Evaluation of Recent VIIRS Sensor Performance in the Coastal Ocean Sherwin Ladner1, Robert Arnone2, Adam Lawson1, Giulietta Fargion3, Jennifer Bowers4 , Paul Martinolich4 , Michael Ondrusek5 , Michelle Wood6,7 1Naval Research Laboratory, Stennis Space Center, MS, USA 2University of Southern Mississippi, Stennis Space Center, MS, USA 3San Diego State University, San Diego, CA, USA 4QinetiQ Incorporated, Stennis Space Center, MS, USA 5NOAA NESDIS, College Park, MD, USA 6NOAA/AOML Ocean Chemistry Division, Miami, FL, USA 7Current Address: Dept. Biology and IE2, Univ. Oregon, Eugene, OR, USA We would like to acknowledge our sponsors at the JPSS Program Office for support of this work. FALL AGU San Francisco, California – December 03-07, 2012

Objectives Evaluate current NRL and IDPS VIIRS Environmental Data Products nLw (l) – Water Leaving Radiance Chlorophyll, backscattering (bb551) Coastal AERONET OC Platform Time Series - nLw(l) AAOT - Venice, Italy Calibration & Validation Ship Cruises Hawaii (NOAA/Ondrusek)  nLw(l) Gulf of Mexico (NMFS Cruise – Mitch Roffer, John Lamkin)  CHL US East Coast (GOMECC2 Cruise – M. Wood)  nLw(l) Navy Panama City Slocum Glider (Optics Only)  bb(551) Inter-sensor comparison with MODIS (nLw(l),bb(551),CHL)

VIIRS – NPP Operational Software for Ocean Color Processing n2gen software (NRL,NASA) – R&D Calibration applied to SDR (AFWA/NAVO) Atmospheric correction – GW NIR w/ 80 aerosol models Glint / Cloud Removal In water Algorithms – QAA - Coastal iteration NOAA Operational IDPS From CLASS (Mx6.0-Mx6.5) Research Software #1 used to evaluate VIIRS sensor and identify issues and improve IDPS VOCC software

CURRENT IDPS OPERATIONAL SYSTEM Mx 6.2 CURRENT NRL APS OPERATIONAL 13 CURRENT NRL APS OPERATIONAL SYSTEM 4 9 39 August 03, 2012 FUTURE Mx6.6 IDPS OPERATIONAL SYSTEM PLANNED FOR JANUARY 2013 Inland lakes Cloud Masks Similar Higher Coastal CHL Aqua 4.7 Masked Pixels (in Black)

Coastal Chlorophyll Retrievals from VIIRS Martha Vineyard’s Coastal Observatory (MVCO) Average Chl range MVCO = 4-6 mg/m3 (August 2011) NRL vs. IDPS v6.4 August 03, 2012 US East Coast NRL Chlorophyll IDPS v6.4 Chlorophyll 1:1 Line Some Coastal Chlorophyll Values Exceeding 200 mg/m3 1. IDPS processing Chlorophyll is to high 2. N2gen retrieving accurate Chl . VIIRS Sensor is showing good agreement with observations

n2gen Inter-Sensor Matchups (VIIRS vs MODIS n2gen) US East Coast – August 03, 2012 VIIRS = 1803 GMT AQUA = 1810 GMT nLw 412 nLw 443 nLw 486 nLw 551 Backscattering Chlorophyll 551nm QAA OC3M VIIRS and MODIS Aqua agree well and are within time and space uncertainty of the products

NASA AERONET-OC (GLOBAL NETWORK) 15 Sites that have approved L2 data – nLw(l) These sites have met the deployment requirements: Platform for unobstructed sky and sea viewing; 2) Bottom effects 3) Superstructure perturbations AAOT P-height S-distance Water depth at which the bottom perturbation adds a contribution of 1% to the SeaPRISM LWN as a function of seawater diffuse attenuation coefficient Kd and irradiance reflectance R (the latter values are defined by the curves in black) assuming a Lambertian seabed irradiance reflectance RB=0.10). Just going to show time series matchup at AAOT. Are doing many others to monitor radiances and gain stability. Right part of slide is requirement of platform 3 New Coastal US Sites: LISCO Site: Western Long Island Sound The observed surface area should be at a distance from the main superstructure larger than the height of the superstructure itself. WaveCIS_Site_CSI_6' site: Gulf of Mexico SeaPrism Eureka - UCS site: South California Bight (Newport Beach)

