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  • Author or Editor: Julien Delanoë x
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Anna E. Luebke
,
Julien Delanoë
,
Vincent Noel
,
Hélène Chepfer
, and
Bjorn Stevens
Full access
Julie Haggerty
,
Eric Defer
,
Adrianus De Laat
,
Kristopher Bedka
,
Jean-Marc Moisselin
,
Rodney Potts
,
Julien Delanoë
,
Frédéric Parol
,
Alice Grandin
, and
Stephanie Divito

Abstract

In the past two decades, more than 150 jet engine power-loss and damage events have been attributed to a phenomenon known as ice crystal icing (ICI). Ingestion of large numbers of ice particles into the engine core are thought to be responsible for these events, which typically occur at high altitudes near large convective systems in tropical air masses. In recent years, scientists, engineers, aviation regulators, and airlines from around the world have collaborated to better understand the relevant meteorological processes associated with ICI events, solve critical engineering problems, develop new certification standards, and devise mitigation strategies for the aviation industry. One area of research is the development of nowcasting techniques based on available remote sensing technology and numerical weather prediction (NWP) models to identify areas of high ice water content (IWC) and enable the provision of alerts to the aviation industry. Multiple techniques have been developed using geostationary and polar-orbiting satellite products, NWP model fields, and ground-based radar data as the basis for high-IWC products. Targeted field experiments in tropical regions with high incidence of ICI events have provided data for product validation and refinement of these methods. Beginning in 2015, research teams have assembled at a series of annual workshops to exchange ideas and standardize methods for evaluating performance of high-IWC detection products. This paper provides an overview of the approaches used and the current skill for identifying high-IWC conditions. Recommendations for future work in this area are also presented.

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Shuyi S. Chen
,
Brandon W. Kerns
,
Nick Guy
,
David P. Jorgensen
,
Julien Delanoë
,
Nicolas Viltard
,
Christopher J. Zappa
,
Falko Judt
,
Chia-Ying Lee
, and
Ajda Savarin

Abstract

One of the most challenging problems in predicting the Madden–Julian oscillation (MJO) is the initiation of large-scale convective activity associated with the MJO over the tropical Indian Ocean. The lack of observations is a major obstacle. The Dynamics of the MJO (DYNAMO) field campaign collected unprecedented observations from air-, land-, and ship-based platforms from October 2011 to February 2012. Here we provide an overview of the aircraft observations in DYNAMO, which captured an MJO initiation event from November to December 2011. The National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft was stationed at Diego Garcia and the French Falcon 20 aircraft on Gan Island in the Maldives. Observations from the two aircraft provide a unique dataset of three-dimensional structure of convective cloud systems and their environment from the flight level, airborne Doppler radar, microphysics probes, ocean surface imaging, global positioning system (GPS) dropsonde, and airborne expendable bathythermograph (AXBT) data. The aircraft observations revealed interactions among dry air, the intertropical convergence zone (ITCZ), convective cloud systems, and air–sea interaction induced by convective cold pools, which may play important roles in the multiscale processes of MJO initiation. This overview focuses on some key aspects of the aircraft observations that contribute directly to better understanding of the interactions among convective cloud systems, environmental moisture, and the upper ocean during the MJO initiation over the tropical Indian Ocean. Special emphasis is on the distinct characteristics of convective cloud systems, environmental moisture and winds, air–sea fluxes, and convective cold pools during the convectively suppressed, transition/onset, and active phases of the MJO.

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Anne-Claire Billault-Roux
,
Jacopo Grazioli
,
Julien Delanoë
,
Susana Jorquera
,
Nicolas Pauwels
,
Nicolas Viltard
,
Audrey Martini
,
Vincent Mariage
,
Christophe Le Gac
,
Christophe Caudoux
,
Clémantyne Aubry
,
Fabrice Bertrand
,
Alfons Schwarzenboeck
,
Louis Jaffeux
,
Pierre Coutris
,
Guy Febvre
,
Jean Marc Pichon
,
Fabien Dezitter
,
Josué Gehring
,
Aude Untersee
,
Christophe Calas
,
Jordi Figueras i Ventura
,
Benoit Vie
,
Adrien Peyrat
,
Valentin Curat
,
Simon Rebouissoux
, and
Alexis Berne

