# Presentation: 763286

## MODIS Land Science Products Production

**MODIS ****Land Science Products Production**

- Robert E. Wolfe
- NASA Goddard Space Flight Center, Code 614.5Greenbelt, MD, USA

- This work was performed in the Terrestrial Information Systems Branch (Code 614.5) at NASA’s Goddard Space Flight Center Laboratory for Terrestrial Physics.

**Acknowledgement**

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**MODIS on EOS Terra and Aqua**

- The MODerate Resolution Imaging Spectroradiometer (MODIS), a key instrument for NASA’s Earth Observing System (EOS)
- MODIS was launched on board the Terra spacecraft in Dec. 1999 (first light on Feb. 24, 2000) and on board the Aqua spacecraft in May 2002 (first light on June 24, 2002)
- Spatial resolution at nadir: 250m (2 bands), 500m (5 bands) and 1000m
- 12 bit (0-4095) dynamic range

**MODIS Land Products**

_**Energy Balance Product Suite**_
- Surface Reflectance
- Land Surface Temperature and Emmisivity
- Bi-directional Reflectance Distribution Function (BRDF) and Albedo
- Snow cover and sea-ice extent
_**Vegetation Parameters Suite**_
- Vegetation Indices
- Leaf area index and Fraction (LAI) and Fraction of Photosynthetically Active Radiation (FPAR)
- Gross and Net Primary Production (GPP/NPP)
_**Land Cover/Land Use Suite**_
- Land Cover/Vegetation Dynamics
- Vegetation Continuous Fields
- Vegetation Cover Change
- Fire/Thermal Anomalies and Burned Area

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**Getting MODIS Land Data**

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**Land Science Team – Phase 2**

- Overall – Phase 1 Land Team intact and strengthened
- Separate funding for Validation Coordination and Rapid Response
- Larger Science Team (27 total)
- Algorithm Maintenance and Validation Team (10)
- EOS Science – Data Users (17)
- Four new/improved Land products: Plant Water Content, Evaporation, Improved Surface Reflectance, Physical Based Continuous Fields and Land Cover
- Land Discipline Leader: Dr. Chris Justice, UMD

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**MODIS Collections**

***Each collection represents an improvement in science quality***

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**MODIS Product Format**

- Hierarchical Data Format (HDF) – self describing file format
- Science Data Sets (SDSs) – 2D, 3D or 4D arrays
- Bit Fields – unsigned integers broken into groups of bits
- Discrete values – e.g., Snow, Cloud, etc.
- Scaled Integers – valid range, scale and offset included
- Attributes – text or other data annotating the file (global) or arrays (SDSs)
- Metadata – ECS product metadata (stored as attributes)
- includes QA information, date/time products acquired/produced, etc.
- .met file contains the ECS core metadata: some fields (QA, etc.) may be updated when product distributed
- HDF-EOS Metadata (SWATH or GRID) – geometric information that relates data to specific earth locations

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- Retrieved geophysical parameters at same location and in same format as MODIS Level 1 instrument data
- 288 granules/day; 5 min.; approx. 2340 x 2030 km
- 250m, 500m and 1km nadir resolutions

**Level 2 Swath**

**Level 2G, 3 and 4 Grids**

- Global Level 3 Products designed for climate modelers
- 0.05o Resolution
- Almost all products are geographic (lat/long)
- Sea-ice is current exception – in polar grid (Snow in C5)

**Climate Modeling Grids **

- (from BU – NBAR CMG – days 193-208, 2001)

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**Land Quality Assurance (QA)**

- QA is an integral part of the MODIS production chain
- Evaluates and documents the scientific quality of the MODIS land products
- Built around central QA activity that coordinates and integrates individual science team member QA activities
- Maintains: on-line global browse and time-series tools, known issues web page, QA tool-kit

- See: http://modis-land.gsfc.nasa.gov/

- Order from DAAC through EOS Data Gateway
- response is a few hours
- services (e.g. subsetting) available for some products
- Get data from DAAC data pools
- most recently produced data are on-line and available via FTP
- Get data from other sources (Science team sites, MODIS Rapid Response, direct broadcast, etc.)

**Land Validation**

- Central validation coordination effort contributes to and leverages off of international validation standards and activities
- Primary techniques includes collection of and comparison with field and aircraft data, and comparison with data and products from other satellites; primary infrastructure is semi-permanent array of EOS Land Core Validation sites

- Reprocessing

- Forward processing

- C*n* – Collection Version *n*

- 2000

- 2001

- 2002

- 2003

- 2004

- Beta

- 2005

- 2006

- 2007

- Validated (Stage 1)

- Provisional

- 20 reflective solar bands (0.4 - 2.2 μm)
- 16 thermal emissive bands (3.5 - 14.5 μm)
- Excellent radiometric and geometric accuracy
- Science team originally formed 13 years ago; team re-competed in 2004
- 3 Disciplines: Land, Oceans, Atmosphere
- Leader: Dr. Vince Salomonson

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**MODIS Land Collection 5 Changes**

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- Use improved Land/Water mask and new Land Cover map based on 3 years of Collection 4 data.
- Refine surface reflectance by adopting a dynamic aerosol model in atmospheric correction and implementing BRDF coupling and adjacency effect correction schemes.
- Improve quality of the Land Surface Temperature by revising the day/night algorithm and improving the detection and filtering of cloud contaminated observations.
- Increase resolution of BRDF/Albedo product to 500m.
- Interpolate ancillary data to remove artifacts in the NPP product.
- Refine LAI/FPAR LUTs to improve numerical accuracy of the radiative transfer simulations.
- Add fractional snow algorithm in the snow product
- Add burned area product.

**NPP VIIRS Land Product Evaluation**

- NPP

- NASA NPP Land Science Team is evaluating VIIRS Land algorithms and data (post-launch) to determine if they are of climate data record quality
- To help the science team perform this function, the VIIRS Land Product Evaluation System (PEATE) is being built using the MODIS approach (production, QA, etc.)
- Land PEATE will:
- generate diagnostic products (e.g., gridded L3 multi-day products, browse, subsets) similar to MODIS
- perform tests of possible algorithm improvements and their impacts on downstream products (e.g., time series test)
- use operational software (with Direct Broadcast wrapper) and science software
- support NASA radiometric and geometric calibration groups (NICSE)

*1 of 5 PEATEs within the **NASA’s Science Data Segment (SDS)*

- Lambert Azimuthal Equal Area (LAEA) – sea-ice products, polar projection

- Sinusoidal (equatorial) – 7.5, 15 and 30 arcsec. resolution (roughly 250m, 500m and 1 km)

*DB Workshop – Benevento, Italy**Oct. 5,  2005*