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21.
Simultaneous observations of surface ozone (O3) with its precursors namely, carbon monoxide (CO) and oxides of nitrogen (NOx) have been taken on diurnal scale from a tropical semi-urban site, Pune (18.54°N, 73.81°E) in India. We present the data
for one year (2003–2004) period to study the salient features of these trace gases. The peak in amplitude of ozone is found
during the noontime whereas in CO and NOX it is observed in the morning hours between 0800 and 0900 H. The concentration of these pollutants drop down considerably
during southwest monsoon months and the diurnal pattern also become very weak. The diurnal trends of these gases are found
to be different for different seasons, which are specific to the receptor site. Model simulations using 3-D chemical-transport
model with regional emission inventories and observed winds have also been carried out. The comparison of model results with
observations, on seasonal basis yielded a reasonable qualitative agreement. The relative role of local emissions and long
range transport in the diurnal pattern for different seasons has been outlined, which reveals that the ozone is highly influenced
by regional/long range transport in this region. The effect of precursor amounts in the morning on afternoon ozone peak levels
has been investigated using the lag correlation study, which reveals that a time lag of 5–7 h is required for most of these
precursor gases to photo-chemically produce ozone to its maximum potential. Results are discussed in the light of available
topographic and meteorological conditions. 相似文献
22.
Weiming WU Zhiguo HE Research Assoc. Prof. National Center for Computational Hydroscience Engineering University of Mississippi University MS USA Postdoctoral Research Assoc. USA.Present at 《国际泥沙研究》2009,24(3):247-259
In-stream and riparian vegetation may significantly affect flow and sediment transport in vegetated channels. A hydraulic model has been developed in this paper to compute the flow discharge in channels with rigid and flexible vegetation under emergent and submerged conditions. An empirical formula has also been presented to determine the bed-load discharge in vegetated channels. The model has been tested against experimental and field data available in the literature. The computed flow discharge and bed-load transport rate agree well with the measured data. 相似文献
23.
One of the longest temperature records available for the equatorial region is provided by Rocketsonde from Thumba (8°N, 77°E), India during the period 1971–1993. In recent times, these data sets are reanalyzed using the up-to-date regression models, which take care of several corrections and parameters, not accounted for in earlier analyses and hence affecting the conclusions. In this paper, annual mean solar response in this data set along with the seasonal solar coefficient is quantitatively estimated now with improved confidence. A negative solar response in the stratosphere (1–2 K/100 solar flux unit, sfu) and a positive response for the mesosphere (0.5–3 K/100 sfu) are found. The negative stratospheric solar response is in contrast to the solar coefficient reported for low latitudes by earlier workers for other stations. 相似文献