Studies of columnar observations and model outputs Brian Mapes University of Miami with thanks to...

Studies of columnar observations Studies of columnar observations and model outputsand model outputs

Brian MapesBrian Mapes

University of MiamiUniversity of Miami

with thanks to many data producers and sharerswith thanks to many data producers and sharers

Looking under the hood of monthly mean data “points”

• Time sections: f(submonthly time x pressure)

– a vast, rich domain– complementary to typical climate model

examination space (lat x lon x months)– Natural domain for observations– Sensible domain for physical processes

Shortcomings• Free-running climate model time axis not directly

comparable to observations– statistical comparisons of course

• Models have climate-regime offsets in space, biasing comparisons at a fixed geo-location– non-mean statistics that is

• Submonthly variations (dynamics-driven) a poor proxy for climate sensitivity (thermo-driven)– tough luck, we do what we can

• Eulerian viewpoint a perverse view of weather– you’re free to leave

inescapable programming tediumCOARE obsKWAJEX obsLBA obsEPIC, JASMINE

KWAJEX CRM

NCAR CAMGFDL AM2NASA GMAO(super-CAM soon?)

cross-forced SCMs•SCAM2 driven by CAM•SCAM driven by AM2

Common data format,

variables,names,units,

flux sign conventions,

etc.

standard raw plots

standard stat plots

inescapable programming tedium

Datasets COARE obsKWAJEX obsLBA obsEPIC, JASMINE(more: ARM? etc?)

KWAJEX 3D CRM

NCAR CAMGFDL AM2NASA GMAO(more: CAM-SP?)


All obs are from warm-wet tropics so far - what I have & know best

Cloud obs rare: satellite TOA rad in~GCM-grid areas, but cloud profiles at

only a few points (cloud radar)

the most GCM-comparable cloud dataset

Driving the whole exercise -- an AMIP, at the very least

weird experiments,not done real carefully so far.

Future?

What variables?

COARE obsKWAJEX obsLBA obsEPIC, JASMINE

KWAJEX CRM



TOA radiation and cloud forcing

cloud fraction and condensed water content (p)

humidity (p)

vertical motion (p)

physical tendenciesheating and drying (p)

rain

CLIMATEIMPACT SCALAR

SCALARLINK TO HYD CYC

structure structure within within tropo-tropo-spheresphere

What plots?COARE IFA obsKWAJEX obsLBA obsEPIC, JASMINE

KWAJEX CRM



CRF: LW+, SW-, net ~0 [obs needclear-sky assumptions]

rain

RHcld frac [ crude f(RH) here ]

Q1, CWC (no obs)

wind divergence and vertical grid

0

100

%

note: net <0 at rainiest times

IFA OBS

What stats?COARE IFA obsKWAJEX obsLBA obsEPIC, JASMINE

KWAJEX CRM



Lag regressions I: scalars vs. reference variable (here, ref = qbudget-derived IFA rain)

reflected SW

reduced OLR

net

(here, other obs. estimates models, other rain types)

TOA rad up:

Other rain vars:


KWAJEX CRM



regressions vs. IFA rainfall

~1 mm/h x 1d ~24 mm rain

net

longwave atm heating longwave atm heating ~ 15% of latent heating~ 15% of latent heating

ocean shading*ocean shading* ~ -20% of latent heat in rain~ -20% of latent heat in rain

* straight regression incl. nocturnal zeroes - not really right approach ~6am diurnal rain peak

What stats?COARE obsKWAJEX obsLBA obsEPIC, JASMINE

KWAJEX CRM



II. lag-height regressions of profile fields vs. surface rain

~1/2 day timescale at a point

44 km radius“MCS-resolving”


KWAJEX CRM



regressions vs. surface rainfallSYNOPTIC SCALE (IFA)

multiscale (incl. several-day timescales)

but no cloud profile observations

What should areal cloud

statistics look like?

