# Presentation: 722801

## Development of GHRSST L2Pcorefor MODIS

- Bryan Franz
- NASA Ocean Biology Processing Group
- Goddard Space Flight Center

## MODIS SST Interaction

- Community

- PO.DAAC
- GHRSST product reformatting and ancillary merge (L2P)
- GHRSST L2P distribution
- Level-3 distribution

- OBPG
- software development and algorithm integration
- production processing
- quality assessment
- archive & distribution

- RSMAS
- algorithm development and coefficient updates
- error fields (tables)
- quality assessment

- Level-3 Standard Products

- GHRSST L2Pcore Products

- Level-2 & Level-3 Standard Products

- Level-3
- Standard

- coefficients

- error tables

- L2P

- GHRSST
- Users

- algorithms

## MODIS SST Activities at OBPG

- Standard Global Production (transitioning from MODAPS/DAAC)
- Level-0 through Level-3
- Terra & Aqua, Day and Night, 11-12um and 4um SST products
- Online archive and distribution (L1A, L2, L3)
- GHRSST L2Pcore Production
- Parallel production effort, at no additional cost
- Level-0 through L2Pcore is operational
- Terra & Aqua, Day and Night, 11-12um and 4um SST products
- Distribution to PO.DAAC for L2P conversion
- User Support
- SeaDAS: distributed processing software, display and analysis
- OCForum: online user support forum, monitored by project staff

## Nighttime 11-12um SST

- RSMAS (modsst)

- OBPG (msl12)

## Nighttime 4um SST

- RSMAS (modsst)

- OBPG (msl12)

## Verification of Algorithm Implementation

-  OBPG - RSMAS

- 11-12um SST
- Differences

- 4um SST
- Differences

## Status of MODIS GHRSST Production 

- L2Pcore files have been available to PO.DAAC via rolling ftp archive since October 2005.
- File content evolving:  recent updates incorporate SSES.

## 11-12um SSES Error Fields

- SSES Bias

- SSES Std Dev

## Status of MODIS GHRSST Production 

- L2Pcore files have been available to PO.DAAC via rolling ftp archive since October 2005.
- File content evolving:  recent updates incorporate SSES
- static tables developed by RSMAS
- function of
- SST
- day or night
- season
- view zenith
- BT difference
- latitude
- quality level

## Quality Levels

- 4um Night

- 11-12um Night

- QL=0

- QL=1

- QL=2

- QL=3

## Quality Levels

- 4um Night QL

- 4um Night SST

- QL=0

- QL=1

- QL=2

- QL=3

## 11-12um Night Quality 3

- Land
- Radiance bad (saturated, masked at Level-1)
- BT out of range (-4 to 33 deg-C)
- SST out of range (-2 to 45 deg-C)
- 4um BT difference too different from reference
- SST too different from reference (5 deg-C absolute)

- 11-12um Night Quality 2

- BT spatial non-uniformity (3x3 max-min > 1.2 deg-C)
- SST too different from 4um SST  (1 deg-C absolute)

- Additional information is available here *http://oceancolor.gsfc.nasa.gov/DOCS/modis_sst/*

## L2Pcore File Content

- ~65MB per 5-min MODIS granule, uncompressed
- ~20GB (288 granules) per day per sensor

## “Potential” Options for L2Pcore File Size Reduction

## “Potential” Options for L2Pcore File Size Reduction

- Deal with it !  The “H” stands for high-resolution.
- our only intended customer is Ed
- is this an L2Pcore or L2P issue ?
- Sub-sample L2Pcore lon/lat along-scan by 8 (28% reduction)
- 4um SST
- eliminate from L2Pcore (19% reduction)
- produce separate L2Pcore for 4um (night) and 11-12um
- eliminate from daytime L2Pcore (mixed day/night?)
- Quality Levels
- zero-out lower quality pixels to improve compression
- reformat from swath to time-ordered vectors and only include best quality pixels.
- Reduction of Resolution
- sub-sample to every 4th pixel & line (4km at nadir, 84% reduction)
- average to 4km at nadir (raises many problems/concerns)

## “Potential” Options for L2Pcore Expansion

- sensor zenith angle
- brightness temps
- chlorophyll concentration
- daytime, cloud & glint-free
- aerosol optical thickness
- daytime, cloud & glint-free

