Dynamics of the elevated land plume over the Arabian Sea and the Northern Indian Ocean during northeasterly monsoons and during the Indian Ocean experiment (INDOEX)

Raman, Sethu; Niyogi, Dev; Simpson, Matthew; Pelon, Jacques

doi:10.1029/2001gl014193

Cited by 15 publications

(17 citation statements)

References 11 publications

(14 reference statements)

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“…Relatively low O 3 values tend to correlate with clean oceanic air or air from lower‐emission continental regions. Previous studies have indicated that not all polluted areas produce ozone [ Raman et al , 2002; Reiner et al , 2001]. The lower portions of Figure 7 depict specific days, 8 and 13 March, where the color coding signifying vertical motion of the trajectories is generally subsident, consistent with patterns described by Raman et al [2002].…”

Section: Detailed Origins Of Tropospheric O3 Maximamentioning

confidence: 55%

“…This analysis of the lower tropospheric ozone (Figures 1 and 4) emphasizes that pollution outflow tends to occur above the marine boundary layer, predominantly between 900 hPa (1 km) and 600 hPa (4 km), as explained for INDOEX in the works of Reiner et al [2001], Raman et al [2002], and Forêt et al [2005]. The lowest kilometer probably does not participate as pollutant outflow from a warm daytime continental mixed layer flows up and over a cooler marine layer.…”

Section: Detailed Origins Of Tropospheric O3 Maximamentioning

confidence: 80%

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Mechanisms for the intraseasonal variability of tropospheric ozone over the Indian Ocean during the winter monsoon

et al. 2007

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[1] We synthesize daily sonde (vertical) information and daily satellite (horizontal) information to provide an empirical description of ozone origins over the northern Indian Ocean during the INDOEX (Indian Ocean Experiment) field campaign (February-March 1999). This area is shown to be a significant portion of the ''high-ozone tropics''. East-west O 3 features and their flow are identified, and ozone origins are compared to other tropical regions, using water vapor as a second tracer. In the study period, multiple processes contribute to O 3 column enhancements, their importance varying strongly by latitude: (1) Low-altitude O 3 pollution over the northern Indian Ocean mainly originates from the Indian subcontinent and is traceable to high emission areas.

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Section: Detailed Origins Of Tropospheric O3 Maximamentioning

confidence: 55%

Section: Detailed Origins Of Tropospheric O3 Maximamentioning

confidence: 80%

Mechanisms for the intraseasonal variability of tropospheric ozone over the Indian Ocean during the winter monsoon

et al. 2007

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“…Along the Indian west coast, the altitude of the top of the pollution plume varied between 3-and 4-km msl, with the deeper plume depths being observed at 12:00 UTC (Chazette, 2003). Continental aerosols are generally observed to be mixed on the vertical throughout the depth of this land plume (Léon et al, 2001;Raman et al, 2002). Temperature profiles obtained from synoptic balloon soundings in Goa during the period running from 6 to 9 March 1999 show the presence of an elevated temperature inversion at this level, fluctuating between 3-and 4-km msl (not shown).…”

Section: Tracer Plume Diurnal Evolution and Propagation Over The Oceanmentioning

confidence: 99%

The structure of the haze plume over the Indian Ocean during INDOEX: tracer simulations and LIDAR observations

