freshwater runoff from greenland sebastian h. mernild ph.d. & post doc. university of alaska...

Freshwater Runoff from Greenland Sebastian H. Mernild

Ph.D. & Post Doc.

University of Alaska Fairbanks

International Arctic Research Center and Water & Environmental Research Center

Runoff from Greenland

Freshwater contribution from:

- GrIS (runoff and calving)

- Local glaciers (runoff and claving)

- Snow cover (runoff)

- Net liquid precipitation (runoff).

Runoff from Greenland

D. Rumsfeld, former U.S. Secretary of Defense:

“There are things we know.

There are things we know we don’t know.

There are things we don’t know we don’t know.”

D. Rumsfeld, former U.S. Secretary of Defense:

“There are things we know.

There are things we know we don’t know.

There are things we don’t know we don’t know.”

Related to runoff from Greenland

Change surface air temperature, 1957-2006Annual Winter

“There are things we know.

- Increasing air precipitation 1% per decade,

- More precipitation falls as rain,

- Longer thawing season 2-3 weeks (since 1993) East Greenland,

- Longer snow-free season 50-60 days (since 1993) East Greenland,

- Negative local glacier net mass balance East Greenland.

“There are things we know.

“There are things we know we don’t know.

There are things we don’t know we don’t know.”

Runoff amount…

Runoff variation (space and time)…

Break-up time…

Max discharge…

Runoff contribution…

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.

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Therefore my Ph.D. and Post Doc.-study…

Few MET and hydrometric data from East Greenland because of rough terrain, harsh climatic conditions, and remote locations.

Only two areas are at present well documented in Met and hydrology:

- Low Arctic Mittivakkat Glacier catchment, Sermilik, Ammassalik Island, SE Greenland.

- High Arctic Zackenberg River catchment, NE Greenland.

Low Arctic, High precipitation,

Large precentage of glacier cover,

High Arctic, Low precipitation,

Low precentage of glacier cover.

East Greenland catchments…

Glacier mass balance and snow modeling by SnowModel:

Spatial snow evolution: Snow accumulation, Snow distribution,

Evaporation,Snow-blowing sublimation,

Snow surface melt.

Spatial Glacier melt: Glacier ice surface melt.

SnowModel is used at Mittivakkat, Zackenberg, and GrIS.

At the moment it is s a NON-glacier dynamic model – but in aumumn 2007 dynamic routines will be incorporated...

Example: Spatial SnowModel SWE Depth and Runoff at the Mittivakkat Glacier catchment

End of Winter SWE Depth Yearly Runoff

Mittivakkat (65°N) (14 km2) Zackenberg (74°N) (101 km2)

Period 1999-2004 1997-2005

P (mm w.eq. y-1) 1,491 255

E + Su (mm w.eq. y-1) 260 * 115 **

R (mm w.eq. y-1) 1,983 1,487

ΔS (mm w.eq. y-1) -616 -1,347

ΔS OBS(mm w.eq. y-1) -600 ------

* Approximately 12% of solid precipitation was returned to the atmosphere. ** Approximately 18% of solid precipitation was returned to the atmosphere.

SnowModel used on glaciers at Mittivakkat and Zackenberg

Runoff modeling:

Time-Area method with SnowModel (hourly time step),

NAM, lumped conceptual model with degree-day (daily time step),

MIKE-SHE, spatial distributed model with SnowModel (daily time step).

Mittivakkat (65°N) Zackenberg (74°N)

Period 1993-2004 1997-2005

Catchment area (km2) 18.4 512

Glacier cover (%) 78 20

Average SIM runoff (mm w.eq. y-1) 1,975 428

Average SIM runoff (m3 y-1) ~37×106 ~219×106

Annual specific SIM runoff (l s-1 km-2) ~63 ~14

Glacier contribution of total

SIM yearly runoff (%) ~ 90 – 95 ~ 50 – 90

Comparison of average freshwater runoff from Mittivakkat and Zackenberg

Runoff from the entire Greenland

Iceberg calving ??? km3 per year

Greenland Ice Sheet ??? km3 per year

Net precipitation ??? km3 per year

Local glaciers/ice sheets ??? km3 per year

Total: ??? km3 per year

2002

MET data from DMI and the Koni Steffen GroupeAt CU, Boulder(1996-2005)

SnowModel

Mass balance and runoff from GrIS

2002

GrIS extent non-summer surface melt(GrIS interior)

GrIS extent non-summer surface melt(GrIS interior)

Mass balance and runoff from GrIS

East Greenland 1999-2004

Iceberg calving 116 km3 per year(Literature studies)

East GrIS 141 km3 per year(SnowModel) (missing: routing the water to the margin)

Net liquid precipitation 168 km3 per year(SnowMode/MicroMet)

Local glaciers/ice sheets 13 km3 per year(satellite pic’s/map of glacier cover and SnowModel)

Total: ~440 km3 per year(equals ~10% of the total freshwater input from the Arctic

Ocean to the Greenland Sea)

Present work…

- GrIS mass balance and runoff (1950-2080) (SnowModel)

DMI-data (HIRHAM 4, 25 km2) (CSU and CU),

- GrIS mass balance and runoff (1996-2006) (SnowModel)

NARR-data

Compare to DMI and Koni Steffen-data

(CSU and CU)

- Routines for glacier dynamic and runoff routing

(SnowModel) (CU)

- Routines for temperature inversion (SnowModel)

(Mittivakkat and Zackenberg) (CSU and UC)

The End

Thanks…!!!