WORLD METEOROLOGICAL ORGANIZATION

UNITED NATIONS ENVIRONMENT PROGRAMME

ITALY

Ozone monitoring and research activities

SUMMARY

The main directions of ozone research in Italy can be sketched as follows:

-Ozone Monitoring. A network of stations to monitor ozone and related chemistry has been set up and is routinely collecting data.

-Observations, laboratory and process studies. A large effort is under way to collect ozone and ozone related quantities with different observational techniques and to improve our understanding of the ozone chemistry with laboratory and process model studies .

-Effects of the ozone on the climate variability. A study to assess the impact of the ozone on the variability of climate at seasonal and interannual timescales is currently under way using General Circulation Models.

-Impact studies. Research is being carried out to identify suitable alternatives to methyl bromide to minimize the impact on the ozone layer.

1. OZONE MONITORING

Routine daily measurements of column ozone are carried out at the stations of Vigna di Valle (42.1°N,12.2°E), Sestola (44.2°N,10.8°E), Brindisi (40.6°N,17.9°E) and Messina (38.2°N, 15.5°E) by Servizio Meteorologico of Aeronautica Militare, by means of three Dobson and four Brewer spectrophotometers. Long series of column ozone data from the Aeronautica Militare stations at Vigna di Valle, Sestola, and Cagliari (39.3°N, 9.0°E) are available. Observations from Cagliari have been interrupted in 1980. Routine measurements are also carried out at S. Pietro Capofiume (44.6°N, 11.6°E, Dobson managed by FISBAT/CNR), at Ispra and Rome (45.8°N, 8.6°E, and 41.9°N, 12.5°E respectively, Brewer spectrometers managed by University of Rome "La Sapienza"). The last three stations are also dedicated to research studies connected to the dynamic of the stratosphere. In the near future a new Brewer spectromer, owned by ENEA, will be installed at Lampedusa (35.5°N, 12.5°E) for long-term routine observations. The Brewer instruments constitute also the kernel for a UV-B monitoring network. At S. Pietro Capofiume FISBAT/CNR once a week performs ECC ozone-sonde launches.

A program of ozone-sonde launches will also be started at Vigna di Valle by Aeronautica Militare. Regular measurements of column and tropospheric ozone are performed at Mt. Cimone (Northern Appennines, 2150 m) with a Differential Optical Absorption Spectrometer, DOAS, by FISBAT/ CNR. Other monitoring activities are carried out by IFA/CNR in Argentina and Antarctica, where Brewer instruments are seasonally installed at Ushuaia, and permanently at Scott and Belgrano stations. A daily bulletin on the UV-B radiation exposure times was disseminated to the public during the summer 1995 by ENEA, in a collaboration with Ministero per l'Ambiente, Atmospheric Environment Service of Canada, and University of Thessaloniki, Greece.

2. OZONE RESEARCH

2.1 Observations and laboratory studies

Many research groups are involved in programs addressed to the study of stratospheric ozone and related problems. Many participated to the European Arctic Stratospheric Ozone Experiment (EASOE, 1991 -92) and to the Second European Stratospheric Arctic and Mid-latitude Experiment (SESAME, 1993- 95). At present lidar instruments from italian institutions or within international collaborations are operational at some stations which participate in the Network for Detection of Stratospheric Changes, NDSC, i.e. at Thule (Greenland, University of Rome "La Sapienza"), Lauder (New Zealand, IROE/CNR), Dumont d'Urville and McMurdo (Antarctica, IROE/CNR and IFA/CNR). From these stations lidar observations of stratospheric aerosol, temperature and ozone are carried out routinely. In particular, the formation, evolution and climatology of Polar Stratospheric Clouds, and their influence on the ozone depletion process, are studied in the high latitude regions during the winter and spring seasons. Within this context, an elastic backscatter lidar from University "La Sapienza" has been operational at Amundsen-Scott South Pole station from 1987 to 1994. The observations from the NDSC stations allowed the analysis of the interactions between ozone and aerosol by correlative measurements, and the study of the long-term temperature structure of the middle atmosphere and the evolution of gravity and planetary waves. A differential absorption ozone and aerosol lidar system is operational at University of L'Aquila. Ozone-aerosol relationships in the aftermath of the Pinatubo eruption, and the influence of the stratospheric volcanic aerosols on the retrieval of the ozone profile have been investigated. Lidar systems dedicated to the study of the middle atmosphere are operational in Rome (University "La Sapienza"), Florence (IROE/CNR), Frascati (IFA/CNR), Brasimone (ENEA).

