Geography Reference
In-Depth Information
(a)
(b)
800
52
5
52
700
50
50
0
600
48
48
−5
500
46
46
−10
44
400
−15
44
42
42
−20
300
40
40
−25
200
116
118
120
122
124
126
128
130
132
134
116
118
120
122
124
126
128
130 132
134
10
10
(c)
(d)
52
52
5
5
50
50
0
0
48
48
−5
−5
46
46
−10
−10
44
44
−15
−15
42
42
−20
−20
40
40
−25
−25
116
118
120
122
124
126
128
130
132
134
116
118
120
122
124
126
128
130 132
134
Fig. 4.8 Difference between the sensible heat flux in Northeast China in 2010 and 2030 under
different scenarios (W/m
2
). a Spatial pattern of the sensible heat flux in 2010, b Difference of the
sensible heat flux between 2010 and 2030 under the BAU scenario, c Difference of the sensible
heat flux between 2010 and 2030 under the REG scenario, d Difference of the sensible heat flux
between 2010 and 2030 under the CES scenario
The result indicates that the latent heat flux increases most obviously in the regions
where the cultivated land mainly converts into forests, while the sensible heat flux
increases most obviously in the regions where the cultivated land mainly converts
into urban and built-up land in Northeast China. A lot of research has indicated
that the terrestrial vegetation cover change can influence the land surface energy
budget through altering the land surface albedo, roughness, etc., and consequently
change precipitation and temperature. In Northeast China, the conversion from
cultivated land into nonagricultural land has been the main reason for the soil
moisture change in regions around cities. The irrigation to cropland can increase
the latent heat flux and decrease sensible heat flux, and consequently have cooling
effects on the land surface. However, the conversion from irrigated cropland into
urban and built-up land has greatly weakened this cooling effect since it decreases
the land surface roughness and increases the land surface albedo, which leads to
the decrease of evapotranspiration as well as the land surface net radiation, and
consequently decreases the latent heat flux and increases the sensible heat flux.
Furthermore, returning cultivated land to forests have positive effects on restoring
the soil water environment, and afforestation can significantly increase the solar
radiation absorbed by the land surface, making the evapotranspiration increase,
which will increase the latent heat flux and decrease the sensible heat flux, and
consequently decrease the temperature. In fact, the land use has changed greatly
