UNIVERSITY OF LEEDS

School of Earth and EnvironmentINSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE

Arctic Summer Cloud-Ocean Study (ASCOS)Ian Brooks, Cathryn Birch, Barbara Brooks, Sarah Norriswith: Michael Tjernström, Caroline Leck, Thorsten Mauritsen, Andreas Held, Joe Sedlar (Stockholm University), Matt Shupe, Ola Persson (NOAA),…and dozens of others!

SODAR

Micro-meteorology masts Tethered balloon

ASCOS science crew 32 scientists from 10 countries

6 weeks on Swedish Icebreaker Oden in central arctic ocean

(87.5N, 8.5 W) Aug 1- Sept 9 2008

ICAS measurements on the ice…

UNIVERSITY OF LEEDS

School of Earth and EnvironmentINSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE

ASCOS – multidisciplinary IPY study of interactions between cloud and sea ice.

OBJECTIVES:• Determine processes controlling artic BL clouds• Determine links between BL structure & evolution to spatial &

temporal variability of clouds• Determine source & evolution of CCN• Determine role of BL turbulence & surface properties in

exchanges of heat/water/aerosol between surface & cloud, and role of entrainment at cloud top

Measurements include : meteorology, aerosol physics & chemistry, gas-phase chemistry, physical

oceanography, marine bio-chemistry, remote sensing (sodar, radar wind profiler, cloud radar, lidar, microwave

radiometers…)

ICAS measurements: 15m & 30m turbulence masts, SODAR, microbarographs, tethered balloon (mean meteorology + turbulence), open-lead flux site, in-

water bubble spectra at open lead, aerosol.Two associated PhD projects within ICAS:(Both with MetOffice CASE support)• Assessment of performance of MetOffice UM surface flux

parameterizations & surface energy balance (Cathryn Birch).• Modelling of arctic BL cloud with LEM & bin-resolved

microphysics (Tom Pleavin)

Arctic climate is warming faster than that anywhere else on earth. Climate models suggest the rate of change may increase, but models also show much more scatter in arctic than anywhere else – generally do a poor job of representing arctic cloud & surface processes. Parameterizations are based on observations in mid-latitudes…not appropriate for unique arctic environment.

UNIVERSITY OF LEEDS

School of Earth and EnvironmentINSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE

15m mast5 turbulence levels (1m – 15.5m)

Instrumenting mast…in bad weather (of course!)

Oden from tethered balloon

UNIVERSITY OF LEEDS

School of Earth and EnvironmentINSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE

Tethersonde: measurements of mean met (P, T, RH) and turbulence, + CLASP aerosol spectra up to ~700-800m. Determine BL

structure & extent of turbulent mixing between sea-ice and boundary layer cloud.

Run 24-hours a day for duration of campaign

DC8 overflights down to ~100m

UNIVERSITY OF LEEDS

School of Earth and EnvironmentINSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE

ASCOS Aerosol MeasurementsBarbara Brooks, Sarah Norris, Ian Brooks – Caroline Leck, Douglas Orsini, Erik Swietlicki,…many others….

Oden Aerosol Lab

Aerosol inlets

Aerosol inletICAS on Oden: OPC & SMPS aerosol volatility measurements

CLASP & LiCOR (CO2/H2O) on helicopter (alongside CPC, met, gas sampling)

Arctic is perhaps cleanest environment on earth. Total aerosol concentrations (>3nm) typically ~100 cm-3 or less. Measured sustained concentrations <10 cm-3…so where does all the CCN come from?

Aerosol container lab

Overflight by NASA DC8 & (Barbara Brooks)

UNIVERSITY OF LEEDS

School of Earth and EnvironmentINSTITUTE FOR CLIMATE AND ATMOSPHERIC SCIENCE

Arctic Mechanisms of Interaction between the Surface and Atmosphere (AMISA)Barbara Brooks & Ola Persson (NOAA, Boulder, Colorado), Al Gasiewski (University of Colorado)

ICAS measurements on NASA DC8: OPC aerosol volatility + CPCs (alongside mean meteorology, cloud microphysics, nephelometers, CCN, multiple radiometers, dropsondes…)

OBJECTIVES:• Determine processes linking cloud properties to synoptic/mesoscale

disturbances, BL structure & surface energy budget• Determine properties of aerosols in /near low-level clouds & inversion• In-situ validation of NASA satellite retreivals• Sea-ice mapping & atmospheric radiometric profiling

6 Flights over arctic sea ice, including 4 over-flights of the ASCOS surface site