Monitoring Bio-Optical Processes Using NPP-VIIRS And MODIS-Aqua Ocean Color Products Robert Arnone (1), Sherwin Ladner (2), Giulietta Fargion (3), Paul Martinolich (4), Ryan Vandermeullen (1), Jennifer Bowers (3), Adam Lawson (2) 1 University of Southern Mississippi, Stennis Space Center, MS. 2 Naval Reserach laboratory, Stennis Space Center MS. 3 San Diego State University, San Diego, CA. 4 QinetiQ Corp, Stennis Space Center, MS. SPIE – Baltimore - April 2013

Monitoring ocean Processes Uncertainty in Ocean products Objective – How rapidly do bio-optical processes change and “Can they be detected using ocean color? “ How do these “ color” changes affect Calibration and Validation Procedures? Evaluate changes from satellite retrieved bio-optical products Assess sensor and processing characteristics that impact hourly changes Assess the satellite retrieved products uncertainty.

- Short term variability – (Hours) -Assumption is satellite is looking at Same ocean color water.. -Uncertainty associated with Inter-comparison of sensors (MODIS / VIIRS) What must we consider in evaluating time change of bio-optical processes ? 1) Water mass advection and physical processes 2) Ocean Color Changes from bio-optical changes - Biological Changes - Growth / decay particle resuspension, 3) Sensor and processes calibration, characterization, angular affects, BRDF, Atmosperhc correction etc. Half Angle Mirror (HAM) left and right side. Ocean Color products Uncertainty MODIS – VIIRS Optimum “tracking” is to use the “same” sensor, for assessing changes. Such as - Geostationary Satellite (example – GOCI)

Pixel Sensor Zenith degrees S-NPP - Daily Orbital Overlap at ~ 30 degree latitude ~ 700 pixel Overlap - Very Similar Solar Zenith ~ 40 degrees. 3 Overlapping ocean Color Products with 110 minutes ! MODIS – Aqua 18:45 18:45 Approach- - Sequential orbits from MODIS and S-NPP – VIIRS S-NPP Left Side of Scan 18: 15 S-NPP Right Side of Scan 19:56

Nov1, 2012 Processed using L2gen Examine the “nLw445” and “ nLw555” and Chlorophyll (OC2) ratio (445/555) (488/555) S- Npp S- NPP MODIS :45

18:15 - NPP 18:45 – MODIS 19:56 –NPP Line 1- Plumes Line 2 – WavCis WavCis ’ 28 52’ 28 52’ Transect #2- - Wide range of water “type” Open and Coastal - East West Angle dependence - Transect through Aeronet – SeaPrism Site -Cloud Development And formation

18:15 - NPP 18:45 – MODIS 19:56 –NPP Line 1- Plumes Line 2 – WavCis South Pass WaveCis cloud

18:15 - NPP 18:45 – MODIS 19:56 –NPP Line 1- Plumes Line 2 – WavCis South Pass WaveCis cloud Wavcis ’ 28 52’ 28 52’ Line 4 Offshore 55 Aqua 1845 NPP 19:55 Eastern Side NPP 18:15 Western Side

Aeronet Along Line 2 transect - NPP and MODIS variations of radiance with 110 minutes Sensor Zenith Angle variations

Variation Sequential along the Transect NPP- Orbits How does the 110 minutes Difference changes affects Open and coastal waters - - High scatter at :55 Bias Higher - Low scatter at 551 How impacts Chlorophyll Product? 1:1

NPP Chlorophyll variation with 110 minutes along transect Note linear Chlorophyll scale. 18:15 orbit – lower chlorophyll at high concentrations / This results address the “Product Uncertainty” with 110 minutes with same sensor. Differences results from a) Biological Processes, b) water mass advection or c) Sensor processing

Impact of Sensor Zenith Angle of ocean color retrievals Impact of Sensor Zenith Angle of ocean color retrievals NPP 18:15 – 1955 difference along the Transect Line nLw 555 Aeronet

Impact of Sensor Zenith Angle of ocean color retrievals Impact of Sensor Zenith Angle of ocean color retrievals NPP 18:15 – 1955 difference along the Transect Line nLw 445 Aeronet

Impact of Sensor Zenith Angle of ocean color retrievals Impact of Sensor Zenith Angle of ocean color retrievals NPP 18:15 – 1955 difference along the Transect Line 19: minute Chlorophyll Bloom ?

