A5060584982- Atmospheric Ozone and Climate
- Atmospheric chemistry and aerosols
- Atmospheric and Environmental Gas Dynamics
- Atmospheric aerosols and clouds
- Ionosphere and magnetosphere dynamics
- Dark Matter and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Planetary Science and Exploration
- Astro and Planetary Science
- Climate variability and models
- Aerospace Engineering and Energy Systems
- Meteorological Phenomena and Simulations
- Spaceflight effects on biology
- Quantum, superfluid, helium dynamics
- Particle physics theoretical and experimental studies
- Methane Hydrates and Related Phenomena
- Scientific Research and Discoveries
- Neutrino Physics Research
- Particle Dynamics in Fluid Flows
- Solar and Space Plasma Dynamics
- Particle Detector Development and Performance
- Aeolian processes and effects
- Air Quality Monitoring and Forecasting
- Radiation Detection and Scintillator Technologies
- Climate Change and Geoengineering
Yale University
2011-2020
Danish Meteorological Institute
2004-2017
Aalborg University
2014
Centre National de la Recherche Scientifique
2000-2009
Laboratoire de Météorologie Physique
2006
University of Wyoming
1997-2000
Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
1997
Finnish Meteorological Institute
1997
Aberystwyth University
1994
University of Wales
1994
A comprehensive investigation of polar stratospheric clouds was performed on 25 January 2000 with instruments onboard a balloon gondola flown from Kiruna, Sweden. Cloud layers were repeatedly encountered at altitudes between 20 and 24 kilometers over wide range atmospheric temperatures (185 to 197 kelvin). Particle composition analysis showed that large fraction the cloud composed nitric acid trihydrate (NAT) particles, containing water molar ratio 3:1; this confirmed these long-sought solid...
The evolution of the aerosols in tropical stratosphere since beginning Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission June 2006 is investigated using with Orthogonal Polarization (CALIOP) lidar data. It shown that current operational calibration requires adjustment tropics. Indeed, on basis assumption pure Rayleigh scattering between 30 34 km leads to an average underestimation ratio by 6% because significant amount up 35 altitude tropics, contrast...
Between November 1999 and April 2000, two major field experiments, the Stratospheric Aerosol Gas Experiment (SAGE) III Ozone Loss Validation (SOLVE) Third European on (THESEO 2000), collaborated to form largest campaign yet mounted study Arctic ozone loss. This international involved more than 500 scientists from over 20 countries. These made measurements across high middle latitudes of Northern Hemisphere. The main scientific aims SOLVE/THESEO 2000 were (1) processes leading loss in vortex...
Abstract. Space borne infrared limb emission measurements by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) reveal formation of a belt polar stratospheric clouds (PSCs) nitric acid trihydrate (NAT) particles over Antarctica in mid-June 2003. By mesoscale microphysical simulations we show that this sudden onset NAT PSCs was caused heterogeneous nucleation on ice cooling phases large-amplitude mountain waves Antarctic Peninsula and Ellsworth Mountains. MIPAS observations...
Abstract. The possible impact of deep convective overshooting over land has been explored by six simultaneous soundings water vapour, particles and ozone in the lower stratosphere next to Mesoscale Convective Systems (MCSs) during monsoon season West Africa Niamey, Niger August 2006. vapour measurements were carried out using a fast response FLASH-B Lyman-alpha hygrometer. high vertical resolution observations instrument show presence accumulation enhanced layers between tropopause at 370 K...
A balloon-borne gondola carrying a particle analysis system, backscatter sonde, and pressure temperature sensors was launched from Kiruna, Sweden, on 25 January 1998. Measurements within polar stratospheric cloud layers inside the Arctic vortex show close correlation between large ratios enhanced particle-related water nitric acid signals at low temperatures. Periodic structures in data indicate presence of lee waves. The H 2 O/HNO 3 molar are consistently found to be above 10 atmospheric...
Abstract. A multi-platform field measurement campaign involving aircraft and balloons took place over West Africa between 26 July 25 August 2006, in the frame of concomitant AMMA Special Observing Period SCOUT-O3 African tropical activities. Specifically aiming at sampling upper troposphere lower stratosphere, high-altitude research M55 Geophysica was deployed Ouagadougou (12.3° N, 1.7° W), Burkina Faso, conjunction with German D-20 Falcon, while a series stratospheric sonde flights were...
