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Comparative Influence of Snow and SST Variability on Extratropical Climate in Northern Winter

Comparative Influence of Snow and SST Variability on Extratropical Climate in Northern Winter. Fanglin Yang RSIS/CPC_NCEP Arun Kumar CPC/NCEP NOAA’s 27th Climate Diagnostics and Prediction Workshop , October 2002. Motivitations.

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Comparative Influence of Snow and SST Variability on Extratropical Climate in Northern Winter

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  1. Comparative Influence of Snow and SST Variability on Extratropical Climate in Northern Winter Fanglin Yang RSIS/CPC_NCEP Arun Kumar CPC/NCEP NOAA’s 27th Climate Diagnostics and Prediction Workshop , October 2002

  2. Motivitations In mid-latitudes, air-sea interaction is one way. Is snow-air interaction also one-way? Compared to remote tropical SST forcing, how important is local snow anomaly in modulating mid-latitude climate variability? In extreme cases, for instance, in ENSO years, how snow and local temperature anomalies interact with each other?

  3. GCM Experiments (NCEP GSM T42L28)

  4. Model Fidelity, σ(Ts)in DJF Observation, CAMS Simulation: SST_SNO

  5. Model Fidelity, σ(Z200)in DJF NCEP/DOE R2 Simulation: SST_SNO

  6. Snow Depth Climatology in DJF Obs: SMMR Simulation: SST_SNO Both are averages for 1979-1987. For model, assumed snow density 300 kg m-3

  7. Comparative Impact Snow vs SST Analysis of Standard Deviations in DJF

  8. Δ{σ(Ts) } in DJF Impact of Snow Variability Impact of SST Variability

  9. Δ{σ(Z200) } in DJF Impact of Snow Variability Impact of SST Variability

  10. Δ{σ(Ts), 30°N-60°N} in DJF Impact of Snow Variability Impact of SST Variability

  11. Rotated EOFs of Z200 in DJF, Atmospheric Modes SST_CSNO SST_SNO EOF 1, 11.6% EOF 1, 13.7% EOF 4, 8.1% EOF 2, 11.2% EOF 3, 9.6% EOF 2, 10.7% EOF 4, 7.3% EOF 5, 7.5%

  12. Composite Analysis for Extreme Cases Impact of Snow Anomaly on the response of Mid-Latitude Climate to Tropical SST Forcing in ENSO Years

  13. Composite Sfc Temp Anomalies in ENSO Years Yang et al., J Climate, 2001 CAMS SST_CSNO SST_SNO SST_SNO - SST_CSNO

  14. Composite Z500 Anomaly in ENSO Years SST_SNO SST_CSNO

  15. Regression of Z200 and Ts with Nino 3.4 Index SST_CSNO Z200 SST_CSNO Ts SST_SNO Z200 SST_SNO Ts

  16. Why the the variability (Anomalies) of surface air temperature is larger in the runs with interactive snow? Snow variation can lead to many land surface and atmospheric quantities to change, such as surface temperature, latent and sensible heat fluxes, surface albedo, cloud cover and so on. These changes also feed back to snow variation (Grossman et al. 1994). Among all these feedbacks, we found snow-albedo feedback is the most effective one in explaining our GCM results.

  17. σ in DJF from SST_SNO, Snow-Albedo Feedback Surface Albedo Snow Depth Surface Downward Solar Surface Upward Solar

  18. Zonal Mean σ in DJF from SST_SNO Why the greatest impact of snow on sfc temperature variability is found in the mid-latitudes?

  19. Amplification by Snow-Albedo Feedback warm phase PNA pattern higher surface air temperature El Niño warmer SST less snow smaller surface albedo more downward solar radiation

  20. Conclusion:Comparative Impact of Snow and SST, DJF, Mid-Latitide

  21. Conclusion: Mid-Latitude Air-Sea and Air-Snow Interactions at Seasonal time scales

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