1. IMAGERY DERIVED CURRENTS FROM NPP Ocean Color Products 110 minutes!
Diurnal changes in ocean color in coastal waters
Robert Arnone1, Ryan Vandermuelen4, Sherwin Ladner2, Inia Soto 1Michael Ondrusek3, Charles Kovach3, Haoping Yang1, Joseph. Salisbury5
University of Southern Mississippi Marine Science Department, Stennis Space Center, MS Naval Research Laboratory, Stennis Space Center, MS
3. NOAA/NESDIS/STAR, Center for Weather and Climate Prediction, College Park, MD 4. SSAI / NASA, GSFC-616.1, Greenbelt, MD University of New Hampshire, Durham, NH
Abstract:
  Coastal processes can change on hourly time scales in response to 1) water mass advection, 2)movement of vertical optical layers and 3)biological activity: all of which influence the color of surface waters. Validation of satellite products in coastal waters require defining temporal and spatial changes to delineate diurnal bio-optical processes. Diurnal color change and ability for satellite ocean color response were determined with in situ and satellite observations. In situ diurnal changes in ocean color in a dynamic coastal region in northern Gulf of Mexico were characterized using AERONET -WavCIS CSI-06 and coupled to the spatial diurnal changes from the overlapping orbits of VIIRS–NPP Ocean color within 100 minutes. New diurnal VIIRS products shows the occurrence and displacement of phytoplankton blooms and decay during the afternoon period.
How fast can ocean color properties change in ~100 minutes?
18:15 - NPP
AERONET - SeaPrism Platform
Transect line
Bloom Decay
Second Pass Greater
(mg/m3)
Chlorophyll
Orbit
Frontal
Movement
Difference
First orbit Second orbit
Advection:
IMAGERY DERIVED CURRENTS FROM NPP
Nov : Nov :50 , 2014
Bloom
WavCis
SeaPrism
Objectives :
->The chlorophyll difference over ~100 minutes between the earlier orbit to the later orbit can identify active ecosystem coastal regions . Shows advantages of a geostationary sensors for diurnal processes.
-> Changes occur from 1) water mass advection and 2) biological activity (i.e. blooms, decay, etc.). The difference image identifies the locations of diurnal changes and if biological activity is blooming or decaying. These change also occur in the SST diurnal changes.
How rapidly does ocean color change in the coastal ocean
what is the spectral uncertainty of these changes?
2. What is the diurnal signal of ocean color in coastal waters?
3. Can the VIIRS 100 minute overlaps detect diurnal changes?
4. Define the % uncertainty of diurnal Ocean color signatures.
5. New products can be developed from diurnal ocean color to define coastal bio-optical and physical processes which support a Geostationary satellite.
Yang et al, 2015
Diurnal changes from VIIRS overlaps in ocean color can
be used to estimate surface currents using Maximum Cross Correlation from 4 different color products. Each product shows different number of retrieved surface current vectors. Certain diurnal ocean color products are better at resolving advection.
Hourly changes in nLw at Wavcis
Matchup VIIRS and MODIS
Diurnal Variability of Chlorophyll and nLw at WavCis
Bloom Decay
(mg/m3)
Chlorophyll
Difference
WavCis
18:260
20:31
West Transect line East
Seaprism
What is the product uncertainty between these NPP products?
Orbital Overlapping
Ocean Color Products minutes!
S-NPP - Daily Orbital Overlap at ~ 30 degree latitude
~ 700 pixel Overlap Very Similar Solar Zenith ~ 40 degrees.
S- NPP
S- NPP MS
Plume
A geostationary sensor (GEOCAPE) will enable identification of the rates of changes for these processes at different locations. These rates are essential to ecological models for forecasting.
Right Side of Scan 19:56
Left Side of Scan 18: 15
GEOCAPE Cruise Sept 12 ,
Pixel
Sensor Zenith degrees D
Aeronet
% Spectral
Changes
MODIS – Aqua 18:45
Ocean Color product uncertainty can also be determined by examining values on either side of the swath.
The color differences are not related to sensor angles - Therefore the color processing is being handled correctly.
Diurnal Spectral Channel uncertainty at stations of the VIIRS overlap . Diurnal changes in Bio-optical Products can be significant.
The matchup up uncertainty of in situ, backscattering 440 nm and absorption at 486 nm with percent diurnal changes in VIIRS overlaps of bb and absorption can influence validation.
The hourly changes in the ocean color are “real” as shown by
the WavCis ocean color and are not satellite processing issues! Many examples of diurnal color changes.
First orbit Second orbit AERONET – Diurnal Changes
Differences between the three in situ stations at locations A and B and the VIIRS overlap could be associated with diurnal changes in the diurnal bio-optical processes which can occur within 100 minutes. The percent changes, ranging from 17% to 35% in the backscattering and absorption products from VIIRS overlap at these 3 stations showed a similar range to the Rrs and nLw changes.
Dec
Oct 22, 2014
Feb11,2014
18:29
Summary:
The percent spectral uncertainty at a station between the VIIRS ~100 minute orbits range from 4% at 410 nm to 31% at 671 nm.
1. Diurnal coastal processes can change the ocean color signatures within hours throughout the day.
WavCis SeaPrism shows hourly color response in the nLw - >>> can be greater than 40% within 60 minutes .
Changes in ocean color can be used to identify diurnal bio-optical and physical processes .
2. VIIRS Orbital overlaps of 100 minutes (afternoon orbital changes ) has capability to detected and validated the diurnal hourly ocean color and diurnal processes .
3. Uncertainty from the diurnal spectral channels in ocean color ranged from % and change with time and space.
Rapid ocean color changes from diurnal processes “must “ be accounted in matchups in coastal ocean color satellite calibration/validation.
4. New ecological products were derived from diurnal ocean color changes from VIIRS - orbital overlaps) : PRODUCTS INCLUDE:
A. DIURNAL DIFFERENCES in chlorophyll -- identifying Phytoplankton BLOOMING and DECAYING regions !
B. Water mass Advection  Ocean Color products estimate surface currents verses biological changes ! VIIRS Orbital Overlap derived currents!!!
5. The diurnal changes detected by VIIRS overlap validates the requirements for Geostationary ocean color satellite.
6. Ocean color products from current polar obiters may be “bias” to the afternoon time of overpass and may not accurately represent a daily mean.
7. Diurnal changes throughout the day can change by over 20% for the bio-optical ecosystem, especially in coastal areas
8. The spatial variability diurnal ocean color changes is a new focus research for a ocean color geostationary satellite GEOCAPE to identify the ocean processes responsible with diurnal color changes. !
Robert Arnone ; Ryan Vandermeulen ; Sherwin Ladner ; Michael Ondrusek ; Charles Kovach, H. Yang, J.Salsbury: " Diurnal changes in ocean color in coastal waters ", Proc. SPIE 9827, Ocean Sensing and Monitoring VIII, (May 17, 2016); doi: / ;
Arnone, R., S. Ladner, et al, “Monitoring bio-optical processes using NPP-VIIRS and MODIS-Aqua ocean color products,” Proc. SPIE 8724, Ocean Sensing and Monitoring V, 87240Q (June 3, 2013),
Yang, H.; Arnone, R.; Jolliff, J.; Estimating Advective near –surface currents from ocean color satellite images. Remote Sensing of Environment Volume 158, 1 March 2015, Pages 1–14