NOAA-14 CALIBRATION INFORMATION AS OF 31 July 1995
Amendments to NOAA Technical Memorandum 107 Appendix-B for NOAA-J/14

A separate Appendix-B to NOAA Technical Memorandum 107 is prepared in advance of each new NOAA polar satellite launch. This Appendix-B contains coefficients necessary for the proper calibration of satellite data from the TIROS-N/NOAA radiometers, and is used primarily by High Resolution Picture Transmission (HRPT) and Direct Sounder Broadcast (DSB) service users. The Automatic Picture Transmission (APT) users who digitize the APT data may find some of these coefficients useful.

APPENDIX-B NOAA-J/14 COEFFICIENTS AVHRR FM-204

A. VISIBLE COEFFICIENTS

(Note: these coefficients were revised on 07/31/95 to the above values from the pre-launch coefficients previously published. This was done using the post-launch techniques as described by N. Rao (posted elsewhere on this web site). Monthly updates to the visible channel coefficients began in November 1996, and are posted elsewhere on this web site.

B. Related Information

The following table lists equivalent widths, integrated solar irradiances, and effective central wavelengths for the AVHRR FM-204

	W	F
Channel 1	0.136	221.42	0.633
Channel 2	0.245	252.29	0.842

Glossary:
G: Slope (% albedo/count)
I: Intercept (% albedo)
W: Equivalent width ()
F: In-band solar irradiance (Wm-2)
: Effective wavelength()

The slope (G) and intercept (I) values are based on the September 1993 calibration of the AVHRR and the October 1993 calibration of the 40 inch integrating sphere performed at ITT. The normalized response functions given for this instrument have been used in the calculation of W, F, and ; further, the 1984 Neckel and Labs solar spectral irradiance values have been used in the calculations of F.

NOAA-J/14 AVHRR FM-204 Calibration

b_I - PRT WEIGHTING FACTORS

CENTRAL WAVE NUMBERS, AVHRR FM-204

When used by the inverse Planck function, these Central Wave Numbers give the minumum error for the specified temperature bands. The thrid band may be useful for sea surface temperatures.

AVHRR FM-204 NOAA-J/14 NORMALIZED RESPONSE FUNCTIONS

AVHRR CHANNEL 3
STARTING WAVE # 2439.02393
INCREMENT 7.92288
NUMBER OF POINTS 60

[0.45873E-04] [0.52313E-04] [0.61172E-04] [0.77791E-04] [0.11592E-03]

[0.19256E-03] [0.32879E-03] [0.55500E-03] [0.91766E-03] [0.14292E-02]

[0.20411E-02] [0.26523E-02] [0.30875E-02] [0.32711E-02] [0.33031E-02]

[0.32812E-02] [0.32686E-02] [0.32987E-02] [0.33478E-02] [0.33947E-02]

[0.34446E-02] [0.34994E-02] [0.35288E-02] [0.35051E-02] [0.34626E-02]

[0.34527E-02] [0.34667E-02] [0.34616E-02] [0.34307E-02] [0.34035E-02]

[0.33940E-02] [0.33839E-02] [0.33583E-02] [0.33299E-02] [0.33153E-02]

[0.33055E-02] [0.32779E-02] [0.32262E-02] [0.31661E-02] [0.31204E-02]

[0.31326E-02] [0.32400E-02] [0.33575E-02] [0.33204E-02] [0.30323E-02]

[0.25347E-02] [0.18938E-02] [0.12394E-02] [0.72931E-03] [0.43543E-03]

[0.28618E-03] [0.20207E-03] [0.14867E-03] [0.11270E-03] [0.85083E-04]

[0.65241E-04] [0.53482E-04] [0.48081E-04] [0.45873E-04] [0.00000E+00]

AVHRR CHANNEL 4
STARTING WAVE # 854.70068
INCREMENT 2.67931
NUMBER OF POINTS 60

[0.23014E-03] [0.27443E-03] [0.34325E-03] [0.46112E-03] [0.64546E-03]

[0.90008E-03] [0.12278E-02] [0.16511E-02] [0.22145E-02] [0.29604E-02]

