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Soil ice in land-atmosphere coupling over the United States

Soil ice in land-atmosphere coupling over the United States. Ahmed B Tawfik & Allison L Steiner. Mathew Taormina - Aviation. Why dirt water can be important during that 4-5 month dead period we called winter . And super computers. Mathew Taormina. Schedule of events.

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Soil ice in land-atmosphere coupling over the United States

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  1. Soil ice in land-atmosphere coupling over the United States Ahmed B Tawfik & Allison L Steiner Mathew Taormina - Aviation

  2. Why dirt water can be important during that 4-5 month dead period we called winter. And super computers. Mathew Taormina

  3. Schedule of events Introduction of the study Methods Results Summary Q & A (more Q , less A)

  4. The Study Thequestion: What is the impact of soil moisture and its phase in land-atmosphere coupling, during winter?

  5. The Study Why this question? Aren’t there more interesting questions to ask about climatological feedback mechanisms?

  6. The Study Almost certainly!

  7. The Study But… The soil moisture has an important role in surface energy balance and the subsequent magnitude of the Sensible Heat and Latent Heat fluxes.

  8. The Study Surface energy balance: Incoming shortwave + Incoming longwave = Reflected shortwave + Emitted longwave + Latent heat flux+ Sensible heat flux+ Subsurface conduction

  9. The Study Sensible Heat Flux: SH =  CdCp V (Tsfc - Tair) Latent Heat Flux: LH =  Cd L V (qsfc - qair)

  10. The Study This mechanism has been documented during boreal summer, but is often neglected during winter (too weak). How do these interactions differ when soil moisture becomes ice?

  11. Next… Introduction of the study Methods Results Summary Q & A (mostly Q , less A) You are here

  12. CLM3.5?!? THAT’S MY FAVORITE VERSION! Methods Models: The AbdusSalaa, International Center for Theoretical Physics (ICTP) Regional Climate model (RegCM) National Center for Atmospheric Research (NCAR) Community Land Model (CLM) version 3.5

  13. Methods Two 23-year simulations were run from 1982-2004. RunI allows the surface to interact freely as per atmospheric update cycle. RunC uses climatological surface moisture to represent an uncoupled land surface.

  14. Methods The Northern Great Planes were a strong area of focus due to stronger coupling and clear seasonal transition. RunC was restricted to climatological averages from RunI.

  15. Methods Changes in atmospheric variables are caused by changes in soil moisture. Standard deviation difference is used to measure coupling:

  16. Methods

  17. Next… Introduction of the study Methods Results Summary Q & A You are here

  18. Results Greater coupling strength is found in October-April than in the summer months. These areas “migrate” with the freezing line.

  19. Results The snow albedo feedback was expected to enhance colder surface temperatures and have a greater affect on available surface energy. However, there was no substantial difference in absorbed solar radiation between RunI and RunC, but there were observed differences in longwave emission

  20. What does this mean???

  21. Results Stefan-Boltzmann Law? Liquid soil moisture is key to controlling ground temperature variability.

  22. Results

  23. Next… Introduction of the study Methods Results Summary Q & A You are here

  24. Summary The impact of winter soil moisture in land-atmosphere feedback coupling is the ability for soil water phase to control surface fluxes.

  25. Summary The feedbacks from these fluxes are rooted from ground temperature (which is a function of percentage liquid moisture). These temperature differences influence available surface energy and can affect the vertical structure of the atmosphere in excess of 700mb during transition months (MSE, large scale precipitation, convective precipitation).

  26. Summary

  27. Summary Soil moisture phase seems more relevant than temperature during winter months. Ensembles need to be ran. Model biases are minimized but they may enhance or dampen coupling strength. What do we do with this observed feedback? Questions?

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