Description: Das Projekt "Direct determinations of polar stratospheric cloud composition" wird vom Umweltbundesamt gefördert und von Freie Universität Berlin, Institut für Experimentalphysik durchgeführt. Objective: There are three primary objectives with this instrument development project: - to improve the design of an existing Lyman- hygrometer to give the instrument increased sensitivity and a lower detection limit for water vapour such that it can be used in conjunction with the CVI to measure the condensed water content of PSCs and upper-tropospheric cirrus clouds. - to adapt a laser-diode spectrometer system used to measure HNO3 for use in stratospheric conditions and incorporate it into the CVI sampling system. This instrument would then be used to measure the nitric acid content of polar stratospheric cloud elements. - to prepare an instrument payload which can be used to directly and in real time measure the composition of the condensed phase in PSCs with quantitative determination of H2O and HNO3 contents. Together with simultaneous measurements of the cloud element number concentration (COPAS project) the goal of the experiment is a comprehensive in situ analysis of the condensed phase in polar stratospheric clouds. General Information: The project involves developing two new instruments for measuring H2O and HNO3, incorporating the instruments into a common payload for deployment on the M-55 Geophysical aircraft, and interfacing the combined instrument payload with the Counter flow Virtual Impactor (CVI) probe developed as part of the COPAS project. a) H2O Instrument The new H2O instrument design will be based on current Lyman hygrometers presently in use on various aircraft payloads. A new instrument based upon these hygrometers which will be optimised for use in the stratosphere will be constructed. The largest challenge will be to increase the sensitivity of the new hygrometer by a factor of 100 relative to the instruments now in use. There are several ways to achieve this decrease in detection limit: a) increase the path length between the Lyman- light source and the detector; b) increase the strength of the light source; c) add fluorescence detectors in parallel with the absorption detectors; d) increase the enrichment factor of the CVI probe. Part of the initial design effort will be to determine the optimal combination of these approaches in terms of achieving a small, lightweight and robust hygrometer. b) HNO3 instrument The measurement of the HNO3 concentration with high sensitivity can be performed by means of absorption measurements of laser diode radiation at 7.5mm over a long path, as it can be realised in a multipass gas cell. The project will develop and test all the optical systems for detecting the absorption lines of HNO3 and be responsible for certification of the optical systems. For this purpose, an improved Herriot cell (after a preliminary test with a White cell) will be employed. ... Prime Contractor: Stockholms Universitet, Department of Meteorology; Stockholm; Sweden.
Types:
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Wolkenbildung ? Wolke ? Bewölkung ? Fluoreszenz ? Impaktor ? Stockholm ? Gaslaser ? Halbleiterlaser ? Messgerät ? Schadstoffgehalt ? Lampe ? Berlin ? Meteorologie ? Laser ? Salpetersäure ? Durchflussmessung ? Sensor ? Strahlungsabsorption ? Wasserdampf ? Schweden ? Absorption ? Chemische Zusammensetzung ? Messtechnik ? Zertifizierungssystem ? Spektralanalyse ? Strahlungsmessung ? Verfahrenskombination ? Flugzeug ? Strahlung ? Anfechtung ? Absorptionslinie ? In-Situ-Verfahren ? Kondensation ? Luftfahrzeug ? Nachweisgrenze ? Stratosphäre ? Troposphäre ? Wassergehalt ? Wasseranalyse ? Analysegerät ? Luftfeuchtigkeit ? Polargebiet ? Produktdesign ? Anreicherung ? Laseranwendung ? Counter-flow-Virtual-Impactor ? PSC ? multipass-gas-cell ? Herriot-cell ? Konzentrationsmessung ? Lyman-Hygrometer ? Nachweisbarkeit ? CVI ?
Region: Berlin
Bounding box: 10.44987° .. 10.44987° x 54.03573° .. 54.03573°
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 1996-02-01 - 1999-01-31
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