earth radiation budget (erb) : ceres calibration status kory j. priestley denise cooper, susan...

Earth Radiation Budget (ERB) : CERES Calibration Status

Kory J. PriestleyDenise Cooper, Susan Thomas, Grant Matthews, Phil Hess,

Peter Szewczyk, Dale Walikainen, Robert Wilson

Achieving Satellite Intercalibration for Climate ChangeThe National Conference Center

Lansdowne, VAMay 16-18, 2006

NASA Langley Research Center / Science Directorate

Instrument Working GroupWebpage Development

http://asd-www.larc.nasa.gov/Instrument/


• Design is based upon the Earth Radiation Budget Experiment (ERBE) philosophy

• Instrument was designed, manufactured and tested by TRW (Redondo Beach, CA)

• Contains three sensor assemblies with cassegrain optics and thermistor bolometer detectors

• Sensors measure thermal radiation in the near-visible through far-infrared spectral region

• Three sensor channels are coaligned and mounted on a spindle which rotates about the elevation axis

• Hemispherical sampling obtained with an azimuthal axis drive system

• Calibration Accuracy Requirements - 0.5% LW, 1.0% SW

CERES Instrument


CERES Terra/Aqua Health & Status

With the exception of the SW channel on the CERES/Aqua FM-4 Instrument,

the CERES Terra/Aqua instruments are functioning nominally…

Spacecraft Instruments LaunchScience Initiation

Collected Data

(Months)

TRMM PFM 11/97 1/98 9

Terra FM1, FM2 12/99 3/00 76 +

Aqua FM3, FM4 5/02 6/02 46 +

? FM5 ? ? ?


CERES Terra/Aqua Health & Status

With the exception of the SW channel on the CERES/Aqua FM-4 Instrument,

the CERES Terra/Aqua instruments are functioning nominally…

Spacecraft Instruments LaunchScience Initiation

Collected Data

(Months)

TRMM PFM 11/97 1/98 9

Terra FM1, FM2 12/99 3/00 76 +

Aqua FM3, FM4 5/02 6/02 46 +

? FM5 ? ? ?

20.3 Instrument Years of Data


Instrument Working GroupWebpage Development


CERES Spectral Response FunctionTRMM/PFM Edition2 Data Products

Note: LWDAY = Total - Shortwave

0.0

0.2

0.4

0.6

0.8

1.0

0.1 1 10 100

Wavelength (Microns)

Re

sp

on

siv

ity (

-)

Shortwave Total Window


• Requirements for CERES are more stringent than ERBE’s by a factor of 2

• Requirements per Ohring et. al. are more stringent than CERES by a factor of 2-3

Spectral Regions

Solar TerrestrialAtmospheric

Window

Wavelengths 0.3 - 5.0 m 5.0 - 200 m 8 - 12 m

Scene levels <100 w/m2-sr >100 w/m2-sr <100 w/m2-sr >100 w/m2-sr All Levels

Accuracy Requirements

0.8 w/m2-sr 1.0 % 0.8 w/m2-sr 0.5 % 0.3 w/m2-sr

Stability Requirements

< 0.14%/yr < 0.1%/yr

Climate

Stability Goals

< 0.6 w/m2/dec

< 0.06 %/yr

< 0.2 w/m2/dec

< 0.02%/yr

Radiometric Performance Requirements

5-Year CERES Mission Lifetime


BDS and ERBE-Like Release Strategy

Edition1 - Static Algorithms and coefficients - baseline product used in cal/val protocol

Edition2 - Utilizes temporally varying coefficients to correct for traceable radiometric drift. All spectral changes are broadband and

‘gray’.

Edition3 - Release date Fall 2006. Will incorporate temporally varying spectral artifacts in the SW measurements. A complete re-analysis of Ground Calibration with additional component characterization measurements.

User Applied Revisions - Advance capabilities to the users prior to the release of the next Edition.

Edition2 products lag Edition1 by a minimum of 4 months


Notification of Revision

CERES BDS (BiDirectional Scan) Terra Edition2 Data Quality Summary

Investigation: CERESData Product: BiDirectional Scan [BDS]Data Set: Terra (Instruments: FM1, FM2)Data Set Version: Edition2

The purpose of this document is to inform users of the accuracy of this data product as determined by the CERES Team. This document briefly summarizes key validation results, provides cautions where users might easily misinterpret the data, provides links to further information about the data product, algorithms, and accuracy, gives information about planned data improvements. This document also automates registration in order to keep users informed of new validation results, cautions, or improved data sets as they become available.

