Systematic observation of westward propagating cloud bands over the Arabian Sea during Indian Ocean Experiment (INDOEX) from Meteosat‐5 data

Désalmand, Françoise; Szantaï, André; Picon, Laurence; Des̄bois, M.

doi:10.1029/2002jd002934

Cited by 7 publications

(6 citation statements)

References 11 publications

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“…Interestingly, over the ocean, the tracer concentration evolution is reminiscent of a propagating front. The propagation speed between P1 and P3 is relatively constant and on the order of 13 m s −1 , consistent with the propagation speed of cloud bands traveling westward over the Arabian Sea ahead of the Indian pollution plume assessed using Meteosat-5 imagery (Désalmand et al, 2003). In P4 (69.9…”

Section: Egusupporting

confidence: 77%

“…Unfortunately, very little observations were available during INDOEX to verify the validity of this proposed scheme over the Arabian Sea. Even though, the influence of this diurnal variability on the optical properties of the continental plume has been highlighted on Meteosat images in the form of a frontal discontinuities in the brightness surface temperature fields oriented parallel to and propagating away from the coastline (Désalmand et al, 2003), little relevant information on the vertical structure of the pollution plume and its evolution over the sea was available. A three day sun-photometer AOD sequence acquired from the R/V SK close to the west Indian coast (see Fig.…”

Section: Egumentioning

confidence: 99%

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

Forêt¹,

Flamant²,

Cautenet³

et al. 2005

Preprint

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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 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 day time play a crucial role in the modulation of the continental boundary layer depth, and in turn, the haze plume depth. The dynamical processes, as well as entrainment at the top of the marine atmospheric boundary layer, also play a crucial role in re-circulating a fraction of the tracers transported over ocean by the monsoon flow above the marine atmospheric boundary layer in the landward (southwesterly) branch of breeze circulation during the next day. This in turn leads to pollutant accumulation in the vicinity of the Indian coastline. Nevertheless, this contribution to the total aerosol load observed during the INDOEX intensive field phase is shown to small compared to that related to massive advection of aerosol from the continent. The nesting of a high horizontal resolution domain (5 km, with 39 vertical levels below 4000 m above mean seal level), allows a better representation of local dynamics, sea and mountains breezes circulations, and therefore a noticeable improvement in the representation of the pollutants plume in the simulation.

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Section: Egusupporting

confidence: 77%

Section: Egumentioning

confidence: 99%

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

Forêt¹,

Flamant²,

Cautenet³

et al. 2005

Preprint

View full text Add to dashboard Cite

show abstract

Section: Tracer Plume Diurnal Evolution and Propagation Over The Oceanmentioning

confidence: 62%

“…Although the influence of this diurnal variability on the optical properties of the continental plume has been highlighted on Meteosat images in the form of frontal discontinuities in the brightness surface temperature fields oriented parallel to and propagating away from the coastline (Désalmand et al, 2003), little relevant information on the vertical structure of the pollution plume and its evolution over the sea was available. A three-day Sun-photometer AOD sequence acquired from the R/V SK, close to the west Indian coast (see Fig.…”

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

View full text Add to dashboard Cite

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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“…In regions where the wind is relatively steady between the coast and the observations point, this results in diurnal cycles in the pollution (where the phase depends on the distance from the coast). These pollution fronts can also be observed as "stripes" of sharp gradients in infrared satellite images (Désalmand et al, 2003), where high aerosol concentrations block the IR radiation from the sea surface and lower the retrieved temperatures. The first evidence of this diurnal behavior was already gathered during the pre-INDOEX FFP campaign in 1998, when rapid increases of an order of magnitude in the aerosol concentrations in all size categories were seen corresponding with the onset of the land breeze in the evening in the coastal city of Trivandrum (Murugavel and Kamra, 1999).…”

Section: Outflow Channels and Layersmentioning

confidence: 99%

Atmospheric pollutant outflow from southern Asia: a review

2010

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Abstract. Southern Asia, extending from Pakistan and Afghanistan to Indonesia and Papua New Guinea, is one of the most heavily populated regions of the world. Biofuel and biomass burning play a disproportionately large role in the emissions of most key pollutant gases and aerosols there, in contrast to much of the rest of the Northern Hemisphere, where fossil fuel burning and industrial processes tend to dominate. This results in polluted air masses which are enriched in carbon-containing aerosols, carbon monoxide, and hydrocarbons. The outflow and long-distance transport of these polluted air masses is characterized by three distinct seasonal circulation patterns: the winter monsoon, the summer monsoon, and the monsoon transition periods. During winter, the near-surface flow is mostly northeasterly, and the regional pollution forms a thick haze layer in the lower troposphere which spreads out over millions of square km between southern Asia and the Intertropical Convergence Zone (ITCZ), located several degrees south of the equator over the Indian Ocean during this period. During summer, the heavy monsoon rains effectively remove soluble gases and aerosols. Less soluble species, on the other hand, are lifted to the upper troposphere in deep convective clouds, and are then transported away from the region by strong upper tropospheric winds, particularly towards northern Africa and the Mediterranean in the tropical easterly jet. Part of the pollution can reach the tropical tropopause layer, the gateway to the stratosphere. During the monsoon transition periods, the flow across the Indian Ocean is primarily zonal, and strong pollution plumes originating from both southeastern Asia and from Africa spread across the central Indian Ocean. This paper provides a review of the current state of knowledge based on the many observational and modeling studies over the last decades that have examined the southern AsianCorrespondence to: M. G. Lawrence (mark.lawrence@mpic.de) atmospheric pollutant outflow and its large scale effects. An outlook is provided as a guideline for future research, pointing out particularly critical issues such as: resolving discrepancies between top down and bottom up emissions estimates; assessing the processing and aging of the pollutant outflow; developing a better understanding of the observed elevated pollutant layers and their relationship to local sea breeze and large scale monsoon circulations; and determining the impacts of the pollutant outflow on the Asian monsoon meteorology and the regional hydrological cycle, in particular the mountain cryospheric reservoirs and the fresh water supply, which in turn directly impact the lives of over a billion inhabitants of southern Asia.

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Systematic observation of westward propagating cloud bands over the Arabian Sea during Indian Ocean Experiment (INDOEX) from Meteosat‐5 data

Cited by 7 publications

References 11 publications

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

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

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

Atmospheric pollutant outflow from southern Asia: a review

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