Regional Modeling of Antarctic Clouds

Keith M. Hines1 and David H. Bromwich1,2

1Polar Meteorology GroupByrd Polar Research Center

The Ohio State University

2Atmospheric Sciences ProgramDepartment of GeographyThe Ohio State University

Issues for Mesoscale Modeling of Antarctic Clouds

• Limited observations for comparison/inspiration/verification• Low aerosol concentrations• Clear-sky precipitation/diamond dust• Thin ice clouds• Ice cloud physics less well understood than liquid cloud physics• Non-spherical ice particles• Are the more frequent Arctic field programs relevant for the

Antarctic?• How can we make use of more advanced (two-moment) cloud

microphysical parameterizations?• How can we make use of remote sensing?• Synergy with ice core studies

Arctic Studies with Cloud Component• SHEBA/FIRE/ARM (1998)

• M-PACE (October 2004)

• ISDAC (IPY)

• ASCOS (IPY)

• STAR (IPY)

What about the Antarctic?

AMPS studies and Antarctic Clouds

AMPS Cloud Forecast Evaluation (Fogt and Bromwich 2008)

December 2003 – February 2005Polar MM530 km basic horizontal resolution for AntarcticaReisner Single-Moment Microphysics

Look at Relative Humidity and Cloud Fraction

McMurdo

South Pole

correlation

bias

Relative Humidity WRT ICE

Predicted vs. Observed Relative Humidity at 700 hPa, 400 hPa and 250 hPa

Overforecast of Relative Humidity Increases with Height in the Troposphere

Estimated Cloud Fraction

for explicit moisture schemes that predict cloud mixing ratio (g m-3)

CF = Σ [ A LIQ CLWP + AICE CIWP ]

(Fogt and Bromwich 2008)

Old: A LIQ = 0.100 ; AICE = 0.0735

New: A LIQ = 0.075 ; AICE = 0.1700(Better matches Lubin’s (1994) absorption coefficient for Antarctic clouds)

(CCM2 mid-latitude)

Compare Simulated to Observed Cloud Fraction at 3 Sites

deficit

excess

excess

deficit

Original

Modified formula

Percent matches by cloud category

partly cloudy

clear

overcast

CF = Σ [ A LIQ CLWP + AICE CIWP ]

PWRF

PWRF

PWRF

Pseudosatellite Regions

Pseudosatellite Product

AMPS

MODIS

Figure shows:

High clouds in (1) well capturedand demonstrated in (2).Excessive clouds in Ross Sea (3) Low clouds over Ross Ice Shelf are not captured.

Overall, statistical testing shows the product better captures high clouds than low clouds

1200 UTC 21 Jan 2006

AMPS Cloud Forecast Evaluation (Nicolas and Bromwich 2010)

October 2003 ; 2006-2007Polar MM530 / 20 km basic horizontal resolution for AntarcticaReisner Single-Moment Microphysics

Look at Cloud Frequency and Precipitation vs. Satellite Remote Sensing,

ICESat GLAS Lidar AMPS Cloud Frequency

October 2003

AMPS Cloud Fraction

CALIPSO/CALIOP Lidar Cloud Frequency

AMPS Cloud Frequency

October 2007 – October 2006

Issues for Mesoscale Modeling of Antarctic Clouds

• Limited observations for comparison/inspiration/verification• Low aerosol concentrations• Clear-sky precipitation/diamond dust• Thin ice clouds• Ice cloud physics less well understood than liquid cloud physics• Non-spherical ice particles• Synergy between Arctic and Antarctic observational and modeling

studies?• How can we make use of more advanced (two-moment) cloud

microphysical parameterizations?• How can we make use of remote sensing?• Synergy with ice core studies