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| Titel |
Ozone and some of the precursors at an urban site in the Kathmandu Valley,
Nepal: Observations and modeling |
| VerfasserIn |
Piyush Bhardwaj, Manish Naja, Rajesh Kumar, Maheswar Rupakheti, Arnico K Panday, Gabriele Pfister, Sasha Madronich, Mary C. Barth, Mark G. Lawrence |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250135898
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| Publikation (Nr.) |
 EGU/EGU2016-16818.pdf |
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| Zusammenfassung |
| An international field campaign SusKat-ABC (a Sustainable atmosphere for the Kathmandu
Valley - Atmospheric Brown Clouds), was conducted during Dec 2012 – June 2013 in
Kathmandu and surrounding regions to assess the influences of local and regional scale
emissions in the Kathmandu Valley. Continuous surface based observations of O3, CO and air
sampling for light hydrocarbons were conducted at the supersite Bode (27.59N, 85.39E, 1326
amsl), near the center of the valley. The diurnal variations at Bode were typical of a
polluted urban site with sharp day time build-up in O3, and CO having higher levels
during morning/evening hours. The average early morning CO levels were higher
during winter (Jan-Feb, ∼ 1250 ppbv) than spring (Mar-May, ∼1000 ppbv) and
reached as high as ∼3000 ppbv. However, daytime O3 levels were slightly higher
during spring (∼62 ppbv) when compared with those during winter (∼54 ppbv).
A distinct seasonal change in the diurnal cycle of O3 was observed and the local
sources within the valley were often supplemented by regional scale pollution. The
influence of northern Indian biomass burning was observed during the first week of
May, during this period daily averaged O3 and CO mixing ratios were about twice
as high at Bode and at the Indian sites. WRF-Chem v3.6.1 simulations showed
large day to night variations in meteorological parameters at supersite Bode. The
daytime differences in temperature and RH between model and AWS were ∼1oC and
10% respectively, however large variations (4-8oC and 40-60% respectively) were
observed during night time. Model was able to capture winds well over the valley and
< 10% differences were observed, however it failed to simulate fog during first
few weeks of January over the Kathmandu valley which might be the reason for
large night-time variations in Temperature and RH. O3 and CO also showed large
differences and showed little to no improvement with increasing model resolution. The
day and night-time differences in O3 were ∼25 and ∼50ppb respectively. NO in
the model was very low ∼0.2 ppb. Similar differences were also calculated for a
mountain top Nagarkot (1898m amsl, east of Bode) and model performed very well
there with differences in temperature and RH during day and night were < 2 oC
and < 15% respectively. Detailed results will be presented during the meeting. |
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