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Advanced Very High Resolution Radiometer (AVHRR)

Information updated on Wed May 23 17:00:56 2007

General Data Description

Measurements from the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA polar orbiting satellites taken over the NSA, SHB, SGP and TWP sites are available for distribution to the ARM community.

Data Stream Names

All data streams are in HDF unless otherwise noted

sgpavhrrX1.b1*
* sgpavhrrX1.b1 has been eliminated see BCR-663

sgpavhrr9X1.a1
sgpavhrr9radX1.a1
sgpavhrr10X1.a1
sgpavhrr10radX1.a1
sgpavhrr11X1.a1
sgpavhrr11radX1.a1
sgpavhrr12X1.a1
sgpavhrr12radX1.a1
sgpavhrr14X1.a1
sgpavhrr14radX1.a1
sgpavhrr15X1.a1
sgpavhrr15radX1.a1
sgpavhrr16X1.a1
sgpavhrr16radX1.a1
sgpavhrr17X1.a1 (showing channel 3a)sgpavhrr17X1.a1 (showing channel 3b)
sgpavhrr17radX1.a1
sgpavhrr18X1.a1 (showing channel 3b)
sgpavhrr18radX1.a1
sgpavhrrgridX1.a1
sgpavhrrlat-longX1.a1
sgpavhrrriversX1.a1
sgpavhrrstateX1.a1

nsaavhrr10X1.a1
nsaavhrr10radX1.a1
nsaavhrr12X1.a1
nsaavhrr12radX1.a1
nsaavhrr14X1.a1
nsaavhrr14radX1.a1
nsaavhrr15X1.a1
nsaavhrr15radX1.a1
nsaavhrr16X1.a1 (showing channel 3a)
nsaavhrr16X1.a1 (showing channel 3b)
nsaavhrr16radX1.a1
nsaavhrr17X1.a1 (showing channel 3b)
nsaavhrr17radX1.a1
nsaavhrr18X1.a1 (showing channel 3b)
nsaavhrr18radX1.a1

nsaavhrriichjX1.a1.jpg ii= 10,11,12,14,15 j=2,4
nsaavhrrcoastX1.a1.hdf
nsaavhrrlat-longX1.a1.hdf

shbavhrr10X1.a1
shbavhrr10radX1.a1
shbavhrr11X1.a1
shbavhrr11radX1.a1
shbavhrr12X1.a1
shbavhrr12radX1.a1
shbavhrr14X1.a1
shbavhrr14radX1.a1

shbavhrrlat-longX1.a1
sheba_latlon_ovrl.hdf

twpavhrr14gacmanX1.a1
twpavhrr14gacnauX1.a1
twpavhrr15gacmanX1.a1
twpavhrr15gacnauX1.a1
twpavhrr16gacmanX1.a1
twpavhrr16gacnauX1.a1

twpavhrr12lacmanX1.a1
twpavhrr12lacnauX1.a1
twpavhrr14lacmanX1.a1
twpavhrr14lacnauX1.a1
twpavhrr16lacmanX1.a1 (showing channel 3a)
twpavhrr16lacnauX1.a1 (showing channel 3b)
twpavhrr17lacmanX1.a1 (showing channel 3b)
twpavhrr17lacnauX1.a1 (showing channel 3b)

twpavhrrdarX1.00 (ASDA format)

Measurement Description

nsaavhrrnnX1.a1.yyyymmdd.hhmmss.hdf
shbavhrrnnX1.a1.yyyymmdd.hhmmss.hdf
sgpavhrrnnX1.a1.yyyymmdd.hhmmss.hdf
twpavhrrnnlacsssX1.a1.yyyymmdd.hhmmss.hdf
twpavhrrnngacsssX1.a1.yyyymmdd.hhmmss.hdf
where nn <= 15

Variable	Name	Type	Units
Ch 1 `albedo'	avhrr_ch1	short	albedo*100%
Ch 2 `albedo'	avhrr_ch2	short	albedo*100%
Ch 3 brightness temperature	avhrr_ch3	short	temp_deg_C
Ch 4 brightness temperature	avhrr_ch4	short	temp_deg_C
Ch 5 brightness temperature	avhrr_ch5	short	temp_deg_C
satellite-solar azimuth angle	rel_azimuth	float	degrees
satellite zenith angle	sat_zenith	float	degrees
solar zenith angle	sun_zenith	float	degrees

nsaavhrrnnradX1.a1.yyyymmdd.hhmmss.hdf
shbavhrrnnradX1.a1.yyyymmdd.hhmmss.hdf
sgpavhrrnnradX1.a1.yyyymmdd.hhmmss.hdf

Variable	Name	Type	Units
Ch 3 calibrated radiances (Channel 3b beginning with NOAA 16*)	avhrr_ch3	short	mW_m-2_st-1
Ch 4 calibrated radiances	avhrr_ch4	short	mW_m-2_st-1
Ch 5 calibrated radiances	avhrr_ch5	short	mW_m-2_st-1

* Note - beginning with NOAA 16 channel 3 only appears in these files during hours when channel 3b is available (usually nighttime hours).

