CGMS-41 NOAA-WP-14
Prepared by NOAA
Agenda Item: II/9
Discussed in WG II
OCEAN PARAMETERS: REPORT ON NOAA VIIRS OCEAN COLOR PRODUCT
ACCURACY AND PREPARATIONS FOR USER READINESS
In response to CGMS action 39.37 and CGMS recommendation 40.30
Work in STAR’s Satellite Oceanography and Climatology Division / CoastWatch supported
by JPSS Proving Ground NOAA began work in 2012(Continuing through 2014) in four
coordinated areas:
Independent Quality Assessment: Establish and sustain user driven independent quality
assessment according to protocols established in consultation with NOAA's operational users.
CoastWatch recommended the use of the IDPS based production system for open waters.
However the recommended system presently does not retrieve acceptable chlorophyll-a
values from coastal waters, specifically in the Gulf of Mexico.
Expand NOAA Operational Use/Users: CoastWatch proposed and achieved significant
expansion of VIIRS ocean color use in four areas: NMFS/fisheries management models,
NWS/NCEP models, and production of HAB products for NWS/OPC (all U.S. coastal areas)
and utilization by commercial interests in the United States.
Develop/deploy Next Generation VIIRS Distribution Portal: Significant progress was
made in the development and deployment of a next generation community consensus data
portal including expanded data search and retrieval features and human user support.
Develop/Deploy User Requested Ocean Color Products: Experimentally generated global
daily merged VIIRS chlorophyll-a products are available for quality assessment and user
readiness.
Related work in two additional areas provide significant support to the work described
above:
Transition of Ocean Color NOAA Unique Products to Operations (Concluding in 2014):
Products used in support of NOAA operations are on schedule to transition to operations in
Marine Optical Buoy Operations (Continuous): Continuous availability of MOBY data is
essential to establishing and maintaining data and product quality, intercomparability
between satellite missions, and user acceptance. Data from MOBY have supported, continue
to support, and support calibration of all known ocean color missions.
CGMS-41 NOAA-WP-14
OCEAN PARAMETERS: REPORT ON NOAA VIIRS OCEAN COLOR PRODUCT
ACCURACY AND PREPARATIONS FOR USER READINESS
Kent Hughes (NOAA)
Ronald Vogel, Heng Gu, Michal Soracco and Yong Sung Kim (SMRC),
Phillip Keegstra, Sathyadev Ramachandran (SPS)
Introduction:
NOAA CoastWatch first demonstrated utility of near-real-time ocean remote sensing in
support of NOAA mission requirements (Beaufort Laboratory, NMFS 1987) and then began
planning a program for interagency access and utilization, (CoastWatch 1992). In
CoastWatch 1998 began distribution of ocean color data for U.S. coastal areas and in 2005
initiated support for the National Ocean Service’s (NOS) Harmful Algal Bloom Forecast and
Warning System. In 2007 CoastWatch is credited with developing NOAA’s first operational
biogeochemical environmental remote sensing system. Studies by NOAA have defined
present requirements and opportunities (NOAA, 2010) and in 2011 the NRC described an
extensive role for ocean color in NOAA including, but not limited to VIIRS.
Technical Approach/Initial Results:
Based on over two decades of experience in developing and supporting NOAA's operational
and scientific ocean color community the CoastWatch proposed and have completed the
following during the first year of work:
Independent Quality Assessment: The team completed an independent user based
assessment of NOAA based ocean color production. The assessment was conducted using
criteria established in collaboration with NOAA’s National Ocean Service (NOS). The NOS
use/user is the most rigorous and longstanding of NOAA users. Specifically they require the
following: VIIRS measurement comparability to heritage measurements in operationally
supported regions, and seamless Line Office utilization with present analysis systems.
NOAA ocean color will be compared with the NASA’s (Ocean Biology Processing Group –
OBPG) community consensus decade-long ocean color climatology. Once satisfactory
comparisons are completed we will initiate comparisons against relevant CoastWatch regions.
The final criteria will be NOS designated comparisons in areas of comparable bathymetry and
chlorophyll concentrations. Quality requirements were also obtained from the National
Marine Fisheries Service/Honolulu Laboratory, and the National Weather
Service/Environmental Modeling Center. Figure 1 below indicates differences in chlorophylla values for the open ocean area around Hawai’i resulting from various processing techniques
in NOAA.
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CGMS-41 NOAA-WP-14
Monthly Chlorophyll
MODIS Climatology for January
•
MODIS (L2gen) NRT for January
MODIS (SWIR) NRT for January
VIIRS Flavors
–
–
IDPS (Ingest IDPS EDRs and create CWhdf L3 files; VRSCW)
L2gen ( Ingest IDPS SDR, use L2gen to create EDR and then L3 CWhdf; VRSSCW)
VIIRS(IDPS) for January
VIIRS(L2gen) for January
22
Figure 1. Comparisons of monthly (January) merged chlorophyll-a using different
processing systems.
