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Brian Mapes climate reading group before Betts visit MSC 307 class just back from monsoon meeting

Land surface thermodynamics, PBL and convective processes, as compared to ocean, and implications. Brian Mapes climate reading group before Betts visit MSC 307 class just back from monsoon meeting Guesses? monsoon w/ global warming?. Read this for next week.

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Brian Mapes climate reading group before Betts visit MSC 307 class just back from monsoon meeting

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  1. Land surface thermodynamics, PBL and convective processes, as compared to ocean,and implications Brian Mapes climate reading group before Betts visit MSC 307 class just back from monsoon meeting Guesses? monsoon w/ global warming?

  2. Read this for next week http://alanbetts.com/research/paper/progress-in-understanding-land-surface-atmosphere-coupling-from-lba-research

  3. Dry vs. wet surfaces animations http://www.meted.ucar.edu/nwp/model_physics/navmenu.php?tab=1&page=3.7.1

  4. Surface Energy Balance Or for steady state

  5. Note that soil and rock have about half the heat capacity of water and that penetration of temperature fluctuations into the solid earth is much shallower than into water. Heat capacity of moist, unfrozen soil is much greater than that of dry soil

  6. soil: 2000x bigger heat capacity (per cubic meter) than air

  7. Heat Budget I Dry Lake, El Mirage, CA 10 June 1950

  8. Heat Budget II Corn Field, Madison, WI 4 September 1952

  9. Heat Budget III Alfalfa, Hancock, WI 19 July 1956

  10. Annual Cycles atMiddle LatitudeSites

  11. Heat Balance Over the Gulf Stream Note importance of currents, which warm the area Dec-Sep and transport net heat to higher latitudes Oct-Nov Gulf Stream 38N, 71W

  12. dry soil wet soil

  13. Add same surface energy with different evaporative fraction dry soil wet soil mse (virtual) dse mse dse

  14. Add same surface energy with different evaporative fraction dry soil wet soil

  15. dry surface wet surface

  16. N-S Wet-dry gradient: monsoon

  17. E-W or global dry-wet sfc gradients(continent-ocean)

  18. Current climate, ocean mean conditions: 18C (set by planetary radiation balances) RH ~ 70% (so that LHF ~ atm. rad. cooling rate) T is nearly adiabatic (dry moist adiabat) because vertical convection is efficient (which in turn is because rad. eq. is unstable, so the troposphere is convecting thoroughly). 6 g/kg moisture is whatever it is 8 g/kg 10 g/kg 15 g/kg qo = 10 To=18 q*o = 14 g/kg RHo = 10/14

  19. Land gets whatever humidity it has from the ocean, so its q is some fraction (say 8/10) of the OCEAN's q. That 8/14 depends on (summarizes) continent shape and all myriad wind statistics. Land and ocean T remain equal aloft by efficient horiz. 'mixing' 6 g/kg 8 g/kg 10 g/kg 15 g/kg ql = 8/10 qo Tland=23C = 8 g/kg

  20. New climate: warmer ocean by 3K because of greater atmospheric emissivity (greenhouse gases), but RH at the surface stays the same because it is set by physics (LHF ~ atm. IR cooling rate, which hasn't changed since radiative fluxes in the new climate are in equilibrium with incoming sunlight, which hasn't changed.) GW 6 g/kg 8 g/kg 10 g/kg 15 g/kg qo = 10/14 *17 =12.1 g/kg To=21 (3K rise) q*o = 17 g/kg RHo = same (10/14)

  21. Land q is still that same fraction (say 8/10) of the OCEAN's q. That 8/10 depends on (summarizes) continent shape and all myriad wind statistics, which (conservative assumption) won't have changed with small climate warming. GW Land and ocean T remain equal aloft by efficient horiz. 'mixing' 6 g/kg 8 g/kg 10 g/kg 15 g/kg ql = 8/10 of qo Tland=28C (5K rise) = 8/10 *12.1 = 9.7 g/kg

  22. Fasullo 2010 ...CMIP3...Despite differences in magnitude, the nature of the feedbacks governing the land–ocean contrast are largely robust ... relative humidity (RH) over land decreases with warming because precipitation and the hydrological cycle are governed pr marily by transports of moisture from the oceans, where increases in lower-tropospheric temperature and saturated humidity fail to keep pace with those over land. ...decreased RH raises the lifting condensation level, even as CAPE increases, and suppresses convective clouds.... particularly strong at low latitudes where the dynamical influence of competing sources of maritime deep convection may further suppress convection.... ...the mean increase in OLR over land (1.0 W/m2/K) is almost double that over the ocean (0.6) ...The contrast results in an increase in the transport of energy from ocean to land relative to the twentieth century...lasting increases in both OLR and absorbed shortwave radiation globally.A conceptualmodel... ...while the land–ocean contrast plays a key role in achieving global radiative equilibrium, it entails disproportionate increases in temperature and aridity over land and therefore is likely to be associated with substantial environmental impacts.

  23. The extra heat of global warming is absorbed solar, not trapped longwave!

  24. Read this for next week http://alanbetts.com/research/paper/progress-in-understanding-land-surface-atmosphere-coupling-from-lba-research

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