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: wangwnuist@163.com

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***