BGC-Argo Satellite matchup to compute variability in the Chl:C ratio of phytoplankton.

This dataset provides matchups between BGC-Argo and MODIS satellites (both atmospheric and ocean color products). This dataset allows users to compare the variability of the Chlorophyll(Chl)  to Phytoplankton Carbon ratio from BGC-Argo floats depending on the light in the mixed layer and link to information obtained from satellites about cloud coverage. 

Quality control previously performed on this dataset and matchup criteria are described in the associated publication

Here are some of the column headers detailed for clarity:

Columns 1-24 represent data from the BGC-Argo floats:

• dt: Datetime in datenum format.
• region : Longhurst Region
• biomes: Biomes according to Fay & McKinley, 2014 (with West Mediterranean biome 18 and East Mediterranean biome 19)
• zenith : Sun zenith angle at time of surfacing 
• kd_490_Xing : Downwelling diffuse attenuation coefficient at 490nm from Xing et al.,2021 method. 
• PAR_0_Argo : PAR(0-) right below the surface also from Xing et al., 2021 
• chla : Median chlorophyll from fluorescence in the mixed layer (corrected for Non-Photochemical Quenching)
• Z_iso : Depth of the 0.415 mol/quanta/m-2/d-1 isolume. 
• Zeu : Euphotic depth, 1% of surface light
• Eg_Argo : Median light level in the mixed layer, bounded by the surface and the mld_mat depth
• MLD : Mixed layer depth, determined using the 0.03 density criteria
• bbp_XXX : Backscattering at a specific wavelength
• Cphyto : Median Phytoplankton Carbon in the mixed layer. Computed from Bbp following Graff et al, 2015
• F_indiv : Calibration factor for Chlorophyll fluorescence according to the method described in Xing et al, 2011. 
• F_median : Median Correction factor for all the float F in a biome
• F_std: Standard deviation of above. 
• Chl_cor : Chla from floats corrected using the F_median factor according to Xing et al., 2011. 
• ratio_cor: Chl_cor /Cphyto.

Columns 25-42 have products from matchups with ocean-color MODIS files:

• sat_dt : Datetime of satellite overpass in the datenum format. 
• chlor_a : Satellite chl obtained from NASA's OBPG hybrid algorithm.
• Ratio_Chl_sat: Ratio of satellite chlorophyll (chlor_a) over BGC-Argo corrected Chl (Chl_cor)
• PAR:  Satellite PAR above the surface (0+)
• PAR_minus : Satellite PAR propagate right below the surface (0-)

Eg_daily is the daily hourly median light in the mixed layer computed as PAR_minus * (Eg_Argo/PAR_0_argo)/24.

Columns 44-48 have products from matchups with atmospheric MODIS files: 

• a_lat, a_lon, a_dt: Same as above but for the atmospheric file
• COT: Cloud optical thickness
• Confident Cloudy: Number of pixels (Out of 25) with the Confident Cloudy flag.