Andrews, Lauren

English

NASA Technical Reports Server

Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Lauren Andrews* with contributions from Richard Cullather, Kristin 
Poinar, Manuela Girotto, the GEOS-S2S Group, & others
*Mistakes my own
IARPC Webinar
30 January 2020
1
Meltwater routing in GEOS: current activities and plans
https://ntrs.nasa.gov/search.jsp?R=20200000778 2020-03-28T18:44:20+00:00Z
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Current representation in GEOS
Ongoing work and 
relevant projects
Meltwater routing in GEOS: current activities and plans
The glacial hydrologic system (in short) 
Near-term plans*
C
ul
la
th
er
 e
t a
l. 
(2
01
9)
M
ah
an
am
a
et
 a
l. 
(2
01
5)
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
The glacial hydrologic system
Chu (2013)
Dynamic impacts on glacier
and ice sheet mass loss
Location and routing delay 
of glacier and ice sheet runoff
Response to current 
climate conditions 
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Smith et al. (2017)
Modified from https://earthobservatory.nasa.gov/images/80677/greenland-melt-ponds
Important surface characteristics:  
Bare ice routing delays
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Important surface characteristics:  
Firn routing modifications
Firn processes and local conditions can 
accelerate or delay meltwater delivery 
to the ocean.  
MacFerrin et al. (2019)
Miège et al. (2016) 
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Important subglacial characteristics
Chandler et al. (2013)
Poinar et al. (2019)
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Glacier and ice sheet representation in GEOS
What’s missing in 
GEOS (for ice sheets 
are glaciers)?
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Previous surface routing What GEOS can do now 
(GEOS-S2S v3)
Glacier and ice sheet representation in GEOS:
surface routing improvements
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Previous surface routing What GEOS can do now 
(GEOS-S2S v3)
Glacier and ice sheet representation in GEOS:
surface routing improvements
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Firn and snow processes
aersol darkening
Glacier and ice sheet representation in GEOS:
near term improvements
M
ah
an
am
a
et
 a
l. 
(2
01
5)
Improved ice surface catchment representation
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Firn and snow processes
aersol darkening
Glacier and ice sheet representation in GEOS:
near term improvements
Improved ice surface catchment representation
ArcticDEM Mosaic v7 (Polar Geospatial Center)
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Glacier and ice sheet representation in GEOS:
routing delay implementation
Gurnell (1993)
W
Locally 
produced
runoff 
Locally 
produced
runoff 
Qin from 
upstream 
catchments
Qout to 
downstream 
catchment 
(ice, land) or 
ocean
Local storage in snow or 
supraglacial features
Linear reservoir model 
𝑄 = 𝑘𝑊; 𝑘 = 𝑓(𝑏𝑎𝑠𝑖𝑛 𝑔𝑒𝑜𝑚𝑒𝑡𝑟𝑦 & 𝑐𝑜𝑛𝑑𝑖𝑡𝑖𝑜𝑛𝑠)
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Related work:
parameterizing surface to bed connections
Yang & Smith (2018) Hoffman et al. (2018)
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Related work:
parameterizing surface to bed connections
Andrews & Poinar (2019)
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Andrews & Poinar
Related work:
parameterizing surface to bed connections
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Schematic of he GEOS 
weakly coupled 
land/atmosphere data 
assimilation system, 
showing the coupling of 
the GEOS EnKF for land 
assimilation to the GEOS 
3D-Var for atmospheric 
assimilation 
(MODIS and SMAP) 
(Soil Moisture and Snow Analysis)
Related work:
snow data assimilation
Toure et al. (2018)
Ad
ap
te
d 
fro
m
 D
ra
pe
r &
 R
ei
ch
le
 (2
01
9)
Land–climate interactions, including snow–atmosphere coupling, are important 
sources of weather and climate predictability. 
High Mountain Asia Program Project (M. Girotto & L. Andrews) will develop 
a coupled Land- Atmosphere- and Ocean- S2S framework with a primary 
goal of snow observation assimilation. 
Global Modeling and Assimilation Office
gmao.gsfc.nasa.gov
National Aeronautics and Space Administration
Expected issues and final thoughts
Goals
• Development of physically consistent ice 
catchments
• Implementation of time delayed routing scheme
• ‘seamless integration’ with current land 
routing scheme
• Firn model/processes
• Aerosol snow/ice darkening
• Reanalysis integration
Likely issues
• Calibration and validation of k and ice 
sheet/glacier runoff
• Differences between model ice extent and 
natural ice extent
• Runoff and calving integration with ocean model
Thoughts
• Subglacial hydrology is not relevant for the 
current versions of GEOS, but this structure 
and a stochastic model for englacial drainage 
features should readily allow its treatment 
within GEOS-ISSM coupled framework.


Meltwater Routing in GEOS: Current Activities and Plans

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