The Antarctic Clouds Experiment: Cloud project(s) under development at AAD

Simon Alexander and Andrew Klekociuk[with special thanks to Nick Chang for Davis lidar measurements]

Australian Antarctic DivisionHobart, Australia

simon.alexander@aad.gov.auandrew.klekociuk@aad.gov.au

Map from Bromwich et al (J. Clim.)

DAVIS (69S, 78E)

CASEY

MAWSON

• (1) “Antarctic Clouds Experiment”• Duration ~5 years, commencing July 2014 (subject to AAD and

peer-review approval)• Characterize optically thin (optical depths <~3) clouds from

the near-surface to the tropopause• Run the Rayleigh lidar at Davis, maybe for ~ 2 years (funding dependent)• The Davis VHF wind-profiling radar will also be running (has an approved

project already), providing horizontal and vertical winds, tropopause altitude

• Construct a climatology of cloud parameters• Cloud thickness, base height, top height, temperature, optical depths etc.• Comparisons with model output

• Tie in with regional studies of clouds from satellite (polar-cap studies have already been done, but regional interest) and high-resolution modelling case-studies

Two projects likely to be proposed to AAD…

Two projects likely to be proposed to AAD…

• (2) “ARM Mobile Facility deployment to Davis and / or Macquarie Island”

• Deployment duration maybe 1 year at each site(?) – let’s discuss. Also could tie in with Southern Ocean cloud projects being discussed at this workshop(?)– Davis Rayleigh lidar and radar (and BoM radiosondes and maybe

ozonesondes) would run while ARM is deployed at Davis to provide useful ancillary data which gives Davis an advantage over other Antarctic sites (only exception being Syowa)

• Would provide numerous data streams and allow climatology of cloud ice / water content, surface LW, SW radiation etc. etc.– Has not been deployed in Antarctic (as far as I know – does anyone

know of any other groups’ plans to deploy there?)– Provide valuable comparisons with e.g. the ARM Alaska data

• Both stand-alone projects but would be mutually beneficial• Note that AAD projects are open in June 2013 and again in June

2015.• To conduct any science in the Antarctic or Macquarie Island requires an

approved AAD project• Would need to mesh this with the ARM funding cycle

• Plan to submit the Antarctic clouds project to AAD in June 2013• ARM project application to AAD in either June 2013 or June

2015• Depends upon community plans, and ARM facility commitments, and

ARM approval (or otherwise)• June 2015 submission would have an earliest Davis ARM deployment of

November 2016, earliest Macquarie Island ARM deployment of March 2017 (based on shipping schedules for recent seasons)

• Note there are some logistics issues with Macquarie Island in ARM deployment – can discuss offline

Two projects likely to be proposed to AAD…

Davis lidar and wind-profiling radar• Radar provides horizontal and vertical winds

from ~ 2 – 15km • Temporal resolution of minutes and vertical

resolution of hundreds of meters• Tropopause detection ~ an hour or two using echo

power profiles

• Lidar provides cloud and temperature data• Cloud resolution typically 37m x 60s• Temperatures at nighttime, only in thin cloud,

resolution ~ 1hr x 1km (N2 Raman channel)

• BoM launches daily or twice-daily radiosondes and ozonesondes (various frequency) at Davis

Kingston Lidar

Single channel multiplexed depolarisation using liquid crystal variable retarder.

Telescope: 300 mm diameter.Laser: 532 nm, 50 mJ per pulse, 50 Hz (2.5 W average power).

Bistatic arrangement (sky-scanning capability - later).

Tropopause-level cirrus cloud case study: a demonstration of

current capabilities

June 14 – 15 2011

DS

M

32 hours of cirrus cloud observations, 14-15 June 2011 (sun always below the horizon)

Fall streaks: ice particles grow in size and sediment out, then evaporate at lower

altitudes

Gravity waves may assist the formation of some cirrus clouds

Very thin clouds above the tropopause

White dots: radar tropopause, red dots: thermal tropopause

Significant amounts of SVC (sub visual cirrus)

Development of a polarization lidar: Observations of clouds throughout the

troposphere

21 October 2012

Clouds on 21/10/12 at Davis, photo: Nick Chang

21 October 2012. Descent of ice cloud base height – possibly indicative of the boundary

layer height

Gravity wave activity regularly

evident

Thin clouds (low R)

Mixture of ice and super-cooled water

clouds

Theory for water clouds

Theory for ice clouds

21 October 2012

Australian Community Involvement

• We are very keen to have Australian (and international) involvement in this project– Observational community – Modelling community (particularly, but not limited to, ACCESS)

• Validation of cloud parameters for NWP, climate models• High resolution modelling process case studies to look at the microphysics

• These projects (lidar clouds & ARM) are in the early stages of development– Advice on the highest priority science we can address is sought– We can tailor observations to suit particular research interests

• Tie-in with other Southern Ocean planned projects?• We (AAD) are happy / keen to lead the ARM project but if someone else here

wishes to do so, or already has plans for ARM in the Southern Ocean / Antarctic, then that’s no problem, although we’d still like to be involved if possible!

• Other possible topics of relevance which may be part of the Antarctic clouds project include:– Stratosphere – troposphere exchange of minor constituents and the role of cirrus

and gravity waves in the Antarctic– Polar Stratosphere Cloud (PSC) microphysics – modelling case studies etc.