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
100
2090-2100
50
46
0
44
− 50
42
− 100
40
− 150
38
− 200
36
− 250
34
− 300
−82
−80
−78
−76
−74
−72
−70
−68
−66
Fig. 7.26 Effects of future urban expansion on average annual precipitation in the Northeast
megalopolis, USA (mm)
the findings of Guo et al. and Zhang et al., though their study area of Beijing is
much smaller than ours on scale (Guo et al.
2006
; Zhang et al.
2009
). The urban
expansion will produce less evaporation, higher surface temperatures, and larger
sensible heat fluxes. This leads to less water vapor and hence less convective
available potential energy. Combination of these factors induced by urban
expansion contributes to regional precipitation reduction in general. Concretely,
due to urban expansion in the Northeast megalopolis, the average annual precip-
itation of the simulation area will decrease by 5.75 mm, 7.10 mm, and 8.35 mm in
the period of 2010-2010, 2040-2050, and 2090-2100, respectively.
7.5.2.3 Average Monthly Temperature Effects
Figure
7.27
depicts the monthly variation of average temperature change driven by
future urban expansion. The urban expansion in the Northeast megalopolis will
result in an average monthly temperature increase in original urban area (urban
area in 1993) in April, May, June, July, and August and decrease in other months
in the period of 2010-2020 (Fig.
7.27
, Panel A). The cooling effect in winter may
be caused by the local circulation change driven by surface energy budgets change.
