Evaporation Measurements from Two Contrasting Arctic Lakes
Peter Blanken
Philip Marsh; Mark Russell; Cuyler Onclin
University of Colorado
Department of Geography
260 UCB, Boulder, CO
80309-0260
blanken@colorado.edu
National Hydrology Research Centre
Environment Canada
11 Innovation Blvd.,
Saskatoon, SK
Canada, S7N 3H5
Are undergoing rapid environmental change (e.g. ice
cover duration change; thaw subsidence and rapid
drainage).
LE
Results
3
4
5
6
Perimeter (km)
7
8
9
Count
0.1
0.2
0.4
0.5
0.6
0.8
0.9
100
1
0
0.1
0.78
0.2
0.3
0.4
0.5
0.6
Circularity
0.7
f = 4πA P
0.8
0.9
2
Fig 1. Histograms of lake
perimeter, area, and circularity
Methods
(circle = 1) for all lakes > 5,000
2
m
in
the
100
x
100-km
study
Eddy covariance (sonic
region.
anemometer and krypton).
Standard suite of corrections.
Ancillary radiation and
meteorological measurements.
2005, 2006, 2007 ice-free
measurements; 30-min means.
200
0
250
200
250
0.57
0
2
2
2
1.5
1.5
1.5
1
1
1
0.5
200
250
DOY 2005
200
250
DOY 2006
200
0
250
200
250
200
200
100
100
100
0
250
200
250
200
200
100
100
100
0
0
0
200
250
DOY 2005
r
0.88
200
250
0.38
200
250
200
250
DOY 2007
10 ­ 11
10 ­ 11
EAST
9 ­ 10
8 ­ 9
8 ­ 9
7 ­ 8
7 ­ 8
6 ­ 7
6 ­ 7
5 ­ 6
5 ­ 6
4 ­ 5
4 ­ 5
3 ­ 4
3 ­ 4
2 ­ 3
2 ­ 3
Fig 2. Wind direction frequency and speed (m s ) for Denis
Lagoon (A) and TUP lake (B) for all data (2005, 2006,
2007). Greater frequency of east winds at Denis Lagoon
compared to prevailing NW winds at TUP lake.
0
0
30
300
330
60
50
300
270
90
240
120
210
150
180
30
60
100
250
200
100
0
0
1
2
3
4
5
6
7
4
5
6
7
­1
U (m s )
1 ­ 2
SOUTH
TUP
200
Rn (W m )
WEST
Denis
150
­2
9 ­ 10
1 ­ 2
330
100
100
50
100
270
90
240
200
100
0
0
1
2
3
Fig 5. 24-hr mean energy
balance components (net
radiation, latent and
sensible heat; W m-2) for
Denis (blue) and TUP (red).
0.55
200
250
DOY 2006
50
Fig 4. 24-hr mean general
meteorological conditions (air
temperature, wind speed,
atmospheric vapor pressure)
for Denis (blue) and TUP
(red).
200
250
DOY 2007
0
200
250
0.91
0
200
200
200
0.5
100
0
-1
1
5
100
2%
SOUTH
0.15
5
4%
EAST
Area (km )
200
5
250
0
11 ­ 12
0.7
10
100
6%
6.18
0.3
10
200
LE (W m )
NORTH
2%
WEST
0
10
200
­2
10
2
0
B
NORTH
6%
0.14
0
200
LE (W m )
2
250
200
LE (W m )
1
200
­2
0
0
250
200
4%
500
0
10 km
200
­2
0
10
0
H
Long (778 m); narrow
(163 m); deep (6 m);
circularity 0.15;
surface area 0.14 km2.
A
9.95
10
0
Typical in Shield terrain
Objectives
3.51
10
0.5
TUP Lake
500
20
0
Rn
Occur at a broad spectrum of size, shape, and volume
distributions across vast areas and latitudinal gradients.
Compare/contrast
two different small
lakes: round and
shallow vs. long and
deep; northern and
southern, to help
address this
question.
20
r
0.92
Fig 6. Controls on the 24-hr
mean latent heat flux from
Denis (blue) and TUP (red):
net radiation; horizontal wind
speed; product of horizontal
wind speed and the difference
between water surface and
atmospheric vapor pressure.
­1
Ude (m s kPa)
Conclusions
Except for wind speed and direction,
met. conditions and net radiation
were indistinguishable at both sites
despite 90 km N-S separation.
120
210
150
180
Fig. 3. Latent (blue) and sensible (red) heat fluxes (W m-2) as
a function of wind direction for all data. We can “see” the
lake with the larger latent heat ~325-100 degrees (Denis:
48% of the data; TUP: 27%); only these data were used in
the subsequent analysis.
250
Although low correlation between LE
between sites, the best predictor of
LE was Ude at both sites.
Despite differences in location, size,
shape, and depth, nearly identical
evaporative water losses (Fig 7).
200
Total E (mm)
Round (3.0 by 2.7 km);
shallow (1 m);
circularity 0.78;
surface area 6.18 km2.
Denis
20
0
U (m s )
Typical in flat,
permafrost terrain.
Play an important role in the energy, water, and carbon
cycles at the local to regional scale.
TUP
30
o
Denis Lagoon
N
How does the magnitude and controls of lake evaporation
vary across this spatial and morphological gradient?
30
­1
Are a ubiquitous part of the landscape : over a 100 x
100-km area surrounding the study sites, there are
3,727 lakes with an area > 5,000 m2 , representing 28%
of the land area.
Ta ( C)
Study Sites
ea (kPa)
Introduction - Northern Lakes:
30
150
100
50
0
0
200
400
600
DOY since Jan 1 2005
800
1000
Fig 7. After three
years, the total
evaporative water
losses were 249
(Denis-blue) and 251
mm (TUP-red) .