n2gen - nLw Matchup @ AAOT – Venice Italy April – October 2012 V5 V6 V5 V6 Operational July 19th V5 V6 V5 V6 What is V5 and V6 – The basis of this reprocessing is the MODIS Calibration Support Teams (MCST) look-up table (LUT) V6.1.15.3 (Based on SeaWiFS Cross Calibration). This is the same LUT that is being applied for the Collection 6 reprocessing of MODIS Aqua Land and Atmosphere products (completed in early 2012 for L1B products, on-going as of this writing (April 2012) for L2 products; note that OBPG actually used the update V6.1.15.4 for reprocessing). It includes time-varying corrections for changes in response versus scan angle (RVS) for bands 8 and 9, which were derived using observations of desert sites. These desert-based corrections largely replicate what the OBPG had previously derived from cross-calibration to SeaWiFS, and previously applied in recent Aqua reprocessings. The results using this LUT alone, however, still showed significant artifacts (residual cross-scan variations and detector/mirror-side striping in derived products). To mitigate these effects, the OBPG developed a cross-calibration approach similar to Meister et al. 2011, but using global MODIS-Aqua Level-3 water-leaving radiance retrievals as the vicarious calibration source. This Aqua-to-Aqua calibration (see below, 'Additional Information') is used to derive temporal adjustments to RVS, relative to the MCST calibration, that significantly reduce residual striping and cross-scan artifacts. SeaPrism:MODIS SeaPrism:VIIRS MODIS:VIIRS wavelength slope r^2 slope r^2 slope r^2 410 1.0205 0.9634 1.0444 0.9640 0.9733 0.9140 443 0.9905 0.9821 0.9223 0.9820 0.9243 0.9554 488 0.9002 0.9911 0.9602 0.9954 1.0725 0.9879 551 0.8981 0.9872 0.9542 0.9885 1.1039 0.9888 671 0.4157 0.8252 0.7060 0.9313 1.3780 0.9837 MCST Look-up Tables (Temporal RVS) V5 = Calibration Issue with 412 & 443nm (SeaWiFS Cross-Calibration) V6 = Calibration Correction (Desert Sites)

n2gen VIIRS/MODIS Rrs vs Hyperpro Matchup Hawaii: September 08-18, 2012 Rrs = nLw/f0 Honolulu 2 Stations MODIS 9/11/12 MODIS 9/12/12 Chl MODIS(2)=Cloud Chl IDPS(2) = Masked VIIRS 9/11/12 VIIRS 9/12/12 Mike/NOAA/Hyperpro. Similar matchups with NOAA MSL12 and NASA l2gen. 1 Station IDPS(1) = Masked Black Pixels Are Masked Mx6.2 VIIRS IDPS 9/11/12 Black Pixels Are Masked Mx6.2 VIIRS IDPS 9/12/12 Data Provided By M. Ondrusek NOAA Hyperpro

n2gen VIIRS/MODIS Rrs vs Hyperpro Matchup Hawaii: September 08-18, 2012 Rrs = nLw/f0 4 Stations Honolulu VIIRS 9/15/12 VIIRS IDPS 9/15/12 Black Pixels Are Masked Mx6.2 Chl MODIS(all)=Glint IDPS(all) = Masked Data Provided By M. Ondrusek NOAA Hyperpro Honolulu VIIRS 9/17/12 Mike/NOAA/Hyperpro. Similar matchups with NOAA MSL12 and NASA l2gen. VIIRS IDPS 9/17/12 Black Pixels Are Masked Mx6.2 Chl 2 Stations MODIS(all)=Glint IDPS(all) = Masked

n2gen VIIRS/MODIS Rrs vs Insitu Matchup GOMECC2: July 22 – August 13, 2012 Aqua VIIRS Aqua VIIRS FL FL FL FL Glint Glint Glint Rrs = nLw/f0 1 Station 2 Stations Michelle/NOAA/ASD. IDPS(1) = NA CLASS VIIRS(2) = Glint IDPS(2) = Masked Data Provided By M. Wood NRL ASD

n2gen VIIRS/MODIS Rrs vs Insitu Matchup GOMECC2: July 22 – August 13, 2012 VIIRS VIIRS IDPS Mx6.0 Glint Delaware Bay NewYork Rrs = nLw/f0 2 Stations 1 Station Michelle/NOAA/ASD. MODIS(1)= Glint MODIS(all) = Cloud IDPS(all) = NA Data Provided By M. Wood NRL ASD

Gulf of Mexico Cruise: April 02 – May 28, 2012 190 Stations April 2012 Monthly Mean Chlorophyll Data from Mitch Roffer and John Lamkin and NMFS cruise CTD – Fluorometer (surface ) NOT HPLC!

