TITLE:  GOES-10 Imager Data [NOAA/CLASS]


Steve Williams
P.O. Box 3000
Boulder, CO 80307-3000

phone: 303-497-8164
email: sfw@ucar.edu


This data set contains 1-km resolution GOES-10 channel 1 (visible) and 4-km
resolution GOES channel 2-5 data in netcdf format. These data were retrieved 
from the NOAA CLASS archive.  The data cover the T-REX period (1 March to 
30 April 2006).  They cover the region from 34-40 N and 115-126 W.  This data
set includes data from all sector scans that cover this region, including any
rapid scan or super rapid scan sectors.


The Geostationary Operational Environmental Satellite (GOES) series of satellites
is owned and operated by the National Oceanic and Atmospheric Administration (NOAA). 

The GOES spacecraft is positioned 35,790 km (22,240 statute miles) above the equator 
allowing it to view a major portion of the Western Hemisphere including southern 
Canada, the contiguous 48 states, major portions of the eastern Pacific Ocean and 
western Atlantic Ocean and Central and South America. Because the Atlantic and 
Pacific basins strongly impact the weather over the United States, coverage is 
typically provided by two GOES spacecraft, one at 75 E west longitude (GOES East) 
and the other at 135E west longitude (GOES West).

The Imager instrument is designed to sense radiant and solar-reflected energy from 
sampled areas of the Earth's surface and atmosphere. The Imager's five spectral 
channels simultaneously sweep an 8 km north-south (N/S) longitudinal swath along 
an east-west (E/W) latitudinal path by means of a two-axis gimballed mirror scan 
system. Beamsplitters separate the spectral channels into the various IR detector sets.

Channel        Detector Type    Nominal Square IGFOV at nadir
1 (Visible)    Silicon          1 km
2 (Shortwave)  InSb             4 km 
3 (Moisture)   HgCdTe           8 km (4 km GOES 12/N/O/P)
4 (Longwave 1) HgCdTe           4 km
5 (Longwave 2) HgCdTe           4 km

Imager Instrument Parameters:

Parameter                      Performance 
FOV defining element           Detector
Channel-to-channel alignment   28 microrad (1.0 km) at nadir
Radiometric calibration        300 K internal blackbody and space view
Signal quantizing              10 bits, all channels
Scan capability                Full earth, sector, area
Output data rate               2,620,800 b/s
Imaging areas                  20.8 Deg E/W by 19 Deg  N/S

Imaging Channels Allocation:

Channel Number     Wavelength Range (microm) Range of Measurement
1                  0.55 to 0.75              1.6 to 100% albedo
2 (GOES 8/9/10)    3.80 to 4.00              4 to 320 K
3 (GOES 8/9/10/11) 6.50 to 7.00              4 to 320 K
4                  10.20 to 11.20            4 to 320 K
5 (GOES 8/9/10/11) 11.50 to 12.50            4 to 320 K 


NCAR/EOL conducted no processing or quality control on these data.

The GOES Support System includes the Command and Data Acquisition (CDA) Station
at Wallops Island, VA, and the Satellite Operations and Control Center (SOCC) at
Suitland, MD. At the CDA station, raw instrument data and telemetry are read out
from the satellite. Data are processed, calibrated, earth-located and converted
to GOES Variable data format (GVAR) and rebroadcast to the satellite along with
spacecraft command schedules. The GVAR data are then broadcast to direct readout
users. SOCC is responsible for the overall safety of the spacecraft, scheduling
of the instruments, data quality and performance. Continuous monitoring and checks
are conducted on orbital position, image navigation and registration, and various
subsystems including primary imager and sounder instruments. It is also responsible
for planning and operating the ground system equipment for GVAR acquisition at
NESDIS, the initial stage of product processing.

The Imager scans pre-determined areas in alternate directions on alternate lines. 
The imaging area is defined by a coordinate system related to the instrument's 
orthogonal scan axis. During imaging operations a scan line is generated by rotating 
the scanning mirror in the east-west direction while concurrently sampling each 
of the active imaging detectors. At the end of the line, the Imager scan mirror 
performs a turnaround, which involves stepping the mirror to the next scan line 
and reversing the direction of the mirror. The next scan is then acquired by 
rotating the scanning mirror in the opposite, west-east direction, again with 
concurrent detector sampling. Detector sampling occurs within the context of a 
repeating data block format. In general, all visible detectors are sampled four 
times for each data block (four times 1 km wide); while each of the active IR 
detectors is sampled once per data block (one times 4 km wide).

