VOCALS. VOCALS THEME To better understand and simulate how marine boundary layer cloud systems...

VOCALS

VOCALS VOCALS THEMETHEME

To better understand and simulate how marine boundary layer cloud systems surrounding the Americas interact with the coupled ocean-

atmosphere-land system on diurnal to interannual timescales.

VOCALS in CLIVAR

• VOCALS is a developing process study within VAMOS, informally led by C. Bretherton.

• WG meetings at VPM3-6.• Active participants:

US (Albrecht, Bretherton, Fairall, Mechoso, Miller, Stevens, Weller) Chile (Garreaud, Ruttland) Uruguay (Terra) Peru (Lagos) Ecuador (Cornejo)

• Science Plan on my web page.

VOCALSVOCALS Scientific IssuesScientific Issues

• Time and space scales of CTBL-continent interaction.

• Regional S/I feedbacks between Sc clouds, surface winds, upwelling, coastal currents and SST in E Pacific.

• Feedbacks of Eastern Pacific cloud topped boundary layer properties on overall tropical circulation and ENSO.

• Climatic importance of aerosol-cloud interactions.

VOCALS STRATEGIESVOCALS STRATEGIES

• Global and mesoscale model evaluation and improvement (e.g parameterization development) using multiscale data sets.

• Model sensitivity studies to refine hypotheses and target observations.

• Science by synthesis/use of existing data sets, enhancement through targeted instrument procurement, algorithm evaluation and development, and enhanced observation periods.

• Co-ordination with oceanographic, aerosol, cloud process communities, including CLIVAR CPTs, CLOUDSAT, etc.

Arica

Lima

San Felix I.

WHOI buoy

Galapagos I.

Scientific Highlights from EPIC & DYCOMS

DYCOMS-II

TAO-EPIC

EPIC2001-Sc

RICO

TAO-EPIC has gathered a nice multiyear dataset

Yearly Feb-Apr precipin SE Pacific ‘ITCZ’

…and freshening

Cronin

2.5 years of data from the WHOI stratus buoy (20S 85W)

Weller

Buoy shows large net heat flux into ocean balancing eddy cooling

Weller

Ocean altimetry shows energetic eddy field

Weller

EPIC 2001

Sc cruise

x

GOES-10 Visible Image October 17 1500 UTC

10°S

20°S

90°W 80°W 70°W

Peru

x

Inhomogeneous clouds6

0 k

m

Lati

tud

e (

ºS)

19

20

21

22

GOES VIS 0545 LTC-band 0200 LT 87 86 85 84 8360 km Longitude

(ºW)1.5

1.0

0.5Heig

ht

(km

)

00

02

04

06October 19 (Local Time)

MMCR

00

06

[cm s-1] ECMWF VERTICAL VELOCITY

[dBZ]10

-10

0

EPIC2001-Sc

Diurnal Cycle

(20S, 85 W)

Bretherton et al. (2004)

Daytime subsidence max

AM subsidence max PM subsidence max

Diurnal variation of horizontal surface wind divergence (Quikscat)

Hypothesis: Subsidence wave driven by diurnal heating cycle over Andes reaches buoy at noon.

seabreeze

?

Wood

18LT06LT

MM5 simulation also shows late afternoon convergence at coast, midnight ascent at buoy!

Garreaud et al. (2004)

Remotely-sensed cloud microphysics from EPIC2001-Sc

Bretherton et al. (2004)

Significant drizzle in clean periods, but mainly evaporates

MODIS visible reflectance, 15Z 20 Oct. 2001

POC(patch of cells)

MODIS effective cloud droplet radius – large (clean) in POC small in coastal pollution

DYCOMS-II RF02POC – drizzle feedback?

Stevens

DYCOMS-II Sc entrainment estimates from RF01

Stevens

Comparison of 6-day mean 20S 85W profiles with models

• All models have adequate Sc, but too shallow a PBL.• CAM2 LWC all in lowest 3 levels (70-630 m).• Observed LWC mainly at 800-1300 m.

(Peter Caldwell, UW)

U. Chile has installed ceilometer and surface met at San Felix Is.

LCL (surface met)

Cloud base (ceilometer)

Shows daytime rise of LCL, cld. base, with synoptic variations

Well-mixed

Decoupled

Mostly clear

Garreaud

Other active issues

• Role of Andes and Amazonia (flow blocking, deep convection) in influencing Sc.

• Comparison of WHOI buoy and TAO-EPIC ocean energy budgets with GCMs.

• Interest in coastal oceanography of region, including O-A interactions thru trapped coastal (e.g. Kelvin) waves.

• ENSO feedbacks with SE and NE Pacific clouds

• Shallow cumulus dynamics/microphysics – Sc to Cu transition (McCaa and Bretherton 2004; Wang et al. 2004)

VOCALS ThrustsVOCALS Thrusts• Continuing diagnostic, model sensitivity,

parameterization studies of SE/NE Pac stratocumulus and variability based on past field studies, satellite/model products, and in-situ observational enhancements.

• Contribution to RICO (Jan 2005, shallow Cu)

• Add ocean diagnostic study component based on ARGO/ODA, cruises, WHOI buoy aimed at better understanding of ocean upwelling/lateral heat transport processes and their reln. to atmospheric variability.

• Global atm./coupled, mesoscale atm., and regional ocean modeling.

• ‘Radiator fin’ coupled O-A-L expt. (Oct 2006)

• Augment San Felix Island instrumentation with wind profiler, radiation, microwave LWP, and aerosol sampler.

• NOAA/ETL sfc/remote sensing instrumentation on Pacific and Atlantic buoy maintenance cruises, and at RICO (funded).

• Develop VOCALS data set through distributed satellite/model/in situ data archive at JOSS. Archive ECMWF and NCEP hi-res column data at WHOI buoy, SFI in co-ordination with CEOP (some funding).

• Work with cloud-climate sensitivity CPT to feed into coupled model development.

VOCALS short-term implementation

VEPIC TimelineVEPIC Timeline

Modeling, Modeling, empirical, empirical,

and and satellite satellite studiesstudies

2003-2010 diagnostic/modeling work 2003 ETL-enhanced cruises SFI profiler VEPIC data archive2004/11 Cloudsat2005/01 RICO2006/10 Radiator expt.

RICO (Rain In Cumulus over the Oceans)

Requested (Fairall)Pan Am Panel Endorsement?

Diurnal subsidence wave

Cld microphys. gradient

Ocn heat transport

Coastal jet

What VOCALS would like from you

• A letter from the panel to Mike Patterson endorsing the use of the Ron Brown in RICO to provide critical time-continuous open-ocean radar, radiometric, turbulence, and other in-situ measurements that will greatly enhance RICO’s potential to contribute to shallow cumulus and cloud microphysical parameterizations in climate models.

• Panel approval of VOCALS as a US CLIVAR sanctioned activity as part of PACS funding AOs.

• Also, panel must consider equatorial EPIC’s heritage.