Expand Operational Use/Users: An exhaustive analysis of NOAA's requirements for ocean
color data and products as a product of the recently NESDIS-funded project NPP Ocean
Color NOAA Unique Products. Operational, science and routine user requests were
categorized and analyzed. Interviews were undertaken with actual users in NOS, NMFS (see
Table 1 below) and NWS to understand and refine their official user requests and in some
cases expand their requirement. New user requests were obtained from the NCEP
Environmental Modeling Center.
NMFS modeling note: The fisheries management application seeks to utilize VIIRS
ocean color and temperature data to dramatically improve the spatial and temporal
resolution of the ecosystem model's input parameters and reduce the input data
variability. Model runs will focus on investigating the implications of applying the fine
spatial and temporal resolution satellite data on model accuracy and precision. We seek to
determine whether VIIRS data improves the accuracy and variability of estimates over
time as compared to those of the relatively coarse input data currently in use. The effect
of these data on estimates of higher trophic level dynamics (fished and forage species) are
of particular interest. We anticipate the highly resolved satellite data will improve
understanding of the relationships between nutrient enrichment to production to harvested
species in our complex ecosystem model. More accurate estimates will improve the
results of the various modeling scenarios needed for better fisheries policy decisionmaking (Figures 2). Figure 3 show the remarkable difference in chlorophyll-a that can be
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CGMS-41 NOAA-WP-14
expected from different satellite platforms and even from the same platform with different
masking.
NCEP/EMC note: Initial results of two experiments using SeaWiFS climatological data
have indicated quantitative improvements in reduction in near-surface ocean temperature
errors on the order of 10% and sea surface height error reduction on the order of 5-10%.
Work will soon begin to actually utilize VIIRS ocean color data from CoastWatch and to
determine optimal spatial and temporal binning data binning.
CoastWatch NPP/VIIRS User Engagement:
User Interviews and Outcomes
Line Office
Sub-Element
Program
Area/Products
Interviewees
and Date(s)
Outcome
1.
2.
National Ocean
Service (NOS)
NCCOS
Imagery support for
operational product:
Harmful Algal Bloom
Forecasts and Warnings
Stumpf and
Tomlinson
February 26, 2013
3.
4.
5.
6.
7.
National Weather
Service (NWS)
National Marine
Fisheries Service
(NMFS)
EMC and OPC
Honolulu
Laboratory /
Pacific Island
Fisheries
Science Center
1.
Incorporation of near
realtime chl a into
regional and global
models. Input of chl into
AWIPS to support
Ecological Forecast
System
Avichal Mehra and
Dave Behringer.
Anthony Siebers
Basin scale resource
management on
decadal / interdecadal
timescales and cruise
support – Pacific Basin
Polovina and
Moxey
March 21, 2013
2.
3.
4.
1.
2.
3.
Major concern re masking of West Florida shelf area
during major HAB. L2gen renders area satisfactorily.
Do not shut down MODIS until end of life, but VIIRS
should be ready.
Parallel operations: MODIS and VIIRS
Require at least one back up platform
Continue independent quality assessment.
Desire regeneration of HAB products using NASA science
quality data.
Lack of inland waters (lakes) makes IDPS product
unacceptable.
Lack of Great Lakes data makes IDPS product
unacceptable.
Consistency AND quality are important. In that order.
Difference between science quality (NASA) and NOAA of
10% is acceptable. Parallel operations with science
quality is important.
Consistent delivery of data, i.e., from constellations is
important.
Require NRT high resolution for cruise support as well as
long time period basin scale for resource management.
Desire data from various missions “stitched” together.
Historically relied on OBPG but would use NOAA data if
quality were assessed, sustained and conveniently
delivered.
Table 1. Results of NOAA operational and scientific user interviews indicating specific
product and quality needs.
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CGMS-41 NOAA-WP-14
Conversion of VIIRS data to Atlantis
Ecosystem Model Grid
VIIRS satellite chlorophyll
S-NPP VIIRS chlorophyll
CoastWatch 2-day avg (Dec 3-4, 2012)
Raster data: UTM coordinates
Georeferenced
grid
Ecosystem model
grid
Chesapeake Bay Program
Georeferenced polygonal grid
8,282 polygons
NOAA/NMFS/NCBO
Atlantis Ecosystem Model
97 polygons
Aggregated from 8,282
Figure 2. Step-wise inclusion of satellite ocean color data into the Atlantis model
Satellite Chlorophyll Inputs to Atlantis Model
SeaWiFS
Two-month average
Dec 2001 – Jan 2002
MODIS standard
MODIS Bay-tuned
VIIRS
Two-month average
Dec 2012 – Jan 2013
Two-month average
Dec 2012 – Jan 2013
Two-month average
Dec 2012 – Jan 2013
High bias for
coastal regions
Tuning reduces
high bias for Bay
High chl mask not
implemented
Figure 3. Satellite chlorophyll-a from various satellite platforms showing the significantly
differing values. Note that vicarious calibration will be applied to VIIRS in the
operational IDPS system beginning in September 2013.