## MODIS GHRSST L2Pcore Distribution and Latency

- Files distributed to JPL PO.DAAC via rolling ftp archive
- Operational since 14 October 2005
- Recent updates to incorporate SSES fields
- Aqua (ftp://oceans.gsfc.nasa.gov/MODISA/GHRSST/)
- Terra (ftp://oceans.gsfc.nasa.gov/MODIST/GHRSST/)
- Quicklook Products
- best available ancillary, predicted attitude/ephmerides
- available ~5 hours from time of observation
- Refined Products
- preferred ancillary, definitive attitude/ephmerides
- available 2-8 days later

## END

## Nighttime 11-12um SST Quality

- RSMAS (modsst)

- OBPG (msl12)

## Nighttime 4um SST Quality

- RSMAS (modsst)

- OBPG (msl12)

## Slide 21

## Operational MODIS-Aqua Data Flow

- table

- L0
- Ingest
- process

- L1A-L1B
- (MOD_PR02)

- L1B-L2
- (MSl12)

- MODISA L2
- table

- Archive - Distrib
- Server

- L3BIN
- (l2bin)

- MODISA L3-bin
- table

- Archive - Distrib
- Server

- MODISA L3-map
- table

- Archive - Distrib
- Server

- Sensor
- CAL

- Sensor
- attribs

- Atm
- corr

- Browser
- CGI /
- httpd

- Ocean Color
- Web Server

- User
- Community

- MySQL
- DB

- Ozone

- L3MAP
- (smigen)

- MET

- MET, Ozone, and OISST data are dynamically selected for each L1A granule

- Product meta data are populated from production DB

- OISST

- Level-0
- Ingest

- MODISA L0
- table

- Archive - Distrib
- Server

- ATT/EPH
- Ingest
- process

- MODISA atteph
- table

- Archive - Distrib
- Server

- L0-L1A
- (MOD_PR01)

- Geo-Location
- (MOD_PR03)

- MODISA L1
- table

- Archive - Distrib
- Server

- Full-resolution day- and nighttime via SEN (~60 GB per day)

- NOAA Realtime
- System

- NASA EDOS
- System

- _Level-2 Production_
- Ocean Color (day)
- SST
- SST4
- GHRSST

- _Level-3 Production_
- Ocean Color (day)
- SST
- SST4

## OBPG Responsibilities for MODIS SST & GHRSST

- Processing will build on the Aqua MODIS data stream already implemented at OBPG (11μm, daytime). This will be extended to night-time 11μm SST retrievals.
- The 4μm SST fields will be added to the data stream, including the option to produce daytime data.
- The RSMAS cloud masking methodology will be implemented for both day-time and night-time data streams.
- OBPG will work with RSMAS in the testing of the integrity of the SST fields (i.e. there should be no significant difference in the products that are generated at MODAPS and those at OBPG when the same algorithms are implemented).
- OBPG will work with RSMAS to implement the GHRSST-specific, L2 processing code. To include both 11 μm (SST) and 4 μm (SST4) through implementation of SST and quality assessment algorithms developed at RSMAS.
- OBPG will work with JPL to ensure the delivery of GHRSST MODIS granules to JPL PO.DAAC via network with the least possible delay (generally within 4-6 hours of satellite observation time as dictated by the availability of the Level-0 MODIS data from the NOAA realtime system.)
- The Terra MODIS data stream will be added as soon as the Aqua SST stream is successfully implemented and when directed to do so by NASA Headquarters.

## OBPG Responsibilities for MODIS SST & GHRSST(on-going activities)

- OBPG will work together with RSMAS to ensure the continuing accuracy of the SST fields, and implement upgrades to the processing algorithms and methodology when necessary.
- OBPG will work together with RSMAS to improve the efficacy of the cloud screening algorithms.
- OBPG will work with RSMAS on the periodic updating of algorithms and retrieval coefficients as required (anticipated to be no more than twice per year), and reprocess the past data to a consistent data set as necessary.
- OBPG will implement improved instrument models as recommended by MCST.
- OBPG will assemble L3 SST products (4km resolution with mutually agreed upon quality criteria ) for timely distribution to the SST community through the OBPG and JPL PO.DAAC.
- OBPG will provide archiving of the MODIS SST
- OBPG will support the web-based MODIS quality assurance utility (functions similar to MQABI)
- OBPG will implement MODIS SST algorithms in the SEADAS software suite using easily supported coding standards and methods.

## SST Quality Flags

- SST Quality Levels