Antarctic sea ice thickness from airborne laser altimetry Tony Worby, - - PowerPoint PPT Presentation

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Mar 15, 2023 247 likes •413 views

Antarctic sea ice thickness from airborne laser altimetry Tony Worby, Jan Lieser, Adam Steer Antarctic Sea Ice Overturning circulation Sea ice extent (in millions of sq km) ARCTIC Max: 16 Min: 6 - 7 Record min in 2007: 4 ANTARCTIC Max: 19

SLIDE 1

Antarctic sea ice thickness from airborne laser altimetry

Tony Worby, Jan Lieser, Adam Steer

SLIDE 2

Overturning circulation

Antarctic Sea Ice

SLIDE 3

ARCTIC Max: 16 Min: 6 - 7 Record min in 2007: 4 ANTARCTIC Max: 19 Min: 3 - 4

Sea ice extent (in millions of sq km)

Source: NSIDC

SLIDE 4

Arctic Antarctic

Sea ice extent: Percent change per decade1979 - 2007

Turner et al., 2009

SLIDE 5

Turner et al., 2009

SH sea ice concentration: trend for Autumn 1979 – 2007

SLIDE 6

Arctic circulation changed in late 1980s

From Stroeve et al, submitted

Stroeve et al., Eos, 2008

SLIDE 7

Rothrock et al., 1999

Decline in Arctic sea ice thickness: 1958-76 to 1993-97

SLIDE 8

Much less is known about Antarctic sea ice thickness

Worby et al., 2008

SLIDE 9

ICESat Data over Antarctic Sea ice Snow-sea ice Freeboard Sea Ice Thickness Oct 4 - Nov 18, 2003 Snow Depth (AMSR-E)

m cm m

Courtesy: Jay Zwally

SLIDE 10

Factor of 2-3

ICESat and AMSR‐E data over Antarctic sea ice zone

Worby et al. 2008b Field observations Satellite data

AMSR‐E snow thickness compared with Antarctic field data

SLIDE 11

Airborne sea ice research

Scanning LiDAR (Surface elevation) Riegl LMS Q240i‐60 Pyrometer (Skin surface temp.) Heitronics KT 19 Inertial Nav System (Location & Orientation) OXTS RT‐4003 GPS Antennae Aerial Photo (Surface charact.) Hasselblad H3D II 50 / Nikon D1x

SLIDE 12

LiDAR freeboard validation

SIPEX Station 6: meanLiDAR: 0.24 m meanin‐situ: 0.25 m

Worby et al., 2011

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250.0
200.0
150.0
100.0
50.0

0.0 50.0 100.0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 snow top ice top bottom

Photo: Tony Worby

In situ measurements on Antarctic sea ice

SLIDE 14

Ice thickness estimation

meanLiDAR: 1.49 m ± 0.53 meanin‐situ: 1.15 m ± 0.67 Archimedes' buoyancy principle:

Worby et al., 2011

SLIDE 15

Surface elevation questions

Worby et al., 2011 Giles et al., 2008

In situ data Satellite radar data

SLIDE 16

Conclusions

Accurate sea ice thickness is critical for climate model

development (particularly ice thickness distribution)

Sea ice thickness retrievals from satellite altimetry require

accurate snow thickness measurements

Surface topography also plays an important role in

determining relative ice:snow thickness (different coefficients in buoyancy equation)

Combination of laser and radar altimetry are important to