Geoscience Reference
In-Depth Information
3.3
. Implications to regional climate
The anthropogenic fraction is responsible for 67.6% to the heating rate
observed over Kanpur region. Over the IGB, the mean annual heating rate is
0
19 K day
−
1
, of which 54.7% contribution comes from anthropogenic
aerosols. The annual heating rate surrounding the major urban locations
in IGB is listed in Table 1. It reveals two points; firstly, similar value
across the locations implies that the pollution level due to anthropogenic
activities leading to the formation of haze is similar in major urban areas.
Secondly, the role of anthropogenic components is much more dominated
in the eastern IGB, as the dusts are not transported up to that much
distance, as discussed earlier. The non-absorbing components contribute
more to the TOA forcing, whereas the absorbing components contribute
more to surface forcing. Hence, when both are present in abundance, the
atmospheric heating would be more, as in the case of winter when BC is the
major absorbing component and in summer when pure dust and dust-BC
mixture are the absorbing components. The most important implication
for such high negative surface forcing is the persistent large reduction of
direct solar radiation in the IGB. On an average, aerosols reduce the net
solar radiation at the surface over the IGB by 14% on the annual scale,
which is even higher (18-20%) over polluted urban locations. The INDOEX
observations have shown that the large surface cooling and atmospheric
heating affect the regional hydrological cycle.
2
As most of the aerosols are
concentrated in the lower atmosphere, that too within the first few km,
atmospheric heating is most effective in this region. The enhanced heating
due to the mixing of anthropogenic and natural aerosols in this region needs
to be addressed in future.
.
64
±
0
.
Table 1. Mean (
±
SD) annual atmospheric heating rate and anthropogenic contribution
to Indo-Gangetic haze over major urban locations.
Heating rate in K day
−
1
Cities
Locations
Anthropogenic
contribution (in %)
Delhi
28.38N, 77.17E
0
.
86
±
0
.
28
67.9
Agra
27.17N, 77.58E
0
.
87
±
0
.
3
57.3
Kanpur
26.28N, 80.20E
0
.
84
±
0
.
27
65.6
Allahabad
25.25N, 81.58E
0
.
8
±
0
.
28
66.5
Varanasi
25.22N, 83E
0
.
84
±
0
.
28
62.8
Patna
25.35N, 85.12E
0
.
82
±
0
.
23
76
Kolkata
22.36N, 88.24E
0
.
72
±
0
.
16
76.8
