AMSU and IR Channels Subsetting Examples
Acknowledgements:To all GES DAAC data support teams.
This work is supported by the NASA/GSFC Earth Science Enterprise.
AIRS Data Subsetting Service at the Goddard Earth Sciences - GES - DISC/DAAC
Gilberto Vicente, Jianchun Qin (JCQ), Jason Li, Irina Gerasimov, Andrey Savtchenko
- NASA Goddard Earth Sciences (GES), Data Information Service Center (DISC), Distributed Active and Archive Center (DAAC), Greenbelt, MD - USA
- S u m m a r y
- This poster describes the web-enabled subsetting services currently available at the GES DISC/DAAC that provide functions for all the Level 1B and Level 2 data products from the AIRS/AMSU/HSB instruments. The on-line services allow users to access the data in interoperable, personalized, real-time, on-demand and on-the-fly manners. The input file can be subsetted by channels only, by parameters only or by channels and parameters.
- The GES DISC subsetting web-based systems are:
- On-Demand Subset system - ODS
- Places orders to the long term tape archive, where all data for the missions durations are kept. Users receive email notification when the subset data are ready for pick-up or have been pushed to the User's host.
- On-the-fly system OTF
- Works with the GES DISC Data Pool only. It is a disk cache of 50 TB of rolling archive, where the data are available for instant download. All data have certain retention time and are replaced with new one as soon as the retention time expires.
- The fine resolution data holdings expire in just several weeks because of the large data volumes and the limited disk space. Many coarser resolution data, like AMSU radiances and the upcoming Level-3 products, will be kept for more than one yearbefore being replaced. The advantage of this subset service is that it is instantaneous, and the only wait time is that of the data download.
- Three major types of AIRS data subsets are available:
- Level 1B Channel/Variable subset
- OTF for Infrared geolocated and calibrated radiances OTF for Visible/Near Infrared geolocated and calibrated radiances OTF for AMSU-A1 & AMSU-A2 combined, geolocated and calibrated brightness temperature ODS for Infrared geolocated and calibrated radiances (coming soon) ODS for Visible/Near Infrared geolocated and calibrated radiances (coming soon) ODS for AMSU-A1 & AMSU-A2 combined, geolocated and calibrated brightness temperature (coming soon)
- 2. AIRS Level 2 Parameter subset
- OTF for Standard final retrieval product in 28 standard pressure levels OTF for Cloud-Cleared IR radiances
- ODS for Standard final retrieval product in 28 standard pressure levels (coming soon) ODS for Cloud-Cleared IR radiances (coming soon)
- 3. AIRS Level 3 Parameter and Spatial subset
- OTF Parameter subsetting (coming soon) OTF Spatial subsetting (coming soon)
Channels Available for Subsetting Services
Users can either specify any channel for the subsetting request or choose a pre-defined set as shown in the table below (Courtesy of Evan Manning, NASA/JPL). This will make it easier for selecting all channels in various frequency ranges.
Algorithm of on-the-fly Subsetting
The core functionality of the HDF-EOS Web-Based Subsetter (HEW), which is developed by the University of Alabama in Huntsville (UAH), has been extracted into a stand-alone callable function known as the HDF-EOS Subsetting Engine (HSE). The AIRS Level-1B and Level-2 subsetter makes use of HSE and can be incorporated into any application that needs to perform HDF-EOS subsetting. The subsetter populates a subsetting criteria data structure which contains the information the HSE needs to operate. This data structure is passed to the HSE which then uses the information to locate and subset the input files into the output files. The output files are then deliver to end user via FTP.
F T P
Overview of GES DAAC Services and Tools Functionality
(Online Disk Cache)
DISC-DAAC Subsetting Service
Parameters Available for Subsetting Services