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Data Set ID:
GLAH09

GLAS/ICESat L2 Global Cloud Heights for Multi-layer Clouds (HDF5), Version 33

GLAH09 Level-2 cloud heights for multi-layer clouds contain cloud layer top and bottom height data at sampling rates of 4 sec, 1 sec, 5 Hz, and 40 Hz. Each data granule has an associated browse product.

Version Summary:

For information about Version 33, see the NSIDC ICESat Description of Data Releases page.

Geographic Coverage

Spatial Coverage:
  • N: 86, S: -86, E: 180, W: -180

Spatial Resolution:
  • 60 m to 70 m x 60 m to 70 m
Temporal Coverage:
  • 20 February 2003 to 11 October 2009
Temporal Resolution: 1288 minute
Parameter(s):
  • Clouds > Cloud Height
  • Clouds > Cloud Vertical Distribution
Platform(s) ICESAT
Sensor(s): ALTIMETERS, GLAS
Data Format(s):
  • HDF
Version: V33
Data Contributor(s): David Hancock, H. Zwally, Robert Schutz, John Dimarzio

Data Citation

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Zwally, H. J., R. Schutz, D. Hancock, and J. Dimarzio. 2013. GLAS/ICESat L2 Global Cloud Heights for Multi-layer Clouds (HDF5), Version 33. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/ICESAT/GLAS/DATA202. [Date Accessed].
No technical references available for this data set.

FAQ

In GLA09 (GLAH09), is there a cloud bottom for every cloud top? How do you match them?

For every top of layer given, there is definitely a bottom of layer given in the same corresponding location in the vector. The tops and bottoms vectors are ordered top-down for each channel (532 nm or 1064 nm) independently. Thus, if Cld_top and Cld_bot are the 10-element arrays that hold the... read more

Since two different algorithms are used in GLA08 (GLAH08) and GLA09 (GLAH09), are the aerosol layers different between the two products?

GLA09 (GLAH09) should not contain elevated aerosol layers, only cloud heights. If the GLA09 (GLAH09) algorithm detects a layer in the data, a cloud/aerosol discrimination routine is called. If the layer is considered cloud, then it is output to GLA09 (GLAH09). If it is... read more

GLA08 and GLA09 were originally designed to use only the 532 nm profiles from GLA07; however, these two products use the 1064 nm channel data in addition to 532 nm. Where do the 1064 nm layers come from, and do the 532 nm and 1064 nm algorithms differ?

The GLAS science team added the 1064 nm-based layer detection just a few months before ICESat launched, because they discovered potentially serious problems in the 532 nm channel. The initial design of the software only used the 532 nm channel because of its superior data quality; however, when... read more

How different are the cloud layer heights in GLA09 identified by the 532 nm and 1064 nm channels?

Users may note duplication of cloud layers in GLA09, meaning that a given layer is reported twice: once from 532 nm and once from 1064 nm (assuming that both channels are operating). If this occurs, the top and bottom of the layer should be slightly different, because two completely different... read more

In GLA09 (GALH09), is there a cloud bottom for every cloud top? How do you match them?

For every top of layer given, there is definitely a bottom of layer given in the same corresponding location in the vector. The tops and bottoms vectors are ordered top-down for each channel (532 nm or 1064 nm) independently. Thus, if Cld_top and Cld_bot are the 10-element arrays that hold the... read more

What data subsetting and reformatting services are available for ICESat/GLAS data?

The following table describes the data subsetting and reformatting services that are currently available for ICESat/GLAS HDF5 data via the NASA Earthdata Search tool.

... read more

How To

Stepping through the HDFView User Guide with GLAS HDF5 Data
HDFView

https://support.hdfgroup.org/products/java/hdfview/

When you first open HDFView, the HDFView window appears with an empty tree and data panel.

The main window consists of six different components... read more

How do I programmatically request data services (e.g. subsetting, reformatting, reprojection) using an API?

The subsetting, reformatting, and reprojection services provided by NSIDC through NASA Earthdata Search can also be accessed programmatically using a WCS-compatible API endpoint. This programmatic access is provided via an HTTP URL containing a... read more