lgm seasonal energetics

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LGM Seasonal Energetics. October, 2009. Annual mean insolation. Reflects Obliquity Change Only (Modern = 23.45 LGM = 22.95). TOA seasonal incoming Insolation. Primarily reflects obliquity (precession change from 102 in modern to 114 in LGM), biggest high latitude effect in summer. - PowerPoint PPT Presentation

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  • LGM Seasonal EnergeticsOctober, 2009

  • Annual mean insolation Reflects Obliquity Change Only (Modern = 23.45 LGM = 22.95)

  • TOA seasonal incoming InsolationPrimarily reflects obliquity (precession change from 102 in modern to 114 in LGM), biggest high latitude effect in summer

  • Insolation Changes Solid = Land average, Dotted = Ocean Average

  • Absorbed Solar RadiationHigh Latitude summer changes dominate

  • ASR by componentsASR = Incoming_SW outgoing_SWOutgoing = what never makes it surface + reflected by surface + residualWhat never makes it to surface = downwelling_TOA downwelling_Surf---- this could be absorbed or reflected but lets assume its reflected by atmos reflected by surface = upwelling_SurfRes = up_TOA - what never makes it surface upwelling surfaceThe residual includes the absorbed (and scattered) downwelling and the upwelling radiation that is absorbed, reflected in the atmos (res = approx. 20% incoming, fairly spatially uniform)

  • ASR by components- all signs are gain to atmosphereSolid = incoming / Dashed = surface / dotted = atmosphere Dashed dot are residual (small)

  • ASR by components- all signs are gain to atmosphereSolid = NET (all terms) / Dashed = surface albedo / dotted = atmosphere Large but not total compensation between the atmos and surface

  • What never makes it to surface (atmos) by componentsTotal = downwelling_TOA downwelling_SurfClear = downwelling_TOA down_SURF_clearCloudy = down_SURF_clear down_Surf

  • Atmospheres effect on ASR changeSigns are defined such that positive mean atmos gainsLGM - MOD

  • More clouds = more reflectionJuly- LGM - MODChange in radiation REFLECTED(+ = more LGM up) SWJuly LGM MODCloud liquid water (vert. Int. in kg) change

  • More clouds = more reflectionJAN- LGM - MODChange in radiation REFLECTED(+ = more LGM up) SWJAN LGM MODCloud liquid water (vert. Int. in kg) changeCloud changes could be multiplied by incoming solar to tryAnd tease out the change in reflected--- if we care

  • Surface Changes- Land OceanSolid = Land Domain / Dotted = Ocean Domain

  • Atmospheric ASR changes/ Land-SeaSolid = Land /Dotted = OceanNote; this is atmos contribution to total ASR, not ASR in the atmosNecessarily (could be atmos albedo change)

  • SURFACE HEAT BUDGET annual meanLGM surface LW goes up despite lower temperature- mustBe because atmos has more vapor

  • SURFACE HEAT FLUX OCEAN DomainPositive = to the atmosphere- LGM has smaller seasonal heat fluxIn both hemispheres because of more extensive sea-ice- NA is weird Bottom Plot TakesInto AccountChange inLand FracIn LGM

  • SURFACE HEAT FLUX LAND DomainPositive = to the atmosphere Bottom is an order of magnitude smaller than ocean

  • FS ChangeLGM gets more heat from ocean in NH winterNOT sure abour SH Land changes

  • Where does the LGM atmosphere get additional winter heat from?JFM FS (colors inW/m^2) and sea Ice concentrationMODERNLGM

  • JFM FS change (LGM-MOD)SEA ICE is from LGM

  • JFM FS change- define regionsof interestComposite around regions of large FS changeWhere does the energy come from

  • Composite FS seasonal cyclesNorth Atlantic RegionsEach region changes its annual mean FS- consequence of uncoupledRun? Are there really large ocean heat transport changes

  • North Atlantic Feb. FS and TSSolid = Modern, Dashed = LGMSea ice edge has large FS gradient, leads to large temp. gradTemp. grad reverses north of Ice edge

  • Global Mean EnergeticsSolid = PI (CAM)/ Dashed = LGM / Dotted = ObservationsShould we be worried about model-observation difference?

