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Polar stratospheric clouds play a key-role in polar ozone destruction. Cold temperatures in the vortex allow formation of these clouds. Depending on the PSC-type different formation-temperatures have to be reached. Synoptic temperatures do not always fall to these formation-temperatures, but waves in the atmosphere can lead to additional cooling of several 10 K, which allows PSC-formation. Whereas the wave-activity at the ESRANGE is very high due to hilly surrounding area, the orographic wave-activity at ALOMAR is expected to be rather small. Waves with long wavelengths will be present at both stations simultaneously. Coordinated measurements of temperature and aerosols will show both the large-scale wave-part and also the locally induced wave-part. Such measurements should allow identification of the different wavelngth scales and in addition contribute to a better estimate of the importance of wave-induced clouds for PSC-formation.
During the past years, atmospheric research in high latitudes has been focussed on processes causing ozone loss in the polar winter lower stratosphere1). Recent research efforts also dealt with regions up to the lower mesosphere, and studied the effects of charged particle precipitation on NO and ozone2)-5). However, the measurement techniques and hence the database for studying such processes in this altitude range are very limited. The Airborne SUbmillimeter Radiometer ASUR6),7) of the Institute of Environmental Physics of the University of Bremen has recently been equipped with a high-resolution spectrometer that will enable the retrieval of vertical profiles of ozone up to an altitude of about 65 - 70 km. Its measurement capabilities comprise also several other species of interest, especially NO. This makes the measurement technique particularly suitable for upper stratospheric/lower mesospheric studies. The lidar at ALOMAR is capable of measuring highly resolved vertical profiles of ozone up to an altitude of 60 km, thus giving the rare opportunity for intercomparison and validation studies in an altitude range reaching from the lower stratosphere to the lower mesosphere. Therefore we propose to perform simultaneous ozone measurements of the ASUR instrument with the ALOMAR lidar, supported by launches of ozone sondes.
The upper troposphere and lower stratosphere are strongly affected by the appearance of gravity waves with different scales. Due to the exponential decrease of the density with the altitude, the upward propagation of these waves is associated with an increase in their amplitudes. Associated with the wave breaking and with deposit of momentum and energy in the background flow, the dynamical and thermal structure at upper stratospheric and mesospheric heights are essentially influenced. However, their sources and the quantitative aspects of these processes are poorly understood at present. Here we are focussing on the investigation of long periodic gravity waves with periods of several hours and horizontal wavelengths of more than hundred kilometres. In contrast to the pure internal gravity waves, these waves are called inertio-gravity waves due to their influence by the rotation of the Earth, described by the Coriolis effect or by the inertial frequency.
Noctilucent clouds (NLC) remain a fascinating phenomenon of the upper atmosphere to study. The questions about the typical particle density and particle size distribution within a NLC are very prominent ones, to which a number of answers have been given, though some of the answers contradict each other. The parameters of particle size distributions can be derived from groundbased lidar measurements of the spectral dependence of the volume backscatter coefficient of an NLC. Such studies have been performed during a number of NLC events by e.g. the ALOMAR Rayleigh/Mie/Raman (RMR) lidar (von Cossart et al., GRL, 26, 1513, 1999). A drawback of these experiments is the wavelength limitation of the RMR lidar, the shortest wavelength of which is 355 nm. At this wavelength, the sensitivity of the lidar to particles with sizes smaller than, say, 25 nm is minimal. Because a considerable part of the entire particle population may have sizes below that threshold, a lingering question remains whether or not this drawback matters for typical NLC distributions. Using the ALOMAR ozone lidar, a measurement of the NLC volume backscatter coefficient at 308 nm becomes possible. Due to the l-4 -dependence of the backscatter coefficients, the latter are almost a factor of 2 larger at this wavelength than at 355 nm. For this reason and in order to gain a fourth wavelength to the spectral distribution, we aim at using the ozone lidar for the outlined project.
Waves play a major role for the momentum and energy transport in the middle atmosphere [Fritts and van Zandt, 1993] by modifying the local temperature field as well as the general circulation when the waves reach the saturation level and break [Holton, 1983; Fritts, 1984]. The MACWAVE rocket campaign is investigating the wave field in polar latitudes during summer and winter. To learn more about the horizontal structure of the wave field, it is important to measure at more than one station. For the monitoring of the vertical transport by the waves, measurements over a large height range are necessary. The combination of lidars, radiosondes and falling spheres will cover the region from the ground up to approximately 105 km. When comparing data, it is important to take into account the different measurement principles and integration times. The rocket will show small scale variations whereas the lidar permits a continuous monitoring of the temperature and wave situation
These investigations confirm the fact that in the stratosphere the ozone is considerably influenced by dynamical processes and it is a good indicator of them. In this context the main objectives of the proposed study are: 1) to investigate the possible relationship between stratospheric ozone perturbations and the temperature enhancement in the upper mesosphere, observed by Shepherd et al. (2001); 2) to examine whether changes in ozone, concomitant with the phenomenon, take place and how and when they would be manifested; and 3) to investigate the stratospheric ozone behaviour during the equinox atmospheric transition in the North Hemisphere, for better understanding of the middle atmosphere dynamics.