Abstract

An international field experiment took place in the Swiss Jura in January 2021 as a milestone of the European ICE GENESIS project (www.ice-genesis.eu/), which aims to better measure, understand, and model the ice/snow particle properties and mechanisms responsible for icing of rotor-craft and aircraft. The field campaign was designed to collect observations of clouds and snowfall at a prescribed range of temperatures (−10° to +2°C). The suite of in situ and remote sensing instruments included airborne probes and imagers on board a SAFIRE ATR-42 aircraft, able to sample liquid and ice particles from the micron to the millimeter size range, as well as icing sensors and cameras. Two 95 GHz Doppler cloud radars were installed on the SAFIRE ATR-42, while six Doppler weather radars operating at frequencies ranging from 10 to 95 GHz (and one lidar) were ground based. An operational polarimetric weather radar in nearby France (Montancy) complements the coverage. Finally, observations of standard meteorological variables as well as high-resolution pictures of falling snowflakes from a multiangle snowflake camera were collected at the ground level. The campaign showed its full potential during five (multihourly) flights where precipitation was monitored from cloud to ground. The originality of this campaign resides in the targeted specific temperature range for snowfall and in the synchronization between the ground-based remote sensing and the aircraft trajectories designed to maximize the collection of in situ observations within the column above the radar systems.

Open access
Cyrille Flamant
,
Jean-Pierre Chaboureau
,
Julien Delanoë
,
Marco Gaetani
,
Cédric Jamet
,
Christophe Lavaysse
,
Olivier Bock
,
Maurus Borne
,
Quitterie Cazenave
,
Pierre Coutris
,
Juan Cuesta
,
Laurent Menut
,
Clémantyne Aubry
,
Angela Benedetti
,
Pierre Bosser
,
Sophie Bounissou
,
Christophe Caudoux
,
Hélène Collomb
,
Thomas Donal
,
Guy Febvre
,
Thorsten Fehr
,
Andreas H. Fink
,
Paola Formenti
,
Nicolau Gomes Araujo
,
Peter Knippertz
,
Eric Lecuyer
,
Mateus Neves Andrade
,
Cédric Gacial Ngoungué Langué
,
Tanguy Jonville
,
Alfons Schwarzenboeck
, and
Azusa Takeishi

Abstract

During the boreal summer, mesoscale convective systems generated over West Africa propagate westward and interact with African easterly waves, and dust plumes transported from the Sahel and Sahara by the African easterly jet. Once off West Africa, the vortices in the wake of these mesoscale convective systems evolve in a complex environment sometimes leading to the development of tropical storms and hurricanes, especially in September when sea surface temperatures are high. Numerical weather predictions of cyclogenesis downstream of West Africa remains a key challenge due to the incomplete understanding of the clouds–atmospheric dynamics–dust interactions that limit predictability. The primary objective of the Clouds–Atmospheric Dynamics–Dust Interactions in West Africa (CADDIWA) project is to improve our understanding of the relative contributions of the direct, semidirect, and indirect radiative effects of dust on the dynamics of tropical waves as well as the intensification of vortices in the wake of offshore mesoscale convective systems and their evolution into tropical storms over the North Atlantic. Airborne observations relevant to the assessment of such interactions (active remote sensing, in situ microphysics probes, among others) were made from 8 to 21 September 2021 in the tropical environment of Sal Island, Cape Verde. The environments of several tropical cyclones, including Tropical Storm Rose, were monitored and probed. The airborne measurements also serve the purpose of regional model evaluation and the validation of spaceborne wind, aerosol and cloud products pertaining to satellite missions of the European Space Agency and EUMETSAT (including the Aeolus, EarthCARE, and IASI missions).

Open access
Bjorn Stevens
,
Felix Ament
,
Sandrine Bony
,
Susanne Crewell
,
Florian Ewald
,
Silke Gross
,
Akio Hansen
,
Lutz Hirsch
,
Marek Jacob
,
Tobias Kölling
,
Heike Konow
,
Bernhard Mayer
,
Manfred Wendisch
,
Martin Wirth
,
Kevin Wolf
,
Stephan Bakan
,
Matthias Bauer-Pfundstein
,
Matthias Brueck
,
Julien Delanoë
,
André Ehrlich
,
David Farrell
,
Marvin Forde
,
Felix Gödde
,
Hans Grob
,
Martin Hagen
,
Evelyn Jäkel
,
Friedhelm Jansen
,
Christian Klepp
,
Marcus Klingebiel
,
Mario Mech
,
Gerhard Peters
,
Markus Rapp
,
Allison A. Wing
, and
Tobias Zinner

Abstract

A configuration of the High-Altitude Long-Range Research Aircraft (HALO) as a remote sensing cloud observatory is described, and its use is illustrated with results from the first and second Next-Generation Aircraft Remote Sensing for Validation (NARVAL) field studies. Measurements from the second NARVAL (NARVAL2) are used to highlight the ability of HALO, when configured in this fashion, to characterize not only the distribution of water condensate in the atmosphere, but also its impact on radiant energy transfer and the covarying large-scale meteorological conditions—including the large-scale velocity field and its vertical component. The NARVAL campaigns with HALO demonstrate the potential of airborne cloud observatories to address long-standing riddles in studies of the coupling between clouds and circulation and are helping to motivate a new generation of field studies.

