ICESat/GLAS Tools at NSIDC

Melinda Marquis

NSIDC Product Team Lead,

AMSR-E and GLAS

Feb. 16, 2005

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20052

Outline: ICESat/GLAS Tools

GLAS on ICESat. Graphic is courtesy of Ball Aerospace.

IDL Visualizer

NSIDC GLAS Altimetry elevation extractor Tool (NGAT)

IDL Readers

Fortran 90 Readers

IDL Ellipsoid Conversion tool

ICESat/GLAS Subsetter

GLAS Tools Page at http://nsidc.org/data/icesat/tools.html

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20053

IDL Visualizer

Reads data from an ICESat/GLAS file and views graphical summaries of variables.

A quick-start tutorial is available on-line to help users get started viewing ICESat/GLAS data.

SCF responded to NSIDC’s request that this package be made to work with the free IDL Virtual Machine (Jan. 2005).

Developed by the GLAS SCF.

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20054

IDL Visualizer

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20055

IDL Visualizer

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20056

NSIDC GLAS Altimetry elevation extractor Tool (NGAT)

Extracts elevation and geoid data from GLAS altimetry products (GLA06 and GLA12-15) and outputs latitude, longitude, elevation, and geoid in ASCII columns.

The NGAT runs under IDL (6.0 or greater) or the free IDL Virtual Machine (IDLVM) available from Research Systems Inc.

Developed by NSIDC (Matt Savoie).

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20057

NSIDC GLAS Altimetry elevation extractor Tool (NGAT)

372402615 03/07/2004 00:31:01.540 61.775047 213.540418 562.026 18.440000 372402615 03/07/2004 00:31:01.565 61.776580 213.539815 561.983 18.434615 372402615 03/07/2004 00:31:01.590 61.778114 213.539224 562.099 18.429231 372402615 03/07/2004 00:31:01.615 61.779650 213.538645 562.267 18.423846 372402615 03/07/2004 00:31:01.640 61.781187 213.538080 562.097 18.418462 372402615 03/07/2004 00:31:01.665 61.782726 213.537528 562.012 18.413077

Record No. Date Time Lat. (deg.) Long. (deg.) Elevation (m) Geoid (m)

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20058

IDL Readers

Read data from an ICESat/GLAS file and prints all the variables in ASCII format.

The readers run under IDL (6.0 or greater) or the free IDL Virtual Machine (IDLVM) available from Research Systems, Inc.

Developed by the GLAS SCF.

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 20059

IDL Readers

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 200510

Fortran 90 Readers

This set of programs reads data from an ICESat/GLAS file and prints all the variables in ASCII format (identical output as IDL reader).

This is sample code to help users develop their own applications.

There is a separate program for each product type ("read_glaxx_file") where xx is the product number.

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 200511

Fortran 90 Readers

The programs are written in Fortan 90 and developed in a HP/UX 11.x runtime environment.

A relatively modern Fortran 90 compiler is required.

Runs on only HP/UX and some Sun platforms.

Developed by the GLAS SCF.

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 200512

IDL Ellipsoid Conversion tool

•Converts between the ICESat/GLAS and WGS-84 ellipsoids.

•ICESat/GLAS geolocated products are given in terms of geodetic latitude, longitude, and height (elevation) above the TOPEX/Poseidon ellipsoid.

•Three programs convert latitudes and elevations between the WGS-84 and the TOPEX/Poseidon ellipsoids.

•Developed by NSIDC (Terry Haran).

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 200513

ICESat/GLAS SubsetterUser enters bounding coordinates and temporal range of interest in a web form on NSIDC’s site.

NSIDC provides the spatially subsetted data.

Developed by NSIDC (Matt Savoie), in conjunction with the GLAS SCF.

NSIDC uses our rSCF (with code dev’d by main SCF) to perform subsetting.

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 200514

Summary• NSIDC has worked with the ICESat/GLAS science

team, SCF and SIPS to provide needed tools to the broad user community. Readers Visualization tools Subsetter

• This collaborative effort benefits users and facilitates use of the ICESat/GLAS data.

• Thanks go to the science team, SCF, SIPS and NSIDC programmers and staff:

John DiMarzio

Kris Barbieri

Jeff Guerber

Jay Zwally

David Hancock

Anita Brenner

Matt Savoie

Terry Haran

Siri Jodha Singh Khalsa

Polar DAAC Advisory Group

Melinda Marquis, NSIDC DAAC Feb. 16, 200515

GLAS Data Products

ShortName Longname Received # of GranulesIngested

GLA01 L1A Global Altimetry Data X  206

GLA02 L1A Global Atmosphere Data X   26

GLA03 L1A Global Engineering Data  X  22

GLA04 L1A Global Laser Pointing Data  X  22

GLA05 L1B Global Waveform-based Range Corrections  X  95

GLA06 L1B Global Elevation Data  X 131

GLA07 L1B Global Backscatter Data X   6

GLA08 L2 Global PBL & Elevated Aerosol Layer Heights  X 3

GLA09 L2 Global Cloud Heights for Multi-layer Clouds  X  3

GLA10 L2 Global Aerosol Vertical Structure Data X  2

GLA11 L2 Global Thin Cloud/Aerosol Optical Depths Data X  2

GLA12 L2 Global Antarctic & Greenland Ice Sheet Alt.  X  2

GLA13 L2 Sea Ice Altimetry Data  X  2

GLA14 L2 Global Land Surface Altimetry Data  X  2

GLA15 L2 Ocean Altimetry Data  X  2

GLA16 is not fully developed