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Likun Wang Cheng-Zhi Zou (Government PI) Haifeng Qian

A Dataset from Stratospheric Sounding Units for Assessment of Temperature Changes in the Stratosphere over the Tibetan Plateau. Likun Wang Cheng-Zhi Zou (Government PI) Haifeng Qian DSFG @ NOAA/NESDIS/STAR , Likun.Wang@noaa.gov. Stratospheric Temperature. Ozone depletion

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Likun Wang Cheng-Zhi Zou (Government PI) Haifeng Qian

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  1. A Dataset from Stratospheric Sounding Units for Assessment of Temperature Changes in the Stratosphere over the Tibetan Plateau Likun Wang Cheng-Zhi Zou (Government PI) Haifeng Qian DSFG @ NOAA/NESDIS/STAR, Likun.Wang@noaa.gov

  2. Stratospheric Temperature • Ozone depletion Less ozone → less solar absorption → cooling stratosphere • Greenhouse effects More greenhouse gas → more trapped radiation the troposphere → cooling stratosphere • “Fingerprint” of natural and anthropogenic climate change From NASA IAP Manabe and Wetherald 1967

  3. Long-term, Near GlobalStratospheric Temperature Measurements • Radiosonde • Top: 30 hPa • MSU Ch4 • Peak: 80 hPa • Ground-based Lidar • Single point • GPS RO • 2001 – Present • SSU • Mid- to Upper Stratosphere • 27 years (1979 - 2006 ) Radiosonde Height From Siedel et al. 2011 IAP

  4. NOAA Satellite Data Stream HIRS HIRS/MSU/SSU HIRS/AMSU SSU MSU IAP

  5. BT Anomalies from SSUs El Chicon Mt. Pinatubo Data must be re-processed for climate studies ! IAP

  6. Current Status: Two available datasets Seidel et al.2011 • For both SSU analyses (Nash and Forrester 1986, Liu and Weng 2009): • No details on data processing • Only zonal or global data available • Discrepancy exists between two datasets IAP

  7. Outline SSU instrument and data issues Data processing details Trend Analysis Dataset Validation Conclusion IAP

  8. 1.5 hPa 5 hPa 15 hPa SSU Instruments Incoming radiation From Miller, 1980, Phil. Trans. R. Soc. Lond. From Brindley et al. 1999 Spectral response is a product of traditional broadband SRF and the CO2 cell absorption line responses. 80hpa From Chen et al. 2010

  9. Cell Pressure Leak Cell pressure drift caused the change of weighting functions, resulting in the change of the measured BTs. The change of the measured BTs is also related to the atmospheric profile. Weighting function Cell pressure varied during instrument life time SSU cell pressure Measured BT IAP

  10. Effects of Increasing atmospheric CO2 CO2 amount 0.25 K/Dec. Ch 1 0.23 K/Dec. Ch 2 0.11 K/Dec. Ch 3 RTM simulations with a fixed profile and cell pressures IAP

  11. Orbit Drift Pressure (hPa) Local solar time Stratosphere has a relatively strong diurnal cycle compared to the troposphere. Diurnal correction is important for SSU. measurements . IAP

  12. Diurnal correction

  13. SSU Data Processing Original SSU BTs Interpolated profiles along each SSU pixels SSU BTs with fixed cell pressures SSU simulations with real and fixed cell pressures Weighting function Correction SSU simulations with fixed and varying CO2 amount SSU BTs with removing CO2 increasing effects SSU BTs with limb adjustments SSU simulations at nadir and off-nadir Limb Correction SSU BTs with diurnal corrections Diurnal correction database Orbital drift correction Well-merged SSU gridded BTs SSU Stratospheric Temperatures IAP

  14. Original vs. Re-constructed El Chicon Mt. Pinatubo IAP

  15. Original vs. Re-constructed IAP

  16. Global Trend IAP

  17. Five-day Grid Products IAP

  18. Spatial Pattern of Trend IAP

  19. Tibetan Plateau Climatology BT anomalies IAP

  20. SSU vs. Lidar Hohenpeissenberg, Germany

  21. SSU versus GPS RO

  22. Global Time Series of BT anomalies (matched grids )

  23. Status Summary • In NOAA/NESDIS, efforts have been made to re-construct a fully-documented, publicly-accessible, well-merged long-term SSU dataset used for respective climate studies. • This newly-developed SSU dataset is composed by gridded brightness temperatures (BTs) that correspond to identical weighting functions (CO2 cell pressure and CO2 amount correction), fixed observational time (diurnal sampling correction), and same view angle (limb correction). • The dataset will be released at: http://www.orbit.nesdis.noaa.gov/smcd/emb/mscat/mscatmain.htm IAP

  24. References Wang, L., C.-Z. Zou, and Qian H., 2011: Construction of Stratospheric Temperature Data Records from Stratospheric Sounding Units. Journal of Climate (Submitted). Wang, L., and C.-Z. Zou, Qian H., 2011: Assessment of Stratospheric Temperature Data Records from SSU using Ground-based Lidar and GPS CHAMP RO data. Journal of Geophysical Research – Atmosphere. (Prepared) IAP

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