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

Forêt, Gilles; Flamant, Cyrille; Cautenet, S.; Pelon, Jacques; Minvielle, F.; Taghavi, Mahmoud; Chazette, Patrick

doi:10.5194/acp-6-907-2006

Cited by 13 publications

(10 citation statements)

References 49 publications

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“…Cross sections of virtual potential temperature and relative humidity have been derived from these dropsonde measurements. They confirm the presence of the two layers (with stable potential temperature values) and the presence of the two stratified inversion layers (with rapid variations of potential temperature with height) observed in Figure 3a of Forêt et al [2006]). Note that the previously described layers of the lower troposphere can clearly be identified, although the trajectory of the airplane (at 12°N) is north of the area where the solitary wave is observed on Meteosat images (between 6°N and 11.5°N).…”

Section: Lifecycle Of Solitary Waves and Involved Mechanismssupporting

confidence: 82%

Dynamics of solitary waves observed over the North Indian Ocean during the Indian Ocean Experiment (INDOEX) 1999

Szantaï¹,

Drobinski²,

Désalmand³

2011

J. Geophys. Res.

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[1] During the Indian Ocean Experiment (INDOEX) experiment (January-March 1999), mesoscale solitary waves have been observed and tracked over the North Indian Ocean on a series of Meteosat-5 satellite images. These solitary waves have a horizontal wavelength of 10-15 km and propagate westward at low level at a speed of 10-18 m/s. Unlike similar wave phenomena observed mainly over land, they have a long lifetime, which can exceed 48 h. A key element explaining the existence and longevity of the solitary waves is the presence of an inversion layer, acting as a waveguide and separating the boundary layer into two sublayers: a lower layer over the ocean (marine boundary layer) and an upper layer originating from the Indian subcontinent (land plume layer). Profiles from radiosondes launched from the Ron Brown and from dropsondes from the Hercules C-130 airplane helped to determine this waveguide structure. A suggested mechanism leading to the generation of solitary waves is a collision between the sea breeze in the vicinity of the West Indian coast and the easterly/northeasterly winter monsoon winds, with a possible contribution of convection reinforced by topography (Western Ghats range), during the local afternoon. Another phenomenon related to sea breeze and local convection in this coastal area, the injection of "bubbles" of moisture into the drier upper boundary layer, has also been identified on European Centre for Medium-Range Weather Forecasts analyses. These bubbles form daily during the afternoon and drift westward over the North Indian Ocean at latitudes around 12°N and progressively subside and dissipate or become integrated into larger air masses.

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Section: Lifecycle Of Solitary Waves and Involved Mechanismssupporting

confidence: 82%

Dynamics of solitary waves observed over the North Indian Ocean during the Indian Ocean Experiment (INDOEX) 1999

Szantaï¹,

Drobinski²,

Désalmand³

2011

J. Geophys. Res.

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“…However, this change is very sharp for MOZART‐simulated AODs. Similar features can be seen over the Arabian Sea, which is one of the haziest oceanic regions globally (Forget et al, ; Ghanti and Ghosh, ) and well‐known for intense dust storms (Vinoj et al, ). Figures and show that during peak aerosol period over IGB and Arabian Peninsula, the MOZART AODs are overestimated compared to observations, whereas for other periods the AODs are underestimated.…”

Section: Resultsmentioning

confidence: 99%

Global and regional evaluation of a global model simulated AODs with AERONET and MODIS observations

