projection of sorce total solar irradiance measurements 5

Projection of SORCE Total Solar Irradiance Measurements5-10 Days Forward for Near Real-Time Applications"

Climate Science Branch, NASA Langley Research Center"

Shashi K. Gupta1, David P. Kratz2, Paul W. Stackhouse, Jr.2,"Parnchai Sawaengphokhai1, and Anne C. Wilber1"

""

1Science Systems and Applications, Inc., Hampton, Virginia"2NASA Langley Research Center, Hampton, Virginia"

""""

2014 SORCE Science Conference"Cocoa Beach, Florida"28-31 January 2014"

Background and Motivation"


•  SORCE TSI Version-14 daily data (up to 30 June 2013) currently in use for CERES processing."

"•  Planned to use SORCE TSI for a CERES sub-project." FLASHFlux: Fast Longwave and Shortwave Radiative fluxes.""•  TOA and Surface LW and SW fluxes in one week of real-time.""•  Satellite observations and coincident meteorology from GMAO

available within 2 days of real-time.""•  TSI data needed to start processing. Seven-day latency of

SORCE created the need to project TSI at least 5 days forward.""•  Objective was to accomplish this with minimal uncertainty even

though no expectation of projecting day-to-day fluctuations."

SORCE Interruption and Source Change"


•  With interruption of SORCE data in July 2013, plans changed."

•  ACRIM3 data was considered. Latency generally too long." In late January 2014, data available to 17 September 2013.""•  Composite dataset from RMIB considered. Latency less" than one month. Data available up to 07 January 2014."

•  RMIB composite can be used for CERES, not for FLASHFlux."

•  Hoping that TCTE data will come online soon and will be" available with a latency comparable to that of SORCE."

•  Explored statistics of available data for help in projection." Long timeseries in hand allowed testing of our methods."

Statistics Explored"


•  Value for last available day (i.e., persistence) and averages over previous 10, 30, and 90 days examined."•  Two sample years were chosen for study."

"Year of high sunspot activity - 1991""Year of low sunspot activity – 2009"

•  1991 data is WRC composite offset to match SORCE."

1356

1358

1360

1362

1364

1366

036

573

010

9514

6018

2521

9025

5529

2032

8536

5040

1543

8047

4551

1054

7558

4062

0565

7069

3573

0076

6580

3083

9587

6091

2594

9098

5510

220

1058

510

950

1131

511

680

Total

Sola

r Irra

dianc

e (W

m-2)

Day Starting 01 Jan 1983

SOLCON-1AU01 Jan 1983 - 30 Jun 2013

SORCE Total Solar Irradiance Version-14

Mean = 1361.0750 S.D. = 0.5177

TSI Timeseries for 1991 (upper) and 2009 (lower)"


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1364

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Total

Solar

Irrad

iance

(Wm-2 )

Day of Year

Measured TSI

Total Solar Irradiance - Comparison with Annual Mean - 1991

Mean = 1361.5573RMS Diff. = 0.7788

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1360

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1364

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Total

Solar

Irrad

iance

(Wm-2 )

Day of Year

Measured TSI

Total Solar Irradiance - Comparison with Annual Mean - 2009

Mean = 1360.5630RMS Diff. = 0.0609

Projection by Persistence - 1991"


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1364

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tota

l Sol

ar Ir

radi

ance

(Wm

-2)

Day of Year

Measured TSI Projected TSI

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1358 1359 1360 1361 1362 1363 1364

Proj

ecte

d TS

I (W

m-2

)

Measured TSI (Wm-2)

5-Day Projection Based on Persistence for 1991

Mean X = 1361.5573Mean Y = 1361.5841Mean Bias = 0.0269

RMS Difference = 0.9933

Projection by 10-Day Averaging - 1991"


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XXXXX X X

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XXXXXXXXXXX XXX XXXXXXX

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1358 1359 1360 1361 1362 1363 1364

Proj

ecte

d TS

I (W

m-2

)

Measured TSI (Wm-2)

1358

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1360

1361

1362

1363

1364

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tota

l Sol

ar Ir

radi

ance

(Wm

-2)

Day of Year


10-Day Averaging

5-Day Projection by 10-Day Averaging for 1991





XXXXXXXXXXXXXXXX X X X XXXXXXXXXXXX X X X X X XXXXXX XX XXXXXXXXXXX XXX XXXX

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X XXXXXXXXXXXXXX X X XXXXXXXXXXXXXXXXXXXXXXXXXXXX

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1364

1358 1359 1360 1361 1362 1363 1364

Proj

ecte

d TS

I (W

m-2

)

Measured TSI (Wm-2)

1358

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1360

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1364

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tota

l Sol

ar Ir

radi

ance

(Wm

-2)

Day of Year


30-Day Averaging






XXXXXXXXXXXXXXXX X X X XXXXXXXXXXXX X X X X X XXXXXX XX XXXXXXXXXXX XXX XXXXXXXXXXXXXXX XXXXXXXXXXX X X X XXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXX XXXX XX XXXXXXXXXXXXXXXXXXXXXXXXXX X X XXXXXXXXXX XXXXXXX XX X XXXXXXXXXXXXXXXXXXXXXXXX X X X XXXXXXXXXXXXXXXXXXXXXXX X X XXXXXXXX X XXXXXXXXX X XXXXXXXXXXXXXXXXXXXXXX X X X XXXXXXXXXX XXXXXXXXXXXXXX X X XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X XXXXXXXXXXXXX X X

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1358 1359 1360 1361 1362 1363 1364

Proj

ecte

d TS

I (W

m-2

)

Measured TSI (Wm-2)


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1364

0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tota

l Sol

ar Ir

radi

ance

(Wm

-2)

