MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney...
Transcript of MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney...
![Page 1: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/1.jpg)
MJOinidealizedandcomprehensivemodels(andobserva6ons)
AdamSobelColumbiaUniversity
(ThanksDaehyunKim,EricMaloney,ShuguangWang,andothersascited)
PhototakenfromAdduAtollduringDYNAMO,November2011
![Page 2: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/2.jpg)
Mo6va6on
• WeseektounderstandthebasicphysicsoftheMJO.• Understandingshouldul6matelybecapturedinanidealizedmodel.• ThehistoryofaOemptstodothisisoneoffailureovermanydecades–
manyidealizedmodels,nocommunityagreement.• Whathaschangednowisthatwehavethecapabilitytosimulate(and
predict!)theMJOincomprehensivemodels.Weshouldusethis.
![Page 3: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/3.jpg)
EvensomeCMIP-classmodelsarenottoobad!
Klingamanetal.2015
![Page 4: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/4.jpg)
Moisture-convection feedback is critical to the MJO. The convection has to be sufficiently sensitive to moisture.
D.Kimetal.2012(andWangandSchlesinger1999;MaloneyandHartmann2001;Leeetal.2003;Linetal.2008;Benedictetal.2013)
![Page 5: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/5.jpg)
Moisture-convection feedback is critical to the MJO. The convection has to be sufficiently sensitive to moisture.
D.Kimetal.2012(andWangandSchlesinger1999;MaloneyandHartmann2001;Leeetal.2003;Linetal.2008;Benedictetal.2013)
ThissuggeststhatthemoisturefieldcarriesthesignaloftheMJO.
![Page 6: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/6.jpg)
Radia6ve-convec6vefeedbackmaintainstheMJO(andtosomeextentsurfacefluxesdotoo)
• MJOweakensoverland(Sobeletal.2008,2010);modeldiagnos6cs(AndersenandKuang2011,Chikira2014)
• mechanismdenial(LanduandMaloney2011,Kimetal.2011,ArnoldandRandall2015,Wangetal.2013,2016,MaandKuang2016)
• budgetstudies(InoueandBack2014;Sobeletal.2014,Woldingetal.2015)
![Page 7: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/7.jpg)
MJOasself-aggrega6onontheEquatorialbetaplaneorsphere(ArnoldandRandall2015)Radia6oniscri6cal.
Nonrota6ng,uniformSST
Rota6ng,uniformSST
![Page 8: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/8.jpg)
Advec6vedrying
Advec6vemoistening
“Moisture mode”: the MJO is essentially a huge blob of moisture that maintains itself by longwave radiative feedback (and maybe surface fluxes) and moves by horizontal moisture advection
LW flux from atmosphere
MaxcolumnMSE&PW
Radia6vewarming
Flow=forcedKelvin/Rossbyresponsetoquasi-steadyhea6ng
![Page 9: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/9.jpg)
W’ is perturbation column moist static energy; U is constant background wind; P’ = P’(W’) – if linear P=W’/¿c; (moisture-convection feedback) E’ = cu‘; zonal wind anomaly is computed diagnostically from P’ using projection (Green’s) function R’ = rP’; Normalized gross moist stability is constant, <1.
A linear moisture mode model (Sobel and Maloney 2012, 2013, JAS)
Green’sfunc6onforwindderivedfromGill(1980)
![Page 10: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/10.jpg)
Extended by Adames and D. Kim (2015) to include meridional moisture advection and horizontal wavenumber-dependent radiation
ObservedsymmetricOLRspectum&theore6caldispersioncurves–westwardgroupvelocityfork>1
Moistureanomaly(contour)Low-levelflow(arrows)MoisturetendencyduetoKelvin(top)
&Rossby(boOom)components
![Page 11: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/11.jpg)
Avarietyofthingscanhappenonaqua-planets.Ifthey’rezonallysymmetric,anMJOokendoesn’tappear.
BrethertonandKhairoutdinov2015
![Page 12: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/12.jpg)
PritchardandYang(2016)–MJO(orsomething)surviveseveninverycoldclimates.S6lllivesbyradia6vefeedback!Doesn’tnecessarilyprefereastwardpropaga6on.
![Page 13: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/13.jpg)
PritchardandYang(2016)–MJO(orsomething)surviveseveninverycoldclimates.S6lllivesbyradia6vefeedback!Thesemeanclimatesareverydifferent–fromeachother,andfromEarth’s.
![Page 14: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/14.jpg)
YetevensmallchangesinbasicstatecanhavealargeimpactonMJOdynamics(MaandKuang2016)
![Page 15: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/15.jpg)
Mul6scalemodels
• “Skeleton”–MajdaandStechmann(2009)andmanysubsequentpapers• High-frequencygravitywavecoupling(YangandIngersoll)• Theseneglectradia6on&surfacefluxesapriori• Thekeymechanisms(notjustthedispersionrela6onorotherpredicted
MJOfeatures)oftheseidealizedmodelsshouldbediagnosableincomprehensivemodels(andobserva6ons)
![Page 16: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/16.jpg)
Finalthoughts• Amodeinwhichmoisture+convec6onanomalieslivealong6me,
maintainedbymoisture-convec6onfeedbackandlongwaveradia6vefeedback,seemsquitegenericinmodelswithenoughmoisturesensi6vity.
• Whenitisneartheequator,largeinhorizontalscale,andgoesslowlyeastward,asittendstodoinourpresentclimate,wecallittheMJO.
• Eastwardpropaga6on(andotherMJOspecifics)appeardependentonthemeanclimate.
• Simplemodelscandomanythingsformanyreasons.Wenowhavethecapabilitytousecomprehensivemodelstotestmechanisms.
![Page 17: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/17.jpg)
Roundy(2012)showsthattheMJO-Kelvinsepara6oninspectraldiagramsresultsfrommixingofeventswithdifferentproper6esineasterly&westerlybasestates.Nosepara6oninmeanwesterlies.Con6nuousMJO-Kelvintransi6on(2012b)?
![Page 18: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/18.jpg)
Infactwecanseethetransi6oninpressure-windrela6oninmanyindividualeventsastheymoveeastfromIndiantoPacificOcean(Sobel&Kim2012).
Surfacepressure(contours)Zonalwindat850hPa(arrows)OLR(colors)
![Page 19: MJO in idealized and comprehensive models (and observaons)...• mechanism denial (Landu and Maloney 2011, Kim et al. 2011, Arnold and Randall 2015, Wang et al. 2013, 2016, Ma and](https://reader035.fdocuments.us/reader035/viewer/2022071508/612986bb164456306b7810e0/html5/thumbnails/19.jpg)
In other models, radiative feedbacks are important while surface turbulent flux feedbacks are not – but both are moist static energy sources
radiative contribution to maintenance of MSE anomaly
Andersen and Kuang 2011