J.-F. Gayet

Université Clermont Auvergne | Univ BPC

Aerosols of the volcanic degassing plumes from Mt. Etna and Mt. Stromboli were probed with in situ instruments on board the Deutsches Zentrum für Luft- und Raumfahrt research aircraft Falcon during the contrail, volcano, and cirrus experiment CONCERT in September 2011. Aerosol properties were analyzed using angular-scattering intensities and partic...

The impact of clouds on weather and climate is determined by their microphysical properties (i.e., the size distribution, water content, optical properties, and shape). Understanding how these properties evolve requires detailed studies with in situ measurements using a suite of different sensors. This article gives an overview of the different tec...

The investigation of the impact of aircraft parameters on contrail properties helps to better understand the climate impact from aviation. Yet, in observations, it is a challenge to separate aircraft and meteorological influences on contrail formation. During the CONCERT campaign in November 2008, contrails from 3 Airbus passenger aircraft of types...

Two complementary case studies are conducted to analyse convective system properties in the region where strong cloud-top lidar backscatter anomalies are observed as reported by Platt et al. (2011). These anomalies were reported for the first time using in-situ microphysical measurements in an isolated continental convective cloud over Germany duri...

The investigation of the impact of aircraft parameters on contrail properties helps to better understand the climate impact from aviation. Yet, in observations, it is a challenge to separate aircraft and meteorological influences on contrail formation. During the CONCERT campaign in November 2008, contrails from 3 Airbus passenger aircraft of type...

Arctic boundary-layer clouds in the vicinity of Svalbard (78° N, 15° E) were observed with airborne remote sensing and in situ methods. The cloud optical thickness and the droplet effective radius are retrieved from spectral radiance data from the nadir spot (1.5°, 350-2100 nm) and from a nadir-centred image (40°, 400-1000 nm). Two approaches are u...

Two complementary case studies are conducted to analyse convective system properties in the region where strong cloud-top lidar backscatter anomalies are observed as reported by Platt et al. (2011). These anomalies were reported for the first time using in situ microphysical measurements in an isolated continental convective cloud over Germany duri...

In this paper, we show that in mixed phase clouds, the presence of ice crystals may induce wrong FSSP 100 measurements interpretation especially in terms of particle size and subsequent bulk parameters. The presence of ice crystals is generally revealed by a bimodal feature of the particle size distribution (PSD). The combined measurements of the F...

In-situ Polar Nephelometer (PN) measurements of unusual ice crystal scattering phase functions, obtained near the cloud-top of a mid-latitude anvil cloud, at a temperature of about −58 °C, were recently reported by Gayet et al. (2012). The ice crystal habits that produced the phase functions consisted of aggregates of ice crystals and aggregates of...

Arctic boundary-layer clouds in the vicinity of Svalbard (78° N, 15° E) were observed with airborne remote sensing and in situ methods. The cloud optical thickness and the droplet effective radius are retrieved from spectral radiance data in nadir and and from hyperspectral radiances in a 40° field of view. Two approaches are used for the spectral...

A contrail from a large-body A380 aircraft at cruise in the humid upper troposphere has been probed with in-situ instruments onboard the DLR research aircraft Falcon. The contrail was sampled during 700 s measurement time at contrail ages of about 1–4 min. The contrail was in the vortex regime during which the primary wake vortices were sinking 270...

In-situ Polar Nephelometer (PN) measurements of unusual ice crystal scattering phase functions were recently reported by Gayet et al. (2012). The ice crystal habits that produced the phase functions were small chain-like aggregates, which had on their surfaces, smaller quasi-spherical ice crystals. The measured-averaged phase functions were feature...

Spectral radiance measurements by a digital single-lens reflex camera were used to derive the directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measurements...

Alors que nous sommes en train de planifier le remplacement des avions français utilisés par la communauté scientifique en recherche atmosphé-rique et en télédétection, nous avons voulu présenter un état des lieux mon-trant les moyens disponibles (les avions, leur instrumentation et leurs filières de traitement des données) et quelques exemples de...

