Aims of the Airborne Polar Experiments is the study and the
characterisation of the chemical and physical properties of PSC and stratospheric aerosols using an airborne platform. For this purpose the high-flying all-weather research aircraft M-55 Geophysica, has been chosen. Such aircraft can operate at an altitude up to 21km. It provides an excellent platform for making such in situ-measurements. The aircraft will be able to perform multiple horizontal transects and also vertical soundings of a particular structure with a large, multi-instrument payload.
The project is articulated in detailed in-situ measurements coupled to microphysical, chemical and transport
models and forecasts for addressing the uncertainties in the quantification of the ozone loss. The first Arctic
mission is scheduled for the period December 20, 1996-January 30,1997 with base in Rovaniemi, Finland.
The scientific payload of Geophysica is composed by both in-situ and remote sensing instruments for aerosols
and trace gases analysis.
1) In-situ Aerosol Instruments:
- ARIAS is formed by a Knollenberg optical counter, a modified FSSP-300 capable of measuring particles with
size diameters in the range 0.4-23 micron and a 3 wavelengths depolarisation backscattered sonde. ARIAS is
able to characterise stratospheric aerosols and PSCs in terms of particle size, shape and refractive index.
- ACAP, is a second photoelectric particle counter which uses a single particle counting technique.
- COPAS is a condensation nuclei counter fed by 3 different inlets, permitting the determination of number
concentration in various size regions of PSC and aerosols.
2) Remote sensing Aerosol instruments:
- ABLE is a 2 wavelengths (532nm and 355nm), 2 polarisation Nd-YAG LIDAR to measure aerosol, PSC and
- MAL is a microjoule diode LIDAR operating at 900nm in the range 200-2000m from the aircraft. this region
is not covered by ABLE
3) In situ Chemical Instruments:
- FOZAN is a chemiluminescence ozone sonde operating on the chemical reaction between O3 in the airflow
and a dye.
- ECOC is an electrochemical ozone sonde.
- ACH is a frost point hygrometer measuring water vapour from 0 up to 10 km.
- FLASH is an optical fluorescent hygrometer measuring low water vapour concentration in the range 10-24 km.
- CVI-PSC composition uses a CVI to sample only PSC particles. 4) Remote sensing Chemical Instruments:
- GASCOD-A, an UV-visible spectrometer for the observation of: O3, NO2, BrO, OClO.
- SAFIRE-A is a far infrared Fourier Transform Spectrometer for the determination of vertical profiles of: O2,
O3, H2O, H2O2, OH, HO2, HDO, HCl, CLO, HBr, HF, CO, HCN.
Modelling activities will guide the APE mission both in the planning of the flights and in the data evaluation.
Chemical and dynamical forecast will design the most appropriate flight profile. Dynamical models coupled to
chemistry will run after each flight to get a first interpretation of stratospheric phenomena. The data coming
form the payload will be interpreted by microphysical box models and by numerical Mie, Ray Tracing and T Matrix algorithms.
Funding SchemeCSC - Cost-sharing contracts
106 91 Stockholm
CB2 1EW Cambridge