This document is a high-level summary and represents the minimum information needed by scientific users of this data product. It is strongly suggested that authors, researchers, and reviewers of research papers re-check this document for the latest status before publication of any scientific papers using this data product.

Table of Contents

•Nature of the BDS Product•Updates to Current Edition•User Applied Revisions•Validation and Quality Assurance•Current Estimated Uncertainty of Data•Cautions When Using Data•Expected Reprocesings•References•Web links to Relevant information•Referencing Data in Journal Articles•Giving Data to Other Users


Terra ES-8 Edition2_Rev1 Summary

•Cal/Val Protocol demonstrates radiometric stability of the data products through 11/2004 of….

Edition1 Edition2 Edition2_Rev1

FM1 FM2 FM1 FM2 FM1 FM2

LWday .3 .6 .125 .125 .125 .125

LWnight .1 .125 <.1 <.1 <.1 <.1

SW .2 .4 .2 .3 .1 .1

WN <.1 <.1 <.1 <.1 <.1 <.1

Note: Values apply to all-sky global averages Units are in %/yr


ProductSpatial

Scale

Temporal

ScaleMetric

Spectral

Band

Internal BBFiltered

RadianceN/A N/A Absolute Stability TOT, WN

On-Board Internal LampFiltered

RadianceN/A N/A Absolute Stability SW

SolarFiltered

RadianceN/A N/A Relative Stability TOT, SW

Theoretical Line-by-LineFiltered

Radiance> 20 Km Instantaneous

Inter-Channel

Theoretical AgreementTOT, WN

Unfiltering Algorithm Theoretical Validation

N/A N/A N/A N/A TOT, SW, WN

Inter-satellite

(Direct Comparison)Unfiltered Radiance

1-deg Grid 1 per crossingInter-Instrument

Agreement, StabilityTOT, SW, WN

VicariousGlobally Matched Pixels

(Direct Comparison)Unfiltered Radiance

Pixel to Pixel DailyInter-Instrument

AgreementTOT, SW, WN

Tropical Mean

(Geographical Average)Unfiltered Radiance

20N – 20S MonthlyInter-Channel

Agreement, StabilityTOT, WN

DCC AlbedoUnfiltered Radiance

>40 Km MonthlyInter-Instrument

agreement, StabilitySW

DCC 3-channelUnfiltered Radiance

>100 Km MonthlyInter-Channel

consistency, stabilityTOT, SW

TIme Space Averaging Fluxes Global MonthlyInter-Instrument

AgreementLW, SW

Lunar Radiance Measurements

Filtered Radiance

Sub Pixel QuarterlyInter-Instrument

AgreementLW, SW, WN

CERES Instrument Radiometric Validation Activities


CERES Onboard Calibration Philosophy

PRT PRT SUN Monitor Diode

ICSBB MAM SWICS

Window Sensor

TotalSensor

Shortwave Sensor

Field-of-ViewCoalignment

Traceability

Sources

RadiometricChannel

ValidationStudies


CERES Onboard SW Calibration EquipmentShortwave Internal Calibration Source (SWICS)

• Quartz-halogen tungsten lamp (2100, 1900, 1700 K spectrums)

• SiPd independently monitors lamp output

• Design specification is +-0.5% stability over 5-year mission

• Designed primarily to transfer Ground Calibration measurements into orbit

Mirror Attenuator Mosaic (MAM)

• Solar Diffuser plate attenuates direct solar view (~5800K Spectrum)

• MAM is a Nickel substrate with Aluminum coated spherical cavities or divots

• Provides a Relative calibration of the Shortwave channel and the SW portion of the Total channel

• Designed to provide a long-term on-orbit SW calibration source.

