Geography Reference
In-Depth Information
48
48
2010-2020
2040-2050
46
46
44
44
42
42
40
40
38
38
36
36
34
34
−82
−80
−78
−76
−74
−72
−70
−68
−66
−82
−80
−78
−76
−74
−72
−70
−68
−66
48
6
2090-2100
46
4
44
2
42
0
40
− 2
38
− 4
36
34
− 6
−82
−80
−78
−76
−74
−72
−70
−68
−66
Fig. 7.25 Effects of future urban expansion on average annual temperature in the Northeast
megalopolis, USA (C)
be more and more notable along with the urban expansion. This may be caused by
the strengthened UHI effect due to urban expansion, which will enhance the rising
flow of urban area and reduce the inflow of cold wet air stream from the sea.
7.5.2.2 Average Annual Precipitation Effects
The urban expansion will mainly decrease the average annual precipitation. The
spatial pattern of average annual precipitation change will be approximately
opposite with that of average annual temperature change (Fig.
7.26
). For some
new urban area and nearby pixels, the average annual precipitation will decrease
by 10-50 mm, while it will reduce by more than 100 mm for some pixels in the
south region of the Northeast megalopolis. This reduction may be caused by
changes in surface hydrology that extend beyond the UHI effect. There are lots of
researches that argue urban expansion resulting in an increase of urban precipi-
tation (Kleerekoper et al.
2012
; Lin et al.
2008
). However, our simulation showed
that the impact of future urban expansion in Northeast megalopolis with mega
cities on precipitation has different rules. This simulation result is consistent with