In this paper, we show that in mixed phase clouds FSSP-100 measurements may be contaminated by ice crystals, inducing wrong interpretation of particle size and subsequent bulk parameters. This contamination is generally revealed by a bimodal feature of the particle size distribution; in other words, in mixed phase clouds bimodal features could be a...

The workshop on in situ airborne instrumentation: addressing and solving measurement problems in ice clouds, June 25-27, 2010, Oregon, aimed to identify unresolved questions concerning ice formation and evolution in ice clouds, assess the current state of instrumentation that can address these problems, introduce emerging technology that may overco...

During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/−58 °C). The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique s...

Spectral radiance measurements by a digital single-lens reflex camera were used to derive the bi-directional reflectivity of clouds and different surfaces in the Arctic. The camera has been calibrated radiometrically and spectrally to provide accurate radiance measurements with high angular resolution. A comparison with spectral radiance measuremen...

The contrail from a large-body A380 aircraft has extensively been probed in the vortex and early dispersion regime with in situ instruments to measure microphysical and optical properties of contrail ice particles on the DLR research aircraft Falcon. Concentrations up to 340 cm⁻³ of ice particles with diameters d >0.9 μm and extinction c...

During the CIRCLE-2 experiment carried out over Western Europe in May 2007, combined in situ and remote sensing observations allowed to describe microphysical and optical properties near-top of an overshooting convective cloud (11 080 m/−58 C). The airborne measurements were performed with the DLR Falcon aircraft specially equipped with a unique se...

One factor limiting the understanding of the climate impact from contrails and aircraft induced cloud modifications is the accurate determination of their optical depth. To this end, 14 contrails were sampled for 2756 s with instruments onboard the research aircraft Falcon during the CONCERT (CONtrail and Cirrus ExpeRimenT) campaign in November 200...

The frequency of occurrence of cirrus clouds and contrails, their life time, ice crystal size spectra and thus their radiative properties depend strongly on the ambient distribution of the relative humidity with respect to ice (RH_ice). Ice clouds do not form below a certain supersaturation and both cirrus and contrails need at least satu...

The frequency of occurrence of cirrus clouds and contrails, their life time, ice crystal size spectra and thus their radiative properties depend strongly on the ambient distribution of the relative humidity with respect to ice (RHice). Ice clouds do not form below a certain supersaturation and both cirrus and contrails need at least saturation cond...

This paper discusses the ratio C between the volume mean radius and the effective radius of ice particles in cirrus and contrails. The volume mean radius is proportional to the third root of the ratio between ice water content and number of ice particles, and the effective radius measures the ratio between ice particle volume and projected cross-se...

Arctic ice cloud formation during winter is poorly understood mainly due to lack of observations and the remoteness of this region. Their influence on Northern Hemisphere weather and climate is of paramount importance, and the modification of their properties, linked to aerosol-cloud interaction processes, needs to be better understood. Large conce...

Preferential horizontally-oriented ice crystals with a prevalent hexagonal-plate shape revealed by the Cloud Particle Imager can explain systematic larger Lidar CALIOP extinctions when compared with extinction derived from co-located in situ measurements. Surprisingly, the Polar Nephelometer does not reveal any signature of 22° (and 46°) halos, sho...

Lineshaped contrails were detected with the research aircraft Falcon during the CONCERT – CONtrail and Cirrus ExpeRimenT – campaign in October/November 2008. The Falcon was equipped with a set of instruments to measure the particle size distribution, shape, extinction and chemical composition as well as trace gas mixing ratios of sulfur dioxide (SO...

Airborne measurements of Lidar backscatter, aerosol concentrations (particle diameters of 4 nm to 50 μm), trace gas mixing ratios (SO₂, CO, O₃, H₂O), single particle properties, and meteorological parameters have been performed in volcanic ash plumes with the Falcon aircraft operated by Deutsches Zentrum für Luft- u...

