NOPR Community:
http://nopr.niscair.res.in/handle/123456789/17265
2019-06-17T05:24:08ZVertical profile variations of NO<sub>2</sub><i> </i>and O<sub>3</sub> using slant column density observations during twilight period
http://nopr.niscair.res.in/handle/123456789/17463
Title: Vertical profile variations of NO<sub>2</sub><i> </i>and O<sub>3</sub> using slant column density observations during twilight period
Authors: Londhe, A L; Bhosale, C S; Meena, G S; Jadhav, D B; Gil, M; Puentedura, O; Yela, M
Abstract: An algorithm developed to derive the
vertical profiles of atmospheric species from their slant column density measurements
using twilight spectroscopy is discussed. The algorithm has been tested by
using the slant column density measurements at polar station, Reykjavik (64°N, 22.6°W)
and tropical station, Pune (l8.53°N, 73.85°E). The vertical profiles of NO<sub>2</sub>
and O<sub>3</sub> are retrieved by considering slant column densities for ten different
solar zenith angles and ten different atmospheric layers of equal thickness. These
vertical profiles are
used to differentiate the tropospheric and
stratospheric contribution of NO<sub>2</sub> and O<sub>3</sub> . The
observations of NO<sub>2</sub> at polar station
and at tropical station showed frequent higher values of tropospheric concentrations
due to pollution episodes and are not correlated with stratospheric NO<sub>2</sub>
and O<sub>3.</sub> The correlation between total column density variations of NO<sub>2</sub>
and O<sub>3</sub> is not observed; however, the stratospheric variations of NO<sub>2</sub>
and O<sub>3</sub> showed good correlation.
Page(s): 291-3011999-12-01T00:00:00ZDetermination of photolysis frequency of O<sup>1</sup>D in the tropical region
http://nopr.niscair.res.in/handle/123456789/17462
Title: Determination of photolysis frequency of O<sup>1</sup>D in the tropical region
Authors: Paul, R; Mitra, A P; Mandal, T K; Srivastava, S K
Abstract: An attempt has been made to estimate the photolysis
frequency of O<sup>1</sup>D in troposphere and stratosphere of the Indian region.
The radiation code Lowtran 7 is used to estimate actinic flux at these altitudes.
An accurate and efficient multiple scattering parametrization along with <i>k</i>-distribution
method has been used in this model. For ozone, observed averaged profile for the
year 1976 as well as 1994 is used for Delhi,
Pune and Thiruvananthapuram. Values as recommended by DeMore <i>et al. [JPL Publication,
</i>1994, p.94] and Michelsen <i>et al. [Geophys Res Lett (USA). </i>21
(1994) 2227.] have been taken for ozone quantum yield. The values of photolysis
frequency of O<sup>1</sup>D are found to be significantly higher for the quantum
yield given by Michelsen <i>et al. </i>A decrease in these values is also observed
in the year 1994 as compared to that in
preceding years up to 1976.
Page(s): 286-2901999-12-01T00:00:00ZSolar beam radiation estimate’s correlation for Bangladesh
http://nopr.niscair.res.in/handle/123456789/17461
Title: Solar beam radiation estimate’s correlation for Bangladesh
Authors: Rahman, M M; Uddin, M A; Islam, M W
Abstract: An empirical
correlation has been developed which correlates the monthly average daily solar beam
radiation with the maximum possible number of bright sunshine
hours. Airmass exponential correlation is also established. The applicability
of these models in climatic conditions of Bangladesh is also
studied. Measured beam radiation and the bright sunshine hour data are
analyzed to find out the regression co-efficient of these correlations
using computer simulation programme by Gaussian elimination
technique. Applying
these correlations, solar beam radiation is computed for
different locations in
Bangladesh. Predicted
results are compared statistically with the experimental observations
considering different statistical errors. The <i>t</i>-statistics is also
applied to test whether or not a model is statistically significant
at a particular confidence level. On the basis of the
analysis, a model has been recommended which is found to be best suited to the
climatic conditions of Bangladesh.
Page(s): 277-2851999-12-01T00:00:00ZFeasibility study of extended range atmospheric prediction through time average Lorenz attractor
http://nopr.niscair.res.in/handle/123456789/17460
Title: Feasibility study of extended range atmospheric prediction through time average Lorenz attractor
Authors: Pal, Pradip K; Shah, Shivani
Abstract: Though the theoretical limit of
atmospheric predictability is only up to 1-2 weeks, temporal and spatial averages
may be predictable up to certain extent for extended range. It is not known
what should be the length of time for averaging to have certain predictability of
time average values. The time average behaviour of Lorenz attractor with and
without forcing shows that there are upper and lower limits of such length of time
for averaging, beyond which the system remains chaotic.
Page(s): 271-2761999-12-01T00:00:00Z