The winter 1996/97 was quite unusual with late vortex formation and polar stratospheric cloud (PSC) development subsequent record low temperatures in March. Ozone depletion the Arctic is determined using ozonesondes. diabatic cooling calculated PV‐theta mapped ozone mixing ratios large depletions, especially at center of where most PSC existence predicted, enhances by up to 80%. average chemical from January 6 April 33, 46, 43, 35, 32 21 % air masses ending 375, 400, 425, 450, 475, 500, 525,...
Polar stratospheric clouds (PSCs) have been observed by balloonborne backscatter sondes from Alert, Thule, Heiss Island, Scoresbysund, Sodankylä, Søndre Strømfjord, and Ny Ålesund during winters 1989, 1990, 1995, 1996 in 30 flights. The observations can be categorized into two main groups: type 1a 1b PSC particles. Type PSCs show the characteristics expected liquid ternary solution (HNO 3 /H 2 SO 4 O) particles, consistent with model simulations. are at all temperatures below condensation...
Abstract. We report in situ and remote observations proving occasional occurrence of solid particles the tropical lowest stratosphere, 200 km from deep convective events. The were found during field campaigns Southeast Brazil (49.03 W 22.36 S). They occur altitude range 17.5 to 20.8 km, at temperatures up least 10 K above expected frost point temperature. While stability ice these altitudes is unexpected a theoretical view, it argued that are indications tropospheric air masses penetrating...
Abstract. The EU HIBISCUS project consisted of a series field campaigns during the intense convective summers in 2001, 2003 and 2004 State São Paulo Brazil. Its objective was to investigate impact deep convection on Tropical Tropopause Layer (TTL) lower stratosphere by providing new set observational data meteorology, tracers horizontal vertical transport, water vapour, clouds, chemistry tropical Upper Troposphere/Lower Stratosphere (UT/LS). This achieved using short duration research...
Abstract. Polar stratospheric clouds (PSC) have been observed in early winter (December 2002) during the SOLVE II/Vintersol campaign, both from balloons carrying comprehensive instrumentation for measurements of chemical composition, size distributions, and optical properties particles, as well individual backscatter soundings Esrange Sodankylä. The observations are unique sense that PSC particles seem to formed under synoptic temperature conditions not being influenced by mountain lee...
Particle size distribution, composition, and optical properties of polar stratospheric clouds (PSCs) have been measured above northern Scandinavia during a nocturnal balloon flight within the vortex on 19 January 2000. The mountain‐wave PSC mainly consisted nitric acid trihydrate (NAT) particles with number densities between 0.01 0.2 cm −3 , median radii 1 to 2 μm volumes up 3 . A comparison data simulations based particle distribution indicates that NAT were aspherical an aspect ratio 0.5....
A microphysical model for Mars dust and ice clouds has been applied in combination with a of the planetary boundary layer (PBL) interpretation measurements by LIDAR instrument on Phoenix mission. The simulates nighttime fall streaks within PBL that are similar structure to observations. observed regular daily pattern water cloud formation precipitation at top is interpreted as diurnal process local cycle which large crystals (30–50 μ m effective radius) results downward transport vapor PBL....
Balloon‐borne measurements of H 2 O, CH 4 , and in January March 2000 show clear evidence for dehydration inside the polar vortex. At 30–50 hPa, total hydrogen is reduced by approximately 0.5 ppmv. This phenomenon apparent all five situ balloon observations this period; therefore it probable that occurred over extended regions a long period winter which was characterized well‐confined vortex low stratospheric temperatures. altitudes below 50 where strongest previous Arctic austral spring,...
In early December 2001, balloon‐borne in situ measurements of particle composition, size, number, phase, and backscatter were completed an Arctic stratospheric cloud composed three distinct layers between 22 26 km. Below 24.5 km, liquid solution droplets water, nitric acid, sulfuric acid a thin ice layer observed. Above this the particles primarily solid trihydrate. Just above at top, where temperatures near or equilibrium temperature for trihydrate, there was narrowly distributed around...
A new algorithm to infer structural parameters such as refractive index and asphericity of cloud particles has been developed by use in situ observations taken a laser backscattersonde an optical particle counter during balloon stratospheric flights. All three main particles, liquid, ice, no-ice solid (NAT, nitric acid trihydrate) polar clouds, were observed two winter flights performed from Kiruna, Sweden. The technique is based on the T-matrix code for aspherical calculate backscattering...
Abstract. We present the first detailed microphysical simulations which are performed online within framework of a global 3-D chemical transport model (CTM) with full chemistry. The describes formation and evolution four types polar stratospheric cloud (PSC) particles. Aerosol freezing other relevant processes treated in explicit way. Each particle type is described by binned size distribution for number density composition. This set-up allows an accurate treatment sedimentation calculation...