Next Generation VIIRS Distribution Portal: For almost two decades NASA has supported
the distribution of ocean color data and products to the user community. With the advent of
ownership of JPSS (beginning with JPSS-1) the responsibility for distribution of those data
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CGMS-41 NOAA-WP-14
and products (eventually including not only ocean color but also sst) will fall to NOAA. The
CoastWatch Team has surveyed the community of systems distributing data and products via
the web to operational and science communities. Results of the survey indicated the need for
expansion and refinement of the NOAA distribution system to better meet users' needs. The
Team has completed work on the following items: VIIRS Granule Selector, Thredds server
for global data, and various portal enhancements. (Figure 4).
Data Portal Enhancements
• VIIRS Granule Selector
• Select granules
from a Google
map
Near real-time
processing status
shown on map
Calendar to
select data for
any date
• Product search results
of “No Results”
augmented with date
range of actual data
holdings
• Operational vs.
experimental search
Google-Map zoom
into granules
View granule true
color image and
download data files
Figure 4. Next-Generation Data Portal showing VIIRS access enhancements.
Develop/Deploy User Requested Ocean Color Products: As mentioned above NASA has
achieved remarkable utilization of ocean color data and products. But as NOAA moves
forward with ownership of the JPSS mission our native experimental and operational product
generation and distribution capability must establish and sustain comparable products and
services. The CoastWatch team has demonstrated the capability to sustain and distribute
global products, at 750m and 4km, including chlorophyll- a and selected NOAA unique
anomaly products needed for NOAA operational applications . As of June 2013 NOAA’s the
following are available from the links indicated in the Appendix.
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CGMS-41 NOAA-WP-14
Global Daily Composite (4km)
VIIRS Chlorophyll, May 18, 2013
Figure 5. CoastWatch produced experimental VIIRS chlorophyll-a global
composite (4km) available at NOAA/STAR Thredds server.
Support Operationalization of NOAA Unique Products and Marine Optical Buoy:
Important work is ongoing which is critical to overall success of VIIRS ocean color becoming
a productive, sustainable and high quality NOAA product. NOAA ocean color products have
been long used in variety of NOAA operational and scientific applications areas. The suite of
ocean color products essential to issuance of the National Ocean Service’s Harmful Algal
Bloom Bulletin is on schedule for transition from research production to operations this Fall
(2013). Essential to the acceptance of ocean color by operational, science and commercial
users is the sustainment of VIIRS ocean color at the highest quality levels. Fundamental in
this regard is the ready availability of MOBY data for VIIRS vicarious calibration. VIIRS
observations when compared with MOBY data established comparability to SeaWiFS.
Beginning in April 2013 MOBY data have been used as the basis for establishing vicarious
calibration coefficients for IDPS processing in NOAA.
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Appendix
CoastWatch ocean color quality assessment links:
-----------------------------------------------------------------------------------------
http://www.star.nesdis.noaa.gov/sod/mecb/coastwatch/NRT-QA/OC-QA-CW.html
http://www.star.nesdis.noaa.gov/sod/mecb/coastwatch/NRT-QA/OC-timeseriesDynamicInterSensor-CW_v4.html
http://www.star.nesdis.noaa.gov/sod/mecb/coastwatch/NRT-QA/OCDailyClimTimeSeriesStats-DynamicInterSensor-filterbyChlor.html
http://www.star.nesdis.noaa.gov/sod/mecb/coastwatch/NRT-QA/OCDailyClimTimeSeriesStats-DynamicInterSensor-filterbyCoastal.html
http://www.star.nesdis.noaa.gov/sod/mecb/coastwatch/NRT-QA/OCDailyClimTimeSeriesStats-DynamicInterSensor-filterbyBathy.html
MOBY data are available at:
-------------------------------------------http://coastwatch.noaa.gov/moby2
CoastWatch produced experimental data and products are available at:
-----------------------------------------------------------------------------------------------------------4km: http://coastwatch.noaa.gov/cwn/search/cwn_most_recent.php?sensor=VIIRS&product=
chlorIDPS&region=WW ; clicking on a thumbnail reveals the variety of data formats. Using
the Data Access page a date range can be set (using 'Global' as the region and 'Chlorophyll
(JPSS IDPS)' as the product) to retrieve older datasets.
750m EDR (granule): The Granule selector page (and calendar)
at http://coastwatch.noaa.gov/cwn/cw_L2.html can be used to see what granule covers your
area of interest. A true color thumbnail will be shown when a granule is clicked on the
Google Map with additional links to the VIIRS EDR in CW HDF4 format (readable by
the CoastWatch Data and Analysis Tool software).
1
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