NOAA Polar Orbiter Data User's GuideSection 1.4.10 |
Introduction Page, NOAA POD Guide TOC, AcronymsOperational dates: Dec. 30, 1994 - present
Afternoon orbit: 1340 LST ascending node, 0140 LST descending node
AVHRR instrument: 5 channels
Spacecraft ID: 3
Abnormalities: The MSU instrument on NOAA-14 failed on March 3, 1995 at 0100 UTC, but was successfully turned back on March 30, 1995.
Table 1.4.10-1 contains the central wave numbers for the AVHRR IR channels for NOAA-14. Table 1.4.10-2 contains the TOVS channel spectral response and HIRS/2 thermal band-correction coefficients for NOAA-14.
| Temperature Range (K) | Ch. 3 (cm-1) | Ch. 4 (cm-1) | Ch. 5 (cm-1) |
|---|---|---|---|
| 190-230 | 2638.652 | 928.2603 | 834.4496 |
| 230-270 | 2642.807 | 928.8284 | 834.8066 |
| 270-310 | 2645.899 | 929.3323 | 835.1647 |
| 290-330 | 2647.169 | 929.5878 | 835.374 |
| Note: The 270-310 K range is applicable for sea surface temperatures. | |||
| Instrument | Ch # | Central Wave # | Description | HIRS/2 Band-Correction Coefficients | |
|---|---|---|---|---|---|
| b | c | ||||
| HIRS/2 | 1 | 668.90 cm-1 | 15 micrometers | 0.002 | 0.99998 |
| 2 | 679.36 cm-1 | CO2 Band | -0.000 | 0.99997 | |
| 3 | 689.63 cm-1 | CO2 Band | 0.011 | 0.99994 | |
| 4 | 703.56 cm-1 | CO2 Band | 0.001 | 0.99994 | |
| 5 | 714.50 cm-1 | CO2 Band | -0.014 | 0.99997 | |
| 6 | 732.28 cm-1 | CO2 Band | 0.026 | 0.99989 | |
| 7 | 749.64 cm-1 | CO2 Band | 0.019 | 0.99991 | |
| 8 | 898.67 cm-1 | Window | 0.067 | 0.99977 | |
| 9 | 1028.31 cm-1 | Ozone | 0.050 | 0.99980 | |
| 10 | 796.04 cm-1 | Water Vapor | 0.021 | 0.99990 | |
| 11 | 1360.95 cm-1 | Water Vapor | 0.073 | 0.99971 | |
| 12 | 1481.00 cm-1 | Water Vapor | 0.284 | 0.99931 | |
| 13 | 2191.32 cm-1 | 4.3 micrometers | 0.021 | 0.99996 | |
| 14 | 2207.36 cm-1 | CO2 Band | 0.020 | 0.99997 | |
| 15 | 2236.39 cm-1 | CO2 Band | 0.024 | 0.99998 | |
| 16 | 2268.12 cm-1 | CO2 Band | 0.018 | 0.99996 | |
| 17 | 2420.24 cm-1 | CO2 Band | 0.026 | 0.99992 | |
| 18 | 2512.21 cm-1 | Window | 0.042 | 0.99993 | |
| 19 | 2647.91 cm-1 | Window | 0.313 | 0.99946 | |
| 20 | 14453.14 cm-1 | Visible Window | n/a | n/a | |
| MSU | 1 | 1.6779 cm-1 | n/a | n/a | n/a |
| 2 | 1.7927 cm-1 | n/a | n/a | n/a | |
| 3 | 1.8334 cm-1 | n/a | n/a | n/a | |
| 4 | 1.9331 cm-1 | n/a | n/a | n/a | |
| SSU | 1 | 669.988 cm-1/15 mb | n/a | n/a | n/a |
| 2 | 669.628 cm-1/5 mb | n/a | n/a | n/a | |
| 3 | 669.357 cm-1/1.5 mb | n/a | n/a | n/a | |
Beginning with the NOAA-13 AVHRR instrument, a new radiance correction procedure is being implemented at NESDIS which corrects both the non-linearity of AVHRR Channels 4 and 5 and the observed offset of the space point from the calibration curve for Channel 3. As was the case with previous instruments, gain and slope calibration coefficients for each channel are imbedded in the Level 1b data stream which allows the user to perform a linear calibration. However, these coefficients are derived using a non-zero radiance of space, Rsp which is a constant for each channel and which makes the radiance corrections independent of the internal calibration target temperature. The slope and intercept coefficients are derived with the following equations:


where G is the slope, I is the intercept, RT is the radiance of the target, CT is the counts of the target, and Csp is counts of space. These coefficients provide a linear radiance, Rlin:

where C is the counts of the channel.
This linear calibration procedure is described in more detail in NOAA Technical Memorandum NESS 107. The following equation provides a corrected radiance, RAD, for AVHRR channels 3, 4, and 5 which is a function only of the linear radiance derived from Eq. (3):

