A historic global ground-based monthly seasonal aerosol climatology based in AERONET data: a database 1993-2013

The first version of this data set is uploaded as a CSV UTF-8 formatted text file [July2021]. It is anticipated that the file will be properly dimensioned and converted to a NETCDF4 file type in the ensuing months. Expanded versions of the database file incorporating a greater number of AERONET sites meeting the criteria as specified in our original typlogy model codes [Hamil, et al. 2016], and a deeper time history to date, and to incorporate the AERONET V3 inversion data products are forthcoming. Data is presented in the csv file as to be converted directly into a matrix of 19 columns by the number of AERONET sites rendered as each of one row as a record. For each record, the columns are as follows: 1. Aeronet_Site_name (text string); 2. Longitude (numeric in decimal degree format); 3. Latitude (numeric in decimal degree format); 4. Elevation (numeric in meters); 5. Data_Time_Start (text string in the format of ddMMyyyy); 6. Data_Time_End (text string in the format of ddMMyyyy); 7. Data_Time_Range_type(text string either "exact" or "nominal" date ranges; columns 8-19) Historic_Monthly_Dominant_Aerosol_type-January(text string) etc. for each month. The Columns 2,3,4 will be converted to numeric cordinates with elevations in NETCDF4 format. The Columns 5 and 6 will convert to date strings in NETCDF4 as mmddyyyy format. The purpose of the dates as listed are merely to provide the end user a date span corresponding to the AERONET retrievals included in the typology and ensuing results. Most are categorized as "nominal" representing the number of years of data. The database in not searchable by any specific month, as the data represent reported dominant monthly types integrated over the AERONET site time range. The remaining columns 7-19 will remain as string variables. The dominant aerosol types correlate to the 5-aerosol typology of Hamill et al 2016, and are not yet modified to the 8-aerosol type classification scheme of Giordano 2019. The aerosol types are "Dust", "Mixed", "Maritime", "Biomass" (biomass burning) and "UI" (urban industrial). The are textual labels for a specific set of aerosol optical properties and their distribution of values about a centroid value, for each referenced aerosol type as used in the typology model code. This set of 5-dimensional values for each optical property can be summarized in the following tables extracted from Hamill et al. 2016 and Giordano 2019 respectively. Left - for 5 -D optical Space with 5 aerosol types [Hamill et al. 2016]. Right - for 5-D optical space classifying 8 aerosol types [Giordano 2019]. The readers should directly refer to the cited literature for detailed explanations and methods of mathematical determination of the tabled values. NOTA BENE: the null record for months without an aerosol type, either due to a lack of AERONET invertible data (such as due to cloud screening or the instrument off-line), or a statistically insufficient amount of data classified by the typology algorithm, are reported as nulls. Hence, they appear as consecutive commas in the csv version of the database file. Database users could make use of the AERONET site associated locations, and the optical property values associated with the reported Historic Dominant Monthly Aerosol Type to forward scatter through a radiative transfer scheme, to arrive at the radiative forcing due to the Bulk Columnar Aerosol without the uncertainty of inferring aerosol types based upon non-intensive aerosol properties.