Hugo Bellenger

French National Centre for Scientific Research | CNRS · Laboratoire de Météorologie Dynamique

The ocean skin is composed of thin interfacial microlayers of temperature and mass of less than 1 mm where heat and chemical exchanges are controlled by molecular diffusion. It is characterized by a cooling of ∼−0.2 K and an increase in salinity of ∼0.1 g/kg (absolute salinity) relative to the water below. A surface observation‐based air‐sea CO2 fl...

The Aeroclipper is a new balloon device that can be attracted and captured by tropical cyclones (TC) and perform continuous in situ measurements at the air–sea interfaces. To estimate the potential effect of Aeroclipper observations on the analysis of TCs, virtual Aeroclipper observations targeting TC Haima (October 2016) were synthesized using an...

Rain alters local sea surface physical and biogeochemical properties but its spatiotemporal variability has led to its overlook in global ocean carbon uptake studies. Different physical and chemical processes in the gaseous and liquid phases control the transfer of carbon dioxide (CO2) between the atmosphere and ocean. Rain impacts the interfacial...

The Northwest Tropical Atlantic (NWTA) is a region of complex surface ocean circulation. The most prominent feature is the North Brazil Current (NBC) and its retroflection at 8°N, which leads to the formation of numerous mesoscale eddies known as NBC rings. The NWTA also receives the outflow of the Amazon River, generating freshwater plumes that ca...

Low‐level clouds over the tropical and sub‐tropical oceans play a crucial role in the planetary radiative energy budget. However, they are challenging to model in climate simulations because they are affected by local processes that are still partially unknown. The control that mesoscale sea surface temperature (SST) structures have on the dynamics...

The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our abi...

jats:p>Abstract. The science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning...

The science guiding the EUREC4A campaign and its measurements is presented. EUREC4A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in our abi...

To advance the understanding of the interplay among clouds, convection, and circulation, and its role in climate change, the Elucidating the role of clouds–circulation coupling in climate campaign (EUREC4A) and Atlantic Tradewind Ocean–Atmosphere Mesoscale Interaction Campaign (ATOMIC) collected measurements in the western tropical Atlantic during...

The science guiding the EUREC4A campaign and its measurements are presented. EUREC4A comprised roughly five weeks of measurements in the downstream winter trades of the North Atlantic – eastward and south-eastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC4A marked a turning point in ou...

This article is part of the special issue “Elucidating the role of clouds–circulation coupling in climate:datasets from the 2020 (EUREC4A) field campaign”. It is not associated with a conference.

To advance the understanding of the interplay among clouds, convection, and circulation, and its role in climate change, the EUREC4A and ATOMIC field campaigns collected measurements in the western tropical Atlantic during January and February 2020. Upper-air radiosondes were launched regularly (usually 4-hourly) from a network consisting of the Ba...

Rainfall induces a vertical salinity gradient directly below the ocean surface, the strength and lifetime of which depend on the size of the rain event, the availability of mixing, and the air‐sea heat fluxes. The presence of rain in turn influences the near‐surface turbulent mixing and air‐sea exchange processes. During a campaign in the midlatitu...

Two L-Band (1.4GHz) microwave radiometer missions, the Soil Moisture and Ocean Salinity (SMOS) and the Soil Moisture Active and Passive (SMAP) missions, currently provide salinity measurements in the first centimeter below the sea surface. At this depth, salinity variability at hourly temporal scales is dominated by the impact of precipitation. The...

A large set of soundings obtained in the Indian Ocean during 3 field campaigns is used to provide statistical characteristics of tropospheric turbulence and its link with gravity wave (GW) activity. The Thorpe method is used to diagnose turbulent regions of a few hundred meters depth in the free troposphere. Above the mixed layer, turbulence freque...

Precipitation Estimates from satellite Sea Surface Salinity.

The Zeng and Beljaars (2005) sea surface temperature prognostic scheme, developed to represent diurnal warming, is extended to represent rain-induced freshening and cooling. Effects of rain on salinity and temperature in the molecular skin layer (first few hundred micrometers) and the near-surface turbulent layer (first few meters) are separately p...

The variability of lower-tropospheric humidity is a crucial feature of the tropical climate. Among the processes that impact moisture budget, the vertical transport by turbulent mixing is generally overlooked. Using observations from CINDY/DYNAMO campaign, this is a first attempt to quantify it over the tropical ocean. Turbulent patches of ~100 m d...

Tropospheric moisture is a key factor controlling the global climate and its variability. For instance, moistening of the lower troposphere is necessary to trigger the convective phase of a Madden-Julian Oscillation. However, the relative importance of the processes controlling this moistening has yet to be quantified. Among these processes, the im...

We investigate the processes responsible for the intraseasonal displacements of the eastern edge of the western Pacific warm pool (WPEE), which appear to play a role in the onset and development of El Niño events. We use 25 years of output from an ocean general circulation model experiment that is able to accurately capture the observed displacemen...

