MERIS Ocean Color Reprocessing 2022.0

Introduction

Reprocessing 2022.0 is a multi-mission reprocessing to incorporate updates in instrument calibration, vicarious calibration, new ancillary sources and algorithm improvements. The affected missions are CZCS, SeaWiFS, OCTS, MERIS, MODIS on Aqua and Terra, VIIRS on SNPP and NOAA-20, OLCI on Sentinel-3A and Sentinel-3B, GOCI, and HICO. Here we describe the changes and results specific to MERIS.

Instrument Calibration

The MERIS data are now based on ESA's 4th reprocessing .

Product Formats

As this is the first reprocessing of MERIS since R2012.0, the file formats and product suites for MERIS will now be brought into alignment with those employed in the R2014.0 multi-mission reprocessing.
This brings the MERIS L2 and L3 data formats consistent with the other supported missions.

Results

Time Series Comparison

The comparison of the MERIS time series for global deep water (>1000m) generated for the R2022 configuration to the corresponding SeaWiFS time series is shown below (left panels). The ratio of MERIS to SeaWiFS is also shown for both R2022 and R2012 (right panels). Overall, the comparison to SeaWiFS is good and the differences in the ratios between R2012 and R2022 are small.

Deep water time series comparisons of MERIS to SeaWiFS for R2022
Figure 1: Global deepwater time series comparisons of MERIS to SeaWiFS

Comparison with In Situ Measurements

Validation of the apparent optical properties (Rrs, Kd490), inherent optical properties (a_giop, aph_giop, adg_giop, bbp_giop), chlorophyll, PAR, PIC, and POC retrievals was performed relative to all available match-ups from SeaBASS and the Aerosol Robotic Network - Ocean Color (AERONET-OC). Statistical analysis, scatter plots and frequency distribution comparisons of the satellite to in situ match-ups are provided below.

Apparent Optical Properties

Remote Sensing Reflectance (Rrs)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS Range In situ Range
Rrs41312220.000260.00128-0.00217, 0.01551-0.00000, 0.01555
Rrs44313490.000010.00108-0.00059, 0.033090.00026, 0.01557
Rrs4901165-0.000400.001070.00032, 0.032680.00078, 0.02442
Rrs510328-0.000290.000720.00084, 0.025940.00119, 0.02538
Rrs560235-0.000180.000670.00096, 0.028290.00095, 0.02862
Rrs6651045-0.000100.00034-0.00025, 0.011790.00003, 0.01078
Rrs681260-0.000130.00035-0.00045, 0.010840.00005, 0.01075






Diffuse Attenuation Coefficients (kd490)
* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
kd4902291.03730*1.33034*0.02204, 0.828070.01190, 3.88735

Inherent Optical Properties

Total Absorption Coefficients (a_giop)

* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
a_giop413250.72762*1.73617*0.01599, 0.626170.02474, 0.95427
a_giop443250.76703*1.48313*0.01644, 0.399440.02039, 0.68512
a_giop490250.74939*1.38455*0.02033, 0.257640.02148, 0.38107
a_giop510250.79854*1.29349*0.03550, 0.213610.03721, 0.30252
a_giop560250.88565*1.15405*0.06290, 0.147150.06415, 0.19487
a_giop665250.99364*1.04291*0.34893, 0.584680.43053, 0.51604





Phytoplankton Absorption Coefficients (aph_giop)

* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
aph_giop413301.11421*1.64520*0.00264, 0.268040.00141, 0.17281
aph_giop443301.14503*1.64879*0.00394, 0.300130.00193, 0.18974
aph_giop490301.19887*1.63031*0.00277, 0.202800.00102, 0.11532
aph_giop510301.18637*1.65676*0.00128, 0.153430.00055, 0.08476
aph_giop560301.62950*2.23103*0.00020, 0.077560.00002, 0.04263
aph_giop665301.35185*1.75562*0.00080, 0.157850.00038, 0.07247





Absorption Coefficient of Non-algal Material plus CDOM (adg_giop)

* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
adg_giop413240.50934*2.77703*0.00160, 0.795630.01868, 0.77681
adg_giop443240.46445*3.01686*0.00093, 0.463640.01140, 0.48832
adg_giop490240.37496*3.60127*0.00040, 0.198970.00507, 0.25096
adg_giop510240.34850*3.82019*0.00029, 0.138810.00334, 0.18523
adg_giop560240.27528*4.58815*0.00007, 0.056440.00138, 0.09013
adg_giop665240.19952*5.51382*0.00010, 0.008530.00033, 0.02001





backscattering coefficient of particles (bbp_giop)

* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
bbp_giop413430.93414*1.36488*0.00038, 0.010750.00067, 0.01028
bbp_giop443430.92384*1.35468*0.00036, 0.010250.00058, 0.00990
bbp_giop490430.89977*1.34889*0.00034, 0.009560.00047, 0.00942
bbp_giop510430.89324*1.34904*0.00032, 0.009300.00044, 0.00922
bbp_giop560430.87145*1.35363*0.00027, 0.008680.00036, 0.00880
bbp_giop665430.83531*1.40285*0.00020, 0.007710.00026, 0.00807
bbp_giop68120.71190*1.40469*0.00133, 0.001370.00186, 0.00194





Chlorophyll a (chlor_a)

* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
MERIS Range In situ Range#Mean Bias Mean Absolute Error (MAE)
chlor_a7171.48986*1.89465*0.01300, 858.281470.01700, 46.64000
Photosynthetically Available Radiation (par)

Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
par1394.551084.5538221.53575, 63.8415511.52175, 60.62418
Particulate Inorganic Carbon (pic)

* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
pic290.17620*7.36911*0.00001, 0.000340.00003, 0.00104
Particulate Organic Carbon (poc)

* statistical calculations based on log10 (implies ignoring values equal to or less than zero)
Product
Name
#Mean BiasMean Absolute Error (MAE)MERIS RangeIn situ Range
poc780.94232*1.47399*19.59990, 564.7651311.31300, 796.91229