This radiance can be converted to temperatures using the energy tables or by using the inverse of the Planck function with the appropriate central wave numbers. No additional temperature correction should be applied. The regression coefficients (A, B and D) to apply this equation for NOAA-14 AVHRR Channels 3, 4 and 5 are contained in Table 1.4.10-3.
| Radiance Correction Coefficients | Channel 3 | Channel 4 | Channel 5 |
|---|---|---|---|
| A | 1.00359 | 0.92378 | 0.96194 |
| B | 0.0 | 0.0003822 | 0.0001742 |
| D | -0.0031 | 3.72 | 2.00 |
| Radiance of Space, Rsp | 0.0069 | -4.05 | -2.29 |
Figures 1.4.10-1 through 1.4.10-5 contain the spectral response curves for NOAA-14 AVHRR Channels 1 through 5, respectively.
Users of SSU data should note that the quality indicator for
invalid blackbody position is always set on NOAA-14. Users
should ignore this condition, assume the data are good and proceed
with processing as usual.
| AVHRR | |||||
|---|---|---|---|---|---|
| PRT counts to temperature coefficients | |||||
| PRT | a0 | a1 | a2 | a3 | a4 |
| 1 | 276.597 | 0.051275 | 1.363E-6 | 0.0 | 0.0 |
| 2 | 276.597 | 0.051275 | 1.363E-6 | 0.0 | 0.0 |
| 3 | 276.597 | 0.051275 | 1.363E-6 | 0.0 | 0.0 |
| 4 | 276.597 | 0.051275 | 1.363E-6 | 0.0 | 0.0 |
| PRT weighting factors | |||||
| b1 | b2 | b3 | b4 | ||
| 0.25 | 0.25 | 0.25 | 0.25 | ||
| HIRS | |||||
| IWT PRT Count to temperature coefficients | |||||
| PRT | a0 | a1 | a2 | a3 | a4 |
| 1 | 301.38795 | 6.52106E-03 | 8.27531E-08 | 4.65675E-11 | 1.45893E-15 |
| 2 | 301.37735 | 6.53105E-03 | 8.36999E-08 | 4.66502E-11 | 1.44768E-15 |
| 3 | 301.39698 | 6.52318E-03 | 8.26203E-08 | 4.65039E-11 | 1.51146E-15 |
| 4 | 301.36675 | 6.52655E-03 | 8.36699E-08 | 4.67894E-11 | 1.41383E-15 |
| SSU | |||||
| PRT count to temperature coefficients | |||||
| a0 | a1 | a2 | |||
| 284.125 | 4.819E-03 | 8.75E-09 | |||
| Thermistor to temperature coefficients | |||||
| b0 | b1 | b2 | b3 | ||
| 375.969 | -203.161 | 179.13 | -85.16 | ||
| c0 | c1 | c2 | c3 | ||
| 375.969 | -203.161 | 179.13 | -85.16 | ||
| MSU | |||||
| PRT Count to resistance coefficients | |||||
| K0 | 495.6 | ||||
| K1 | 107.8 | ||||
| PRT Resistance to temperature coefficients | |||||
| e0 | e1 | e2 | |||
| 1A | 29.003197 | .429363 | .3144484E-04 | ||
| 2A | 28.514892 | .4280371 | .3028803E-04 | ||
| 1B | 28.455605 | .428430 | .3021258E-04 | ||
| 2B | 29.113998 | .425768 | .3159801E-04 | ||
| Radiance of space (Nsp) | |||||
| Channel | Nsp( mW/sr- m2 - cm-1) | ||||
| 1 | 0.000086 | ||||
| 2 | 0.000096 | ||||
| 3 | 0.000084 | ||||
| 4 | 0.000092 | ||||
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