The reflected solar radiation channels (1 & 2) data are in albedo units and are calculated using the prelaunch channel characteristics , and are stored as short integers in units of albedo (%) * 100. The conversion from digital counts (n) to albedo (alb) follows:

alb = a +b*n

Satellite NOAA-12	a	b
Channel 1	-4.44908	0.104223
Channel 2	-3.99256	0.10144

For NSA NOAA-14, time dependent coefficients are used. The table is updated whenever new coefficients are released by NOAA. See NOAA-14 Coefficients

The infrared channels are given as brightness temperatures, which are stored as signed two byte integers in increments of 0.01^oC. These are derived using the in-flight calibration data derived from measurements of cold space and the on-board black-body calibration target.

Angles are calculated from the orbit geometry and are stored as floating-point numbers.

Beginning with NOAA 16, channel 3 becomes channel 3b (the thermal (longwave) channel; and channel 3a is added in daylight hours. However, on NOAA 16, channel 3a failed in April 2003 and beginning on May 1, 2003 channel 3b appears at all time. See Unidata reference

The wavelengths of the channels can be found at NOAA 16 AVHRR Subsystem Summary

Temporal Coverage

North Slope Alaska (NSA)

Satellite	Start Date	End Date
avhrr10	1997-11-09	1999-10-09
avhrr12	1997-10-01	2007-03-31
avhrr14	1997-10-01	2007-03-31
avhrr15	1998-11-10	2007-03-31
avhrr16	2003-03-08	2007-03-31
avhrr17	2003-03-09	2007-03-31
avhrr18	2005-09-25	2007-03-31

Southern Great Plains (SGP )

Satellite	Start Date	End Date
avhrr9	1994-09-15	1995-08-02
avhrr10	1994-09-15	1994-12-30
avhrr11	1994-07-21	1994-09-11
avhrr12	1994-07-22	2007-09-22
avhrr14	1995-01-18	2002-08-05
avhrr15	2000-07-05	2007-09-22
avhrr16	2000-12-09	2005-10-19
avhrr17	2002-06-27	2007-09-22
avhrr18	2005-10-14	2007-09-22

Tropical Western Pacific (TWP)

Satellite	Start Date	End Date
avhrrkwaj12	2000-07-12	2002-09-10
avhrrkwaj14	2000-07-12	2007-03-31
avhrrkwaj16	2001-03-02	2005-08-29
avhrrkwaj17	2002-09-15	2007-03-31
avhrrkwaj18	2005-10-15	2007-03-31
avhrr14gacman	1996-11-22	2001-10-31
avhrr14gacnau	1996-11-22	2001-10-31
avhrr15gacman	2002-01-01	2002-10-01
avhrr15gacnau	2002-01-01	2002-10-01
avhrr16gacman	2001-10-27	2002-10-01
avhrr16gacnau	2001-10-27	2002-10-01

SHEBA Surface HEat Budget of the Arctic (SHB)

Satellite	Start Date	End Date
avhrr10	1997-11-09	1998-10-24
avhrr11	1998-03-14	1998-10-13
avhrr12	1997-10-01	1998-10-31
avhrr14	1997-10-01	1998-10-31

SGP AVHRR data are available at the ARM Archive within a day or two after collection. Data files that are missed are filled in from tapes sent by SeaSpace with an approximate delay of a month.

NSA AVHRR data are available at the ARM Archive approximately six months after date of collection.

The 1 km and 4-km resolution files provided by the University of Miami for Manus and Nauru are available with about a 1 year delay.

The TWP 1-km resolution files provided by Aeromet, received at their station in Kwajalein covering TWP Nauru are available with a one month delay.

The TWP files provided by the Australian BOM covering Darwin are available approximately three months after they are collected. These files are only available in there native ASDA format.

Area Covered

For NSA, the image data are remapped into a polar stereographic projection centered at latitude 71^o 18.00' N, longitude 156^o 41.00' W, covering the area shown below.

Figure 1. Area covered by the remapped NSA images

The images consist of 512x512 1km² pixels, and the geographic location of these is available in a separate file.

 The image data are remapped into a polar stereographic projection centered at latitude 77^o N, longitude 155^o W, covering the area shown below.

Figure 2. Area covered by the remapped images

 

The images consist of 800x800 1km² pixels, and the geographic location of these is available in a separate file.

For SGP, the images are rectified to a Mercator projection, centered at the SGP Central Facility (36.605^o N, 97.485^o W).  Each image consists of 500 lines of 350 pixels, and the pixel size is 1km ².

