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Papers by NAGARAJU CHILUKOTI
International Journal of Climatology, Aug 19, 2018
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Atmospheric Research
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Leachate migration modeling is a necessary part of conducting exposure assessments in the develop... more Leachate migration modeling is a necessary part of conducting exposure assessments in the development of land disposal regulations for solid wastes. Development of toxicity characteristics to define leachate concentration levels that pose unacceptable risks to humans and the environment requires modeling studies for a wide range of leachate generation-migration scenarios. The study investigated the influence of five alternative modeling initial
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Atmospheric Science Letters, 2013
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Atmospheric Environment, 2010
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Atmospheric Environment, 2011
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ABSTRACT Satellite Remote Sensing data and spatially generated field observations provide crucial... more ABSTRACT Satellite Remote Sensing data and spatially generated field observations provide crucial parameters in numerical atmospheric models to define realistic surface boundary conditions. In this study two important parameters i.e., vegetation and soil categories are generated for application in the PSU/NCAR mesoscale model MM5 for realistic representation of the surface conditions over the Indian region in the model. The vegetation cover is derived from the MODIS satellite data, vegetation fraction by computing vegetation index from the IRS-P4, and the soil categories from soil resource maps generated through intensive ground surveys. The revised surface data are incorporated in the MM5 mesoscale model and twenty four numerical experiments are conducted using the Noah land surface parameterization to study the model performance for a set of six seasonal cases and considering the effects of changing vegetation, soil types separately. The MM5 model is used with 3 nested domains and with the initial / boundary conditions obtained from 6 h interval 1x1 degree NCEP final analyses. Results indicate the model predictions for surface energy fluxes, air temperature, humidity, wind field, PBL height are sensitive to the changes in the surface conditions. The modified vegetation case is found to induce relatively larger changes in the predictions than the revised soil case. Simulations with modified vegetation and soil categories give higher correlations and lower error statistics for various meteorological parameters due to the changes in albedo, roughness coefficient, and thermal diffusivity parameters used in land surface scheme of the model.
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The present study investigates the variability of surface ozone (O3) and its precursors (NOX, CO)... more The present study investigates the variability of surface ozone (O3) and its precursors (NOX, CO) at different time scales for 3-year period (2016–2018) using continuous ground-based observations from 25 stations located within the Indian Capital Delhi (28.83°N, 77.81°E). Observations indicate that there is a clear spatial heterogeneity and seasonality in surface O3 where larger magnitudes (40–60 ppb) are observed during pre-monsoon season, and 10–20 ppb in other seasons. The frequency distribution exhibits that 70% of O3 concentrations are in the range of 10–50 ppb, while 10% lies larger than 50 ppb and the remaining 20% is mostly confined within 50–80 ppb. Further, a detailed analysis on the diurnal cycle of surface ozone and its precursors performed over IMD Lodhi Road location. Analysis of diurnal cycles show maximum and minimum O3 concentrations during the morning and nocturnal hours, with a rate of change 4.8 ± 1.96 and −7.4 ± 0.95 ppb h−1, respectively. On the other hand, the...
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Journal of Climate
Land-use and land-cover change (LULCC) is one of the most important forcings affecting climate in... more Land-use and land-cover change (LULCC) is one of the most important forcings affecting climate in the past century. This study evaluates the global and regional LULCC impacts in 1950–2015 by employing an annually updated LULCC map in a coupled land–atmosphere–ocean model. The difference between LULCC and control experiments shows an overall land surface temperature (LST) increase by 0.48 K in the LULCC regions and a widespread LST decrease by 0.18 K outside the LULCC regions. A decomposed temperature metric (DTM) is applied to quantify the relative contribution of surface processes to temperature changes. Furthermore, while precipitation in the LULCC areas is reduced in agreement with declined evaporation, LULCC causes a southward displacement of the intertropical convergence zone (ITCZ) with a narrowing by 0.5°, leading to a tripole anomalous precipitation pattern over the warm pool. The DTM shows that the temperature response in LULCC regions results from the competing effect betw...
