Das Projekt "Bodengestuetzte Fernerkundung der Stratosphaere bei SoendreStroemfjord, Groenland" wird vom Umweltbundesamt gefördert und von Max-Planck-Institut für Chemie (Otto-Hahn-Institut) durchgeführt. An intensive field study of the winterly arctic stratosphere is proposed to begin in the early fall 1994 and lasting until spring 1995. The aim is to evaluate processes which are responsible for the intensified Ozone destruction recently observed in the north hemisphere stratosphere. For achieving these objectives the composition and the dynamics of the stratosphere will be followed by a series of groundbased remote sensing instruments provided and operated by an international team of scientists. Vertical columns of stratospheric 03, NO2, OC10 and BrO are determined with high quality DOAS in the ultraviolet and visible spectral region (MPI). The frequent lee waves and associated PSC s will be followed by a combined RADAR and LIDAR. The RADAR can detect the three-dimensional wind vector and the LIDAR provides aerosol and temperature profiles (SRI). A balloon facility will be installed at Sondre Stromfjord for the launch of backscatter/ozone sondes (University Wyoming/DMI). The Colorado State University Regional Atmospheric Model is available at DMI and will be used for the simulation of orographic force waves (DMI). A chemical box-model which includes radiation will be used to model the diurnal profiles of the stratospheric species (MPI). The joint study of the MPI fuer Chemie, the Danish Meteorological Institute, Stanford Research International and the University of Wyoming will address the questions: 1) What are the mechanisms causing OCLO to appear early in the winter? 2) Can polar stratospheric clouds be observed during lee wave activity and what is the impact on the production of activated chlorine? 3) Is the ozone decline in the arctic vortex connected to an increase in activated chlorine and what is the role of the Pinatubo aerosol? 4) What is the behaviour of the ozone compared to the years before? The evaluated data will be stored in the NILU data base.
Das Projekt "Chronologie der Vereisungen der noerdlichen und der suedlichen Hemisphaere" wird vom Umweltbundesamt gefördert und von Universität Bern, Geologisches Institut durchgeführt. A new radiocarbon chronology shows that piedmont glacier lobes in the Chilean Andes achieved maxima at 14500-14700; 21000;23100; 27500; 29000; and at least once higher 35000 years before present, all within a cold and wet Subatarctic Parkland environment. Massive glacier collapse, which began shortly before 14'350 years ago and was followed by an influx of North Patagonian Rain Forest species, terminated the last glaciation. In the Southern Part of New Zealand, an additional glacial maximum is recorded at 17'500 years before present, along with a Younger Dryas age readvance at 11050 years ago. These glacier peaks in South Pacific mid-latitude mountains replicate ice-rafting pulses in the North Atlantic Ocean. Further, the last termination began suddenly and simultaneously in both polar hemispheres prior to the resumption of the modern mode of deep-water production in the Nordic Seas. Such tight interhemispheric coupling is difficult to explain by regional North Atlantic events such as Laurentide ice-sheet surges or thermohaline switches. Rather, it implies global forcing that had its source in the atmosphere.
Das Projekt "Nord-Sued-Klimaverbindung und Kohlenstoffkreislauf waehrend der vergangenen 250000 Jahre" wird vom Umweltbundesamt gefördert und von Universität Bern, Physikalisches Institut, Abteilung für Klima- und Umweltphysik durchgeführt. Leading Questions: Is a period of stable and mild climate lasting 10000 years an exception? Are the rapid and drastic climatic changes observed in Greenland ice cores global events? How are global climatic changes coupled between the two hemispheres? Abstract: The aim of this proposal is to understand the dynamics of the climate system over the last 250,000 years, using an interactive approach between paleodata acquisition and modelling. A special emphasis is given lo the climatic interaction between the northern and southern hemispheres and the role of the carbon cycle. This includes - The reconstruction from existing bipolar (Antarctica and Greenland) ice cores of temperature changes as well as of different important climatic factors influencing the Earth's radiative balance greenhouse gases, ice volume, aerosols, - Modelling the isotopic composition of the precipitation and the dust cycle using AGCM, - Modelling climate and carbon cycle dynamics using a hierarchy of models to investigate the different mechanisms of the interhemispheric transmission of climate signals. The collaborative effort will allow - to describe with high resolution bipolar changes of climatic parameters observed from ice cores with a specific focus on interstadial and glacial-interglacial transitions, - to provide new information on greenhouse trace gas-climate interactions during the past, - to provide estimate of global climate sensitivity over the last 250 kyr, - to understand the mechanisms of the interhemispheric dynamics of the climate system, - to describe the temporal sequence of the processes generating the climate variability over climatic cycles, - to understand how and why the carbon cycle has undergone the variations observed on the paleoCO2 record. Benefits of this work will include a better understanding of the processes governing climatic and environmental changes and of climate sensitivity It will also provide data over a large range of climatic conditions, helping the validation of the climate models used for predicting future climate.
Das Projekt "STEP/ESMOS/ALPS: Europaeische Stratosphaerenueberwachungsstationen in den Alpen: Ein europaeischer Beitrag zum Netzwerk fuer den Nachweis von Veraenderungen der Stratosphaere (NDSC)" wird vom Umweltbundesamt gefördert und von Universität Bern, Institut für Angewandte Physik durchgeführt. This proposal is based on ground-based observations performed at mid-latitude in Europe, in order to study the chemical and physical processes determining the stratospheric composition and its variations and changes. The measurements are made by means of number spectroscopic methods: Lidar (ozone, temperature, aerosols); Microwave radiometry (ozone, NO2); IR high resolution spectroscopy (HC1, HF, HNO3, C1ONO2, NO2, NO, N2O, CH4). This study relies on the 'Alpine Station' selected for the Network for the Detection of Stratosphere Change (NDSC) as the mid-latitude, Northern hemisphere site. The objectives are to make intensive coordinated ground-based observations to provide climatological measurements of ozone total amounts and vertical profiles, aerosol vertical distributions, C1O vertical profiles, NO2, NO reservoirs and long-lived tracers total amounts; to provide validated ground-based measurements at mid-latitudes to meet the SESAME scientific objectives in 1994 and 1995; to study the seasonal and interannual variability of the measured trace species; to study the aeronomic processes involved in atmospheric composition changes at mid-latitude; to study the role of volcanic aerosols on ozone and NO2 reduction observed after the Mt Pinatubo eruption, by expanding the observations during the decay of volcanic aerosols during the next two years and by the development of aerosol modelling; to provide measurement to test and improve stratospheric models including heterogeneous processes and to validate the current and planned satellite observations of the stratosphere (eg UARS and ERS2/GOME). The validated data will be archived in the data center of NILU.