Trajectory studies of polar stratospheric cloud lidar observations at Sodankyla (Finland) during SESAME: Comparison with box model results of particle evolution
Year: 1999
Authors: Rizi V., Redaelli G., Visconti G., Masci F., Wedekind C., Stein B., Immler F., Mielke B., Rairoux P., Woste L., Del Guasta M., Morandi M., Castagnoli F., Balestri S., Stefanutti L., Matthey R., Mitev V., Douard M., Wolf J.P., Kyro E., Rummukainen M., Kivi R.
Autors Affiliation: Dipartimento di Fisica, Università degli Studi, L\’Aquila, Italy; Istituto Nazionale di Geofisica, L\’Aquila, Italy; Freie Universitat Berlin, Berlin, Germany; IROE/CNR, Firenze, Italy; Observatorie Cantonal Neuchatel, Neuchatel, Switzerland; Universitè Lyon, Villeurbanne, France; Finnish Meteorological Institute, Sodankylä, Finland; Dipartimento di Fisica, Univ.` degli Studi – L\’Aquila, via Vetoio, Localita Coppito (L\’Aquila), I-67010, Italy
Abstract: Polar stratospheric clouds (PSC) were observed with the multi-wavelength lidar of the MOANA project (Modelling and Observations of Aerosols in the Northern Atmosphere) during SESAME (Second European Stratospheric Arctic and Mid-latitude Experiment). The physical state, liquid or solid, of the cloud particles can be inferred from the lidar data. Using isentropic back-trajectories to obtain the thermal history of the sampled air masses, it is possible to reconcile most of the observations with current ideas on PSC formation and evolution. When the cloud particles were identified as liquid, changes in the size distribution of the droplets along the trajectory were calculated using a micro-physical box model. Backscatter ratios calculated from the size distributions are in broad agreement with the lidar data, giving confidence in current understanding of the evolution of ternary solution (H2SO4, HNO3 and H2O) droplets. Results from two soundings are shown which bear on the problem of the formation of solid particles. In the first, solid particles were detected. The air mass had cooled to the frost point 12 hours earlier. In the second no solid particles were detected although the air temperature was below the nitric acid trihydrate existence point, and had decreased by 12 K in the previous 14 hours.
Journal/Review: JOURNAL OF ATMOSPHERIC CHEMISTRY (PRINT)
Volume: 32 (1) Pages from: 165 to: 181
KeyWords: Cloud microphysics; polar stratospheric cloud, air analysis; arctic climate; article; cloud; comparative study; Finland; model; stratosphereDOI: 10.1023/A:1006120226379