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Stand on the Plateau, Study on the Plateau

Stand on the Plateau, Study on the Plateau. Promoting Satellite Applications in the TPE Water and Energy Cycle Studies: Chance and Challenge Kun Yang In stitute of Tib etan Pl ateau Research Chinese Academy of Sciences.

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Stand on the Plateau, Study on the Plateau

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  1. Stand on the Plateau, Study on the Plateau Promoting Satellite Applications in the TPE Water and Energy Cycle Studies: Chance and ChallengeKun YangInstitute of Tibetan Plateau ResearchChinese Academy of Sciences 2nd Third Pole Environment Workshop, 26-28 October 2010, Kathmandu, Nepal

  2. Lack of data in TP studies CMA stations Nearly no stations in west and > 4800 m

  3. TP hydro-meteorological studies need • Radiation • Soil moisture • Land fluxes • Land surface temperature • Water vapor • Albedo • …… Need satellite products!

  4. Verify satellite products before applied • Satellite products: usually developed, calibrated and validated in lowlands • TP represents an extreme • High elevation • Low air mass • Low aerosol • …… • TP providesan opportunity to validate a satellite product’s global applicability

  5. Outline • Assessment of RS/DA products • Development of satellite products • Application of satellite products • Challenge of satellite applications

  6. Outline • Assessment of RS/DA products • Radiation budget: GEWEX-SRB and ISCCP-FD • Water vapor: AIRS and MODIS • Albedo: MODIS • Development of satellite products • Application of satellite products • Challenge of satellite applications

  7. Rad observations in Tibet

  8. Yang et al. (2006 GRL) GEWEX-SRB V2.5 under-estimates ~50 Wm-2 Partially due to neglect of elevation effects Shortwave Rad: Obs. vs GEWEX-SRB v2.5 Mean Rad

  9. Mean bias in Rsw after accounting for elevation effects (Yang et al., 2008 JGR)

  10. Longwave Rad: Obs. vs ISCCP-FD Yang et al. (2006 GRL)

  11. Assessment of satellite water vapor JICA GPS network

  12. Assessment of MODIS Precipitable Water Vapor 24 GPS Receivers All-sky Statistics Bias=mean(MOD-GPS) Std=Standard deviation RMSE= Root mean square error NRMSE= 100*RMSE/mean(GPS) Mean=mean(MOD) MaxDiff= Max(abs(MOD-GPS)) Cloudy Clear-sky (ByDr. Lv Ning )

  13. For ground sites > 3000 m MOD-PWV assessment under clear-sky After Optimization Before Optimization We propose a formula to correct the large uncertainty for high-altitude regions (By Dr. Lv Ning )

  14. AIRS-PWV assessment under clear-sky Qin et al. JMSJ, submitted

  15. Outline • Assessment of satellite products • Development of satellite products • Soil moisture and land fluxes • Radiation • Application of satellite products • Challenge of satellite applications

  16. Microwave Wsfc Tbobs LSM Tbsim Surface radiation Vegetation emission Tg, Tc, Wsfc RTE Vegetation layer Surface Microwave data assimilation TMI/AMSR/AMSR-E (6.9/10.6 and 18.7 GHz) Minimization scheme F(Tbobs-Tbsim) (Yang et al., 2007 JMSJ)

  17. Validation at Tibet site (Yang et al., 2007 JMSJ)

  18. Assessment of soil moisture estimate at a Mongolian site (Yang et al., 2009 JHM)

  19. An example: 2003 Seasonality of distributed Bowen Ratio LDAS NCEP Compared to NCEP, LDAS shows a reasonable seasonal march and regional contrast between eastern Tibet and western Tibet

  20. Outline • Assessment of satellite products • Development of satellite products • Application of satellite products • Tibet warming trend: elevation dependence • Atmospheric heating sources • Challenge of satellite data applications

  21. Backgrounds This figure is adopted from Liu and Chen’s paper. They concluded “there exists a clear tendency of the surface temperature trends to increase generally as the site elevation rises “ by analyzing station data from nearly 0 m to 4800 m.

  22. CMA stations

  23. Warming rate above 5000 m ? 200m increment 500m increment Warming rate Warming rate Based on CMA data How warming rate depends on elevation?

  24. MODIS station Can MODIS data show the warming dependence on elevation? (dz=500 m) MODIS Station Warming rate

  25. 4800m ? Warming rate derived from MODIS data (Qin et al., 2009)

  26. Outline • Assessment of satellite products • Development of satellite products • Application of satellite products • Challenge of satellite applications • Validation issue: Scale match • Application issue: Accuracy

  27. Soil moisture validation: Scale-match validation

  28. Cal/Val central Tibet site of SMOS and SMAP soil moisture 39 sets, starting on 30 July 2010 4500-4700 m Naqu Each SMTMS station: 4 levels 0-3 cm, 20 cm, 40 cm, 100m

  29. Radiation accuracy for glacier and snow surfaces 1.27m / month Palong No.4 SE-Tibet mass and energy balance station

  30. RS-estimated downward solar radiation Under-estimated by 100 Wm-2 (from 240 to 140), due to the difficulty to discriminate cloud and snow surface (Lu et al., 2010 JGR)

  31. Summary • Satellite data are very helpful for understanding the status, processes, and modeling in this region • Need to improve the accuracy of satellite products and to develop new products for this region Thank you for your attention！

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