Why is it difficult to resolve future projections of Arctic-midlatitude linkages?
1. Why is it difficult to resolve
future projections of
Arctic-midlatitude linkages?
Zachary Labe
(Currently - postdoc with Libby)
Yannick Peings & Gudrun Magnusdottir
(PhD work - UC Irvine)
2 December 2020
Colorado State University
BMRRTH
Group Meeting
2. INPUT LAYER
HIDDEN LAYERS
OUTPUT LAYER
Layer-wise Relevance Propagation2-m Temperature
“2000-2009”Decade:
Labe and Barnes, in prep
REVEALING CLIMATE SIGNAL WITH XAI
19. [Newson, 1973;
Nature]
“…great warming of the
lower layers of the
troposphere over the
Arctic basin... In fact,
there is a lowering of
mid-latitude continental
temperatures near the
surface”
25. [ SIT ]
Sea Ice
Thickness
Depth between sea
surface and ice/snow
layer
[ SIC ]
Sea Ice
Concentration
Fraction (%) of seawater
covered by ice
Snow
Ice
[ SIE ]
Sea Ice
Extent
Area of seawater
covered by any
amount of ice (>15%)
26. [ SIT ]
Sea Ice
Thickness
Depth between sea
surface and ice/snow
layer
[ SIC ]
Sea Ice
Concentration
Fraction (%) of seawater
covered by ice
Snow
Ice
[ SIE ]
Sea Ice
Extent
Area of seawater
covered by any
amount of ice (>15%)
27. [ SIT ]
Sea Ice
Thickness
Depth between sea
surface and ice/snow
layer
[ SIC ]
Sea Ice
Concentration
Fraction (%) of seawater
covered by ice
Snow
Ice
[ SIE ]
Sea Ice
Extent
Area of seawater
covered by any
amount of ice (>15%)
29. R/V Lance – Greenland Sea – May 2017
Turbulent heat fluxes
[ SIC ]
30. R/V Lance – Greenland Sea – May 2017
Turbulent heat fluxes
[ SIC + SIT ]
31. WACCM4
Whole Atmosphere
Community Climate
Model version 4 –
Specified Chemistry
“high top”
chemistry-climate
atmosphere
model
Physical
parameterizations
from CAM4
• 66 vertical levels – extending to
5 x 10-6 hPa (140 km)
• 1.9° latitude x 2.5° longitude
• QBO prescribed from
radiosonde observations
• Improved representation of
sudden stratospheric warming
(SSW) events
• fixed radiative forcings from
year 2000
32. Future Arctic
How does sea-ice thickness
decline influence the large-
scale atmospheric response?
Significant thermodynamic
response over Arctic Ocean
Poleward weakening of jet
LABE ET AL. 2018, GRL
33. Future Arctic
Significant thermodynamic
response over Arctic Ocean
Poleward weakening of jet
LABE ET AL. 2018, GRL
How does sea-ice thickness
decline influence the large-
scale atmospheric response?
37. Assess the role of the Quasi-biennial
Oscillation (QBO) on the atmospheric
response to Arctic sea-ice loss
(Non)linearity in the polar
stratosphere?
