AMSU Bias Adjustments Larry McMillin Jiang Zhao Climate Research - - PowerPoint PPT Presentation

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AMSU Bias Adjustments Larry McMillin Jiang Zhao Climate Research - - PowerPoint PPT Presentation

Mar 08, 2023 277 likes •1.06k views

AMSU Bias Adjustments Larry McMillin Jiang Zhao Climate Research and Applications Division National Environmental Satellite, Data, and Information Service Washington, D.C. Larry.McMillin@noaa.gov L.M. McMillin NOAA/NESDIS/ORA Why

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SLIDE 1

L.M. McMillin NOAA/NESDIS/ORA

AMSU Bias Adjustments Larry McMillin Jiang Zhao Climate Research and Applications Division National Environmental Satellite, Data, and Information Service Washington, D.C. Larry.McMillin@noaa.gov

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SLIDE 2

L.M. McMillin NOAA/NESDIS/ORA

Why Adjustments are necessary

  • Retrieval systems use the difference between measured radiance

and those calculated from a known state to determine changes to the state to make the radiance values agree

  • Biases in the difference lead directly to biases in the retrieval
  • Two factors are required to know the bias

– (1) The out of field response – (2) The out of field radiation sources

  • (1) is measured before launch, but (2) is generally unknown
  • All retrieval systems use some sort of empirical adjustment
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SLIDE 3

L.M. McMillin NOAA/NESDIS/ORA

Possible Error Sources

  • In general

– A fraction of the radiation is removed – Some Radiation is added

  • Added radiation can be emitted from

– The earth, but outside the main lobe – Space – The spacecraft

  • Emitted from the spacecraft
  • Reflected from the spacecraft
  • Electronics
  • Any solution should be general enough to include these
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SLIDE 4

L.M. McMillin NOAA/NESDIS/ORA

Procedures for Bias Adjustment

  • (1) Screen for cloud effects (local consistency with 4.0 for land

and 3.75 for sea)

  • (2) Equalize the sample sizes

– Find the spot with the smallest sample – For each profile, find the closest matching profile in all the other spots (use the minimum value of the maximum difference)

  • Calculate radiances
  • Subtract to get the measured – calculated difference
  • Predict the difference from

– The radiance values – The spot number - doesn’t do anything now – The sine and cosine of the latitude (proxy for orbital position)

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SLIDE 5

L.M. McMillin NOAA/NESDIS/ORA

Prediction Models Tried

  • Constant value only
  • Constant plus channel itself as a single predictor
  • Constant plus all predictors
  • The first two were close in accuracy
  • The last was significantly more accurate
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SLIDE 6

L.M. McMillin NOAA/NESDIS/ORA

RMS summary for channels 5 - 14

  • The following slides show the RMS summaries for channels 5 –

14

  • The full regression is more accurate
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SLIDE 7

L.M. McMillin NOAA/NESDIS/ORA

Color Order

  • -- channel 1 blue
  • -- channel 2 green
  • -- channel 3 red
  • -- channel 4 cyan - not red
  • -- channel 5 magenta - not green
  • -- channel 6 yellow - not blue
  • -- channel 7 gold
  • -- channel 8 aqua
  • -- channel 9 violet
  • -- channel 10 olive green
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SLIDE 8

L.M. McMillin NOAA/NESDIS/ORA

RMS (k) for Land - 18 Predictors (Channels 5 – 14)

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SLIDE 9

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Land – Mean + Channel (channels 5 – 14)

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SLIDE 10

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Land – Mean Subtracted (channels 5 – 14)

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SLIDE 11

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) for Sea – 18 Predictors (Channels 5 – 14)

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SLIDE 12

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Sea – Mean + Channel (channels 5 - 13)

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SLIDE 13

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Sea – Mean only + Channel (Channels 5 – 14)

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SLIDE 14

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Sea – Mean Only (Channels 5 – 14)

