Detection and analysis of water vapor transport

Water vapor, though a minor constituent of Earth’s atmosphere, plays a major role in the atmospheric radiation budget and the global water cycle. Atmospheric water vapor concentrations are highly variable due to the complex interplay between their sources (evaporation) and sinks (condensation and precipitation) in combination with transport and mixing. They strongly decrease with temperature and thus with altitude. Accurate measurement of water vapor is essential for better understanding its transport and cloud formation in the atmosphere and their impact on both weather and climate. To this end the institute develops and deploys lidars and in-situ hygrometers onboard aircraft

Long-lived contrails and convective cirrus above the tropical tropopause

This study has two objectives; 1) it characterizes contrails at very low temperatures and 2) it discusses convective cirrus in which the contrails occurred. 1) Long-lived contrails and cirrus from overshooting convection are investigated above the tropical tropopause at low temperatures down to -88°C from measurements with the Russian high-altitude research aircraft M-55 “Geophysica” and related observations during the SCOUT-O3 field-experiment near Darwin, Australia, in 2005. A contrail was observed to persist below ice saturation at low temperatures and low turbulence in the stratosphere for nearly one hour. The contrail occurred downwind of the decaying convective system “Hector” of 16 November 2005. The upper part of the contrail formed at 19 km altitude in the tropical lower stratosphere at 60 % relative humidity over ice at -82°C. The 1-h lifetime is explained by engine water emissions, slightly enhanced humidity from Hector, low temperature, low turbulence, and possibly nitric-acid hydrate formation. The long persistence suggests large contrail coverage in case of a potential future increase of air traffic in the lower stratosphere. 2) Cirrus observed above the strongly convective Hector cloud on 30 November 2005 was previously interpreted as cirrus from overshooting convection. Here we show that parts of the cirrus were caused by contrails or are mixtures of convective and contrail cirrus. The in situ data together with data from an upward-looking lidar on the German research aircraft “Falcon”, the CPOL radar near Darwin, and NOAA-AVHRR satellites provide a sufficiently complete picture to distinguish between contrail and convective cirrus parts. Plume positions are estimated based on measured or analyzed wind and parameterized wake vortex descent. Most of the non-volatile aerosol measured over Hector is traceable to aircraft emissions. Exhaust emission indices are derived from a self-match experiment of the Geophysica in the polar stratosphere in 2010. The number of ice particles in the contrails is less than 1 % of the number of non-volatile aerosol particles, possibly because of sublimation losses and undetected very small ice particles. The radar data show that the ice water content in convective overshoots is far higher than measured along the flight path. These findings add insight into overshooting convection and are of relevance with respect to hydration of the lower stratosphere

Long-lived contrails and convective cirrus above the tropical tropopause

Contrails of the Russian high-flying research aircraft M-55 "Geophysica" are investigated in measurements above the tropical tropopause during the SCOUT-O3 field-experiment near Darwin, Australia, in 2005. The aircraft reached 19 km altitude, far above the tropopause with −87 °C temperature at 17 km. In-situ, lidar, and microwave-temperature profiler measurements on board the Geophysica are used. An upward-looking lidar on the German research aircraft "Falcon", the CPOL radar near Darwin, and NOAA-AVHRR satellites provide complementary data. Exhaust emission indices are derived from a self-match experiment of the Geophysica in the polar stratosphere in 2010. Plume positions are estimated based on measured or analyzed wind and parameterized wake vortex descent. One contrail is detectable in a photo, and characterized in-situ during contrail formation downwind of the overshooting convective system "Hector" of 16 November 2005. The upper part of the contrail formed in the tropical lower stratosphere at ~ 60 % relative humidity over ice at −82 °C. The ~ 1-h lifetime is explained by engine water emissions, slightly enhanced humidity from Hector, low temperature, low turbulence, and possibly nitric-acid hydrate formation. The long persistence suggests large contrail coverage from future high-flying aircraft. Further Geophysica contrail parts are found in the measurements inside the strongly convective Hector clouds on 30 November 2005. Most of the non-volatile aerosol measured over Hector is traceable to aircraft emissions. Cirrus clouds observed by lidar above the anvil occur in coincidence with computed contrail positions. The upper part of the stratospheric anvil can be explained as contrail cirrus in this case. The radar indicates that the cirrus was measured in-situ mostly besides and above overshooting convection, and the maximum ice water content in the overshoots is far higher than measured along the flight path. The evidence suggests that parts of the ice clouds measured are contrails or mixtures of convective and contrail cirrus. The number of ice particles in the contrails is less than 1 % of the number of non-volatile aerosol particles, possibly because of sublimation losses and undetected very small ice particles. The findings are of relevance with respect to hydration of the lower stratosphere, overshooting convection, and future increases of air traffic in the lower stratosphere

Planetary boundary layer structure over the European alps and po basin: airborne lidar and aerosol observations

Μη διαθέσιμη περίληψηNot available summarizationPresented on: Geophysical Research Letter

Uncertainties in the simulation of XCO2 plumes from power plant emissions: A comparison between 6 high-resolution atmospheric transport models

Power plants are a major source of CO2 globally. Although their emissions are routinely monitored in many countries especially in the developed world, these numbers are often not publicly available and a complete global record is still far from reality. An important goal of Europe's planned Copernicus CO2 satellite mission CO2M is therefore to provide an independent quantification of power plant emissions worldwide. Emissions may be estimated from satellite XCO2 observations by simulating the plumes with an atmospheric transport model and finding those emissions that minimize a cost function of the differences between simulation and observations. Here we present a comparison of CO2 plume simulations from six high-resolution models, three Large Eddy Simulation models, two mesoscale Eulerian models, and one Lagrangian particle dispersion model. Simulations were conducted for two large coal-fired power plants, Belchatow in Poland and Jänschwalde in Germany, which were extensively observed with aircraft in situ and remote sensing measurements during the CoMet campaign in May-June 2018. The observations provide a unique opportunity to study the capability of the models to simulate such plumes in a realistic manner and to design optimal modelling and emission quantification strategies. The Belchatow plume was sampled under highly convective and turbulent conditions whereas the Jänschwalde plume was observed in a more stable weather situation. The models are able to reproduce these differences by simulating a highly structured turbulent plume for Belchatow and a more Gaussian-shaped plume for Jänschwalde. However, the models differ in many details including the horizontal and vertical spread of the plumes, suggesting that in addition to resolution the specific choices of turbulence and advection scheme have a significant impact on the results. Our findings suggest that estimating emissions from individual images is particularly challenging for turbulent plumes. Since turbulence intensity evolves with the build-up of the convective boundary layer, a satellite overpass well before noon would likely be an advantage