Lake evaporation, the nexus between the lake hydrological
cycle and its energy balance, is sensitive to climate change.
Two hypotheses have been proposed to explain interannual
variations in lake evaporation. In the first hypothesis, water
surface evaporation will increase as air temperature rises,
at a rate of about 7% K-1 predicted by the Clausius-
Clapeyron equation. The second hypothesis, supported by
the universal decline trends in pan evaporation tied to
global diming, is that evaporation variabilities are
controlled by variabilities in the surface solar radiation.
Lake Evaporation in a Changing Climate Wei Wang1, Xuhui Lee1,2, Lei Zhao3, Zachary M. Subin4
1. Yale-NUIST Center on Atmospheric Environment, Nanjing University of Information Science & Technology, Nanjing, 210044, China; Email: [email protected]
2. School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, 06511, USA
3. Woodrow Wilson School of Public and International Affairs, Princeton University, Princeton, NJ, 08544, USA
4. Princeton Environmental Institute, Princeton University, Princeton, NJ 08544, USA
AMS 22BLT
# 15
To investigate the mechanisms underlying the response of
long-term lake evaporation variations to climate change,
using NCAR’s CLM4.5-LISSS (Lake, Ice, Snow, and
Sediment Simulator).
nR G E H
H
E
1 1+ 1
nE R G
β – Bowen ratio (dimensionless)
H – sensible heat flux (W m-2)
λE – latent heat flux (W m-2)
Rn – net radiation (W m-2)
G – heat flux into lake (W m-2)
α – Priestley-Taylor coefficient with a standard value of
1.26 (dimensionless)
Δ – slope of saturated vapor pressure curve relative to
temperature (Pa K-1), increasing with air temperature
(Ta) nonlinearly.
γ – psychrometric constant (Pa K-1) (e) Bowen ratio difference, 2091-2100 mean
minus 2006-2015 mean
0 50 100 150 2000
50
100
150
200
E
-Mo
d (
W m
-2)
E-Obs (W m-2
)
y=0.94x, N=27, R=0.82, p<0.01
I=0.90, RMSE=21.27 W m-2
(c) Evaporation difference, 2091-2100 mean
minus 2006-2015 mean (d) Freshwater flux (precipitation minus evaporation)
difference, 2091-2100 mean minus 2006-2015 mean
(f) The temporal sensitivity of latent heat flux to
air temperature from 2005 to 2100
(b) Standard deviation of latent heat flux
Global lakes are divided into five broad climate zones (tropical, arid, temperate, cold and polar)
according to the Köppen-Geiger climate classification. qa - specific humidity (g kg-1). U10- mean wind
speed at 10 m height (m s-1). K↓- downward solar radiation (W m-2). *** indicates that the variable trend
is significant at 99% significant level. NS means that no significant trend is detected.
(a) Bowen ratio varying with air
temperature for every lake-year
(c) Bowen ratio varying with air
temperature for 2005-2100 global lake
area-weighted mean
(d) Temporal sensitivity of Bowen ratio
to air temperature for every lake-year
Validation of lake evaporation simulated with NCAR’s CLM4.5-LISSS. Left panel:
comparison with monthly observations at Lake Taihu. Right panel: comparison with
annual mean evaporation data found in the literature for 27 lakes.
(b) Bowen ratio varying with air
temperature for every lake 2005-2100 mean
0o 60
oE 120
oE 180
oW 120
oW 60
oW
80oS
40oS
0o
40oN
80oN
40
60
80
100
120
140
160
180
200(a)
W m-2
0o 60
oE 120
oE 180
oW 120
oW 60
oW
80oS
40oS
0o
40oN
80oN
4
6
8
10
12
W m-2
(b)
0o 60
oE 120
oE 180
oW 120
oW 60
oW
80oS
40oS
0o
40oN
80oN
50
100
150
200
250
300
350
400
450
mm year-1
(c)
0o 60
oE 120
oE 180
oW 120
oW 60
oW
80oS
40oS
0o
40oN
80oN
-500
-250
0
250
500(d)
mm year-1
0o 60
oE 120
oE 180
oW 120
oW 60
oW
80oS
40oS
0o
40oN
80oN
-0.3
-0.25
-0.2
-0.15
-0.1
-0.05
0(e)
0o 60
oE 120
oE 180
oW 120
oW 60
oW
80oS
40oS
0o
40oN
80oN
0
2
4
6
8
10
W m-2
C-1
(f)
(a) 2005-2100 mean latent heat flux
Regions Ta
oC decade
-1
qa
g kg-1
decade-1
U10
m s-1
decade-1
K↓
W m-2
decade-1
Rn
W m-2
decade-1
λE
W m-2
decade-1
β
decade-1
Tropical 0.39***
0.33***
0.02***
0.48***
1.55***
1.99***
-0.005***
Temperate 0.39***
0.24***
NS 0.46***
1.23***
1.67***
-0.006***
Arid 0.34***
0.24***
-0.006***
-0.40***
0.83***
1.32***
-0.004***
Cold 0.23***
0.13***
NS -1.40***
-0.27***
0.38***
-0.008***
Polar 0.24***
0.09***
NS -1.41***
-0.41***
0.28***
-0.012***
Global 0.28***
0.18***
NS -0.81***
0.27***
0.85***
-0.007***