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Basic hydrology, limnology, and climatology of the El’gygytgyn Crater region
Matt Nolan • University of Alaska FairbanksJulie Brigham-Grette • UMass Amherst
With support from the U.S. National Science Foundation, Kristin Scott Nolan,and the Lake El’gytygyn international science team
Walrus Snout PointSnout Bay
Buckle Point
The Bears Back
Outlet
1998 Core
N
Physical Overview of Lake El’gygytgyn AreaDigital Elevation Model
We created a digital elevation model of the region which can be used in a variety of terrestrial studies. The crater is roughly 18 km in diameter with a
watershed area of 293 km2 and lake area of 110 km2.
Physical Overview of Lake El’gygytgyn AreaDigital Elevation Model
Roughly 50 streams enter the lake and basic physical statistics were compiled on them using this DEM. This local stream numbering system should be adopted by researchers here to facilitate collaborations and minimize confusion. Coordinates exist for all outlets.
Physical Overview of Lake El’gygytgyn AreaImagery
We purchased Ikonos imagery of the crater region in 2001. This imagery was used to make a variety of 3D visualizations and is useful for a variety of terrestrial studies.
Water tracks
Submarine delta formation
Physical Overview of Lake El’gygytgyn AreaBathymetry
Using bathymetry from Russian sources (which seems quite accurate), we calculated lake volume and hypsometries. The lake contains roughly 14 km3 of water.
Though 175 meters seems deep, it is actually shallow compared to its 12 km width.
Physical Overview of Lake El’gygytgyn AreaWeather
A weather station was established in July 2000, and is presumably still running (if it hasn’t been shot again).
This station records air temperature, relative humidity, barometric pressure, wind speed and direction, rainfall, snow pack, solar radiation balance, and soil moisture.
August 31 September 1
Physical Overview of Lake El’gygytgyn AreaWeather
Enough said about how quickly the weather can change?
Physical Overview of Lake El’gygytgyn AreaWeather
Locally measured wind directions indicate a dominant trend. We hypothesize that this trend leads to water currents which work in concert with the stream delta
formation on the western shore to create the unique shape of the lake.
Prograding stream sediments
Bedrock
Physical Overview of Lake El’gygytgyn AreaWeather
Locally measured wind directions indicate a dominant trend. We hypothesize that this trend leads to water currents which work in concert with the stream delta
formation on the western shore to create the unique shape of the lake. That is, the center of the crater is not directly beneath the center of the lake.
Prograding stream sediments
Bedrock
Crater rim and center
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
Thermistor strings located in the deepest part of the lake indicate a textbook pattern of temperature stratification in winter and complete mixing in summer.
We did not detect any thermocline in summer, likely due to constant winds stirring up the water in this wide, thin lake.
Physical Overview of Lake El’gygytgyn AreaWeather
Locally measured air temperature compares quite well with the NCEP global reanalysis model output for this area, indicating that the NCEP model (running from 1948 to present) can be used as a reliable proxy for real measurements when needed.
Physical Overview of Lake El’gygytgyn AreaWeather
Given this good correlation, the NCEP data can also be used to help understand the dominant storm tracks and climate trends here, which is something I plan to do in the
near future, using tools like Hysplit and self-organized SLP maps as seen here.
Physical Overview of Lake El’gygytgyn AreaWeather
The NCEP reanalysis (1948-2002) is used to create give a sense of typical air temperature conditions throughout the year. March and April will no doubt be the
most comfortable and productive times for winter drilling.
Physical Overview of Lake El’gygytgyn AreaWeather
The NCEP reanalysis indicates that the region is currently undergoing a warming trend. This warming trend is being driven by winters with fewer extreme low temperatures,
which is good for winter drilling. It’s still plenty cold enough to make thick ice though.
E. 08 Nov 99 F. 25 Nov 99 G. 02 Dec 99 H. 26 Dec 99
A. 17 Sep 99 B. 26 Aug 99 C. 22 Oct 99 D. 01 Nov 99
I. 12 Jan 00 J. 05 Feb 00 K. 01 Nov 99 L. 05 Feb 00
N. 19 Mar 01 O. 19 Mar 01 P. 21 Mar 01M. 11 Nov 00 N. 11 Nov 00
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
We used space-borne SAR to track lake ice dynamics, including freeze-up, snowmelt, and breakup. Here, an interesting pattern of lake ice bubbles is seen developing.
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
These bubbles (the bright areas) are likely caused by the respiration and decomposition of living things. Given that the water is less than 3C, it is likely that warm dense water
from the shallow shelves sinks to the deepest part of the lake, even in winter, suggesting the deepest area may be biogeochemically different than its surroundings.
A. 17 May 99 B. 18 May 99
C. 8 May 00 D.11 May 00
G. 18 May 00 H. 19 May 00
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
We can determine the onset of snowmelt by the disappearance of the bullseye pattern, because SAR cannot penetrate wet snow.
E. 26 Apr 99
F. 17 May 00
I. 16 June 00: Landsat 7
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
The northern edge of the lake is usually blown free of snow, piling it up deeper to the south (as much as 1.5 meters). Ice melt begins at the edges of the lake, where the
shelves are present and surface streams pile up warm water.
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
D. 05 July 00C. 11 July 99A. 08 July 99
Lake ice breakup begins with moat formation along the margins. This frees the ice to move with the wind, where it begins getting hung up with the deltas at streams 12-14 (Snout Point and Buckle Point). Once these leads form, large pans are free to rotate
and crush, leading to rapid distintigration of the candle ice.
Table 1. Important dates of lake ice dynamics derived from SAR.
Winter
Onset of Lake Ice Freezing
Onset of Lake Ice
Snowmelt
Onset of Lake Ice Moat
Formation
Completion of Lake Ice Melt
1997-1998 No Data < 8 July < 8 July 8 July – 9 Aug
1998-1999 > 6 Oct17 May – 18 May
24 June – 4 July28 July – 13 Aug
1999-200016 Oct – 19 Oct
8 May – 11 May
23 June – 2 July16 July – 19 July
2000-200118 Oct – 20 Oct
14 May - 17 May
20 June – 23 June
13 July – 17 July
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
I plan to update this chart and combine it with further modeling as part of new work.
180
160
140
120
100
80
60
40
20
0
Ice
and
Sn
ow T
hick
ness
(cm
)
9/1/1999 11/1/1999 1/1/2000 3/1/2000 5/1/2000 7/1/2000 9/1/2000Date
-25
-20
-15
-10
-5
0
5
10
15
Te
mpe
rature (C
)
Modeled Ice Thickness
NCEP Air Temperature
Modeled Snow Thickness
Measured Lake Ice Coverage
Physical Overview of Lake El’gygytgyn AreaLake Ice Dynamics and Water Mixing
We can model lake ice breakup pretty well. As part of new work, I hope to determine the range of condition necessary to maintain a permanent ice cover, as well as model ice
sublimation, to determine the conditions necessary for lake levels to drop substantially.
Physical Overview of Lake El’gygytgyn AreaOutreach
We have a number of 3D visualizations of the lake online. These give a good sense of the what the crater region is like. You can also find some 360° panoramas there.
Physical Overview of Lake El’gygytgyn AreaOutreach
As part of future work, I plan to create several hundred high resolution spherical panoramas of the crater, in different seasons. I’m happy to train others to do this too.
Here is a demo of a similar project I am doing in north-eastern Alaska.