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AIRS NRT Products and Images

Here you can find information and links to:

1. AIRS Near-Real-Time (NRT) Data Products

2. AIRS NRT Images

3. AIRS NRT MapViewer

   

 

1. AIRS NRT data products

The AIRS Near Real Time products are currently available for Level-1B and Level-2.  The table below provides links to the AIRS NRT data files.  Note that access to AIRS NRT data requires prior user registration.  For details, please see: LANCE Registration.

AIRS NRT products are produced by the same core science algorithms as in the routine science data production, but using predicted ephemeris in place of definitive ephemeris and the NRT processing proceeds whether or not the previous or subsequent Level 1b granules are present or whether the forecast surface pressure is present.  Routine AIRS data production uses the rectified orbital parameters and satellite position that is accurate to better than 50 meters. NRT data production uses predicted orbital parameters, required to be accurate to 400 meters and generally accurate to 100 meters. Orbital prediction is slightly less accurate towards the end of the day UTC. Solar flares impact the accuracy of the orbit prediction.  More on the differences between the NRT and routine processing can be found in this document: Difference between AIRS NRT and Standard Products.

The advantage of NRT data is its fast turnaround time, generally available within 3 hours of observations globally. They can be utilized in regional weather forecast models as well as in support of field campaigns. For the Guide Documents of all AIRS Products, please refer to the following site.

http://disc.sci.gsfc.nasa.gov/AIRS/documentation.

AIRS is managed by NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif., under contract to NASA. JPL is a division of the California Institute of Technology in Pasadena.

 

AIRS NRT Data Products (7 most recent days available)

Product Name
Description

Spatial Resolution

Average File Size (Mb)
AIRIBRAD_NRT
Version 5 L1B IR geolocated radiances
13.5 km@nadir
56
AIRIBRAD_NRT_BUFR 324-channel subset of Version 5  L1B IR geolocated radiances in BUFR format
13.5 km@nadir
7
AIRVBRAD_NRT
Version 5 L1B Vis/Near IR geolocated radiances
2.3 km @ nadir
11
AIRABRAD_NRT
Version 5 L1B AMSU-A1 & AMSU-A2 combined, geolocated & calibrated brightness temperatures
45 km @ nadir
0.6
AIRIBQAP_NRT
Version 5 L1B IR quality assurance subset
N/A
2.4
AIRVBQAP_NRT
Version 5 L1B  Vis/Near IR quality assurance subset
N/A
1.1
AIRX2RET_NRT
Version 6 L2 standard retrieval product using AIRS IR and AMSU
45 km @ nadir 3.9
AIRI2CCF_NRT Version 6 L2 cloud-cleared radiances using AIRS IR and AMSU 45 km @ nadir 13.6
AIRX2SUP_NRT Version 6 L2 support product using AIRS IR and AMSU 45 km @ nadir 21

  

AIRS NRT Data Products via FTP    (requires registration)

Product
Server
Directory Path
Level-1B
 
/data/Aqua_NRT
 
Level-2

  

2. NRT IMAGERY, AVAILABLE VIA OGC WEB MAP SERVICE

The images in this section are served using the Open Geospatial Consortium (OGC) Web Map Service (WMS) and Web Coverage Service (WCS). These services allow simple visualization of  data and enable clients to build customized maps with data coming from different networks.

In the simplest case, the client is your browser, the command is a specially formatted URL, and the return from the WMS is an image that your browser will display. Mouse over images below to see how the URL's should be formatted.

The samples on this page return images in

   PNG   GeoTIFF   KMZ

Although AIRS NRT images on this page are directly available in PNG and  GeoTIFF, GIF and JPEG can also be acquired, by changing the "FORMAT=image/png" keyword in the URL request that is sent to the WMS server. The links to KMZ (GoogleEarth) formats refer to KMZ files that have been pre-set to communicate with the WMS server as appropriate.

We georegister into images only a sample of all AIRS Near Real Time retrievals. The imaging is done immediately after the  NRT  data are output from the processing system.  Thus the images are constantly refreshed and made available to dedicated AIRS NRT WMS and WCS servers.

 The AIRS NRT images consist of AIRS granules mapped to a global cylindrical projection. The granules are mapped as they arrive from the NRT production line, for a given Calendar Day. No averaging is applied, and hence data are simply overlaid on the map. For improved presentability, the maps are larger, and hence with finer resolution, than the native data resolution would allow. To achieve that, the data are resampled using the nearest neighbor approach. As a result, certain pixilation can be seen in the maps, but this effect actually correctly reflects the data footprint location, projection, and size on the maps, using rectangular idealization. Since data are projected in near-real time, it is for the given UTC calendar day. Thus produced daily maps will look different from the standard operational products, where the range of the data-day is defined differently.

Table 1 summarizes the maps of AIRS variables currently served through WMS and WCS.

