NOAA Polar Orbiter Data User's Guide

Section 1.4.10

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1.4.10 NOAA-14

Operational 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.

Table 1.4.10-1. NOAA-14 Central Wave Numbers for AVHRR IR Channels.
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.

Table 1.4.10-2. NOAA-14 TOVS Channel Spectral Response and HIRS/2 Thermal Band-Correction Coefficients.
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:

G = {R sub T - R sub {sp}}/{C sub T - C sub {sp}}
I = R sub {sp} - G x C sub{sp}

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:

R sub {lin} = G x C + I

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):

RAD=A x R sub {lin} + B x {R sub {lin}}^2+D

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.

Table 1.4.10-3. Radiance correction coefficients for NOAA-14 AVHRR Channels 3, 4, and 5.
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.

Table 1.4.10-4. PRT coefficients for all instruments on NOAA-14 (from NESS 107, App. B).
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


Figure showing NOAA-14 spectral response curve for AVHRR Channel 1

Figure showing NOAA-14 spectral response curve for AVHRR Channel 2

Figure showing NOAA-14 spectral response curve for AVHRR Channel 3

Figure showing NOAA-14 spectral response curve for AVHRR Channel 4

Figure showing NOAA-14 spectral response curve for AVHRR Channel 5

Amended May 5, 1999



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