[0.38816E-02] [0.49335E-02] [0.60684E-02] [0.72210E-02] [0.83148E-02]

[0.92778E-02] [0.10070E-01] [0.10669E-01] [0.11054E-01] [0.11248E-01]

[0.11288E-01] [0.11218E-01] [0.11087E-01] [0.10952E-01] [0.10867E-01]

[0.10831E-01] [0.10802E-01] [0.10738E-01] [0.10648E-01] [0.10604E-01]

[0.10683E-01] [0.10912E-01] [0.11206E-01] [0.11463E-01] [0.11600E-01]

[0.11619E-01] [0.11555E-01] [0.11438E-01] [0.11251E-01] [0.10932E-01]

[0.10417E-01] [0.96638E-02] [0.86844E-02] [0.75014E-02] [0.61428E-02]

[0.47139E-02] [0.33721E-02] [0.22763E-02] [0.15297E-02] [0.10645E-02]

[0.78012E-03] [0.57781E-03] [0.40669E-03] [0.26838E-03] [0.16717E-03]

[0.10619E-03] [0.78904E-04] [0.74105E-04] [0.80549E-04] [0.00000E+00]

AVHRR CHANNEL 5
STARTING WAVE # 787.40137
INCREMENT 1.74978
NUMBER OF POINTS 60

[0.10568E-03] [0.14907E-03] [0.26039E-03] [0.49931E-03] [0.91686E-03]

[0.18490E-02] [0.39154E-02] [0.68996E-02] [0.99628E-02] [0.12261E-01]

[0.13237E-01] [0.13583E-01] [0.14026E-01] [0.14395E-01] [0.14533E-01]

[0.14626E-01] [0.14784E-01] [0.14956E-01] [0.15077E-01] [0.15088E-01]

[0.14993E-01] [0.14853E-01] [0.14730E-01] [0.14682E-01] [0.14698E-01]

[0.14731E-01] [0.14731E-01] [0.14655E-01] [0.14508E-01] [0.14323E-01]

[0.14132E-01] [0.13963E-01] [0.13806E-01] [0.13634E-01] [0.13416E-01]

[0.13131E-01] [0.12838E-01] [0.12645E-01] [0.12663E-01] [0.12985E-01]

[0.13384E-01] [0.13364E-01] [0.12859E-01] [0.12317E-01] [0.11981E-01]

[0.11725E-01] [0.11199E-01] [0.96217E-02] [0.66253E-02] [0.35059E-02]

[0.16572E-02] [0.90176E-03] [0.52967E-03] [0.27114E-03] [0.12649E-03]

[0.72636E-04] [0.57373E-04] [0.44226E-04] [0.30198E-04] [0.00000E+00]

Radiance Correction Procedures for AVHRR FM-204

The response of the AVHRR channels 4 and 5 in counts is slightly non-linear and can be expressed as a quadratic function of laboratory target radiance. On the other hand, the channel 3 response has been found to be quite linear. However, the pre-launch calibration data indicates that the channel 3 space view response (assuming the radiance of space is zero) does not lie on the measured calibration curve derived from measurements of the laboratory target.

Beginning with the AVHRR FM-204 instrument, a new radiance correction procedure is being implemented at NESDIS which corrects both the non-linearity of 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 gain and intercept coefficients are derived with the following equations:

G = (RT - RSP)/(CT - CSP) and I = RSP- G * CSP (1)

These coefficients provide a linear radiance: RLIN = G * C + I (2)

This linear calibration procedure is described in more detail in NOAA Technical Memorandum NESS 107. The following equation provides a corrected radiance for AVHRR channels 3, 4 and 5 which is a function only of the linear radiance derived from equation 2:

RAD= A * RLIN + B * RLIN * RLIN + C (3)

With the energy tables or by using the inverse of the Planck function with the appropriate central wave numbers, this radiance can be converted to temperature. No additional temperature correction should be applied. The coefficients to apply this equation for channels 3, 4 and 5 of FM. 204 are as follows:

In summary, users of level 1B data need only apply equations 2 and 3 using the slope and intercept values imbedded in the level 1B data. Users of direct readout data must also apply equation 1.

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