 

Table 1. AIRS Variables served by WMS and WCS
Map Notation Description

Map pixel size*
(km)

IR_Precip_Est Regression-based estimate of daily precipitation based on clouds and relative humidity from Level 2 IR/MW retrieval (AIRX2SUP_NRT). Analogous to and forms a continuous record when used with TOVS precipitation index. (mm/day) 33x33
CO Total column CO (from Level 2 AIRX2RET_NRT)
 
33x33
RGB False-color image using 3 visible channles (from Level 1B AIRVBRAD_NRT)
 
3x3
BT_diff_SO2 Brightness temperature difference Tb(1361,44cm-1)-Tb(1433.06 cm-1) used as an indicator of SO2 release from volcanoes. Values under -6K (deep red in the images) have likely volcanic SO2 (from Level 1B  AIRIBQAP_NRT)
 
10x10
Prata_SO2 ** Authored by Fred Prata, Norwegian Institute for Air Research, this algorithm yields column SO2 amounts, in Dobson Units (DU), using a spectrum of AIRS IR bands in the range of  1319.63-1396.60 cm-¹.  The Level 1B Near-Real Time IR Radiances, AIRIBRAD_NRT, are the source data. 10x10
Dust Score **
Variable "dust_score"  (from Level1B AIRIBQAP_NRT) is used. Pixels where dust_score is less than 360, or flags are less than -1 (land is allowed), are rejected from the map.
 
10x10

*Not to be confused with the native resolution of the retrieval

** Dust score and Prata_SO2 images are similar in that AIRS is not sensitive to small amounts of either, dust or SO2. More over, SO2 must appear in the midtroposphere (~7 km) to ensure good absorption signal. Thus, these maps look empty most of the time.

 

 

2.1. PNG Format

Note, these tables serve as examples of how to build WMS-compliant url's (mouse over the images).  The actual NRT images range extends to -9 Days. Change the keyword "LAYERS" in the url, like: LAYERS=AIRS_CO_A-6day

 

 

 

  Today Yesterday

IR_Precip_Est

(day)

IR_Precip_Est

(night)

mm/day
CO
(day)
CO
(night)

  

Dust Score *

DustScore_bar

GB
(day)
   
BT_diff_SO2 (day)
BT_diff_SO2 (night)
SO2_bar.png

Prata_SO2 *

(day)

Prata_SO2 *

(night)

* Dust score and Prata_SO2 images are similar in that AIRS is not sensitive to small amounts of either, dust or SO2. More over, SO2 must appear in the midtroposphere (~7 km) to ensure good absorption signal. Thus, these maps look empty most of the time.


 

2.2. GeoTIFF Format

  • Note that GeoTIFF is a special format intended for GIS (Geographic Information System) Tools, such as ArcInfo, and these images are served from the WCS server. Most likely, the links in the table below will not show in a simple browser session, and your browser will prompt you to launch a relevant application, or save the image. You can customize the GeotIFF images by modifying the keywords in the URL to the WCS server. 
  • The tables below serve as examples of how to build WCS-compliant url's (mouse over the images). The actual NRT images range extends to -9 Days. Change the keyword "coverage", like: coverage=AIRS_SO2_A-1Day. Note the difference with the WMS syntax.

 GeoTIFF Format

  Today Yesterday
CO
(day)
CO
(night)

    

RGB
(day)
   
BT_diff_SO2 (day)
BT_diff_SO2 (night)
SO2_bar.png

 

 

2.3. KMZ, the compressed Keyhole Markup Language (KML)

KML is an XML-based language schema for expressing geographic annotation and visualization on existing or future Internet-based, two-dimensional maps and three-dimensional Earth browsers, like GoogleEarth. We link here to the KMZ - the compressed version of KML - because browsers can attempt to open KML as plain XML file, whereas our goal is to view global imagery, through GoogleEarth, or other relevant browser. An important distinction in this approach is that one file can contain multiple images ("Places") that can be overlayed for simultaneous three-dimensional views. The KMZ below can be easily combined and overlayed in various ways, using for instance GoggleEarth's "Places" and "Layers" folders. 

 You must have GoogleEarth (or other appropriate tool) installed on your computer to view the KMZ as images.

KMZ Format

RGB* (Visible 3-km) Today Yesterday -2 Days -3 Days -4 Days -5 Days -6 Days -7 Days -8 Days -9 Days
IR_Precip_Est Today Yesterday -2 Days -3 Days -4 Days -5 Days  -6 Days -7 Days -8 Days -9 Days
BT_diff_SO2 Today Yesterday  -2 Days -3 Days  -4 Days  -5 Days  -6 Days -7 Days -8 Days -9 Days
Prata_SO2 Today Yesterday -2 Days -3 Days -4 Days -5 Days -6 Days -7 Days -8 Days -9 Days
CO Today Yesterday -2 Days  -3 Days  -4 Days  -5 Days  -6 Days -7 Days -8 Days -9 Days
Dust Score  Today Yesterday -2 Days  -3 Days  -4 Days  -5 Days  -6 Days -7 Days -8 Days -9 Days

 *Note:

  • AIRS NRT imagery is broken into tiles that are seamlessly served as one image, to speed up regional viewing. Even though the Visible false color RGB are broken into tiles too, their global coverage at 3-km resolution still makes the tiles very big. Please, allow more time the RGB image to refresh in your application. 
  • The Prata_SO2 images are generated by an algorithm authored by Fred Prata, Norwegian Institute for Air Research.

 

 

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