THE ENERGY BUDGETS OVER HUAIHE RIVER BASIN
DURING LAPS PERIODSHU Guoquan(胡国权) andDING Yihui（丁一汇）National Climate Center, CMA, Beijing 100081
HU Guoquan,Ph.D.

address: Laboratory for Climate Change Studies
National Climate Center
China Meteorological Administration
No.46 Zhongguancun Nan Dajie, Haidian
Beijing ,100081, P. R. China
TEL:(8610)68408676

FAX:(8610)68408758 or (8610)62180679

E-mail:hugq@cma.gov.cn

ABSTRACTIn different synoptic conditions and at different time scales, the analysis of the energy
budgets by Bowen Ratio Method and Bulk Schemes over Huaihe River Basin during the fieldobservation periods of 2003-2005 shows:1)In summer, the energy budgets calculated by Bowen Ratio method show that theaveraged latent heat flux is 4 times more than the averaged sensible heat flux during the fieldobservation period. The latent heat flux account for more than 80％ of the net radiation, and thisis the similar to the case of the 1998.
2)In the whole period, the upward long-wave radiation, the upward and downward
short-wave radiation, the net radiation, the sensible and latent heat flux, the soil heat flux change
in phase, but the variation of the downward long-wave is not all in phase in the observation period
and is complex.
3)The energy budgets in clear and cloudy conditions: the variation of total cloud amount isout of phase with the values of the sensible heat flux and the latent heat flux4) The energy budgets in rainy and rainless conditions: during the rainy period, the values ofthe sensible and latent heat flux are small, but during no rainy period thereafter the values of themreach maximum.
5) The variation of the latent heat flux is in phase with the evaporation measured byevaporating dish, , which indicates that the latent heat flux calculated by bulk schemes is reliable.

I. DATA AND COMPUTATIONAL METHODThe Energy budgets observations are mainly in the field at Shouxian Station (117°23′E，32°57′N).
The exchange between the land and the air can be studied by the equation of the underlying
surface energy balance.
The underlying surface energy balance equation:
Rn =H+LE+G
Where Rn is the net radiation, G is the soil heat flux, H is the sensible heat flux, and LE is
the latent heat flux.

And,Rn = Srd − Sru + Lrd − Lru
where, Srd and Sru are downward and upward short-wave radiations, Lrd and Lru are
downward and upward long-wave radiations.
G, Srd, Sru, Lrd and Lru can be obtained by observation, but H and LE can be gotten byfollows,
1. Bowen Ratio Method
Based on the energy diffusion function, the Bowen Ratio can be expressed by the following:(1)Bowen Ratio β = H / LE = γ Δt / Δewhere γ is the psychrometric constant,Δt and Δe are the gradient of temperature andwater vapor pressure in vertical.
(2)After Bowen Ratio obtained, H and LE can be calculated by the following equations:

LE = ( Rn − G ) /(1 + β )H = Rn − G − LE = β LE
2. Bulk Schemes:
The sensible heat flux

H = ρC p CT U S (Ta − Tg )The latend heat flux

LE = ρLC EU S (q a − q g )The momentum flux

Fm = ρC D Us 2

Where ρis the air density near land, CP is the specific heat of air at constant pressure,
L is the latent heat of vaporization, CT, CE and CD are the bulk drag and transfer coefficients ofsensible, latent heat and momentum, Ta and Tg are the air and underlying surface temperature,respectively, qa and qg are specific humidity of the air and the underlying surface, Us is the windspeed at 10 m.
3.Eddy Correlation method
The sensible heat flux

H = ρC p w′T ′The latend heat flux

LE = ρL w′q ′Where w′ , T ′ , and q ′ are the fluctuation of vertical wind velocity, temperature, andhumidity, respectively. The overbar indicates time averaging.

II. THE ENERGY BUDGETS CALCULATED BY BOWEN RATIOMETHOD
III. THE ENERGY BUDGETS CALAULATED BY BULKSCHEMESIV. CONCLUSIONS AND DISCUSSION

800

7.56006400

4.520030

1.5-2000

Sensible Heat Flux(W/m2) 感热通量Srd 向下短波辐射
Lru 向上长波辐射Latent Heat Flux (W/m2) 潜热通量Sru 向上短波辐射
Rn 净辐射降雨 （mm）

90:05
0:50
1:35
2:20
3:05
3:50
4:35
5:20
6:05
6:50
7:35
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22:35
23:20

热 通 量 ,辐 射（ W /m 2 ）259-Sep. 16, 2003
1000

time

Soil Heat Flux (w/m2) 土壤热通量
Lrd 向下长波辐射
rain

Fig.1 The diurnal variation of energy budgets, rainy

800

0.5

600

0.4

400

0.3

200

0.2

00.1

-200

0

Sensible Heat Flux(W/m2) 感热通量Srd 向下短波辐射
Lru 向上长波辐射

Latent Heat Flux (W/m2) 潜热通量Sru 向上短波辐射
Rn 净辐射降 雨 （ mm ）

0.6

0:05
0:50
1:35
2:20
3:05
3:50
4:35
5:20
6:05
6:50
7:35
8:20
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9:50
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12:5013:35
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22:35
23:20

热 通 量 ,辐 射（ W /m 2 ）259-Oct. 24, 2003
1000

time

Soil Heat Flux (w/m2) 土壤热通量
Lrd 向下长波辐射
rain

Fig.2 The diurnal variation of energy budgets, rainless