KWAJEX 3D CRMthanks Marat

TOA: obs TOA: obs-forced CRM

4-8 units, vertical

up to 16, vertical

condensatecan’t blow

away


KWAJEX CRM

NCAR CAM - IFAGFDL AM2 - IFANASA GMAO(super-CAM soon?)


regressions vs. surface rainfall - AM2

layers

upward development

time jitters sometimes

TOA about balanced, long

time scales

zigzag layers

july - 10 mm/d


KWAJEX CRM

NCAR CAM - IFAGFDL AM2 - IFANASA GMAO(super-CAM soon?)


AM2 - a different month

slow upward development

TOA closely balanced, long

time scale

zigzag layers

nov - 11 mm/d


KWAJEX CRM

NCAR CAM - IFAGFDL AM2NASA GMAO(super-CAM soon?)


regressions vs. surface rainfall - CAM

3-day waves

vertical thanks to ‘convective’ fraction but…

CRF not well linked to rain

events

…condensed water not

coherent in vertical

jan - 7 mm/d


KWAJEX CRM

NCAR CAM - IFAGFDL AM2 - IFAGMAO 140E/8N July(super-CAM soon?)


regressions vs. surface rainfall - GMAO

upward development, zigzag layers

a bit stark but about like IFA

2xKwajCRM ice content

freezing level schism

rain event met fields - obs

<-KWX

IFA->

rain event met fields - CAM-IFA

<-Jan

Dec->

rain event met fields - 3 models

CAM AM2GMAO

But are these brief rain-event fluctuations a Climate Process?

• hypothesisDivergence profile in tropical rain events

linked to profile of divergent winds

linked to profile of total winds?

( -> coupling issues…climate by any standard)

? Let’s look

CAMGMAO

Top- stats of div regression sections (lag-height) Bottom- stats of total wind speed (time-height)

each curve shows 1 month of data

AM2IFAmean

stdev w/in 6-day lag section

mean

stdev

All 3 GCMs have unrealistic surface-intensified div fluctuations

but no near- surface enhancement of wind fluctuations

KWAJEX is 3rd line; LBA 4

CAM-jangly wind profiles

1000 vs 850 not right

GMAO-midlevel swoop

wind profile results

• hypothesis too simplistic

• BUT– Systematic windspeed profile differences from

observations are clear at low levels!

Regressions wrt TOA CRF “events”?

• Weird idea: submonthly TOA CRF has ~no feedback to the weather that causes it, so there’s less expectation of a repeatable “life cycle”

• Proxy for climate sensitivities? – ? Maybe, if tau << {days, years, decades, etc.} ?

• Anyway, try it (but I have no obs yet)– use 24h smoothing to kill diurnal cycle

24h-smoothed TOA -CRF as base time series -- CAM 85W 20S

CRF<0, big slow changesSWup>0

Whiter w/clouds at 975 not 925

Another month at 85W 20S -- CAM

Complicated mixture of events

SWup>0CRF<0

faster changes, polymodal pdf?

AM2 - 85W 20S whiteness varies little; regression structure not stable

steady -30ish CRF

(Q1 data missing) PBL-based clouds rise to ~550mb here !?Minghua’s AM2 “midlevel” cloud (ISCCP)

Cross-forced SCMs (CAM <-> AM2)

• V. advection of SCM fields by prescribed vertical velocity from other GCM

• H. advection prescribed (non-interactive)

• Look at LBA (Amazon) just for fun

LBA obs (via Minghua’s shop), & GCMs

AM2CAMLBA obs

(warning: clear sky not careful)

(sorry: Q1 missing)

AM2CAMLBA obs

LBA models

AM2 CAMSCAM driven by AM2omega

Cloud style CAMlike

LBA models

AM2 CAMSCAM2 driven by CAMomega

Cloud style AM2 ish

Future plans - team efforts?COARE obsKWAJEX obsLBA obsEPIC, JASMINE

KWAJEX CRM



Common data format,

variables,names,units, sign

conventions

standard raw plots

standard stat plots

clickable from Bony index plot

co-ra.com/~bem

more to come

MORE DATAin (p,t) space

SCMs! CRMs!EXPERIMENTS!

OBS! other people

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