Monitoring polar climate change from space Thorsten Markus Cryospheric Sciences Branch NASA Goddard...

Monitoring polar climate change from space

Thorsten Markus Cryospheric Sciences Branch

NASA Goddard Space Flight CenterGreenbelt, MD

IPY sea ice project in the Antarctic sea ice

The big news last year: The record minimum in Arctic sea ice

Data from satellite passive microwave data

2007Previous minimum

2005

From Rothrock et al.

From Holland and Bitz, 2006

February 1996 September 1996

February 1996 September 1996

Importance of sea ice (1): Global energy balance; Ice/snow albedo feedback

Ocean

Forest

Snow/ice

Importance of sea ice (2): Ocean circulation

What makes the ocean move?1) Wind-driven surface currents 2) Thermohaline circulation

Change in temperature 30 years after collapse of the thermohaline circulation

Michael Vellinga, Hadley Centre

Importance of sea ice (3): Ecology, e.g. polar bears

February 1996 September 1996

??

From Gordon and Comiso, 1988

Moisture flux

Albedo

Ice drift

PrecipitationProcesses:

Warmer temperatures

More moisture

More precipitation

More freshwater input into ocean

More stable Southern Ocean

Less entrainment of WDW

Antarctic sea ice increase with global warming?

More sea ice production

Warmer temperatures

More moisture

More precipitation

More freshwater input into ocean

More stable Southern Ocean

Less entrainment of WDW

Antarctic sea ice increase with global warming?

More sea ice production

Thicker snowon sea ice

More snow-to-ice conversion

More thermal insulation

Less basal freezing

Change in sea ice volume as a function of precipitation(Balance between thermal insulation and snow-to-ice conversion)

IPY sea ice campaign in the Antarctic sea icePart of the project was dedicated to validate ICESat measurements

What is ICESat?

hs

hi

hf

i

s

w

ICESat (laser altimeter)

Cryosat2 (radar altimeter, 2009)

hs = snow depthhi = ice thickness hf = freeboard

What is missing? The 3rd dimension!

Preliminary ICESat freeboard measurements (for cloud-free areas only) on top of AMSR-E sea ice concentrations.

ICESat-derived freeboard(the height over the sea ice above water)

It is a long process to carefully validate satellite measurements of the polar regions and international collaboration is essential.

The polar regions are experiencing drastic changes and we still don’t fully understand all the processes but we cannot effort to turn our heads away.