38. Assess the role of the Quasi-biennial
Oscillation (QBO) on the atmospheric
response to Arctic sea-ice loss
Composite response by
QBO phase (~67 years)
Modulation
by QBO
Sea ice
experiments
40. Assess the role of the Quasi-biennial
Oscillation (QBO) on the atmospheric
response to Arctic sea-ice loss
Composite response by
QBO phase (~67 years)
Modulation
by QBO
Sea ice
experiments
Future (2051-2080)
Historical (1975-2005)
41. Assess the role of the Quasi-biennial
Oscillation (QBO) on the atmospheric
response to Arctic sea-ice loss
Composite response by
QBO phase (~67 years)
Modulation
by QBO
Sea ice
experiments
Future (2051-2080)
Historical (1975-2005)
42. Assess the role of the Quasi-biennial
Oscillation (QBO) on the atmospheric
response to Arctic sea-ice loss
Modulation
by QBO
Sea ice
experiments
Composite response by
QBO phase (~67 years)
Easterly (QBO-E)
Westerly (QBO-W)
43. Assess the role of the Quasi-biennial
Oscillation (QBO) on the atmospheric
response to Arctic sea-ice loss
Modulation
by QBO
Sea ice
experiments
Composite response by
QBO phase (~67 years)
Easterly (QBO-E)
Westerly (QBO-W)
44. Assess the role of the Quasi-biennial
Oscillation (QBO) on the atmospheric
response to Arctic sea-ice loss
Sea ice
experiments
Composite response by
QBO phase (~67 years)
Modulation
by QBO
Surface (thermodynamic)
Troposphere/Stratosphere
51. MOTIVATION
ARCTIC SEA ICE
MID-LATITUDE
WEATHER
Sea-ice thickness variability is important for reinforcing the
atmospheric response
Strength of Siberian High closely related to Eurasia cold spells
QBO can modulate teleconnections due to Arctic sea-ice loss
52. MOTIVATION
ARCTIC SEA ICE
MID-LATITUDE
WEATHER
Sea-ice thickness variability is important for reinforcing the
atmospheric response
Strength of Siberian High closely related to Eurasia cold spells
QBO can modulate teleconnections due to Arctic sea-ice loss
53. MOTIVATION
ARCTIC SEA ICE
MID-LATITUDE
WEATHER
Sea-ice thickness variability is important for reinforcing the
atmospheric response
Strength of Siberian High closely related to Eurasia cold spells
QBO can modulate teleconnections due to Arctic sea-ice loss
72. Atmospheric response sensitive to changes in Arctic sea-ice
thickness variability and background state (QBO)
Role of sea ice is small relative to Arctic amplification
(and internal variability)
Zachary Labe
zmlabe@rams.colostate.edu
@ZLabe
73. Atmospheric response sensitive to changes in Arctic sea-ice
thickness variability and background state (QBO)
Role of sea ice is small relative to Arctic amplification
(and internal variability)
QUESTIONS…
Zachary Labe
zmlabe@rams.colostate.edu
@ZLabe
97. Dependence of the
Siberian High response on
polar mid-tropospheric
warming
Gray bar shows the
uncertainty range between
NCEP/NCAR R1 and ERA5
for 10-year epochs
98. 1. Climate models forced only by sea-ice anomalies do not
capture the vertical extent of Arctic warming
2. Increase in 1000-500 hPa layer is linked to a strengthening of
the Siberian High and cold anomalies in eastern Asia
3. Role of the stratosphere is unclear due to large internal
variability at future global warming levels of 2°C
Arctic amplification >> sea-ice loss
99. 1. Climate models forced only by sea-ice anomalies do not
capture the vertical extent of Arctic warming
2. Increase in 1000-500 hPa layer is linked to a strengthening of
the Siberian High and cold anomalies in eastern Asia
3. Role of the stratosphere is unclear due to large internal
variability at future global warming levels of 2°C
Arctic amplification >> sea-ice loss
114. 1. Small signal in dynamical response to sea ice decline
relative to internal variability and climatology
2. Strong surface warming and increase in precipitation mostly
confined to Arctic Ocean
3. AGCM experiments need even larger ensembles (>200
members) to address the noise
Is the circulation response to Arctic sea ice
loss actually robust in the context of
internal variability?
119. NAME SEA ICE FORCING DURATION
Historical Average 1976-2005 LENS SIT
Average 1976-2005 LENS SIC
ONDJFM;
200 members
Future Future 2051-2080 LENS SIT
Future 2051-2080 LENS SIC
ONDJFM;
200 members
All experiments have average 1976-2005 LENS SST*
Atmospheric General Circulation Model
Experiments