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<p>Land use and land cover change (LULCC) is one of the most important forcings aff... more <p>Land use and land cover change (LULCC) is one of the most important forcings affecting climate in the past century. This study evaluates the global biogeophysical LULCC impacts in 1950&#8211;2015 by employing an annually updated LULCC map in a coupled land&#8211;atmosphere&#8211;ocean model. The difference between LULCC and control experiments shows an overall land surface temperature (LST) increase by 0.48 K in the LULCC regions and a widespread LST decrease by 0.18 K outside the LULCC regions. A decomposed temperature metric (DTM) is applied to quantify the relative contribution of surface processes to temperature changes. Furthermore, while precipitation in the LULCC areas is reduced in agreement with declined evaporation, LULCC causes a southward displacement of the intertropical convergence zone (ITCZ) with a narrowing by 0.5&#176;, leading to a tripole anomalous precipitation pattern over the warm pool. The DTM shows that the temperature response in LULCC regions results from the competing effect between increased albedo (cooling) and reduced evaporation (warming). The reduced evaporation indicates less atmospheric latent heat release in convective processes and thus a drier and cooler troposphere, resulting in a reduction in surface cooling outside the LULCC regions. The southward shift of the ITCZ implies a northward cross-equatorial energy transport anomaly in response to reduced latent/sensible heat of the atmosphere in the Northern Hemisphere, where LULCC is more intensive. Tropospheric cooling results in the equatorward shift of the upper-tropospheric westerly jet in both hemispheres, which, in turn, leads to an equatorward narrowing of the Hadley circulation and ITCZ.</p>
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Geophysical Research Letters, 2008
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International Journal of Climatology
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International Journal of Climatology, Aug 19, 2018
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Atmospheric Research
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Leachate migration modeling is a necessary part of conducting exposure assessments in the develop... more Leachate migration modeling is a necessary part of conducting exposure assessments in the development of land disposal regulations for solid wastes. Development of toxicity characteristics to define leachate concentration levels that pose unacceptable risks to humans and the environment requires modeling studies for a wide range of leachate generation-migration scenarios. The study investigated the influence of five alternative modeling initial
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Atmospheric Science Letters, 2013
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Atmospheric Environment, 2010
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Atmospheric Environment, 2011
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ABSTRACT Satellite Remote Sensing data and spatially generated field observations provide crucial... more ABSTRACT Satellite Remote Sensing data and spatially generated field observations provide crucial parameters in numerical atmospheric models to define realistic surface boundary conditions. In this study two important parameters i.e., vegetation and soil categories are generated for application in the PSU/NCAR mesoscale model MM5 for realistic representation of the surface conditions over the Indian region in the model. The vegetation cover is derived from the MODIS satellite data, vegetation fraction by computing vegetation index from the IRS-P4, and the soil categories from soil resource maps generated through intensive ground surveys. The revised surface data are incorporated in the MM5 mesoscale model and twenty four numerical experiments are conducted using the Noah land surface parameterization to study the model performance for a set of six seasonal cases and considering the effects of changing vegetation, soil types separately. The MM5 model is used with 3 nested domains and with the initial / boundary conditions obtained from 6 h interval 1x1 degree NCEP final analyses. Results indicate the model predictions for surface energy fluxes, air temperature, humidity, wind field, PBL height are sensitive to the changes in the surface conditions. The modified vegetation case is found to induce relatively larger changes in the predictions than the revised soil case. Simulations with modified vegetation and soil categories give higher correlations and lower error statistics for various meteorological parameters due to the changes in albedo, roughness coefficient, and thermal diffusivity parameters used in land surface scheme of the model.
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
The present study investigates the variability of surface ozone (O3) and its precursors (NOX, CO)... more The present study investigates the variability of surface ozone (O3) and its precursors (NOX, CO) at different time scales for 3-year period (2016–2018) using continuous ground-based observations from 25 stations located within the Indian Capital Delhi (28.83°N, 77.81°E). Observations indicate that there is a clear spatial heterogeneity and seasonality in surface O3 where larger magnitudes (40–60 ppb) are observed during pre-monsoon season, and 10–20 ppb in other seasons. The frequency distribution exhibits that 70% of O3 concentrations are in the range of 10–50 ppb, while 10% lies larger than 50 ppb and the remaining 20% is mostly confined within 50–80 ppb. Further, a detailed analysis on the diurnal cycle of surface ozone and its precursors performed over IMD Lodhi Road location. Analysis of diurnal cycles show maximum and minimum O3 concentrations during the morning and nocturnal hours, with a rate of change 4.8 ± 1.96 and −7.4 ± 0.95 ppb h−1, respectively. On the other hand, the...
Bookmarks Related papers MentionsView impact
Journal of Climate
Land-use and land-cover change (LULCC) is one of the most important forcings affecting climate in... more Land-use and land-cover change (LULCC) is one of the most important forcings affecting climate in the past century. This study evaluates the global and regional LULCC impacts in 1950–2015 by employing an annually updated LULCC map in a coupled land–atmosphere–ocean model. The difference between LULCC and control experiments shows an overall land surface temperature (LST) increase by 0.48 K in the LULCC regions and a widespread LST decrease by 0.18 K outside the LULCC regions. A decomposed temperature metric (DTM) is applied to quantify the relative contribution of surface processes to temperature changes. Furthermore, while precipitation in the LULCC areas is reduced in agreement with declined evaporation, LULCC causes a southward displacement of the intertropical convergence zone (ITCZ) with a narrowing by 0.5°, leading to a tripole anomalous precipitation pattern over the warm pool. The DTM shows that the temperature response in LULCC regions results from the competing effect betw...
Bookmarks Related papers MentionsView impact
<p>Land use and land cover change (LULCC) is one of the most important forcings aff... more <p>Land use and land cover change (LULCC) is one of the most important forcings affecting climate in the past century. This study evaluates the global biogeophysical LULCC impacts in 1950&#8211;2015 by employing an annually updated LULCC map in a coupled land&#8211;atmosphere&#8211;ocean model. The difference between LULCC and control experiments shows an overall land surface temperature (LST) increase by 0.48 K in the LULCC regions and a widespread LST decrease by 0.18 K outside the LULCC regions. A decomposed temperature metric (DTM) is applied to quantify the relative contribution of surface processes to temperature changes. Furthermore, while precipitation in the LULCC areas is reduced in agreement with declined evaporation, LULCC causes a southward displacement of the intertropical convergence zone (ITCZ) with a narrowing by 0.5&#176;, leading to a tripole anomalous precipitation pattern over the warm pool. The DTM shows that the temperature response in LULCC regions results from the competing effect between increased albedo (cooling) and reduced evaporation (warming). The reduced evaporation indicates less atmospheric latent heat release in convective processes and thus a drier and cooler troposphere, resulting in a reduction in surface cooling outside the LULCC regions. The southward shift of the ITCZ implies a northward cross-equatorial energy transport anomaly in response to reduced latent/sensible heat of the atmosphere in the Northern Hemisphere, where LULCC is more intensive. Tropospheric cooling results in the equatorward shift of the upper-tropospheric westerly jet in both hemispheres, which, in turn, leads to an equatorward narrowing of the Hadley circulation and ITCZ.</p>
Bookmarks Related papers MentionsView impact
Geophysical Research Letters, 2008
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International Journal of Climatology
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