Full access
Karine Sellegri
,
Mike Harvey
,
Maija Peltola
,
Alexia Saint-Macary
,
Theresa Barthelmeß
,
Manon Rocco
,
Kathryn A. Moore
,
Antonia Cristi
,
Frederic Peyrin
,
Neill Barr
,
Laurent Labonnote
,
Andrew Marriner
,
John McGregor
,
Karl Safi
,
Stacy Deppeler
,
Stephen Archer
,
Erin Dunne
,
James Harnwell
,
Julien Delanoe
,
Evelyn Freney
,
Clémence Rose
,
Clément Bazantay
,
Céline Planche
,
Alfonso Saiz-Lopez
,
Jesús E. Quintanilla-López
,
Rosa Lebrón-Aguilar
,
Matteo Rinaldi
,
Sandra Banson
,
Romain Joseph
,
Aurelia Lupascu
,
Olivier Jourdan
,
Guillaume Mioche
,
Aurélie Colomb
,
Gus Olivares
,
Richard Querel
,
Adrian McDonald
,
Graeme Plank
,
Beata Bukosa
,
Wayne Dillon
,
Jacques Pelon
,
Jean-Luc Baray
,
Frederic Tridon
,
Franck Donnadieu
,
Frédéric Szczap
,
Anja Engel
,
Paul J. DeMott
, and
Cliff S. Law

Abstract

The goal of the Sea2Cloud project is to study the interplay between surface ocean biogeochemical and physical properties, fluxes to the atmosphere, and ultimately their impact on cloud formation under minimal direct anthropogenic influence. Here we present an interdisciplinary approach, combining atmospheric physics and chemistry with marine biogeochemistry, during a voyage between 41° and 47°S in March 2020. In parallel to ambient measurements of atmospheric composition and seawater biogeochemical properties, we describe semicontrolled experiments to characterize nascent sea spray properties and nucleation from gas-phase biogenic emissions. The experimental framework for studying the impact of the predicted evolution of ozone concentration in the Southern Hemisphere is also detailed. After describing the experimental strategy, we present the oceanic and meteorological context including provisional results on atmospheric thermodynamics, composition, and flux measurements. In situ measurements and flux studies were carried out on different biological communities by sampling surface seawater from subantarctic, subtropical, and frontal water masses. Air–Sea-Interface Tanks (ASIT) were used to quantify biogenic emissions of trace gases under realistic environmental conditions, with nucleation observed in association with biogenic seawater emissions. Sea spray continuously generated produced sea spray fluxes of 34% of organic matter by mass, of which 4% particles had fluorescent properties, and which size distribution resembled the one found in clean sectors of the Southern Ocean. The goal of Sea2Cloud is to generate realistic parameterizations of emission flux dependences of trace gases and nucleation precursors, sea spray, cloud condensation nuclei, and ice nuclei using seawater biogeochemistry, for implementation in regional atmospheric models.

Open access
Véronique Ducrocq
,
Isabelle Braud
,
Silvio Davolio
,
Rossella Ferretti
,
Cyrille Flamant
,
Agustin Jansa
,
Norbert Kalthoff
,
Evelyne Richard
,
Isabelle Taupier-Letage
,
Pierre-Alain Ayral
,
Sophie Belamari
,
Alexis Berne
,
Marco Borga
,
Brice Boudevillain
,
Olivier Bock
,
Jean-Luc Boichard
,
Marie-Noëlle Bouin
,
Olivier Bousquet
,
Christophe Bouvier
,
Jacopo Chiggiato
,
Domenico Cimini
,
Ulrich Corsmeier
,
Laurent Coppola
,
Philippe Cocquerez
,
Eric Defer
,
Julien Delanoë
,
Paolo Di Girolamo
,
Alexis Doerenbecher
,
Philippe Drobinski
,
Yann Dufournet
,
Nadia Fourrié
,
Jonathan J. Gourley
,
Laurent Labatut
,
Dominique Lambert
,
Jérôme Le Coz
,
Frank S. Marzano
,
Gilles Molinié
,
Andrea Montani
,
Guillaume Nord
,
Mathieu Nuret
,
Karim Ramage
,
William Rison
,
Odile Roussot
,
Frédérique Said
,
Alfons Schwarzenboeck
,
Pierre Testor
,
Joël Van Baelen
,
Béatrice Vincendon
,
Montserrat Aran
, and
Jorge Tamayo

