Antarctic Airborne Measurements

Tom Lachlan-Cope(Alexandra Weiss, Russ Ladkin)

British Antarctic Survey

Instruments• Temperature + Humidity• Radiation• Turbulence (wind) • Fast Temperature, Humidity and CO2• Cloud probe• Aerosol• Camera• Laser Altimeter• Surface temperature

Human activity responsible for Larsen Ice Shelf collapse

Figure 1. Difference between positive and negative summer SAM

10-m wind field

• There is a significant recent trend in the Southern Hemisphere Mode (SAM) towards its positive phase in summer: result is 20% stronger circumpolar westerly winds.

• This reduces the blocking effect of the Peninsula, resulting in greater frequency of advection of relatively warm maritime air across the northern Peninsula from west to east (Fig. 1).

• A combination of a climatological temperature gradient across the barrier and the formation of a föhn wind (warm and dry) on the lee side causes a summer temperature sensitivity to the SAM that is three times greater east of the Peninsula than to the west.

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Flight track

Ascent Descent

Sea Ice Formation

• Air/sea/ice interaction• Boundary layer modification• Formation of deep ocean currents

IRT (surface Temp)

Air Temperature

CONVECTIVE HEAT TRANSFER OVER THIN-ICE COVERED COASTALPOLYNYASE. K. Fiedler, T. A. Lachlan-Cope, I. A. Renfrew, and J. C. King

JGR Oceans - inpress

Clouds

Increase in Cloud Condensation Nuclei

• Increased CCN mean more smaller cloud drops – not more cloud.

• More smaller drops mean increased albedo (clouds are whiter).

• More smaller drops mean less precipitation• Less precipitation mean clouds last longer• So in the end more clouds – perhaps.

What do we want to know

• Are Antarctic clouds similar to mid-latitude clouds?

• How can we represent Antarctic Clouds within climate models?

This Season

• ICEBELL– Aircraft measurements of sea ice coincident with

ship measurements– Scanning laser altimeter fitted

• Offcap– Measurements of cross Peninsular flow– Aircraft and ground based measurements

• Cloud measurements

Future work

• Arctic studies– Combined ground based and aircraft

measurements of aerosols and clouds.– Using BAS Twin Otter and NERC BA 146

• Aerosol inlet fitted to Twin Otter.