• Solar Cal results to date are suspect due to large initial drift in MAM surface reflectances…


CERES Solar Calibration Results

-2

-1

0

1

2

3

4

5

6

7

May-02 Nov-02 May-03 Nov-03 May-04 Nov-04

Date

Se

ns

or

Re

sp

on

se

, Pe

rce

nta

ge

Ch

an

ge

FM3 SW FM3 TOT

-2

-1

0

1

2

3

4

5

6

7

May-02 Nov-02 May-03 Nov-03 May-04 Nov-04

Date

Se

ns

or

Re

sp

on

se

, Pe

rce

nta

ge

Ch

an

ge

FM4 SW FM4 TOT

-2

-1

0

1

2

3

4

5

6

7

Feb-00 Aug-00 Feb-01 Aug-01 Feb-02 Aug-02 Feb-03 Aug-03 Feb-04 Aug-04

Date

Se

ns

or

Re

sp

on

se

, Pe

rce

nta

ge

Ch

an

ge

FM1 SW FM1 TOT

-2

-1

0

1

2

3

4

5

6

7

Feb-00 Aug-00 Feb-01 Aug-01 Feb-02 Aug-02 Feb-03 Aug-03 Feb-04 Aug-04

Date

Se

ns

or

Re

sp

on

se

, Pe

rce

nta

ge

Ch

an

ge

FM2 SW FM2 TOT


Terra SW Internal Calibration ResultsFM1 In-Flight Internal Calibration Results

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

2/1/00

6/1/00

10/1/

00

2/1/01

6/1/01

10/1/

01

2/1/02

6/1/02

10/1/

02

2/1/03

6/1/03

10/1/

03

2/1/04

6/1/04

10/1/

04

2/1/05

6/1/05

Date

Sen

sor

Res

po

nse

Ch

ang

e, P

erce

nt

SW-L1 SW-L2 SW-L3

Normalized to Start of Mission

FM2 In-Flight Internal Calibration Results

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

2/1/00

6/1/00

10/1/

00

2/1/01

6/1/01

10/1/

01

2/1/02

6/1/02

10/1/

02

2/1/03

6/1/03

10/1/

03

2/1/04

6/1/04

10/1/

04

2/1/05

6/1/05

Date

Sen

sor

Res

po

nse

Ch

ang

e, P

erce

nt

SW-L1 SW-L2 SW-L3

Normalized to Start of Mission


CERES SSF Ed2B SW TOA Flux Anomaly

Clear Ocean

Clear Desert


Spectral Degradation : SWICS vs. Earth Spectra

0 1 2 3 4

Wavelength (micron)

0 1 2 3 4

Wavelength (micron)

Sp

ectr

al R

esp

on

se,

N

orm

aliz

ed R

adia

nce

1.0

0.8

0.6

0.4

0.2

0.0


LEO Missions Subject to Spectral Darkening

Bandpasses of Selected Instruments

0

1

2

3

4

5

6

7

8

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Wavelength (Microns)

Ind

ex

Modis SeaWifs LandSat7 Toms SORCE-SIM SORCE SOLSTICE GOME


Spectral Darkening on Similar Missions

Global Ozone Monitoring Experiment (GOME) Spectral Darkening

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Wavelength/Radiometric Channel (um)

Rela

tive R

esp

on

se

1996

1997

1998

1999

2000

2001


SD degradation (accumulated at a 6-month period) as a function of wavelength

Faster degradation rate after fixing the SD door at “open position”

Yr 1

Yr 2

Yr 3

Yr 4

Yr 5

Modis Solar Diffuser Spectral Degradation


Direct Comparison of Nadir Radiance Measurements

Two CERES instruments on a common platform allows for a unique validation opportunity…..

Direct Comparison of simultaneous Nadir measurements

Each CERES/Terra instrument views nadir every 3.3 seconds

Thus, we obtain nearly simultaneous measurements of the same geo-location (t < 3.3 seconds)….

Spatial, angular, and temporal sampling issues are virtually eliminated.

26,000 co-located (but not independent) measurements in a given day, provides a very rigorous statistical tool.

Results can be discretized by scene type to enhance the analysis.