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SLIDE 15

L.M. McMillin NOAA/NESDIS/ORA

  • The following slides show the RMS values by channel
  • 1 slide per channel
  • The colors show sample days

– March cases are unique for the higher peaking channels

  • 1st 15 are land
  • 2nd 15 are sea
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SLIDE 16

L.M. McMillin NOAA/NESDIS/ORA

Days in the sample

  • 1 - 01/02/2003 blue
  • 2 - 05/27/2003 green
  • 3 - 10/18/2003 red
  • 4 - 12/05/2003 cyan
  • 5 - 01/22/2004 magenta
  • 6 - 03/10/2004 yellow
  • 7 - 08/01/2004 gold
  • 8 - 09/18/2004 aqua
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SLIDE 17

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 1 Land

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SLIDE 18

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 2 Land

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SLIDE 19

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 3 Land

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SLIDE 20

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 4 Land

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SLIDE 21

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 5 Land

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SLIDE 22

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 6 Land

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SLIDE 23

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 7 Land

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SLIDE 24

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 8 Land

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SLIDE 25

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 9 Land

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SLIDE 26

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 10 Land

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SLIDE 27

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 11 Land

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SLIDE 28

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 12 Land

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SLIDE 29

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 13 Land

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SLIDE 30

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 14 Land

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SLIDE 31

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 15 Land

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SLIDE 32

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 1 Sea

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SLIDE 33

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 2 Sea

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SLIDE 34

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 3 Sea

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SLIDE 35

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 4 Sea

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SLIDE 36

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 5 Sea

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SLIDE 37

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 6 Sea

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SLIDE 38

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 7 Sea

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SLIDE 39

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 8 Sea

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SLIDE 40

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 9 Sea

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SLIDE 41

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 10 Sea

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SLIDE 42

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 11 Sea

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SLIDE 43

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 12 Sea

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SLIDE 44

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 13 Sea

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SLIDE 45

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 14 Sea

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SLIDE 46

L.M. McMillin NOAA/NESDIS/ORA

RMS (K) Channel 15 Sea

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SLIDE 47

L.M. McMillin NOAA/NESDIS/ORA

  • The next slide show the mean bias as a function of spot
  • The days are shown in color
  • One slide per channel
  • Land cases are shown first then sea
  • Note the spot to spot consistency near channel 8

– This is probably some sort of interference

  • Spot 30 values are much larger than spot 1 values for upper

peaking channels

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SLIDE 48

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 1

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SLIDE 49

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 2

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SLIDE 50

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 3

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SLIDE 51

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 4

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SLIDE 52

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 5

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SLIDE 53

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 6

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SLIDE 54

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 7

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SLIDE 55

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 8

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SLIDE 56

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 9

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SLIDE 57

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 10

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SLIDE 58

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 11

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SLIDE 59

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 12

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SLIDE 60

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 13

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SLIDE 61

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 14

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SLIDE 62

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) land - channel 15

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SLIDE 63

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 1

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SLIDE 64

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 2

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SLIDE 65

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 3

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SLIDE 66

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 4

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SLIDE 67

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 5

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SLIDE 68

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 6

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SLIDE 69

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 7

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SLIDE 70

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 8

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SLIDE 71

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 9

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SLIDE 72

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 10

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SLIDE 73

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 11

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SLIDE 74

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 12

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SLIDE 75

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 13

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SLIDE 76

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 14

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SLIDE 77

L.M. McMillin NOAA/NESDIS/ORA

Unadjusted bias (K) sea - channel 15

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SLIDE 78

L.M. McMillin NOAA/NESDIS/ORA

Conclusions

  • Empirical adjustments are required for AMSU

– Efforts to characterize sources are needed but may not be enough

  • There are spot to spot biases for some channels

– These are small – But large compared to the variability over the samples

  • Using a multiple channel prediction provides a significant gain in

accuracy

  • Adjustments are consistent over months
  • The residuals for many sounding channels are within the error

limits required for retrievals

  • Surface channels are hard to determine because knowledge of the

surface effects limits accuracy