Evaluation of the Atmosphere Correction on sequential NPP products Evaluation of the Atmosphere Correction on sequential NPP products NPP 18:15 – 1955 difference along the Transect Line Lt( ) = Lr( ) + La( ) + Lu( ) La 865 used for determining Aerosol Model and Epsilon (spectral La( ) )

b) Evaluation of the Atmosphere Correction on sequential retrievals Evaluation of the Atmosphere Correction on sequential retrievals NPP 18:15 – 1955 difference along the Transect Line Lt( ) = Lr( ) + La( ) + Lu( ) La 865 used for determining Aerosol Model and Epsilon (spectral La( ) Aerosol model pair used NPP 18:15 used 35-36, 34 – 35 ), Modis used NPP 19: 56 used and All very Similar.

Changes in ocean color products over short time scales Changes in ocean color products over short time scales -Examined changes of the Spectral Channels 443 – Examined difference in Open and coastal water - Examined angular differences within NPP - Examine the Atmosphere channels – correction. Examples of changes in short scale chlorophyll retrievals from MODIS and NPP

20: 16 NPP 21: 22 MODIS 22:27 NPP Southern California Current June 25, – Minutes 20: 16 NPP 20: 16 NPP 21: 22 MODIS 21: 22 MODIS 22:27 NPP 22:27 NPP Changes in ocean color products Changes in ocean color products over short time scales over short time scales

Figure 8 - Southern California Chlorophyll Sequence within 111 minutes derived from S-NPP and MODIS from June 25, 2012 from 20:16 – 22:27 GMT. The lower “zoomed in” panels show possible bio-optical changes from upwelling and advective changes along the coasts. 20: 16 S- NPP 21: 22 MODIS 22:27 S- NPP A B A B Monterey Bay CC

20: 16 S- NPP 21: 22 MODIS 22:27 S- NPP Monterey Bay Changes in Satellite retrievals Chlorophyll with 121 minutesA B

Gulf Stream Florida Coast Sequential NPP Orbits 101 Minutes 17:37 GMT 19:18 17:37 19:18 Florida

17:37 19:18 A A B B CC Gulf Stream A. B. Figure 9- a) November 3, 2012, NPP Chlorophyll products along the North Wall of the Gulf Stream off of Florida from 17:37 and 19:18 GMT b) Enlarged area along the chlorophyll from at changes at different locations.

SUMMARY: Monitoring Bio-Optical Processes Using NPP-VIIRS And MODIS- Aqua Ocean Color Products 1) Sequential Orbits of NPP and MODIS within the same day were used to evaluate Ocean Color Products for monitoring changes in bio-optical processes. 2) Explored variability of bio-optical products within approximately 100 minutes 3) Evaluated capability of ocean color to monitoring short scales bio-optical processes. Examined : 1. Water mass advection and bio-optical processes 2. Examined uncertainty possibly resulting from sensor characteristics and ocean color processing. Demonstrated sequential satellite orbits can establish the satellite products uncertainty for calibration / validation. Demonstrated ocean color capability to characterize the bio-optical processes by using overlapping orbits and multiple satellites. SPIE – Baltimore 2013

Questions? Acknowledgements: Thanks is given to the NOAA JPSS program for funding support

19:31- NPP 17:50 – NPP

Nov :15 Sensor Zenith 19:56 Solar Zenith – Very Simialr

Day :18 33 Nov 3, Mosaic #2 South East US – Nov 3 Mosaic 2 scenes from 1737 Can use the 2 boxes to extract.

# 4 Feb 17, Have additional slides. Northern Gulf of Mexico VIIRS and MODIS 2 areas. Sequential orbits minutes MODIS