Source: http://hdfeos.org/workshops/ws04/presentations/Wolfe/Wolfe.ppt

1. MODIS Land and HDF-EOS
MODIS Land and HDF-EOS
HDF-EOS Workshop Presentation
September 20, 2000
Robert Wolfe
NASA GSFC Code 922, Raytheon ITSS
MODIS Land Science Team Support

2. MODIS Land Science Team Products
MODIS Land Science Team Products
• Goals :
– operationally produce terrestrial remotely sensed products that may be
used by expert and non-expert community
– establish a 10 year record that has continuity with precursor systems, e.g.,
AVHRR, and the future NPP and NPOESS VIIRS missions
• The MODIS products were developed primarily to serve the global
change research community (MODIS has global, near daily coverage)
and have many other potential applications
• The MODIS Land Science team was completively selected to develop
peer-reviewed product generation algorithms (10 Principal
Investigators, lead: Chris Justice, UVA)
HDF-EOS
2

3. MODIS Land Product Overview (1/3)
MODIS Land Product Overview (1/3)
• Radiation Budget
Variables
– Surface
Reflectance
– Surface
Temperature and
Emissivity
– Snow and Ice
Cover
– BRDF and Albedo
HDF-EOS
3

4. MODIS Land Product Overview (2/3)
MODIS Land Product Overview (2/3)
• Ecosystem Variables
– Vegetation Indices
– Leaf Area Index
(LAI) and Fractional
Photosynthetically
Active Radiation
(FPAR)
– Vegetation
Production
– Net Primary
Productivity (NPP)
HDF-EOS
4

5. MODIS Land Product Overview (3/3)
MODIS Land Product Overview (3/3)
• Land Cover
Characteristics
• Fire and Thermal
Anomalies
• Land Cover
• Vegetation Cover
Conversion
HDF-EOS
5

6. MODIS Production and Distribution
MODIS Production and Distribution
Level 0
Instrument Data
Level 1, Ocean
and Atmos.
Products
GSFC DAAC
•
User
Community
MODIS Land production
commenced 02/26/2000
•
Product checkout is
underway, driven by
instrument calibration,
geolocation, algorithm code
stability and data
dependencies
•
Land products Beta release
from the DAACs began
08/04/2000
•
Current products are for
evaluation purposes
Ocean and
Atmosphere
Products
Level 1
Products
MODAPS
Land Snow and
Ice Cover
Products
Land
Non-cryospheric
Products
NSIDC DAAC
EDC DAAC
User
Community
HDF-EOS
6

7. MODLAND Grids
MODLAND Grids
•
•
Fine resolution grids for the L2G, 3 and 4 products are based on two map
projections:
– Integerized Sinusoidal Grid (ISIN)
– Lambert Azimuthal Equal-Area (LAEA) (polar grids)
– Almost all of the fine resolution products will be made in the ISIN
• Exception: Sea-ice products are made in the in the LAEA
projection with the grid centered at the north and south poles
(EASI Grid implementation)
– Grid cell size varies by product and is either (approx.) 0.25 km, 0.5
km or 1 km – actual size depends on the projection
– Each grid is broken into non-overlapping tiles which cover approx.
10 x 10 deg. area
Coarse resolution global Climate Modeling Grid (CMG) products are
made in a geographic projection with grid cell sizes of 0.25 or 0.5 deg.
HDF-EOS
7

8. ISIN Grid
ISIN Grid
HDF-EOS
8

9. HDF-EOS Usage (1/2)
HDF-EOS Usage (1/2)
• Both swath and grid format
Type
Interim Archive
L2 Swath
1
5
ISIN
8
30
LAEA (Polar)
3
2
CMG (Geog.)
0
19
Total
12
56
Total
6
38
5
19
68
• 2d, 3d and some 4d SDS arrays
• Global and SDS attributes
HDF-EOS
9

10. HDF-EOS Usage (2/2)
HDF-EOS Usage (2/2)
• Subsetting/mosaicing
– Collaborated with UAH in HEW development
– Used operationally for 24 Core Validation Sites and planned for
Fluxnet sites
• Resampler
– Collaborating with EDC/SDSM&T to develop resampler
– Could be used for DAAC services and end user
– L2 and L3 regridding support
• MODLAND developed QA Tools for Team
– Extensions to IDL/ENVI and Unix command line
– Bit field handling, etc.
HDF-EOS
10

11. Good things about HDF/HDF-EOS
Good things about HDF/HDF-EOS
• Made collaboration easier between geographically
distant scientists/developers
– Self documenting file format allows easy exchange of
information between processes
• Standard method of representing geolocation
HDF-EOS
11

12. HDF-EOS Gripes (1/2)
HDF-EOS Gripes (1/2)
• Toolkit doesn't support all HDF objects and access types
– Hybrid HDF and HDF-EOS approach used to create/read files
– Also need to use SDP toolkit to manipulate metadata
• Subsettting on 3/4 dimensional arrays is difficult
– ex. take bands 3 & 5 from 7 bands array (3d) and store
in 2 band array (3d)
– downstream users need to which 2 bands were selected
• HDF Specific
– No convention for support of bit fields
– Performance depends on layout in 3 or 4 dimensional arrays
HDF-EOS
12

13. HDF-EOS Gripes (2/2)
HDF-EOS Gripes (2/2)
• Swath format does not support external
geolocation files
– workaround -- two geolocation arrays: one accurate 1
km external
file and one 5 km internal array
– 5 km array takes up more space and not as accurate
• Vendor support growing but still lacking
HDF-EOS
13

14. For More Information
For More Information
URL: http://modis.gsfc.nasa.gov/
HDF-EOS
14