1. Lei Shi NOAA National Climatic Data Center Asheville, NC, U.S.A.
Inter-satellite differences of HIRS longwave channels derived from global observation
Lei Shi
NOAA National Climatic Data Center
Asheville, NC, U.S.A.

2. Datasets HIRS channels 1-12 Two pairs of satellites
NOAA-14 and NOAA-15 (transition from HIRS/2 to HIRS/3)
NOAA-17 and METOP-A (transition from HIRS/3 to HIRS/4)
Two sources of overlapping data
Short-term global SNO
Julian Days in 2003 for NOAA-14 and NOAA-15 pair
Julian Days in 2009 for NOAA-17 and METOP-A pair
Multi-year polar SNO
for NOAA-14 and NOAA-15 pair
for NOAA-17 and METOP-A pair
30 years

3. M02
Credit: Hai-Tien Lee,

4. NOAA-14 and NOAA-15

5. NOAA-17 and METOP-A

6. Atmospheric Transmission Spectrum

7. N14-N15 Channel 4

8. N17-M02 Channel 4

9. N14-N15 Diff as function of Tb

10. N17-M02 Diff as function of Tb

11. N14-N15 Diff as function of lapse rate

12. N17-M02 Diff as function of lapse rate

13. N14-N15 Channel LRF ISD Mean LRF Mean ISD STD LRF STD Correlation
Channel
LRF
ISD Mean
LRF Mean
ISD STD
LRF STD
Correlation
Short-term Global 1
CH2-CH1
-1.74
-10.45
1.85
2.90
-0.243 2
CH3-CH2
-0.85
-0.26
0.42
0.87
-0.228 3
CH4-CH3
-0.10
13.86
0.31
4.90
0.391 4
CH5-CH4
4.02
12.56
1.14
2.61
0.963 5
CH6-CH5
0.79
12.78
0.26
2.42
0.754 6
CH7-CH6
0.51
13.16
2.70
0.297 7
CH8-CH7
2.50
16.65
0.67
4.45
0.795
Multi-year Polar
-1.22
-7.90
1.10
4.82
0.361
-0.54
-0.42
0.62
2.78
0.411
-0.32
4.95
0.47
5.77
0.563
1.45
5.27
1.08
2.48
0.830
0.21
4.60
0.40
3.09
0.412
0.24
3.67
0.30
3.53
0.351
0.57
3.03
0.73
3.87
0.839
All
-1.49
-9.17
1.89
0.098
-0.73
-0.27
1.15
-0.007
-0.12
11.72
0.33
6.87
0.305
3.39
10.66
1.78
0.976
0.66
10.85
0.39
4.92
0.870
0.45
11.19
5.21
0.495
2.11
13.98
7.40
0.922

14. N17-M02 Channel LRF ISD Mean LRF Mean ISD STD LRF STD Correlation
Channel
LRF
ISD Mean
LRF Mean
ISD STD
LRF STD
Correlation
Short-term Global 1
CH2-CH1
-1.79
-11.58
3.67
5.38
-0.606 2
CH3-CH2
-0.83
0.27
0.65
1.32
-0.114 3
CH4-CH3
0.10
8.90
0.51
4.23
0.393 4
CH5-CH4
1.29
14.38
0.61
5.12
0.900 5
CH6-CH5
-0.60
11.43
0.34
4.02
-0.813 6
CH7-CH6
-0.10
9.85
0.30
-0.567 7
CH8-CH7
-0.33
17.20
0.36
8.13
-0.370
Multi-year Polar
-2.18
-9.39
4.13
6.73
-0.461
-0.59
-1.01
0.73
3.23
0.115
-0.41
1.63
0.85
4.64
0.744
0.35
5.99
0.49
3.61
0.747
-0.20
4.18
0.32
3.28
-0.527
0.22
3.32
0.37
3.21
-0.414
-0.05
4.08
0.48
4.76
-0.389
All
-1.92
-10.83
3.84
5.96
-0.544
-0.75
-0.17
0.69
2.25
-0.029
-0.07
6.42
5.56
0.621
0.97
11.52
6.13
0.917
-0.47
8.96
0.38
5.11
-0.805
0.01
7.62
4.87
-0.623
-0.23
12.72
0.42
9.48
-0.457

15. Linear regression for CH4 inter-satellite difference
ISDN14-N15 = x ΔTbCH5-CH4 – 0.993
ISDN17-M02 = x ΔTbCH5-CH4 – 0.287

16. Conclusions
The multi-year polar SNO generally provides larger observation ranges of brightness temperatures in channels 1-4.
The global SNO extends the brightness temperature observations to the warm sides for channels 5-12, and captures the occurrences of larger inter-satellite differences for most HIRS longwave channels.
For HIRS channel 4, the inter-satellite differences are the largest in low latitudes where both lapse rate and Tb are large.
The difference in inter-satellite difference patterns in low latitudes and high latitudes produces a fork feature in channel-4 Tb scatter plots between overlapping satellites.