Sheel

Guleria

Ramachandran

2017

Intl Journal of Climatology

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Aerosol optical properties vary widely globally due to their short residence time and the large variability in their composition and size resulting from varying sources. In this study, we make use of the three‐dimensional global atmospheric chemistry transport model MOZART (Model for OZone And Related chemical Tracers), to simulate Aerosol Optical Depths (AODs) and compare with observations from MODIS (Moderate Resolution Imaging Spectroradiometer, level‐3) on board the Terra satellite and AERONET (AErosol RObotic NETwork level‐2), at regional and global scale for the period 2000–2007. The AOD values at a reference wavelength 550 nm are reported for all the data sets. Model and observations show intense aerosol burden over the parts of the world where developing countries are located. On a regional scale, varying features are noted for different regions depending upon topography, regional emissions and weather conditions. MOZART captures the general features observed in AERONET and MODIS fairly well; however, in biomass burning dominated regions (Central South America, South Africa, and North Australia) it underestimates the observed AOD. In industrial regions (North Europe and Mediterranean) MOZART overestimates the observations and over dust dominant regions (Saharan Africa, Middle East, and East Asia), the model AODs are comparable to AERONET and MODIS observations. In general, MOZART simulated AOD show similar seasonal and regional variability as observed in AERONET and MODIS. Our results are similar to the most commonly used models, i.e. GOCART (the GOddard Chemistry, Aerosol, Radiation, and Transport) and GEOS‐4 (Goddard Earth Observing System‐version 4).

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“…The validity of this hypothesis depends on the amount of turbulence at the layer interface [ Russell et al , 1998]. As we do not have data giving information on the (un)stability of the interface MBL‐free troposphere, we chose to consider the most observed case in open ocean: the mixing between the two layers [ Russell et al , 1998; Rasch et al , 2001; Bates et al , 2002; Welton et al , 2002; Forêt et al , 2006]. Thus, we consider in the following a single aerosol layer containing mixed marine and BB aerosols.…”

Section: Discussionmentioning

confidence: 99%

Marine and biomass burning aerosols in the southern Indian Ocean: Retrieval of aerosol optical properties from shipborne lidar and Sun photometer measurements

Duflot¹,

Royer²,

Chazette³

et al. 2011

J. Geophys. Res.

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[1] We document aerosol extinction properties in the southern Indian Ocean. A unique data set of shipborne measurements has been collected with a dual Rayleigh-Mie lidar aboard the research vessel Marion Dufresne during two campaigns: one around Madagascar during the Southern Hemisphere late summer and one close to the Kerguelen Islands during the biomass burning (BB) season. During this latter, a layer containing a mix of BB and marine aerosols extending up to ∼3 km above mean sea level (amsl) has been observed from [31°S, 69°E] to [24°S, 59°E]. Both vertical structure and aerosol optical properties have been retrieved from the inversion of the lidar signals. Sun photometer-derived aerosol optical thickness (AOT) at 355 nm is used to constrain the lidar inversion. We obtain a mean integrated value of backscatter-to-extinction ratio (BER) (extinction-to-backscatter ratio, or so-called lidar ratio, LR) of 0.039 ± 0.009 sr −1 (26 ± 6 sr) and 0.021 ± 0.006 sr −1 (48 ± 12 sr) for the marine aerosols layer, and for the mixing between BB and marine aerosols with an uncertainty of 0.009 sr −1 (6 sr) and 0.004 sr −1 (9 sr), respectively. Lidar calibration is used to inverse data without any simultaneous Sun photometer measurements (as nighttime data), and the temporal evolution of the optical properties and vertical extension of the BB aerosol plume is documented. The presence of BB aerosols is in agreement with Lagrangian model GIRAFE v3 (reGIonal ReAl time Fire plumEs) simulations, which show the South American and Southern African BB origin of the encountered aerosol layer.

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

Cited by 13 publications

References 49 publications

Dynamics of solitary waves observed over the North Indian Ocean during the Indian Ocean Experiment (INDOEX) 1999

Dynamics of solitary waves observed over the North Indian Ocean during the Indian Ocean Experiment (INDOEX) 1999

Global and regional evaluation of a global model simulated AODs with AERONET and MODIS observations

Marine and biomass burning aerosols in the southern Indian Ocean: Retrieval of aerosol optical properties from shipborne lidar and Sun photometer measurements

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