GOES-WEST Imager Scan Sectors in Routine Mode>

Frame Name            Boundaries       Duration    Scan Times
                                       (mm:ss)     (UTC)
Full Earth            Earth Edge       26:10       0000, 0300, etc
Northern Hemisphere   0-66N/90W-170E    9:00       xx00, xx30
Southern Hemisphere   0-45S/115W-170E   7:00       xx22, xx52
PACUS                 12-60N/90-175W    5:00       xx15, xx45 

During GOES Rapid Scan Operations (RSO), four views of the continental United 
States (CONUS) are provided at approximately 7.5 minute intervals in a half hour 
period. A northern hemisphere scan for both GOES East and GOES West satellites is 
also included in the 30 minute cycle. This yields eight views of the continental 
U.S. per hour.

During GOES Super Rapid Scan Operations (SRSO), approximately 10 one-minute 
interval scans are provided every half hour using prescribed 1000 x 1000 km 
sectors. The remaining time in the half hour cycle is devoted to scans of the 
northern hemisphere and CONUS (or sub-CONUS for GOES-WEST).

The raw data in the visible channel are relativized and normalized at the CDA, 
but no calibration is applied. The raw data in the IR channels are calibrated 
using spacelooks and a heated internal blackbody. The spacelook calibration 
positions the scanning mirror at an extreme E-W coordinate permitting a view of 
space. The frequency of these spacelooks depends on the activity of the instrument. 
The rates vary from once every second to once every 36.6 seconds. A Blackbody 
calibration sequence is initiated every 30 minutes. During the sequence, the 
scanning mirror is rotated in the N-S direction through an angle of approximately 
180 degrees to present a view of the Blackbody surface to the imaging detectors. 
The Blackbody surface temperature is maintained at a nominal 290. K. For more 
information on GOES calibration see 


4.1  File Naming conventions


 goes10 is the satellite
 2006 is the year
 120 is Julian day
 000014 is the scan start time (hhmmss - UTC)
 BAND_01 is the channel included (here visible)

There are also metadata files containing information on bad lines that are
named as above except in the place of BAND_XX there is meta.

4.2  Data Format
These data are in netcdf format.

Complete information on netcdf format is available from UCAR Unidata:

Satellites measure upwelling radiation from the Earth. Visible radiation is 
generally what our eyes see. Infrared radiation is sensitive to the temperature 
of the surface (e.g., clouds, oceans, etc). The satellites sensor converts radiation 
falling on the sensor to a voltage which is generally reported in counts (often 
ranging from 0-255 counts for 1-byte data or 0-1023 for 10-bit data). Satellite 
image calibration is the conversion of this count value to a radiance, which is 
then often converted to a temperature (for infrared) or reflectance (for visible). 

The netCDF files raw provide satellite data from the Area files. So data in netCDF 
files must first be converted from 16-bit to 10-bit data by dividing by 32. Then 
use this result to calibrate the IR observations to radiance or brightness 
temperature and the visible observations to radiance or scaled reflectance.
Information on the conversion from 10-bit data to radiance/brightness 
temperature/reflectance can be found at:

The GVAR calibration is described on the NESDIS website:

Calibration information is also available from NASA at the GOES Project Office:


AVHRR Level 1b data are present as a collection of data sets. Each data set 
contains data of one type for a discrete time period. Thus, for AVHRR, there 
are separate HRPT, LAC, and GAC data sets. Time periods are arbitrary subsets of 
orbits, and may cross orbits (i.e., may contain data along a portion of an 
orbital track that includes the ascending node, the reference point for counting 
orbits). Generally, GAC data sets are available for corresponding time periods 
and usually have a three to five minute overlap between consecutive data sets. 
Level 1b (following FGGE terminology) is raw data in 10 bit precision that have 
been quality controlled, assembled into discrete data sets, and to which Earth 
location and calibration information has been appended, but not applied. Other 
parameters appended are: time codes, quality indicators, solar zenith angles, 
and telemetry.