Airborne lidar and in-situ measurements of the aerosol properties were conducted between Svalbard Island and Scandinavia in April 2008. Evidence of aerosol transport from Europe and Asia is given. The analysis of the aerosol optical properties based on a multiwavelength lidar (355, 532, 1064 nm) including volume depolarization at 355 nm aims at dis...

Lineshaped contrails were detected with the research aircraft Falcon during the CONCERT – CONtrail and Cirrus ExpeRimenT – campaign in October/November 2008. Thereby the Falcon was equipped with a set of instruments to measure particle properties such as the particle size distribution, shape, extinction, chemical composition as well as trace gas co...

A probabilistic model of the ice shattering effects on in-cloud measurements performed with instruments designed with inlets, which have the circular cross-section, is presented. Applications are made for the Polar Nephelometer and PMS FSSP instruments. The model provides rough estimates of the effects on microphysical measurements and assigns the...

During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR), which was conducted in Svalbard in March and April 2007, tropospheric Arctic clouds were observed with two ground-based backscatter lidar systems (micro pulse lidar and Raman lidar) and with an airborne elastic lidar. In the time period of the ASTAR 2007 campaign, an inc...

Large uncertainties remain in estimating the climate impact from contrails. In particular it is unknown, whether the aircraft type has an influence on contrail properties. Therefore, microphysical and radiative properties of contrails were detected with the DLR research aircraft Falcon during the CONCERT campaign in October/ November 2008. During 1...

Preferential horizontally-oriented ice crystals with a prevalent hexagonal-plate shape revealed by the Cloud Particle Imager can explain systematic larger Lidar CALIOP extinctions when compared with extinction derived from co-located in situ measurements. Surprisingly, the Polar Nephelometer does not reveal any signature of 22° (and 46°) halos, sho...

Airborne lidar and in-situ measurements of the aerosol properties were conducted between Svalbard Island and Scandinavia in April 2008. Evidence of aerosol transport from Europe and Asia is given. The analysis of the aerosol optical properties based on a multiwavelength lidar (355, 532, 1064 nm) including depolarization at 355 nm aims at distinguis...

The vertical distribution of ice crystals in Arctic boundary-layer mixed-phase (ABM) clouds was investigated by airborne remote-sensing and in situ measurements during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign in March and April 2007. Information on the spectral absorption of solar radiation by ice and liquid w...

During the airborne research mission ASTAR 2004 (Arctic Study of Tropospheric Aerosols, Clouds and Radiation) performed over the island of Svalbard in the Arctic a constant-temperature hot-wire Nevzorov Probe designed for aircraft measurements, has been used onboard the aircraft POLAR 2. The Nevzorov probe measured liquid water (LWC) and total cond...

The POLARCAT project aims to quantify the contribution and impact of trace gases and aerosols transported to the Arctic region. Within the frame of this project, the French ATR-42 research aircraft, equipped particularly with in-situ and remote sensing instrumention, was deployed during 2 measurement campaigns in 2008. While during the spring campa...

1] Airborne measurements of spectral upwelling radiances (350 – 2200 nm) reflected by cirrus using the Spectral Modular Airborne Radiation measurement sysTem (SMART)-Albedometer were made over land and water surfaces. Based on these data, cloud optical thickness t and effective radius R eff of the observed cirrus were retrieved. By using different...

Airborne measurements in Arctic boundary-layer stratocumulus were carried out near Spitsbergen on 9 April 2007 during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign. A unique set of co-located observations is used to describe the cloud properties, including detailed in situ cloud microphysical and radiation measurem...

Airborne measurements in Arctic boundary-layer stratocumulus were carried out near Spitsbergen on 9 April 2007 during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign. A unique set of co-located observations is used to describe the cloud properties, including detailed in situ cloud microphysical and radiation measurem...

During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR), which was conducted in Svalbard in March and April 2007, tropospheric Arctic clouds were observed with two ground-based backscatter lidar systems (micro pulse lidar and Raman lidar) and with an airborne elastic lidar. An increase in low-level (cloud tops below 2.5 km) cl...

