The HIRS cloud-cleared products were developed from the
HIRS 1B data set. The International
TOVS Processing Package (ITPP) was used to calibrate the raw
counts into brightness temperature for TIROS-N, NOAA-6,
-7,-8,-9,-10,-11,-12,-14 and ATOVS and AVHRR processing
package (AAPP) was used for processing NOAA-15 and
NOAA-16.. A modified ISCCP approach
was used for cloud-clearing and multiple channel regression was
developed for limb correction. We currently have data
available for each satellite starting in November 1978 and
ending December 2001. Version 2 extends the data from December
1999 to December 2001.
The first processing stage conducted in the spring 2000 used a cloud detection method and limb correction algorithm so to produce a clear-sky scan line and gridded data sets. The second version data were created the summer of 2002. Version 2 provides an all-sky data set containing cloud-top retrievals using the CO2 slicing method of Wylie and Menzel. Orbit statistic files have additional statistics on the skewness and kurtosis of each orbit.
Details of the products derived from our process are given below. File name formats are given for each product and the file name key is provided. Software for reading the satellite-view and gridded products can accessed via anonymous ftp. Data and software requests can be made to Darren.L.Jackson@noaa.gov.
These files containing statistical information about each HIRS orbit, satellite and channel. The parameters include mean, maximum, minimum,standard deviation, skewness and kurtosis of brightness temperature, number of observations, number of ITPP bad data, and number of bad data as determined by additional quality control. There are about 220 orbital files with total data volume of about 355 Mb.
These data give all the clear-sky HIRS observations at the resolution
of the satellite observations. Data are stored in daily files that
consume about 4-5 Mbytes each. The entire HIRS clear-sky satellite
view archive is approximately 90 Gbytes. These pixel data have a
55 byte record structure. We have Fortran and IDL code that reads
these data and applies limb correction. Addition coefficient files
are need for the limb correction.
VARIABLE | DATA TYPE | DESCRIPTION | SCALE & OFFSET |
itime | int*4 | GMT time in seconds from start of day | itime=time*100 |
ilon | int*2 | longitude in degrees (0 to 359.99; GM eastward) | ilon=(lon-180)*100 |
ilat | int*2 | latitude in degrees (-90 to 90) | ilat=lat*100 |
iline | int*2 | line number(1-1100) | NA |
isp | byte | scan position (1-56) | NA |
iszen | int*2 | solar zenith angle in degrees (0-90) | iszen=angle*100 |
ialt | int*2 | satellite altitude in km | ialt=altitude*10 |
isf | byte | spare | NA |
iref | byte | reflectance | iref=reflectance*100 |
itb | int*2(19) | channels 1-19 brightness temperatures (Kelvin) | itb=(TB-100.)*100 |
These data give all the all-sky HIRS observations at the resolution
of the satellite observations. Data are stored in daily files that
consume about 4-5 Mbytes each. The entire HIRS clear-sky satellite
view archive is approximately 380 Gbytes. These pixel data have a
55 byte record structure. We have Fortran and IDL code that reads
these data.
VARIABLE | DATA TYPE | DESCRIPTION | SCALE & OFFSET |
itime | int*4 | GMT time in seconds from start of day | itime=time*100 |
ilon | int*2 | longitude in degrees (0 to 359.99; GM eastward) | ilon=(lon-180)*100 |
ilat | int*2 | latitude in degrees (-90 to 90) | ilat=lat*100 |
iline | int*2 | line number(1-1100) | NA |
isp | byte | scan position (1-56) | NA |
iszen | int*2 | solar zenith angle in degrees (0-90) | iszen=angle*100 |
ialt | int*2 | satellite altitude in km | ialt=altitude*10 |
iref | byte | reflectance | iref=reflectance*100 |
itb | int*2(19) | 7 channels 4-8,10,12 brightness temperatures (Kelvin) | itb=(TB-100.)*100 |
ipct | int*2 | Pressure at cloud top (Mb) | NA |
iem | byte | IR emissivity of cloud (%) | NA |
itc | INT*2 | Temperature of cloud top (K) | itc=(TEMPERATURE-100.)*100. |
itsfc | INT*2 | Surface temperature used in CO2 slicing routine(K) | itsfc=(TEMPERATURE-100.)*100. |
idelrad | INT*2 (4) | Radiance (clear) - Radiance (cloud) for HIRS channels 4-7 | NA |
iclear | INT*2 | Temperature of cloud top (K) | itb=(TEMPERATURE-100.)*100. |
ipctrto | INT*2 (5) | The cloud height solutions for the CO2 pairs + window | NA |
iused | byte | Flag indicates which ratio was used | NA |
Satellite & Date | File Name | Data type |
TN,N7,N9,N11: all; N14:1/95-6/96 | HIRS_CS_tape1.A.dlt | clear sky | N14:7/96-12/01; N16:3/01-12/01 | HIRS_CS_tape2.A.dlt | clear sky | N6,N8,N10,N12,N15: all | HIRS_CS_tape1.M.dlt | clear sky | N6:7/79-4/83; N8:4/83-8/83 | HIRS_C2_tape1.M.dlt | all-sky | N8:9/83-5/84; | HIRS_C2_tape2.M.dlt | all-sky | HIRS_C2_tape3.M.dlt | all-sky | HIRS_C2_tape4.M.dlt | all-sky | HIRS_C2_tape5.M.dlt | all-sky | TN:11/78-1/81; N7:7/81-10/83 | HIRS_C2_tape1.A.dlt | all-sky | N7:11/83-1/85; N9:1/85-12/87 | HIRS_C2_tape2.A.dlt | all-sky | N9:1/88-10/88; | HIRS_C2_tape3.A.dlt | all-sky | HIRS_C2_tape4.A.dlt | all-sky | HIRS_C2_tape5.A.dlt | all-sky | HIRS_C2_tape6.A.dlt | all-sky |
All gridded data are INT*2 with array arrangement of LON x LAT X CHN. LON and LAT are determined by resolution. Latitudes only range from 70N-70S. Channel array element is 20 representing each HIRS channel. Data were created on PC, so byte swapping might be an issue. The mean fields are scaled and offset (MEAN = INT2/100. + 100.) while the standard deviation fields were only scaled (STD = INT2/100.). Count values do not need modification. Missing values are -99 AFTER offset and scale are applied. First grid box (1,1) is located at (0.5E,69.5S). Longitudes move eastward. All data values for channels 1-19 are brightness temperatures expressed in Kelvin. Channel 20 is reflectance with values between 0 and 1.