The purpose of the CHAOS_A project is to perform measurements under "Antarctic conditions" during the polar vortex period with the new assembled spectrometer in order to perform tasks that cannot be achieved at low latitudes namely OClO detection. Therefore the campaign focus more in technical aspects than scientific ones. The period of observation may be short to achieve results of scientific interest and those will depend on the meteorology of the stratosphere (position of the polar vortex relative to the station, temperatures at the lower stratosphere, etc). The OClO results will be compared with those obtained by the NILU (Andoya) and Heidelberg U.
Study aerosol properties (size and composition) in the infrared spectral region
The major goal of the process study between April 15 and May 15, 2003 is to obtain quantified information on reaction path-ways, products and net deposition of mercury during Arctic sunrise.
In situ measurements in the stratosphere shall be carried out by means of different balloon soundings. The main goal is the investigation of aerosols in the tropopause-region and in the stratosphere during wintertime. Because generation of aerosols strongly depends on water vapour content, also water vapour will be measured.
The Italian Space Agency (ASI), in cooperation with CNR, would like to develop a balloon launch site at Ny-Ålesund. The polar stratospheric air circulation pattern can make it possible to perform Long Duration Balloon (LDB) Flights. The balloons would circumnavigate the northern Polar Regions collecting data in astrophysics, aeronomy, as well as other atmospheric, cosmic and biological sciences. The location on Svalbard is interesting for LDB flights because of : o easy access and transportation of equipment /material/personnel o well established infrastructures/support organization o the flight would occur over mostly unmanned areas o the recovery of the payload could easily happen on the land Currently two experiments are being built as LDB payloads in anticipation of launching from Ny-Ålesund in 2004 and 2005. These are astro-physics experiments to observe the galactic and cosmic microwave radiation. This facility would accommodate science teams from both Italy and around the world.
Study of the energy exchange between atmosphere, sea ice and ocean during freezing and melting conditions; within that, measurements of solar radiation (visible and UV) and optical properties, snow and sea ice characteristics, vertical heat and salt fluxes, oceanographic parameters.
To distinguish between atmospheric and marine transport of contaminants to northen latitudes by comparison inventories of lake and fjordic sediments.
Monitoring solar wind-magnetosphere-ionosphere coupling processes from the aurora.
The general objective of the proposed project is to increase the understanding of the Mercury Depetion Events occoring in the Arctic sunrise and quntify the input of mercury to polar ecosystems during this events.
Study of the energy exchange between atmosphere and ice sheets by means of measurment of solar radiation
ASTAR, Arctic Study of Tropospheric Aerosol and Radiation is a a joint German (AWI Potsdam) - Japanese (NIPR Tokyo) campaign with participation from NASA LaRC Hampton, VA (USA). In addition to AWI, NIPR, and NASA LaRC the following institutions contributed to the project: Hokkaido University (Japan), Nagoya University (Japan), Norwegian Polar Institute Tromsoe/ Longyearbyen (Norway), NILU Kjeller (Norway), MISU Stockholm (Sweden), NOAA-CMDL Boulder, CO (USA) and Max Planck Institute for Aeronomy Katlenburg-Lindau (Germany). The campaign is based on simultaneous airborne measurements from the German research aircraft POLAR 4 and ground-based measurements in Ny-Ålesund. The main goals of the project are - to measure aerosol parameters of climate relevance, like extinction coefficient, absoprtion coefficients and phase function. - to create an Arctic Aerosol Data Set for climate impact investigation by using the regional climate model HIRHAM. - to carry out comparison measurements with the SAGE II (Stratospheric Aerosol and Gas Experiment) and the ground based Raman-Lidar.
In preparation to the launch of the SAGE III experiment in March 2001, NASA and the European Union performed the SOLVE / THESEO-2000 campaign, which had three components: (i) an aircraft campaign using the NASA DC-8 and ER-2 airplanes out of Kiruna/Sweden, (ii) launches of large stratospheric research balloons from Kiruna, (iii) validation excercises for the commissioning phase of SAGE III. The German Arctic research station Koldewey in Ny-Ålesund/Spitsbergen contributes to (i), (ii), and (iii) by performing measurements of stratospheric components like ozone, trace gases, aerosols (PSCs), temperature and winds. The measurement results were transmitted quasi online to the flight planning center in Kiruna, in order to allow a better directing of the air plane flights. In addition the Koldewey-Station has been designated a validation anchor site for the SAGE III validation. The activities are organized within a NASA accepted proposal of ground-based validation support by the NDSC Primary Station at Ny-Ålesund, Spitsbergen and by a SAGE III validation working group for Ny-Ålesund. The main observation periods are from December 1999 to March 2000.
In order to get detailed vertical ozone profiles above the range of standard electrochemical ozonesondes (typically 35 km), a radiosonde together with an optical ozonesensor is launchend with a special plastic foliage balloon. The balloon payload consists of a digital radiosonde (DFM 90) using GPS for altitude measurements and a two channel filter spectrometer (optical sensor) to measure the vertical ozone distribution up to more than 40 km altitude. The ozone profiles obtained by the optical sensors will be compared with ground-based microwave and lidar ozone observations as well as with the standard balloon-borne ozone measurements with electrochemical ozone sensors.
The aim of the project is to study the properties (radiative effects, composition) of aerosols using FTIR emission spectroscopy. To determine seasonal changes in aerosol properties the measurements will be carried out year round on a weekly schedule.