Gulf of Mexico Cruise – April 02 – May 28, 2012 NRL n2gen ~55% More Retrievals Than IDPS (Masking) IDPS Errors in VIIRS CHL compared to insitu CHL Bias [avg(logC1-logC2)] = 0.088 RMSE[avg(logC1-logC2)2] = 0.029 Average Relative Error = 13.4% N = 71 One problem from literature (Campbell & O’Reilly, Metrics for Quantifying the Uncertainty in a Chlorophyll Algorithm,2006) with using dataset like NOMAD is that the distribution of the data is not representative of the global chlorophyll (seawifs). Errors increase with increasing chl values. NOMAD Matdhup y-axis is bias. Check literature to make sure. log(VIIRS CHL) – log(insitu CHL)

Panama City, FL Slocum Glider Deployment November 08 – November 16, 2012 bb532 11/08/12 bb532 11/09/12 bb532 11/10/12 IDPS IDPS IDPS Panama Panama Panama City, FL City, FL City, FL VIIRS VIIRS VIIRS Average Relative Error = 5.75%, 13.24% Insitu (glider) vs. Satellite (VIIRS,IDPS) Backscattering 532nm Glider Near Surface (<2m) BB Slope Algorithm (Gould, et.al - ). Atmospheric Correction / different aerosol models. Linear relationship between bb @ wavelength. Know bb at one bb estimate for another. 11/08 11/09 11/10 Glider n2gen IDPS Glider 1514 – 2131 VIIRS 1850 Glider 1850 – 2212 VIIRS 1905 Glider 1500 – 2112 VIIRS 1846 Differences in Processing Aerosol models, IOP Algorithm, etc.

Summary : VIIRS Ocean Color Evaluated VIIRS ocean color EDR products using processing from NRL’s n2gen (R&D) and VOCCO (IDPS) VIIRS Coastal Ocean Color EDR’s (nLw/Rrs, Chlorophyll and bb 551) compare well with insitu Ship/AERONET-OC and MODIS IDPS EDR’s products are over masking (Mx6.0-6.5) – limited matchups Update of IDPS EDR’s (Jan 2012 - Mx6.6) - suggest setting / using quality flags Monitoring sensor and radiometric calibration stability using global validation network  requires IDPS updates (Mx6.6) Follow-on cruises and validation planned in near future Ongoing monitoring and evaluation of VIIRS products Navy’s initial assessment of VIIRS ocean color products indicates ocean products are of high quality and plans for operational use APS v4.10 currently going thru OpEval at NAVO

Sponsor Acknowledgements: Questions? Sponsor Acknowledgements: JPSS Program Office NOAA Ocean Acidification Program (GOMECC2 Cruise) Disclaimer (NOAA co-authors): The opinions expressed here are those of the individual scientist/authors and not the organizations.

n2gen VIIRS/MODIS Rrs vs Insitu Matchup GOMECC2: July 22 – August 13, 2012 VIIRS VIIRS MODIS Aqua MODIS Aqua VIIRS Y=1.097x R2=0.82 VIIRS Y=1.0357x R2=0.88 MODIS Aqua y = 0.9917x R2 = 0.86 MODIS Aqua y = 0.9518x R2 = 0.99 MODIS Aqua MODIS Aqua

Comparison of Processing Software Packages IDPS and NRL APS (n2gen)

Panama City, FL Slocum Glider Deployment November 08 – November 16, 2012 bb 532 Time Series (Entire Deployment) Slocum Glider Bottom = * VIIRS bb 551nm -> 532nm Insitu (glider) vs. Satellite (VIIRS) – Near Surface (<2m) 11/08 11/09 11/10 11/08 11/09 11/10 Glider 1514 – 2131 VIIRS 1850 1850 – 2212 1905 1500 – 2112 1846 Average Relative Error = 5.75% Slope=0.95 R2=0.84 Panama City, FL 11/10/12 7daylp BB Slope Algorithm (Gould, et.al - ).

Inter-Sensor Matchups (VIIRS vs MODIS n2gen) Navy Ocean Optical Backscattering Product – US East Coast Bb 551nm QAA Bb 547nm QAA 08/03/2012 MODIS 1810 GMT NPP VIIRS 1840 GMT U.S. East Coast U.S. East Coast 0.0005 0.002 0.008 0.032 0.13 0.5 1/m

n2gen VIIRS/MODIS Rrs vs Insitu Matchup GOMECC2: July 22 – August 13, 2012 VIIRS VIIRS MODIS Aqua MODIS Aqua GOMECC2 Satellite (VIIRS-n2gen) vs. Insitu (ASD) Rrs Average Relative %Error: 410nm 443nm 486nm 551nm VIIRS(5) 7.55 4.32 6.15 16.10 MODIS(3) 12.92 9.73 9.49 16.57 VIIRS VIIRS MODIS Aqua MODIS Aqua 22