Cirene: Air—Sea Interactions in the Seychelles—Chagos Thermocline Ridge Region

Vialard, Jérôme; Duvel, Jean-Philippe; McPhaden, Michael J.; Bouruet‐Aubertot, Pascale; Ward, Brian; Key, E.; Bourras, Denis; Weller, Robert A.; Minnett, Peter J.; Weill, Alain; Cassou, Christophe; Eymard, Laurence; Fristedt, Tim; Basdevant, C.; Dandonneau, Yves; Duteil, Olaf; Izumo, Takeshi; Montégut, C. de Boyer; Masson, Sébastien; Marsac, Francis; Menkès, Christophe E.; Kennan, Sean C.

doi:10.1175/2008bams2499.1

Cited by 132 publications

(130 citation statements)

References 51 publications

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“…In the future, it is hoped that the analysis and understanding of the salinity stratification effect will improve owing to the ongoing international efforts conducted for performing large number of measurements of the salinity closer to the sea surface than traditional in situ measurements and at several depths close to the sea surface, either using autonomous drifters (Reverdin et al, 2012) or high resolution profilers, like the ARGO-STS (Anderson and Riser, 2012) or the ASIP profiler (Ward et al, 2004;Vialard et al, 2009). In addition, the long time series of SMOS and Aquarius SSS together with these new measurements will allow wider validation of new remotely sensed SSS.…”

Section: Discussionmentioning

confidence: 99%

Sea surface freshening inferred from SMOS and ARGO salinity: impact of rain

et al. 2013

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Abstract. The sea surface salinity (SSS) measured from space by the Soil Moisture and Ocean Salinity (SMOS) mission has recently been revisited by the European Space Agency first campaign reprocessing. We show that, with respect to the previous version, biases close to land and ice greatly decrease. The accuracy of SMOS SSS averaged over 10 days, 100 × 100 km 2 in the open ocean and estimated by comparison to ARGO (Array for Real-Time Geostrophic Oceanography) SSS is on the order of 0.3-0.4 in tropical and subtropical regions and 0.5 in a cold region. The averaged negative SSS bias (−0.1) observed in the tropical Pacific Ocean between 5 • N and 15 • N, relatively to other regions, is suppressed when SMOS observations concomitant with rain events, as detected from SSM/Is (Special Sensor Microwave Imager) rain rates, are removed from the SMOS-ARGO comparisons. The SMOS freshening is linearly correlated to SSM/Is rain rate with a slope estimated to −0.14 mm −1 h, after correction for rain atmospheric contribution. This tendency is the signature of the temporal SSS variability between the time of SMOS and ARGO measurements linked to rain variability and of the vertical salinity stratification between the first centimeter of the sea surface layer sampled by SMOS and the 5 m depth sampled by ARGO. However, given that the whole set of collocations includes situations with ARGO measurements concomitant with rain events collocated with SMOS measurements under no rain, the mean −0.1 bias and the negative skewness of the statistical distribution of SMOS minus ARGO SSS difference are very likely the mean signature of the vertical salinity stratification. In the future, the analysis of ongoing in situ salinity measurements in the top 50 cm of the sea surface and of Aquarius satellite SSS are expected to provide complementary information about the sea surface salinity stratification.

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Section: Discussionmentioning

confidence: 99%

Sea surface freshening inferred from SMOS and ARGO salinity: impact of rain

et al. 2013

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“…In particular, the stationary front of the s-ITCZ between 10°S and 0° corresponds well with the remarkable meridional gradients of the SST. The location of the SST gradients also corresponds with the Seychelles-Chagos thermocline ridge region (Hermes and Reason 2008;Vialard et al 2009). In addition, the relationship between the high (low) SLP in Fig.…”

Section: Kinematic and Thermodynamic Structures Of The Mjo At Each Stagementioning

confidence: 91%

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

Moteki

2015

Journal of the Meteorological Society of Japan

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In this study, we investigated the equatorially antisymmetric features in the initiation processes of the MaddenJulian oscillation (MJO) event in late October during the cooperative Indian Ocean experiment on intraseasonal variability in the year 2011. This MJO event developed when the thermal equator was drastically shifted from the Northern Hemisphere to the equator from September to October as the Mascarene High over the southern Indian Ocean decayed and shifted southward. The large-scale fields of sea level pressure, temperature, and moisture around the MJO exhibited equatorially antisymmetric features. According to their different features in terms of surface convergence, temperature, and moisture, MJO convection over the Indian Ocean after its onset consisted of four distinct convective components: the southern intertropical convergence zone between 10°S and 0° along the meridional sea surface temperature (SST) gradients (s-ITCZ), the northern-ITCZ at the southern edge of the high SST above 29°C over the Bay of Bengal, the vortex disturbance over the Arabian Sea (VDAS) in association with the zonal SST gradients, and the westward-propagating diurnal convection originating from Sumatra. In particular, the double-ITCZ and VDAS were characterized by a steady, low-level convergence zone along the surface potential temperature gradients forced by the SST. Before the onset of the MJO convection, the double-ITCZ was characterized by cross-equatorial vertical circulation that was baroclinically tilted northward, and s-ITCZ convection was inhibited owing to the strong Mascarene High. After the onset, single, larger-scale upward motion was barotropically formed over the equator because of the equatorward shift of the double-ITCZ. Such changes in the equatorially antisymmetric meridional circulation are relevant for the organization of the MJO convection.

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“…BPCLs are designed to drift and make observations with a payload of a few kg in the lower troposphere for durations of up to several weeks (Vialard et al, 2009). Two versions were used, the standard one of 2.5 m in diameter, launched pressurized, which is limited to a maximum float altitude of about 2.5 km (Ducrocq et al, 2014), and one developed for ChArMEx of 2.6 m in diameter, launched unpressurized to reach a float altitude of more than 3 km in altitude.…”

Section: Balloon Operationsmentioning

confidence: 99%

Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

et al. 2016

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Abstract. The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental setup also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote-sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modeling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to producing high levels of atmospheric pollutants or intense biomass burning events in the region. However, numerous mineral dust plumes were observed during the campaign, with the main sources located in Morocco, Algeria and Tunisia, leading to aerosol optical depth (AOD) values ranging between 0.2 and 0.6 (at 440 nm) over the western and central Mediterranean basins. One important point of this experiment concerns the direct observations of aerosol extinction onboard the ATR-42, using the CAPS system, showing local maxima reaching up to 150 M m −1 within the dust plume. Non-negligible aerosol extinction (about 50 M m −1 ) has also been observed within the marine boundary layer (MBL). By combining the ATR-42 extinction coefficient observations with absorption and scattering measurements, we performed a complete optical closure revealing excellent agreement with estimated optical properties. This additional information on extinction properties has allowed calculation of the dust single scattering albedo (SSA) with a high level of confidence over the western Mediterranean. Our results show a moderate variability from 0....

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Cirene: Air—Sea Interactions in the Seychelles—Chagos Thermocline Ridge Region

Cited by 132 publications

References 51 publications

Sea surface freshening inferred from SMOS and ARGO salinity: impact of rain

Sea surface freshening inferred from SMOS and ARGO salinity: impact of rain

Equatorially Antisymmetric Features in the Initiation Processes of the Madden-Julian Oscillation Observed in Late October during CINDY2011

Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

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