et al. 2006

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Abstract. Three-dimensional, nested tracer simulations of a pollution plume originating from the Indian sub-continent over the Indian Ocean, in the framework of the Indian Ocean Experiment (INDOEX), between 5 and 9 March 1999, were performed with the Regional Atmospheric Modeling System (RAMS), to provide insight into the transport patterns of the pollutants, as well as to investigate the dynamical mechanisms controlling the vertical structure of the plume and its evolution in the vicinity of the Maldives Islands. Airborne and ground-based LIDAR observations of the structure of the haze plume made on 7 March 1999 were used to assess the quality of the simulations, as well as the impact of grid resolution on the vertical structure of the simulated plume. It is shown that, over the Arabian Sea, in the vicinity of the Maldives Islands, the pollutants composing the plume observed by the airborne LIDAR essentially originated from the city of Madras and that the vertical structure of the plume was controlled by the diurnal cycle of the continental boundary layer depth. A combination of tracer simulations and remote sensing observations (airborne LIDAR, ship-borne photometer, ground-based LIDAR in Goa) was used to analyse the diurnal evolution of the haze plume over the sea. We find evidence that the sea breeze circulation and orographic lifting taking place in the southern part of the Indian sub-continent during the daytime play a crucial role in the modulation of the continental boundary layer depth, and in turn, the haze plume depth. The eastward shift of the subtropical high from central India to the Bay of Bengal after 6 March lead to an increase in the tracer concentrations simulated over the Arabian Sea, in the region of intensive observations north of the Maldives, as transport pathways form Hyderabad and Madras were modified significantly. The nesting of a high horizontal resolution Correspondence to: G. Forêt (foret@lisa.univ-paris12.fr) domain (5 km, with 39 vertical levels below 4000 m above mean seal level) allows for a better representation of local dynamics, the circulation of sea and mountains breezes, and therefore a noticeable improvement in the representation of the pollutants' plume in the simulation.

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“…On some occasions, they exhibited high extinction‐to‐backscatter ratios implying the presence of absorbing aerosols, potentially arising from biomass burning regions over India [ Franke et al , 2003]. According to Raman et al [2002], the strength and coherence of the elevated plume was influenced by the diurnal variation of the structure of the upwind continental boundary layer.…”

Section: Introductionmentioning

confidence: 99%

Aerosol lofting from sea breeze during the Indian Ocean Experiment

Verma¹,

Boucher²,

Venkataraman³

et al. 2006

J. Geophys. Res.

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This work was carried out to understand the mechanisms leading to lofting and large‐scale advection of aerosols over the Indian Ocean region due to interaction of the sea breeze with the northeast monsoon winds along the west coast of India. European Centre for Medium‐Range Weather Forecasts (ECMWF) wind fields for the months of February and March 1999 were analyzed at various times of day. Intense sea breeze activity was observed at 1200 UT (1730 local time) along the west coast of India with average intensity larger in March than in February. The sea breeze was seen to extend inland deeper in March than in February. Lofting of air observed as high as 800 hPa (approximately 2 km above sea level) could lead to entrainment of aerosols into the free troposphere and long‐range transport. Upward motion of air was observed everywhere along the west coast of India (from 8° to 20°N), on average higher in March than in February, because of convergence between the sea breeze and the synoptic‐scale flow. A region of intense lofting of air and well‐defined convergence was observed along the coast of the Karnataka region (12°–16°N). A simulation with a general circulation model nudged with ECMWF data indicated that the intrusion of marine air masses with low concentrations of organic matter is seen as deep as 64 km inland in the evening (1500 UT). Intrusion of the sea‐salt plume is seen to a maximum distance of around 200 km from 1500 until 2300 UT. A well‐developed lofted layer of aerosols as high as 3 km was also simulated during sea breeze activity along the west coast of India. The general circulation model simulation shows a clear diurnal evolution of the vertical profile of the aerosol extinction coefficient at Goa but fails to reproduce several features of the lidar observations, for example, the marked diurnal variability of the upper layers between 1 and 3 km. However, the model simulates a diurnal cycle at the surface (0–0.7 km) that is not apparent in lidar measurements. The model simulates long‐range transport and captures the lofted plume downwind of the west coast of India. However, there was a 1–2 day delay in the model transport of lofted aerosols at higher layers to Hulule, 700 km downwind of India, when compared to lidar observations.

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Dynamics of the elevated land plume over the Arabian Sea and the Northern Indian Ocean during northeasterly monsoons and during the Indian Ocean experiment (INDOEX)

Cited by 15 publications

References 11 publications

Mechanisms for the intraseasonal variability of tropospheric ozone over the Indian Ocean during the winter monsoon

Mechanisms for the intraseasonal variability of tropospheric ozone over the Indian Ocean during the winter monsoon

The structure of the haze plume over the Indian Ocean during INDOEX: tracer simulations and LIDAR observations

Aerosol lofting from sea breeze during the Indian Ocean Experiment

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