Figure 3. Area covered by the remapped SGP images

Figure 4. Area covered by the TWP Manus AVHRR data

Figure 5. Area covered by TWP Nauru AVHRR data

Data Stream Inputs

For the 1 km resolution images, these data streams are generated from AVHRR data supplied by the University of Alaska and SeaSpace in TDF format for the NSA and SGP respectively and from AVHRR data supplied by Aeromet at Kwajulain in McIDAS format for the TWP Nauru.

The 1 km resolution images covering SHEBA were also supplied by the University of Alaska.

The University of Miami supplies the 4 km resolution TWP Manus and Nauru AVHRR and the 1 km resolution Kwajalein, Manus and Nauru AVHRR data in HDF format. Monthly Hovmuller diagrams are produced for each of the regions and for the lac and gac data.

Data Stream Names
nsaavhrrX1.00
sgpavhrrX1.00
twpavhrrkwajX1.00
twpavhrrnnlacX1.a1.00
twpavhrrnngacX1.a1.00

Hovmuller diagram data streams:
twpavhrrnnlacsssX1.a1.yyymm00.000000.xxx.gif
where nn= 12, 14, 16, 17
sss = Manus, Nauru
xxx = lat, lon

Notification Form Link

NSA AVHRR Notification Form
SGP AVHRR Notification Form
TWP AVHRR Notification Form

Related Links

Office of Satellite Operations Home Page
Advanced Very High Resolution Radiometer - AVHRR
NOAA KLM Users Guide
prelaunch channel characteristics
NOAA Polar Orbiter Data User's Guide

NOAA Response Functions

Description of ASDA Format
C Tool to access ASDA Format Files
AVHRR ASDA File Format Example

Contacts

ARM Mentor

Richard Wagener

ARM Software Developer

Min Liang

Data Source

Institution

SGP

SeaSpace

NSA

Geophysical Institute, University of Alaska Fairbanks

TWP

GAC coverage of TWP Manus and Nauru

University of Miami, Rosenstiel School of Marine and Atmospheric Science

LAC coverage of Nauru from Kwajalein

Aeromet

LAC coverage of Darwin and Manus from Darwin

BOM

Processing History

This information is currently unavailable.

Reprocessing History

Reprocessing Date

This information is currently unavailable.

Start End Reprocessing

This information is currently unavailable.

Reason Reprocessing

This information is currently unavailable.

FAQ

This information is currently unavailable.

Data User Notes

Note A: Incorrect data type

There is a known bug in earlier versions of tdftohdf which gives the incorrect data type code, 23, unsigned short integers, instead of 22, for signed short integers. If you use this information in converting the values read from the files to geophysical units, the answer may be wrong as the sign bit is misinterpreted. This affects most of the data currently available through the ARM Archive. Use of the information given in the HDF file header (metadata) gives the correct values.

File formats

Information on reading hdf formatted files can be found at: Reading netCDF, HDF, and GRIB Files

Lat/Lon grid and coastline overlays

For the NSA, SHB, SGP and TWP matching sets of overlay files showing a latitude and longitude grid and the positions of the coastline and selected lakes and rivers are also available. The overlay files consist of an "image" of value 1 everywhere, except at the positions of the features in which case the pixel value is zero. Thus the overlays can be written into the image by multiplying them together; the image data remain unchanged and the overlain pixels become zero. The overlay images are in byte format.

Also available are HDF files (*lat-lonX1.00.hdf) that contain two arrays with the same dimension as the corresponding data-files, one of the latitude of each pixel, and the other the longitude. The images are distributed as short words, rather than bytes to preserve accuracy.

The various overlay files can be found at The ARM Archive IOP web site in the ref_data subdirectory.

Example Data

NSA AVHRR Image

Quicklook Links

AVHRR images covering the North Slope of Alaska. These images were acquired by the University of Alaska and cropped to cover the NSA area. These are for channels 2 and 4 of the AVHRR on the NOAA 12 and 14 satellites. They are useful for qualitative information about the conditions at the NSA/AAO site.

Glossary

This information is currently unavailable.

Acronyms

ASDA    Australian Satellite Data Archive
AVHRR	Advanced Very High Resolution Radiometer
BOM     Bureau of Meteorology
GAC	Global Area Coverage
HDF	Hierarchical Data Format
LAC	Local Area Coverage
NOAA	National Oceanic and Atmospheric Administration
NSA	North Slope of Alaska
SGP	Southern Great Plains
SHB	SHEBA
SHEBA	Surface HEat Budget of the Arctic Ocean
TDF	Terascan Data Format
TWP	Tropical Western Pacific

Citable References

This information is currently unavailable.

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Last Modified: May 23, 2007

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