Monitor and Improve the GOES Imager Infrared Calibration Accuracy: - - PowerPoint PPT Presentation

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Monitor and Improve the GOES Imager Infrared Calibration Accuracy: - - PowerPoint PPT Presentation

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Monitor and Improve the GOES Imager Infrared Calibration Accuracy: An Application of GSICS Fangfang Yu 1 , Xiangqian Fred Wu 2 and Mitch Goldberg 2 1: ERT, Inc @ NOAA/NESDIS/STAR 2: NOAA/NESDIS/STAR 11 November 2011 GSICS GEO-LEO

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Monitor and Improve the GOES Imager Infrared Calibration Accuracy: An Application of GSICS

Fangfang Yu1, Xiangqian “Fred” Wu2 and Mitch Goldberg2

1: ERT, Inc @ NOAA/NESDIS/STAR 2: NOAA/NESDIS/STAR 11 November 2011

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NASA Sounder Science Team Meeting

GSICS GEO-LEO Inter-Calibration

  • Global Space-based Inter-Calibration System (GSICS)

» International collaboration to improve and harmonize the

  • perational satellite calibration accuracy through a variety of inter-

calibrations » GEO-LEO inter-calibration to improve the GEO IR calibration accuracy

  • GEO-LEO Inter-calibration

» Reference instruments: AIRS and IASI » Both radiometers are very stable

– Negligible diurnal and seasonal calibration variation – Long-term stable since in-orbit – High spectral calibration accuracy – Very small difference radiometric between AIRS and IASI

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NASA Sounder Science Team Meeting

Data Processing Flowchart

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Masks, flags, … SRFs, PSFs, …

  • 2. Collocating
  • 3. Transforming
  • 4. Filtering

Archive ~1 month Archive ~1 month Archive ~ 1 year Archive ~ 1 year Analysis Data Comparison Data Collocated Data Subset MON Data Subset REF Data

  • 1. Subsetting

Orbital Prediction

  • Colloc. Criteria

MON Level 1 Data REF Level 1 Data

Collocation Transformation Analysis

  • Spatial collocation
  • Temporal collocation
  • Viewing geometry alignment
  • Assume no in-orbit SRF change
  • JMA’s gap-filling method to fill the

missing spectra

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NASA Sounder Science Team Meeting

Products

Data Analysis

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Analysis Data

Correcting Monitoring/Diagnosing Improvement of correction algorithm Satellite Data Users Instrument Calibration

  • Corr. Coeffs
  • Mon. L1 Data

Re-Cal Data Reports/Tables /Figures GSICS GEO-LEO inter-calibration correction is traceable to IASI standard

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NASA Sounder Science Team Meeting

GSICS GEO-LEO Correction Algorithm

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GEO Correct

I b b a I 1 + − =

LEO GEO

I b a I * + =

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NASA Sounder Science Team Meeting

GSICS Correction Result (1)

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NASA Sounder Science Team Meeting

GSICS Correction Result (2)

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¡Before ¡Correc)on: ¡3K ¡Bias ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡ ¡A2er ¡Correc)on: ¡ ¡~0K ¡Bias

Tb difference between observed and calculated for GOES-12 Ch6 (13.3µm) before and after the GSICS correction Courtesy of T. Zhu

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NASA Sounder Science Team Meeting

GSICS Correction Coeffs.

  • http://gsics.nesdis.noaa.gov:8080/thredds/catalog.html

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NASA Sounder Science Team Meeting

GOES Diurnal Calibration Variation

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Ch3 Ch4 Ch5 winter (K) 0.18 0.79 0.71 Summer (K) 0.19 0.61 0.5 0.00 0.20 0.40 0.60 0.80 1.00 Diurnal Cal. Variation (K)

GOES-11 Imager Ch3/4/5 Diurnal Cal. Variation

mean(ΔTbGEO-AIRS,i) –mean(ΔTbGEO-AIRS, j)

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NASA Sounder Science Team Meeting

GOES-12 Calibration Monitoring

10 Decontamination Events

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NASA Sounder Science Team Meeting

Evaluation of Angular Dependent Scan-Mirror Emissivity Correction

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NASA Sounder Science Team Meeting

SRF Revision

  • ITT revised the G13 Ch6 (13.3m) SRF during the PLT period.
  • NOAA shifted the SRF by -2.6 cm-1 with GOES vs AIRS collocated analysis

data

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NASA Sounder Science Team Meeting

SRF Revisions for GOES14/15 Ch3 (6.5µm) and Ch6 (13.3µm)

  • ITT revised the SRFs twice during the PLT period, but with still large

simulated Tb biases

  • NOAA shifted the SRFs using GOES vs. IASI analysis data
  • New SRFs were implemented at the satellites on August 9, 2011.

9/23/2011

Bias before revision Bias after Revision GOES - AIRS GOES - IASI GOES - AIRS GOES - IASI G14 Ch3 +0.99 +0.97 +0.07 +0.10 G14 Ch6

  • 0.48
  • 0.55
  • 0.11
  • 0.12

G15 Ch3 +2.04 +2.12

  • 0.04

+0.00 G15 Ch6 +0.77 +0.74 +0.01

  • 0.02
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NASA Sounder Science Team Meeting

Summary

  • The well-calibrated hyperspectral sounding radiometers is very

powerful in evaluating/monitoring/diagnosing the broad-band GOES IR calibration accuracy

» Diurnal » Seasonal » Long-term » Scan mirror emissivity correction » MBCC performance » Improve the radiometric calibration accuracy

  • As the reference instruments, the instruments should have stable

calibration accuracy at corresponding terms

  • The fundamental correction of the GOES midnight calibration

anomaly using the GSICS data is undergoing…

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NASA Sounder Science Team Meeting

Back-up

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NASA Sounder Science Team Meeting

GOES Calibration Issues and Operational Remedies

  • Midnight Calibration Anomaly

» Causes:

– Extra radiation reflected by the BB to the detectors – Scattered solar radiation contamination at space view

» Remedy: Midnight Blackbody Calibration Correction (MBCC)

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Original calibration slopes of GOES-8 Imager Ch2 (from Johnson et al. 1996)

  • Angular dependent scan-mirror emissivity

» Absorptive feature of the Silicon dioxide (SiOx) coating to the scan mirror » Remedy: corrected with a 24-h scan view scan.

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NASA Sounder Science Team Meeting

GOES-11 Calibration Monitoring

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NASA Sounder Science Team Meeting

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