During the airborne research mission ASTAR 2004 (Arctic Study of Tropospheric Aerosols, Clouds and Radiation) performed over the island of Svalbard in the Arctic a constant-temperature hot-wire Nevzorov Probe designed for aircraft measurements, has been used onboard the aircraft POLAR 2. The Nevzorov probe measured liquid water (LWC) and total cond...

During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign, which was conducted in March and April 2007, an optically thin ice cloud was observed south of Svalbard at around 3 km altitude. The microphysical and radiative properties of this particular subvisible midlevel cloud were investigated with complementary remote s...

The paper presents the results of in situ observations related to Arctic clouds where possible ice-multiplication via stellar-crystal fragmentation processes is discussed. The microphysical and morphological cloud-parameters are derived from airborne measurements performed with a Cloud Particle Imager (CPI). One principal idea of this study is to d...

As part of POLARCAT-FRANCE, an aircraft campaign took place in Kiruna (North Sweden) in March-April 2008. The major objective was to study the impact of transport processes on ozone and aerosol distributions and cloud microphysics in the Arctic region. An ATR-42 equipped with remote sensing instrument (3 wavelength backscatter lidar, radar) and in-...

During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign, which was conducted in March and April 2007, an optically thin ice cloud was observed at around 3 km altitude south of Svalbard. The microphysical and radiative properties of this particular subvisible midlevel cloud were investigated with complementary remote s...

Arctic boundary-layer clouds were investigated with remote sensing and in situ instruments during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign in March and April 2007. The clouds formed in a cold air outbreak over the open Greenland Sea. Beside the predominant mixed-phase clouds pure liquid water and ice clouds we...

Previous studies have reported that the two channels at 10.6 and 12 μm allow a determination of the optical thickness and effective size of ice cloud, for particle size less than 100 μm. In the context of the CALIPSO mission, a sensitivity study based on radiative transfer calculations has shown that the shape of non spherical ice particles and to...

A comparison of satellite data with simulations from global circulation models shows that there is a lack of cirrus cloud amount in large-scale models above and in the lee of mountains. The formation of orographic cirrus clouds due to gravity waves is usually not parameterized in large-scale models. To improve the simulation of such orographically...

Boundary layer clouds were investigated with a complementary set of remote sensing and in situ instruments during the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR) campaign in March and April 2007. The clouds that formed in a cold air outbreak over the open Greenland sea showed a variety in their thermodynamic state. Beside the...

During the international ASTAR experiment (Arctic Study of Aerosols, Clouds and Radiation) carried out from Longyearbyen (Spitsbergen) from 10 May to 11 June 2004, the AWI (Alfred Wegener Institute) Polar 2 aircraft was equipped with a unique combination of remote and in situ instruments. The airborne AMALi lidar provided downward backscatter and D...

Theoretical phase-functions representing randomly oriented fractal ice-crystals, bullet-rosettes, ice aggregates, and an ensemble of ice crystals are compared to measured phase-functions using a Polar Nephelometer located in the Antarctic. The Polar Nephelometer operated at a wavelength of 0.80 µm and measured the scattering phase-functions of indi...

A methodology of employing statistical procedures, specifically the principal component analysis (PCA) technique, to assess cirrus cloud data reliability is described. The approach is demonstrated by an example of a study of optical and microphysical characteristics measured during two campaigns performed at midlatitudes in the pristine Southern (S...

We have analysed relative humidity statistics from measurements in cirrus clouds taken unintentionally during the Measurement of OZone by Airbus In-service airCraft project (MOZAIC). The shapes of the in-cloud humidity distributions change from nearly symmetric in relatively warm cirrus (warmer than -40°) to considerably positively skew (i.e. towar...

We have analysed relative humidity statistics from measurements in cirrus clouds taken unintentionally during the Measurement of OZone by Airbus In-service airCraft project (MOZAIC). The shapes of the in-cloud humidity distributions change from nearly symmetric in relatively warm cirrus (warmer than -40°C) to considerably positively skew (i.e. towa...