Day of Year


90-Day Averaging



Projection by Persistence - 2009"


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0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tota

l Sol

ar Ir

radi

ance

(Wm

-2)

Day of Year


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XXXXXXXXXXXXXXX

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1358 1359 1360 1361 1362 1363 1364

Proj

ecte

d TS

I (W

m-2

)

Measured TSI (Wm-2)


5-Day Projection Based on Persistence for 2009




1358

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0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tota

l Sol

ar Ir

radi

ance

(Wm

-2)

Day of Year


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1358 1359 1360 1361 1362 1363 1364

Proj

ecte

d TS

I (W

m-2

)

Measured TSI (Wm-2)


Mean X = 1360.5630Mean Y = 1360.5617Mean Bias = -0.0013




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0 30 60 90 120 150 180 210 240 270 300 330 360 390

Tota

l Sol

ar Ir

radi

ance

(Wm

-2)

Day of Year



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1358 1359 1360 1361 1362 1363 1364

Proj

ecte

d TS

I (W

m-2

)

Measured TSI (Wm-2)




Summary Results - 1991"


0.02

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0.04

0.05

0.06

0.07

0 10 20 30 40 50 60 70 80 90 100

Mea

n B

ias

(Wm

-2)

Averaging Period (Days)

5-Days 7-Days 10-Days

0.7

0.8

0.9

1.0

1.1

1.2

0 10 20 30 40 50 60 70 80 90 100

RM

S D

iffer

ence

(Wm

-2)



Bias and RMS Difference Between Projected and Actual TSI Values for Different Averaging Periods and Projection Lengths - 1991

Table 2. Comparison of mean bias and root mean square difference (RMSD) for between measured and projected total solar irradiance (TSI) values for different averaging periods and projection lengths. The year 1991 (a high solar activity year) was used in this illustration. Values of statistical parameters are in Wm-2.

Projection Length (Days)

Statistical Parameter


1 10 30 90

5 Bias 0.0269 0.0393 0.0530 0.0512 RMSD 0.9933 0.9303 0.8309 0.7926

7 Bias 0.0347 0.0406 0.0562 0.0523 RMSD 1.0944 0.9491 0.8402 0.7930

10 Bias 0.0454 0.0409 0.0597 0.0534 RMSD 1.0758 0.9639 0.8411 0.7920

Summary Results - 2009"


Table 3. Comparison of mean bias and root mean square difference (RMSD) for between measured and projected total solar irradiance (TSI) values for different averaging periods and projection lengths. The year 2009 (a quiet sun year) was used in this illustration. Values of statistical parameters are in Wm-2.

Projection Length (Days)

Statistical Parameter


1 10 30 90 5 Bias 0.0006 -0.0013 -0.0040 -0.0112 RMSD 0.0628 0.0707 0.0577 0.0594 7 Bias 0.0002 -0.0021 -0.0045 -0.0117 RMSD 0.0716 0.0707 0.0588 0.0601

10 Bias -0.0014 -0.0032 -0.0054 -0.0123 RMSD 0.0816 0.0786 0.0600 0.0608

0.04

0.05

0.06

0.07

0.08

0.09

0 10 20 30 40 50 60 70 80 90 100

RM

S D

iffer

ence

(Wm

-2)



Bias and RMS Difference Between Projected and Actual TSI Values for Different Averaging Periods and Projection Lengths - 2009

-0.020

-0.015

-0.010

-0.005

0.000

0.005

0 10 20 30 40 50 60 70 80 90 100

Mea

n B

ias

(Wm

-2)



Timeseries of Annual Averages and RMS Differences"


1360.0

1360.5

1361.0

1361.5

1362.0

1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013

Total

Sola

r Irra

dianc

e (W

m-2) Annual Average

31-Year (1983-2013) Mean = 1361.0774

0.0

0.2

0.4

0.6

0.8

1.0

1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013

RMS

Diffe

renc

e (W

m-2)

Year

RMS Difference

Annual Averages (1983-2013) and RMS Difference From Annual Average

Summary and Concluding Remarks"


•  The original goal was to use daily SORCE TSI data with 7-day latency" and project it 5 days forward for use in FLASHFlux processing.""•  With that or similar data stream available, we can project 5 days" forward using averages of previous 10, 30, or 90 days with" uncertainties < 1.0 Wm-2 during years of high sunspot activity;" < 0.1 Wm-2 during quiet years. Corresponding biases are <0.1 Wm-2 and ≅0.01 Wm-2 respectively. Based on these results, we chose to" use 90-day averaging in our projections." "•  With the present interruption of SORCE data, its use for FLASHFlux" is on hold. When TCTE data become available (hopefully, with" similar latency) use for FLASHFlux will be reconsidered. In the " meantime, FLASHFlux will continue to use a value of 1361 Wm-2.""•  Edition-4 of CERES processing is using SORCE Version-14 up to" 30 June 2013. Composite data provided by Royal Meteorological" Institute of Belgium (RMIB) scaled to match SORCE data will be " used from 1 July 2013 onward until TCTE data become available."

Back-up Slides"


Need for Projection"


•  Today’s date: 29 Jan 2014.""•  Satellite observations and" meteorology available for: 27 Jan 2014." For processing to start, TSI needed.""•  Latest SORCE data available for: 22 Jan 2014." Hence, the need to project SORCE 5 days. "

Lag Correlations"


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0 1 2 3 4 5 6 7 8 9 10

Auto

corre

latio

n

Lag (Days)

J Auto_Corr_1991

Auto_Corr_2009

Autocorrelation in 1991 and 2009 TSI Timeseries

projection of sorce total solar irradiance measurements 5

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