  • 3 Box Surface Temp.Elevation change in LGM is a potential issueLarger LGM high latitude seasonal cycle

  • 3 Box Atmos Temp.Elevation change in LGM is a potential issueSlightly Larger LGM high latitude seasonal cycle

  • 3 box temp- amplitudesSeasonalTemp.Amplitude

  • 3-BOX_EnergiesSOLID = MODERN / DASHED = LGM / Dotted = 4 X co2LGM polar region has less seasonality in ASR (albedo is higher) but Equally large changes in FS

  • 3 BOX energy changes (LGM/quad-PI)SH has smaller ASR amplitude but even smaller MHT variability, so the OLR and MHT amplitude upNH Summer changes dominate

    LGM PIIs SOLID

    Quad PIIs dashed

  • 3 box seasonal amplitudes(ASR-FS) is the energy fluxed to the atmosphere. Seasonal cycle ASR goes down in the LGM(enhanced albedo) but so does FS, so the energy fluxed to the atmosphere is unchanged. The partitioning of that energy between OLR and MHT is interesting.

  • 6 box energies- PI (cam) and obsSolid = observations / dashed = modeled

  • 6-box temperatures- TS

  • 6-box temperatures- TV

  • 6 box temp amplitudes

  • 6-box energies- **SAME LAND MASK** (modern grid boxes with >95% LFRAC)LGM = dashed/ MOD =SolidLess energy into LGM Ocean = more energy into LGM atmos over ocean = larger temp variability over ocean -> less zonal heat transport to the land -> larger seasonal cycle over landSolid =PI

    Dashed = LGM

    Dotted = quad

  • 6-box energies- LGM/quad-PI

  • Land Domain Seasonal AmplitudesLess LGM ASR cycle- but less energy is exported zonally because ocean temps. Have a larger seasonal cycle. The energy accumulated over land doesnt change muchTotal energy accumulated = MHT, OLR, and CTEN (quadrature) variabilityZHTTo landIs outOf phaseWith ASR

  • Ocean Domain Seasonal AmplitudesNote- ASR and ZHT are in phase over ocean

  • Change in non-open ocean

  • Diffusive heat transportStart with zonal mean vertically averaged tempMOD = RED / LGM =BLUE solid=raw / dashed = trunc. Legendre exp.Not many zonal mean differences beyond the global mean I interpolateBelow the TopographyTo makeA verticallyIntegratedTemp record That isnt biasedBy topography(I think)

  • Heat transport divergenceMOD = RED / LGM =BLUE solid=raw / dashed = trunc. Legendre exp.Not many zonal mean differences

  • Legendre Fourier expand temp and MHT_div

  • LGM MOD legendre four. Coef.sStronger annual mean temp. grad. In LGM. Seasonal changes are moreComplex; Annual mean heat flux changes also up in LGM

  • Back out DNot all wavenumbers fall on a line of constant D- BUT the #2 in the LGM and MOD do- D/a^2 = .98

  • Reconstruct HT, from T and DD is held constant, from the mod Wave#2 fit- SH placement is offT isTruncatedAt wave#6

  • Reconstruct HT from T and D

  • MAX HT reconstruct

  • B_mht from 3 box models - TVB_MHT values are 3 +/- .4 (2 sigma) and 2 +/-.1 for NH and SHWe used 3.4 in EBM; R^2 are .86 and .89 for NH and SH

  • B_mht from 3 box models -TSB_MHT values vary widely between models- however R^2 values are Slightly better and = .87 and .91 for NH and SH

  • B_olr from 3 box modelAsterisk =NHSquare = SH

    Solid = NHLinear

    Dashed = SHLinear

  • Zonal mean temperatures

  • Meridional Cross Section Temp.

  • Delta Meridional Cross Section Temp.

  • Zonal Mean Seasonal Amplitude Temp.

  • Zonal mean specific humidity(OCEAN DOMAIN ONLY)

  • Delta Zonal mean specific humidity(OCEAN DOMAIN ONLY)

  • PERCENT Delta Zonal mean specific humidity(OCEAN DOMAIN ONLY)

  • Summer winter LW heating(JJA DJF NH and DJF-JJA SH)LW heating OPPOSSES the seasonal cycle

  • Quad pi change in annual mean LW heatIn general, counters the mean state change- convection does that

  • Seasonal amplitude LW heating

  • Quad PI seasonal amplitude LW