Deep Blue, 2=Mixed)"] - `Deep_blue_angstrom_exponent_land` ["Deep Blue Angstrom Exponent (412-470nm)"] - It is advised to use this parameter with caution (see Sayer et al. 2013; https://doi.org/10.1002/jgrd.50600) - `Latitude` ["Geodetic Latitude"] - `Longitude` ["Geodetic Longitude"] - `Lsf` ["Land_sea_Flag(based on MOD03 Landsea mask 0 = Ocean, 1 = Land and Ephemeral water 2 =Coastal)"] - `MIDAS_DOD_UNCERTAINTY` ["MIDAS DOD uncertainty with masked values"] - `Modis-coarse-dust-optical-depth-at-550nm` ["MODIS-COARSE-Dust-optical-depth-at-550nm_through_MERRA2"] - It is NOT advised to use these data since they are under investigation (testing phase) - `Modis-fine-dust-optical-depth-at-550nm` ["MODIS-FINE-Dust-optical-depth-at-550nm_through_MERRA2"] - It is NOT advised to use these data since they are under investigation (testing phase) - `Modis-total-dust-optical-depth-at-550nm` ["MODIS-TOTAL-Dust-optical-depth-at-550nm_through_MERRA2"] - These data have been used in Gkikas et al. (2020). - `Sensor_zenith` ["Sensor Zenith Angle, Cell to Sensor"] - `Sza5` ["Solar Zenith Angle, Cell to Sun"] - `Time` ["Day"] 4. Contact Users can contact with Antonis Gkikas (<agkikas@academyofathens.gr>;<agkikas@noa.gr>) for any further details and clarifications regarding the MIDAS dataset.