The Mediterranean region is frequently affected by heavy precipitation events associated with flash floods, landslides, and mudslides that cause hundreds of millions of euros in damages per year and, often, casualties. A major field campaign was devoted to heavy precipitation and f lash f loods from 5 September to 6 November 2012 within the framework of the 10-yr international Hydrological Cycle in the Mediterranean Experiment (HyMeX) dedicated to the hydrological cycle and related high-impact events. The 2-month field campaign took place over the northwestern Mediterranean Sea and its surrounding coastal regions in France, Italy, and Spain. The observation strategy of the field experiment was devised to improve knowledge of the following key components leading to heavy precipitation and flash flooding in the region: 1) the marine atmospheric f lows that transport moist and conditionally unstable air toward the coasts, 2) the Mediterranean Sea acting as a moisture and energy source, 3) the dynamics and microphysics of the convective systems producing heavy precipitation, and 4) the hydrological processes during flash floods. This article provides the rationale for developing this first HyMeX field experiment and an overview of its design and execution. Highlights of some intensive observation periods illustrate the potential of the unique datasets collected for process understanding, model improvement, and data assimilation.

Full access
Andreas Schäfler
,
George Craig
,
Heini Wernli
,
Philippe Arbogast
,
James D. Doyle
,
Ron McTaggart-Cowan
,
John Methven
,
Gwendal Rivière
,
Felix Ament
,
Maxi Boettcher
,
Martina Bramberger
,
Quitterie Cazenave
,
Richard Cotton
,
Susanne Crewell
,
Julien Delanoë
,
Andreas Dörnbrack
,
André Ehrlich
,
Florian Ewald
,
Andreas Fix
,
Christian M. Grams
,
Suzanne L. Gray
,
Hans Grob
,
Silke Groß
,
Martin Hagen
,
Ben Harvey
,
Lutz Hirsch
,
Marek Jacob
,
Tobias Kölling
,
Heike Konow
,
Christian Lemmerz
,
Oliver Lux
,
Linus Magnusson
,
Bernhard Mayer
,
Mario Mech
,
Richard Moore
,
Jacques Pelon
,
Julian Quinting
,
Stephan Rahm
,
Markus Rapp
,
Marc Rautenhaus
,
Oliver Reitebuch
,
Carolyn A. Reynolds
,
Harald Sodemann
,
Thomas Spengler
,
Geraint Vaughan
,
Manfred Wendisch
,
Martin Wirth
,
Benjamin Witschas
,
Kevin Wolf
, and
Tobias Zinner

Abstract

The North Atlantic Waveguide and Downstream Impact Experiment (NAWDEX) explored the impact of diabatic processes on disturbances of the jet stream and their influence on downstream high-impact weather through the deployment of four research aircraft, each with a sophisticated set of remote sensing and in situ instruments, and coordinated with a suite of ground-based measurements. A total of 49 research flights were performed, including, for the first time, coordinated flights of the four aircraft: the German High Altitude and Long Range Research Aircraft (HALO), the Deutsches Zentrum für Luft- und Raumfahrt (DLR) Dassault Falcon 20, the French Service des Avions Français Instrumentés pour la Recherche en Environnement (SAFIRE) Falcon 20, and the British Facility for Airborne Atmospheric Measurements (FAAM) BAe 146. The observation period from 17 September to 22 October 2016 with frequently occurring extratropical and tropical cyclones was ideal for investigating midlatitude weather over the North Atlantic. NAWDEX featured three sequences of upstream triggers of waveguide disturbances, as well as their dynamic interaction with the jet stream, subsequent development, and eventual downstream weather impact on Europe. Examples are presented to highlight the wealth of phenomena that were sampled, the comprehensive coverage, and the multifaceted nature of the measurements. This unique dataset forms the basis for future case studies and detailed evaluations of weather and climate predictions to improve our understanding of diabatic influences on Rossby waves and the downstream impacts of weather systems affecting Europe.

Full access