This study describes how the hull temperature (Ttop) measurements from multisensor surface velocity program(SVP) drifters can be combined with other measurements to provide quantitative information on near surface vertical temperature stratification during large daily cycles. First, Ttop is compared to the temperature measured at 17 -cm depth from...

We analyse the ability of CMIP3 and CMIP5 coupled ocean–atmosphere general circulation models (CGCMs) to simulate the tropical Pacific mean state and El Niño-Southern Oscillation (ENSO). The CMIP5 multi-model ensemble displays an encouraging 30 % reduction of the pervasive cold bias in the western Pacific, but no quantum leap in ENSO performance co...

We present the global general circulation model IPSL-CM5 developed to study the long-term response of the climate system to natural and anthropogenic forcings as part of the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). This model includes an interactive carbon cycle, a representation of tropospheric and stratospheric chemistry, a...

The strongest large-scale intraseasonal (30–110 day) sea surface temperature (SST) variations in austral summer in the tropics are found in the eastern Indian Ocean between Australia and Indonesia (North- Western Australian Basin, or NWAB). TMI and Argo observations indicate that the temperature signal (std. *0.4 C) is most prominent within the to...

The ability of coupled ocean-atmosphere general circulation models (CGCMs) to simulate the El Niño Southern Oscillation (ENSO) has largely improved over the last few years. Nevertheless, the diversity of model simulations of present-day ENSO characteristics indicate current limitations in our ability to model this climate phenomenon and anticipate...

Strong intraseasonal westerly wind bursts (WWBs) in the tropical Pacific Ocean generate zonal surface current anomalies that can advect the pool of warm water that is normally confined to the western Pacific Ocean (the "western Pacific warm pool") eastward, a process that has been implicated in the development of El Niño events. However, the relati...

During boreal winters, perturbations of the convection by the Madden-Julian Oscillation (MJO) peak over three basins distributed in longitude south of the Equator: the eastern Indian Ocean (IO), the south of the Maritime Continent (MC) and the western Pacific Ocean (PO). We use the observed Outgoing Longwave Radiation (OLR) and low-level wind to id...

We detect and characterize each large-scale intraseasonal perturbation in observations (1979–2009) and in coupled general circulation models of Institut Pierre Simon Laplace (IPSL) and of Centre National de Recherches Météorologiques (CNRM). These ensembles of intraseasonal perturbations are used to assess the skill of the two models in an event-by...

The role of air–sea interaction in the diurnal variations of convective activity during the suppressed and developing stages of an intraseasonal convective event is analyzed using in situ observations from the Mirai Indian Ocean cruise for the Study of the Madden–Julian oscillation (MJO)-convection Onset (MISMO) experiment. For the whole period, co...

1] Using an atmospheric Global Circulation Model (GCM), we study the dynamical response of the tropical atmosphere to large-scale convective perturbations. We hypothesize that such perturbations can be triggered by intraseasonal SST anomalies. We thus compare two ensembles of simulations forced either with actual daily SST fields (high frequency, H...

During periods of light surface wind, a warm stable layer forms at the ocean surface with a maximum sea surface temperature (SST) in the early afternoon. The diurnal SST amplitude (DSA) associated with these diurnal warm layers (DWLs) can reach several degrees and impact the tropical climate variability. This paper first presents an approach to bui...

During the Validation of the Aeroclipper System under Convective Occurrences (VASCO) test experiment in January and February 2007, eight Aeroclipper prototypes were launched from Mahé Island in the tropical Indian Ocean. The Aeroclipper is a streamlined balloon maintained in the atmospheric surface layer by a guide rope dragging on the ocean surfac...

The seasonal evolution of the 20–90-day intraseasonal variability (ISV) of the convection in the Indo-Pacific region presents intriguing features related to monsoon dynamics: (i) a sharp ISV maximum in May for the southern Bay of Bengal and in June for the eastern Arabian Sea, (ii) a maximum ISV over the west Pacific in July–September when the ISV...

Atmospheric tropical convection is strongly modulated at intraseasonal timescales (periods of 20 to 90 days). Ocean may play a critical role in atmospheric convective activity at this timescale. Sea Surface Temperature (SST) variations would indeed perturb surface fluxes and act to destabilise the atmosphere and trigger convection on the large scal...

Dans les tropiques, la convection atmosphérique est fortement modulée à l'échelle intrasaisonnière (périodes de 20 à 90 jours). L'océan jouerait un rôle important dans l'activité atmosphérique à cette échelle. Les variations de Températures de Surface de l'Océan (TSO) perturberaient en effet les flux de surface et déstabiliseraient l'atmosphère pou...

Dynamics of vibro-fluidised granular gas is investigated experimentally using the transfer of grains from a compartment through a horizontal slit at a given height h . It is demonstrated that the transfer rate j varies linearly with the grain number N in the box when N remains small; however j(N) becomes strongly non linear as soon as the number n...