1. NOAA/NESDIS/Center for Satellite Applications and Research
Radiance Performance of SNPP/ATMS in Comparison to Recalibrated POES/AMSU-A Cheng-Zhi Zou, Xianjun Hao, and Manik Bali
Thanks Bruce for the introduction. The title of my talk is ‘MSU/AMSU/SSU CDR development. I gave a talk three years ago in the STAR science forum about the MSU inter-calibration and trend and I kept talking this subject in the last few years in various occasions and hope people don’t get tired of it. But today I try to provide a comprehensive review of the current status and a discussion of various science issues include various bias correction, validation, inter-comparisons, web data support, and so on. I have reserved the room for two hours, but I will only talk about 45 minutes to one hour and allow plenty of time for questions. So don’t get scared about the length of the talk as suggested in the announcement.
NOAA/NESDIS/Center for Satellite Applications and Research
GSICS MW Subgroup Web Meeting, January 12, 2018

2. Purpose
I) Evaluation of ATMS Radiance Performance for Climate Trend Detection
MSU/AMSU-A has been used for creating atmospheric temperature Climate Data Record (CDR) for climate trend detection and monitoring
The last NOAA satellite carrying AMSU-A is NOAA-19; EUMETSAT will launch its last AMSU- A on MetOp-C next year
Evaluating the long-term radiance performance of ATMS is the first step toward this merging goal
II) Examining the Idea of Using IMICA Re-calibrated MSU/AMSU-A Radiance FCDR as an In- Orbit Reference for Characterizing Biases of Other Microwave Instruments
STAR has recalibrated AMSU-A temperature sounding channels using Integrated Microwave Inter-Calibration Approach (IMICA, Zou and Wang 2011, 2013)
There is an interest in the GSICS microwave community to use the IMICA recalibrated MSU/AMSU-A as an in-orbit reference to monitor biases of other microwave instrument
Mitch provided long time support for project from the program side, such as leveraging funding.
And Fuzhong also provides program support and coordinate the CRTM team to work with our product development team. You may notice that most of my SDS science team members are from his Branch.
I also want to thank Changyong for his long time support from scince side. I can always count on his support when I need a discussion on science. even when I need support from his team members.

3. AMSU-A/ATMS Sounding Channels
ATMS AMSU-A
Focusing ATMS temperature sounding channels 5-15
These channels have the same channel frequency as the AMSU-A channels 4-14
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.

4. Integrated Microwave Inter-Calibration Approach (IMICA)
Before Recalibration (Operational Calibrated)
Calibration coefficients were determined by satellite overlap observations
Calibration coefficients were fixed over the entire life cycle of a satellite
Using SNO, CRTM, global-ocean means, etc. as tools to calculate calibration coefficients
Remove or minimize time-varying inter-satellite biases
σ : ~ 0.1 K; Bias~0.5-1K
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
After Recalibration (IMICA recalibrated)
σ: ~ 0.03 K; Bias~0.2K

5. Data Processing Approach
IMICA calibrated AMSU-A data include
limb-adjustment to convert footprints at
different angles to nadir observations
Generate daily and monthly gridded
maps for limb-adjusted data from multiple
scan positions
Grid resolution is 1° by 1° lat/lon
Long-term monthly time
series were generated from
these maps
Similar ATMS gridded data were
generated from nadir-only observations
(observations with scan angles less than
3.3)
For both AMSU-A and ATMS, each daily
grid cell contains multiply FOVs to reduce
noise
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
Scanning patterns of AMSU-A (blue) and ATMS (black). The unit is kilometer for both the horizontal and vertical coordinates. The beam widths of FOVs are 3.3° and 2.2° for AMSU-A and ATMS, respectively. Red circle indicates grid boxes for binning
Lower Panel: AMSU-A FCDR daily gridded map for limb-adjusted multi-pixel means

6. POES Satellite Orbital Drifts
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
SNPP

7. Instrument Stability SNPP/ATMS NOAA-18/AMSU-A
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
NOAA-18/AMSU-A

8. Possible Reasons Causing Inter-Satellite Biases
Calibration biases
Errors in warm target temperature
Errors in cold space view temperature
Inaccurate calibration nonlinearity
Sampling Biases
Diurnal differences between satellites
Mitch provided long time support for project from the program side, such as leveraging funding.
And Fuzhong also provides program support and coordinate the CRTM team to work with our product development team. You may notice that most of my SDS science team members are from his Branch.
I also want to thank Changyong for his long time support from scince side. I can always count on his support when I need a discussion on science. even when I need support from his team members.

9. Impact of Diurnal Drift on Inter-Satellite Biases
Yearly Mean Inter-sensor Biases Over Ocean
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
Yearly Mean Inter-sensor Biases Over Land
Long-term mean bias pattern between NOAA -18 and NOAA-15 for channel 4
If diurnal drift effects are large,
values of inter-satellite biases depend on
time periods selected for the calculation

