koji fujita
TRANSCRIPT
Climate regime and Sensitivity of Asian Glaciers Revealed by GAMDAM Glacier Inventory
ClimDev 14 Jan. 2015
Akiko Sakai and Koji Fujita Nagoya University
GAMDAM: Glacier Area Mapping for Discharge in Asian Mountains
1st Motivation <glacier inventory>
Glacier
Sea level change Water resource
Glacier volume change
Glacier Inventory
Kääb et al., 2012 Gardner et al., 2013
Discharge from glacier
Karser et al., 2010 Immerzeel et al., 2010
Mass balance profile Area-altitude
distribution of glaciers
Alt
itu
de
Positive Equilibrium Negative
- +
Important parameter to estimate river runoff
BUT Gridded data observed data
2nd Motivation <precipitation in mountain>
at Karabat kak Glacier
Observation
Sakai et al. (in prep.)
Purpose
Glacier
1. Create quality controlled glacier inventory
2. Estimate precipitation over glaciers using an ELA concept
to reveal climate regime
Target region: High Mountain Asia
Glacier Area Mapping for Discharge in Asian Mountains
Coverage & Data source
Manual delineation • Data source
– LANDSAT (USGS)
(1999-2003)
226 path-row
356 scenes – Thermal band
– Contour line
– Slope
– Basin polygon
– Google Earth
• Delineation tests
• Two years, total 10 persons
• 82,776 glaciers in total no glacier
Nuimura et al. (2014TCD, in 2nd review)
GAMDAM vs. ICIMOD
HKH region Area (×103 km2)
GAMDAM 40.3
ICIMOD 40.6
Each 0.5×0.5 degree grid cell
Consistent each other
Nuimura et al. (2014TCD, in 2nd review)
Median elevation of GAMDAM GAMDAM Glacier Inventory
& ASTER-GDEM2
Glacier Inventory of China (Shi, 2008)
Nuimura et al. (2014TCD, in 2nd review)
Median Altitude vs. Observed ELA
Mass balance at median elevation = 0 (in the past few decades)
Braithwaite & Raper (2009)
ELA observation at 10 glaciers Dyurgerov (2002); Fujita & Nuimura (2011)
Balanced budget ELA = Median glacier elevation ELA: equilibrium line altitude mass balance =0
rmse = 71 bias = + 2.8
GAMDAM glacier inventory + GDEM2
Ob
serv
atio
n
Sakai et al. (2014TCD, in revision)
Calculating Optimized Precipitation at ELA
GAMDAM Glacier Inventory
Input data <ERA-Interim > Air temperature (level) Solar radiation(surface flux ) Wind speed (surface flux 10m) Relative humidity (surface)
precipitation=APHRODHITE ×Ap
Mass balance model Fujita & Ageta (2000) (energy balance model)
Yatagai et al. (2009, 2012)
Sakai et al. (2014TCD, in revision)
APHRODITE precipitation
Yatagai et al. (2009, 2012)
Optimized precipitation at ELA
Sakai et al. (2014TCD, in revision)
Validation –Winter Balance-
Observed data at 12 glacier Dyurgerov (2002)
1979-2004
Validated by observed winter balance
rmse to observation Aphrodite snow = 503 mm Optimized snow = 292 mm
Sakai et al. (2014TCD, in revision)
Summer accumulation
Winter accumulation
JJA precipitation ratio
Analysis –Ta vs. Pr at ELA-
Summer accumulation
Winter accumulation
Sakai et al. (2014TCD, in revision)
Summary & Perspectives
A novel GAMDAM glacier inventory
Optimized precipitation at ELA
Spatially heterogeneous glacier response over the High Mountain Asia
• The GAMDAM will be provided/merged to Randolph v5 within this year
Contact: Akiko Sakai <[email protected]>
• Contributions of Sensitivity, dAT and dPR to changes in glaciers