The uptake of reactive nitrogen species on ice crystals in cirrus clouds was investigated by simultaneous aircraft-based measurements of gas- and condensed-phase NOy, ice particle size distribution and total aerosol surface area. The measurements were performed in 2000 during the INCA campaign at northern and southern midlatitudes at local autumn....

In situ measurements of the partitioning of aerosol particles within cirrus clouds were used to investigate aerosol-cloud interactions in ice clouds. The number density of interstitial aerosol particles (non-activated particles in between the cirrus crystals) was compared to the number density of cirrus crystal residuals. The data was obtained duri...

We have analysed relative humidity statistics from measurements in cirrus clouds taken unintentionally during the Measurement of OZone by Airbus In-service airCraft project (MOZAIC). The shapes of the in-cloud humidity distributions change from nearly symmetric in relatively warm cirrus (warmer than −40°) to considerably positively skew (i.e. towar...

Microphysical and optical measurements were performed in midlatitude cirrus clouds at temperatures between −33°C and −60°C during southern and northern Interhemispheric Differences in Cirrus Properties From Anthropogenic Emissions (INCA) field experiments carried out at equivalent latitudes (53°S and 55°N) from Punta Arenas in the Southern Hemisphe...

Based on in-situ observations performed during the Interhemispheric differences in cirrus properties from anthropogenic emissions (INCA) experiment, we introduce and discuss the cloud presence fraction (CPF) defined as the ratio between the number of data points determined to represent cloud at a given ambient relative humidity over ice (RHI) divid...

A thermal volatility technique is used to provide indirect information about the chemical composition of the aerosol involved in cirrus cloud formation. The fraction of particles that disappears after being heated to 125°C is termed volatile and the fraction that disappears between 125 and 250°C is termed semi-volatile. Particles that still remain...

In situ measurements of the partitioning of aerosol particles within cirrus clouds were used to investigate aerosol-cloud interactions in ice clouds. The number density of interstitial aerosol particles (non-activated particles in between the cirrus crystals) was compared to the number density of cirrus crystal residuals. The data was obtained duri...

The occurrence frequency of cirrus clouds as function of ambient relative humidity over ice, based on in-situ observations performed during the INCA experiment, show a clear difference between the campaign carried out at Southern Hemisphere (SH) midlatitudes and the campaign carried out at Northern Hemisphere (NH) midlatitudes. At a given relative...

Radiative properties of cirrus clouds in relation to their microphysical characteristics were studied during the airborne FRENCH-DIRAC campaign. It was held in September/October 2001 in south western France and over the Mediterranean sea. During this campaign, two aircrafts were involved. A TBM 700 aircraft devoted to insitu measurements has carrie...

Original microphysical and optical measurements were obtained in cirrus clouds on the Southern and Northern hemispheres during the INCA experiments using four independent techniques: (1) the Counterflow Virtual Impactor, (2) the PMS FSSP-300, (3) the PMS 2D-C and (4) the Polar Nephelometer probes. The combination of these four techniques provides a...

The retrieval of cirrus cloud microphysical properties in a multilayer cloud system is a challenge due to the usually low optical thickness of the ice cloud under investigation. However, it is estimated that about 50% of all cirrus clouds occur in such multilayer systems. Here, we present a method that uses a combination of five observations by the...

In-situ observations of aerosol particles contained in cirrus crystals are presented and compared to interstitial aerosol size distributions (non-activated particles in between the cirrus crystals). The observations were conducted in cirrus clouds in the Southern and Northern Hemisphere midlatitudes during the INCA project. The first campaign in Ma...

Water vapour data inside cirrus clouds from in-situ measurements with an aircraft-borne frost-point hygrometer are analysed. These data have been obtained during two field campaigns, performed in the Southern and Northern hemisphere mid latitudes. There were many occurrences of ice supersaturation inside the investigated cirrus, with a higher frequ...