ENHANCED TEMPERATURE INCREASES
IN HIGH ALTITUDE REGIONS
JIM MILLER AND IMTIAZ RANGWALA
COLLABORATORS:
YONGHUA CHEN
GARY RUSSELL
MIKE FERRARI
JENNIFER FRANCIS
CATHERINE NAUD
MING XU
San Juan Mountains, Colorado
Photo: I. Rangwala, June 2007
OUTLINE
POTENTIAL CAUSES OF ENHANCED WARMING
(ALBEDO, WATER VAPOR, CLOUDS)
GLOBAL CLIMATE MODEL SIMULATIONS
(ARCTIC AND TIBETAN PLATEAU)
POSITIVE FEEDBACK LOOPS
ENHANCED WARMING BY WATER VAPOR
EXAMPLES (TIBETAN PLATEAU, ALPS,
SAN JUAN MTS., COLORADO)
SUMMARY
WATER
IMPACTS CLIMATE CHANGE
AND
IS IMPACTED BY CLIMATE CHANGE
IN ALL THREE PHASES
SOLID
LIQUID
GAS
SOLID
SOLID, LIQUID,GAS
LIQUID
Coupled Climate Model
Schematic
MODEL SIMULATIONS
 GISS AOM (3o Latitude x 4o Longitude)
Coupled Atmosphere – Ocean GCM
(Russell et al. 1995; http://aom.giss.nasa.gov)
 9 layers of atmosphere and 13 layers of ocean
 Transient experiments
 Time period: 1850 – 2100 (250 years)
 Analysis of the model output for Tibetan Plateau
Modeling Feedbacks – Climate Change Experiments
2090
Polar Amplification of Global Warming
1979
2005
2060
2030
2002
Francis et al.
Modeling Feedbacks – Illustration of feedbacks
TEMP.
_
+
SEA ICE
ABS. SOLAR
+
_
ALBEDO
Chen et al., 2005
TEMPERATURE
+
+
WATER VAPOR
DLF
DLF
+
DLF = Downward longwave flux
WINTER
Tibetan Plateau (TP)
Tibetan
Plateau
Late 20th Century Climate Change in the TP
 One of the highest rates of warming in the
northern hemisphere
[Liu and Chen, 2000]
 Largest warming during winter
[Du et al., 2004;
Liu and Chen, 2000; Shenbin et al., 2006; You et al., 2007]
 Winter warming at least twice as high as
any other season
[Liu and Chen, 2000]
 Elevation dependent warming (EDW) trend
between 1960-1990
[Liu and Chen, 2000]
Causes have not been adequately addressed !
Tibetan
Plateau Observed
vs Modeled: Elevation Dependent Warming
Liu and Chen, 2000
Tibetan
Plateau
Modeled DLR vs Specific Humidity (q)
Output from 1950-2100
Observed q: 1961-2000
Slope: Sensitivity of DLR to q
1-D Radiative Transfer Model (RRTM) Experiments
Case: Tibetan Plateau
Study: Assessed changes in downwelling longwave radiation (at surface) for a
higher and lower elevation location for a summer and a winter month
Experimental Setup:
Changes in DLR by increasing q by 0.4 g/kg in the Boundary Layer
6
• 1-D Radiative Transfer Model
5
• 29 atm. layers
• “q” increased only in the BL by
0.4 g/kg
DLR change (W/m2)
• Atm. Column from ERA-40
4
3
2
1
0
High – 5138m
Low – 114m
High - Dec
Low - Dec
High - Jun
Low - Jun
The Jungfrau
Observations of SWVF from Swiss Alps
Monthly means in DLR and q from 2001-2004
Jungfraujoch – 3584m, Locarno Monti – 388m
Rucksthul et al., 2007 (JGR)
San Juan Mountains, Colorado
LIQUID
Rangwala, et al., 2010, AAAR
Senator Beck Study Plot (SBSP)
“DLR – q” relationship from higher
up in the San Juans
Elevation = 12,200 ft
Swamp Angel Study Plot (SASP)
Center for Snow and Avalanche Studies, Silverton
Elevation = 11,050 ft
SUMMARY
ENHANCED WARMING CAUSED BY
SNOW/ICE ALBEDO FEEDBACK
LATE SPRING AND EARLY SUMMER
WATER VAPOR
WINTER AND FALL WHEN
SPECIFIC HUMIDITY IS LOW
ELEVATION DEPENDENT WARMING(?)
SIMILARITIES/DIFFERENCES IN ARCTIC
San Juan Mountains, Colorado
Photo: I. Rangwala, June 2007
Wemenuchi Wilderness
San Juan Mountains, Colorado
Photo by I. Rangwala, Aug. 2007,