10. Inter-Sensor Biases Between POES/AMSU-A and SNPP/ATMS
Inter-Sensor Biases: ATMS-AMSU time period is 12/ /2017
AMSU/AT MS
Channels
N18- N15
N18- Aqua
ATMS- N18
ATMS- Aqua
# of months
148 63
4/5
-0.11
0.07
0.33
Aqua ch4
5/6
0.01
0.03
0.49
6/7
N15 ch6
0.11
1.17
7/8
-0.02
-0.18
0.88
0.66
8/9
-0.06
0.32
0.09
9/10
-0.10
0.48
0.25
10/11
-0.04
-0.03
0.62
0.57
11/12
N15 ch11
0.59
0.54
12/13
0.82
0.87
13/14
0.97
14/15
N15 ch14
-0.08
0.23
0.16
AMSU-A channel 5 vs ATMS Channel 6
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
Inter-satellite difference time series of global ocean mean brightness
temperatures from AMSU-A observations between POES satellite pairs
and those between POES AMSU-A and SNPP ATMS

11. Possible Reasons Causing Seasonal Variability In Inter-Satellite Difference Time Series
Diurnal differences between satellites
Frequency mismatch
Sun-heating inducted instrument temperature variability in radiances due to inaccurate calibration
(for IMICA recalibrated AMSU-A data, this effect was minimized
because more accurate calibration coefficients were developed and
used in the calibration, Zou and Wang 2011)
Mitch provided long time support for project from the program side, such as leveraging funding.
And Fuzhong also provides program support and coordinate the CRTM team to work with our product development team. You may notice that most of my SDS science team members are from his Branch.
I also want to thank Changyong for his long time support from scince side. I can always count on his support when I need a discussion on science. even when I need support from his team members.

12. Standard Deviation Tells Potential Issues in ATMS Observations
ATMS ch5 needs investigation
AMSU/AT MS
Channels
N18- N15
N18- Aqua
ATMS- N18
ATMS- Aqua
148 63
4/5
0.032
Aqua ch4
0.063
5/6
0.043
6/7
N15 ch6
0.058
7/8
0.031
0.033
0.026
8/9
0.020
0.024
0.037
0.019
9/10
0.023
10/11
0.027
0.016
0.025
11/12
N15 ch11
0.017
12/13
0.051
0.042
0.022
13/14
0.085
0.067
14/15
N15 ch14
0.093
0.073
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
AMSU-A ch11 vs ATMS ch12 for a comparison

13. Possible Reasons Causing Non-Zero Trends in Inter-Satellite Difference Time Series
Diurnal drifts between satellites
End-point effects
Calibration drift due to inaccurate calibration
Calibration changes
Mitch provided long time support for project from the program side, such as leveraging funding.
And Fuzhong also provides program support and coordinate the CRTM team to work with our product development team. You may notice that most of my SDS science team members are from his Branch.
I also want to thank Changyong for his long time support from scince side. I can always count on his support when I need a discussion on science. even when I need support from his team members.

14. Absolutely Stability of ATMS Radiances
Trends (K/Dec) of Inter-Sensor Difference Time Series
AMSU-A ch13 vs ATMS ch14
N18- N15
N18- Aqua
ATMS-N18
ATMS- Aqua
148 63
4/5
-0.064
Aqua ch4
-0.059
Aqua ch4
5/6
0.039
0.021
6/7
N15 ch6
-0.116
7/8
0.049
-0.099
0.086
-0.012
8/9
-0.085
-0.166
0.088
0.029
9/10
0.017
-0.135
0.008
-0.026
10/11
-0.015
-0.052
-0.017
0.011
11/12
N15 ch11
-0.071
-0.010
-0.016
12/13
-0.160
0.234
-0.020
13/14
-0.268
0.420
-0.025
14/15
N15 ch14
-0.352
0.493
-0.018
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
ATMS-Aqua reached a stability at 0.02K/Dec for all channels;
This is good enough for trend detection.
Because both satellites are calibrated independently, this suggested that both ATMS and Aqua reached an absolute stability within 0.02K/Dec.
This number could get smaller when overlaps get longer

15. Scene Temperature Dependent Biases in ATMS
ATMS shows scene
temperature dependent biases;
suggesting its calibration
nonlinearity is not accurate
This project focus on developing MSU/AMSU atmospheric temperature CDRs. The window channels will be addressed by another NOAA group.
In summary, we work on 15 atmospheric temperature channels, involving 15 satellites, with tempral coverage from late 1978 to present.
Each channel needs to be intercalibrated seperately.
With that, let me first talk about the MSU atmospheric temperature CDR development. The MSU started from 1978 on TIROS-N and ended on NOAA-14 in May So we don’t have MSU observations now. We have already completed the MSU CDR development and gained a lot of experiences. We have developed many new techniques for various bias correction procedure. So I am going to talk with more details on this instrument.
Long-term mean bias pattern between NOAA -18 and NOAA-15
for channel 8

16. Conclusion ATMS needs reprocessing/recalibration
ATMS had a calibration change in March 2017, causing bias jumps relative to reference satellite
ATMS are warmer than IMICA calibrated AMSU-A for all channels before March 2017
ATMS channel 5 is likely to have a frequency mismatch with AMSU-A channel 4 on the order of 10 MHz
ATMS radiances reached a absolute stability within 0.02K/Dec for all temperature sounding channels
Calibration nonlinearity of ATMS are inaccurate for certain channels
NOAA-16 needs further recalibration since the calibration coefficients determined from overlaps before cannot fully describe its behavior afterwards
ATMS needs reprocessing/recalibration
Using re-calibated/inter-calibrated AMSU-A data as a reference provides useful information on ATMS radiance performance
So here is a summary that needs to be deal with in the MSU/AMSU reprocessing. These issues include, but are not limited to, ……….
In this talk, I’ll be focusing on the intersatellite biases and warm target temperature contamination; but also touch a little bit on other problems.