Terra Edition2 Nadir Direct Comparison

1.005

1.000

0.995

0.990

0.985

1.015

1.010

1.005

1.000

0.995

0.990

0.985

0.980Mar-00 Mar-01 Mar-02 Mar-03 Mar-04

All-Sky

FM1 in Xtrack

FM2 in Xtrack

All-SkyClear OceanSW2

f

SW1f

SW2f

SW1f

SW Nadir Radiances

Mar-00 Mar-01 Mar-02 Mar-03 Mar-04

FM1 in Xtrack

FM1 in RAPS


Terra Edition2 Nadir Direct Comparison

1.005

1.000

0.995

0.990

0.985

1.015

1.010

1.005

1.000

0.995

0.990

0.985

0.980Mar-00 Mar-01 Mar-02 Mar-03 Mar-04

All-Sky

FM1 in XTRACK

FM1 in RAPS

All-SkyClear OceanSW2

f

SW1f

SW2f

SW1f

SW Nadir Radiances

FM1 in Xtrack

FM1 in RAPS


Fixed Azimuth Plane Scanning(FAPS, Xtrack)

Rotating Azimuth Plane Scanning(RAPS)

Primary CERES Operational Modes


RAPS

Whats the difference between RAPS and FAPS?

FAPS

Ground Track

Scan Plane


RAPS

Whats the difference between RAPS and FAPS?

FAPS


Edition2_Rev1 Scaling Factors

1.00

1.01

1.02

1.03

Mar-00 Mar-01 Mar-02 Mar-03 Mar-04 Mar-05

All Sky Clear Ocean

1.00

1.01

1.02

1.03

Mar-00 Mar-01 Mar-02 Mar-03 Mar-04 Mar-05

All Sky Clear Ocean

1.00

1.01

1.02

1.03

Jul-02 Jan-03 Jul-03 Jan-04 Jul-04 Jan-05

All Sky Clear Ocean

1.00

1.01

1.02

1.03

Jul-02 Jan-03 Jul-03 Jan-04 Jul-04 Jan-05

All Sky Clear Ocean

Terra - FM1

Terra - FM2

Aqua - FM3

Aqua - FM4


Application of Edition2_Rev1 Scaling Factors




ICSBB MAM SWICS

Window Sensor

TotalSensor

Shortwave Sensor


Traceability

Sources

RadiometricChannel

ValidationStudies




ICSBB DCC SWICS

Window Sensor

TotalSensor

Shortwave Sensor


Traceability

Sources

RadiometricChannel

ValidationStudies

Albedo

Moon


DCCalb = frad(ed1cv)*{flx(ssf)/ufrad(ssf)} * DM(sz)/Fs

0.54

0.55

0.56

0.57

Mar-00 Sep-00 Mar-01 Sep-01 Mar-02 Sep-02 Mar-03 Sep-03 Mar-04 Sep-04 Mar-05

Date

Fil

tere

d A

lbed

o (

-)

FM1 FM2

Terra Deep Convective Cloud Filtered Albedo


Validation of Pointing Knowledge Using Lunar Radiances

Objective: Utilize the full moon as a quasi-point source to complete a near steady-state raster scan across the CERES FOV.

Goals

•Validate pre-launch alignment measurements

•Measure inter-channel relative pointing accuracy

•Map out spatial non-uniformities in the CERES Optics/Detectors

•This type of mapping is not performed under vacuum prior to launch.

By combining knowledge of the motion of the moon relative to the spacecraft and the programmability of the the CERES Instruments we obtain……..


Elevation

8-degt = 1 min

13-degt = 3 min

18-degt = 5 min

Spaceclamp

7.1° 1° 1.5°1.3° 1.3°1°

Azimuth

Lunar Track

CERES Lunar ScanningExperimental Design


Lunar Scanning Results – CERES Optical Transfer Function

Monte-Carlo Ray Trace(FELIX)

FM-1 Total

FM-1 Shortwave

FM-1 Window


Terra ES-8 Edition2_Rev1 Summary

•Cal/Val Protocol demonstrates radiometric stability of the data products through 11/2004 of….

Edition1 Edition2 Edition2_Rev1

FM1 FM2 FM1 FM2 FM1 FM2

LWday .3 .6 .125 .125 .125 .125

LWnight .1 .125 <.1 <.1 <.1 <.1

SW .2 .4 .2 .3 .1 .1

WN <.1 <.1 <.1 <.1 <.1 <.1

Note: Values apply to all-sky global averages Units are in %/yr

earth radiation budget (erb) : ceres calibration status kory j. priestley denise cooper, susan...

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