VOCALS

VOCALS THEME 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.

VOCALS Scientific 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 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.

Scientific Highlights from EPIC & DYCOMS DYCOMS-II RICO Galapagos I. TAO-EPIC Lima EPIC2001-Sc Arica WHOI buoy San Felix I. Scientific Highlights from EPIC & DYCOMS

TAO-EPIC has gathered a nice multiyear dataset Yearly Feb-Apr precip in 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 GOES-10 Visible Image October 17 1500 UTC Peru x 90°W 80°W 70°W Peru The Sc leg of the EPIC cruise went to investigate the Sc region in the SE Pacific. Here’s the W coast of S America. You can see the large areas of broken clouds within regions of unbroken clouds, but if you look more closely you can also see smaller scale (or mesoscale) features. I’ll come back to those in a moment. Here’s the ship track. The ship, the NOAA Ronald H Brown, spent six days at a WHOI IMET buoy here at 20 S, 85 W. The data I’m presenting here all come from this time period.

Inhomogeneous clouds GOES VIS 0545 LT C-band 0200 LT MMCR 60 km Latitude (ºS) 19 20 21 22 GOES VIS 0545 LT C-band 0200 LT 87 86 85 84 83 Longitude (ºW) 1.5 1.0 0.5 Height (km) 00 02 04 06 October 19 (Local Time) MMCR Here’s an example of some of the data we obtained. On the right is a GOES visible satellite image taken at 545 am local time on October 19th. You can see some unbroken as well as some broken Sc. The ship position is marked with the red circle. The yellow line shows the approximate advection over the previous 6 hours. This time period corresponds to the MMCR time-height section shown here (midnight to 6 am). From the satellite image we see that during this time broken Sc were passing over the ship (that is, clouds and holes). In the MMCR image we confirm this. We also see that there was significant drizzle falling out of some of these clouds. To get a better idea of what the heavily-drizzling cells passing over the ship looked like, we turn to the scanning C-band radar data. This image was obtained at 2 am local time. It shows reflectivity from the vertically-averaged cloud layer (remember these are very thin clouds) with the same color scale as the MMCR. The ship is in the center, and the data extends to a 30 km radius. There are some very strong drizzle cells passing over the ship. In each image, we can see a large degree of mesoscale variability, and both radars show us this is associated with a significant amount of drizzle. Lets go to another example…

EPIC2001-Sc Diurnal Cycle (20S, 85 W) Daytime subsidence max [cm s-1] ECMWF VERTICAL VELOCITY Daytime subsidence max EPIC2001-Sc Diurnal Cycle (20S, 85 W) 10 [dBZ] -10 Bretherton et al. (2004)

Diurnal variation of horizontal surface wind divergence (Quikscat) Wood seabreeze ? AM subsidence max PM subsidence max Hypothesis: Subsidence wave driven by diurnal heating cycle over Andes reaches buoy at noon.

MM5 simulation also shows late afternoon convergence at coast, midnight ascent at buoy! 06LT 18LT 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 RF02 POC – drizzle feedback? Stevens

DYCOMS-II Sc entrainment estimates from RF01 Stevens

Comparison of 6-day mean 20S 85W profiles with models (Peter Caldwell, UW) 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.

U. Chile has installed ceilometer and surface met at San Felix Is. Decoupled Cloud base (ceilometer) LCL (surface met) Well-mixed Mostly clear Garreaud Shows daytime rise of LCL, cld. base, with synoptic variations

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 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)

VOCALS short-term implementation 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.

Modeling, empirical, and satellite studies VEPIC Timeline 2003-2010 diagnostic/modeling work 2003 ETL-enhanced cruises SFI profiler VEPIC data archive 2004/11 Cloudsat 2005/01 RICO 2006/10 Radiator expt. Modeling, empirical, and satellite studies

RICO (Rain In Cumulus over the Oceans)

Requested (Fairall) Pan Am Panel Endorsement?

Diurnal subsidence wave Cld microphys. gradient Coastal jet Ocn heat transport

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.