Lower-Tropospheric Temperature (TLT) Climate Data Record Using NOAA/NESDIS/STAR Recalibrated MSU Observations<br />Wenhui ...
Outline<br />Background<br />Methods for Developing TLT Product Using NOAA/NESDIS/STAR Recalibrated MSU Radiances<br />Res...
Background<br /><ul><li>Microwave Sounding Unit (MSU, 1978/11-2006/9)
9 instruments (NOAA TIROS-N – NOAA-14)
4 channels </li></ul>Channel 2- mid-troposphere (TMT)<br />Channel 3 - upper-troposphere<br />Channel 4 - lower-stratosphe...
Widely used in long-term atmospheric Tb trends studies
MSU Lower Tropospheric Temperature (TLT)</li></ul>TMT Affected by stratosphere cooling effect<br />TLT: weighted average o...
Background<br /><ul><li>Two MSU TLT products available</li></ul>Using NOAA pre-launch calibrated observations<br />Univers...
Methods for STAR TLT Product<br />Using NOAA/NESDIS/STAR Recalibrated MSU  Radiances (v1.2)<br />           (Zou et al. 20...
Can reduce inter-satellite bias by an order of magnitude compared to NOAA pre-launch calibration </li></li></ul><li>Method...
Methods for STAR TLT Product<br />Satellite Altitude & Orbital Decay Effect Correction<br /><ul><li>Satellite altitudes ar...
Satellite altitude trends to decay over time
Cause  view zenith angle changes, effects vary with different limb positions </li></li></ul><li>Methods for STAR TLT Produ...
Methods for STAR TLT Product<br />Diurnal Drift Effect Correction same as STAR TMT products (Zou and Wang 2009)Using RSS m...
Results <br />5-day averaged MSU global mean TLT & TMT time series<br />Temporal Coverage: 1978/11-2006/9<br />Spatial Cov...
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Wenhui_Wang.LowerTroposphericTemperatureClimateDataRecordUsingNOAANESDISSTARRecalibratedMSUObservations.pptx

  1. 1. Lower-Tropospheric Temperature (TLT) Climate Data Record Using NOAA/NESDIS/STAR Recalibrated MSU Observations<br />Wenhui Wang1 & Cheng-Zhi Zou2<br />1IMSG at NOAA/NESDIS/STAR<br />2NOAA/NESDIS/Center for Satellite Applications and Research<br />IGARSS<br />Vancouver, Canada<br /> July 25-29, 2011<br />
  2. 2. Outline<br />Background<br />Methods for Developing TLT Product Using NOAA/NESDIS/STAR Recalibrated MSU Radiances<br />Results and Discussion<br />Summary and Future Works<br />
  3. 3. Background<br /><ul><li>Microwave Sounding Unit (MSU, 1978/11-2006/9)
  4. 4. 9 instruments (NOAA TIROS-N – NOAA-14)
  5. 5. 4 channels </li></ul>Channel 2- mid-troposphere (TMT)<br />Channel 3 - upper-troposphere<br />Channel 4 - lower-stratosphere <br /><ul><li>11 scan angles: 0 – 47.35°
  6. 6. Widely used in long-term atmospheric Tb trends studies
  7. 7. MSU Lower Tropospheric Temperature (TLT)</li></ul>TMT Affected by stratosphere cooling effect<br />TLT: weighted average of TMT Tb<br /> at different view angles<br /> (Spencer and Christy, 1992,2003; Mears and Wentz, 2009)<br />TLT=T3+T4+T8+T9-0.75(T1+T2+T10+T11)<br />i=1-4, 8-10 scan positions<br /> Reduce stratosphere cooling effect<br />
  8. 8. Background<br /><ul><li>Two MSU TLT products available</li></ul>Using NOAA pre-launch calibrated observations<br />University of Alabama group (UAH)<br />Remote Sensing Systems group (RSS)<br />Major Issues need to addressed<br />Calibration Errors (Warm Target Contamination)<br />Orbital Decay Effect<br />Diurnal Drift Effect<br />TLT trends have important policy making implications<br />Purpose of this study<br />Generate STAR TLT product using NOAA/NESDIS/STAR recalibrated MSU radiances<br />Comparing STAR TLT with other two research groups<br />
  9. 9. Methods for STAR TLT Product<br />Using NOAA/NESDIS/STAR Recalibrated MSU Radiances (v1.2)<br /> (Zou et al. 2006, 2009, 2010)<br /><ul><li>Simultaneous Nadir Overpass (SNO) Method to generate consistent climate data records (CDR)</li></ul>http://www.star.nesdis.noaa.gov/smcd/emb/mscat/mscatmain.htm<br /><ul><li>Remove Warm Target (WT) Contamination at root level
  10. 10. Can reduce inter-satellite bias by an order of magnitude compared to NOAA pre-launch calibration </li></li></ul><li>Methods for STAR TLT Product<br />Using NOAA/NESDIS/STAR Recalibrated MSU Radiances<br />NOAA 10 -14 averaged σ of intersatellite biases <br />SNO calibration (curve) <br />SNO + Christy Bias Correction (straight line)<br />Christy Bias Correction is used to removes residual WT contamination after SNO calibration<br />Noises in TLT are 2 times as large as those in MSU channel 2 (TMT)<br />
  11. 11. Methods for STAR TLT Product<br />Satellite Altitude & Orbital Decay Effect Correction<br /><ul><li>Satellite altitudes are different (morning versus noon satellites)
  12. 12. Satellite altitude trends to decay over time
  13. 13. Cause view zenith angle changes, effects vary with different limb positions </li></li></ul><li>Methods for STAR TLT Product<br />Satellite Altitude & Orbital Decay Effect Correction <br /> Simulated altitude effect climatology <br />Community Radiative Transfer Model (CRTM)<br />NASA MERRA reanalysis<br />All observations adjusted to 850 km altitude<br />Rate of Tb change with satellite altitude (K/km)<br />
  14. 14. Methods for STAR TLT Product<br />Diurnal Drift Effect Correction same as STAR TMT products (Zou and Wang 2009)Using RSS monthly averaged diurnal anomaly climatology<br />Before Diurnal Correction<br />NOAA 11 - NOAA 10<br />Adjust the scene radiances at different observation time to the local noon time <br />After Diurnal Correction<br />
  15. 15. Results <br />5-day averaged MSU global mean TLT & TMT time series<br />Temporal Coverage: 1978/11-2006/9<br />Spatial Coverage: -82.5° – +82.5 °<br />
  16. 16. Results: Spatial Trend Patterns (1978-2006) <br />TLT After Orbital Drift Effect Correction<br />TMT (channel 2) <br />TLT Without Orbital Decay Effect Corr.<br />
  17. 17. Comparing STAR, UAH (v5.3), RSS (v3.2) MSU TLT Products (1979 - 2003)<br />
  18. 18. Summary and Future Works<br />Generated MSU TLT product using NOAA/NESDIS/STAR recalibrated channel 2 radiances<br />STAR TLT shows a global warming trend of 0.145 K/dec (1978-2006),<br />STAR TLT has the smallest warming trends compared to UAH and RSS TLT products<br />Larger differences exist during 1979 – 1986<br />Next Step<br />Generate TLT product using recalibrated Advanced Microwave Sounding Unit A (AMSU-A) observations (1998 – present)<br />Generate MSU/AMSU-A TLT merged Product<br />
  19. 19.
  20. 20. Results<br />TLT show similar trend stability as TMT (Zouand Wang, 2010)<br />Christy bias correction (almost horizontal lines) <br />Constant bias correction <br />

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