Aerosol depolarization, multi-wavelength backscattering and, occasionally, ozone profiles are measured at Rome and Florence. Measurements of aerosol and temperature profiles are carried out from Frascati: the long term behaviour of the thermal structure of stratosphere and mesosphere and the propagation of gravity waves are among the main arguments of study. The evolution of the temperature profile and of the gravity waves is studied at Brasimone with a Rayleigh and Na resonance scattering lidar. From these stations in Italy and at the NDSC stations the evolution of the volcanic stratospheric aerosol layer produced by the eruption of Mt. Pinatubo (Philippines, 1991) has been followed in detail, and the modifications produced on the stratospheric dynamics, radiation and composition, also affecting ozone, have been investigated. A multi-wavelength and depolarization lidar, developed in an international cooperation which includes IROE/CNR and ENEA, will be operated at Sodankyla, Finland. UV filter photometers are under development at FISBAT/CNR. Laboratory spectroscopic studies of oxygen and other atmospheric constituents are being carried out at Assergi (L'Aquila) in the Gran Sasso National Laboratory, by University "La Sapienza and University of L'Aquila. Spectroscopic studies of the atmosphere by DOAS instruments (FISBAT/CNR), allowing the determination of the column amount of ozone, NO_x, SO₂, OCIO and BrO, are carried out at Mt. Cimone and at Terra Nova Bay (Antarctica), where observations are obtained also during the polar winter and spring period with an automatic instrument. IFA/CNR has developed a laser backscatter-sonde (MAS, Multi-wavelength Aerosol Scatterometer), flown on balloons in Arctic and Antarctica, for the measurement of the aerosol backscatter and the inference of the particle dimensions.

In a collaboration between IROE/CNR, University of Florence, University of Bologna and other international institutes, far IR high resolution spectrometers for measurement of ozone and other trace gases (H₂0, HCI, HF, OH, H₂O₂, HOCI, HDO, ClO, N₂O, HNO₃, HCN, CO, N₂O₅) in the atmosphere have been developed for balloon experiments. These instruments have been also used for ground-truth observations for satellite measurements (e.g. for the Upper Atmosphere Research Satellite, UARS). Several other instruments are performing ground-truth experiments for UARS and for the Global Ozone Monitoring Experiment, GOME. IMGA/CNR is involved in the ozone, aerosol and cloud data retrieval process for the space-borne GOME spectrometer, and in the development of the Ozone Monitoring Instrument, the next-generation ozone spectrometer to be flown in 1999. In a cooperation with Russian institutes (Central Aerological Observatory, Myasishchev, Aviaecocentre) the Air-borne Polar Experiment, APE, is being carried out. This experiment, which involves also CNR, ENEA, the Italian Antarctic Program and several Universities, is addressed to the study of the polar stratosphere by means of instruments installed on a high- altitude aircraft, the M-55 Geophysika. This aircraft is able to reach 21 km altitude with a 1500 kg payload. Many of the planned instruments are developed in Italy: the payload includes a pressurized elastic backscatter lidar (Air-Borne Lidar Experiment, ABLE), a Fourier Transform spectrometer (Spectroscopy of the Atmosphere with Far-lR Emission-Airborne, SAFIRE-A), a DOAS spectrometer (GASCOD), a multi-wavelength backscatter instrument (air-borne MAS), and an in situ ozone sampler (OS-AP-GP). A first campaign with five flights in the Arctic regions is foreseen for the 1996-97 winter.

2.2 Modelling studies

The investigation of the ozone depletion process and its relationships with climate is being carried out at different institutions.

At University of L'Aquila two-and three dimensional dynamical models which include radiative transfer and heterogeneous chemistry are used to describe the depletion phenomenon. A microphysical model of polar stratospheric clouds has been developed and has been incorporated in the analysis. Microphysical models of polar stratospheric clouds and radiative transfer models have also been developed at The University "La Sapienza" and at IFA/CNR.

It is of great practical interest to assess the impact of long-term variations on the climate, given the important role played by the stratospheric ozone in the absorption of short-wave radiation and as regulator of the stratosphere dynamics. Such impacts can only be assessed by using general circulation models of the atmosphere. Numerical general circulation models at T30 resolution are currently being used by the IMGA/CNR laboratory to perform extensive studies of the variability of climate with prescribed Sea Surface Temperatures, focusing on the period 1961-1994. It is about to start a new program to use the model in the assessment of ozone impacts for the period 1979-1993; in this project (VASTOZ) a simulation will be performed by prescribing the observed total ozone from the TOMS data on a monthly basis. A comparison with a control simulation utilizing the standard climatological distribution of ozone will allow an assessment of the sensitivity of the climate anomalies to the decreasing trend in ozone concentration. The stochastic nature of the atmosphere will be addressed by performing an ensemble of simulations. Special enphasis will be placed on temperature at ground, short-wave radiation at the ground and in general on the surface energy balance.

Modelling studies are among the keys towards the goal of predicting ozone distributions at short (1-2 days) and long (seasonal) time scales. In-line or off- line UV-models can be used to generate predictions of surface UV radiation that can be disseminated to or the public and/or government agencies, services, civil defense and other users. The availability of timely, accurate and reliable information of this kind appear to be particularly important for the case of Italy, a Mediterranean country with a high insulation and a substantial portion of the nation at high elevation .

3. RESEARCH ON SUITABLE ALTERNATIVES TO METHYL BROMIDE (MB)

The Italian programme supports research aimed at finding alternatives to MB for soil disinfestation in Italian intensive vegetable and ornamental crop production, both indoor and outdoor. Among alternatives developed up to now, soil solarization, particularly when applied under greenhouse, permits to achieve satisfactory disease, pest and weed control on a variety of economically important crops. In order to improve its effectiveness, research is at present focusing on the combination of solarization with the use of biocontrol agents. On the other hands the use of virtually impermeable films, permits to curb (from 60 to 30 g/m²) the dosage of MB applied and, consequently, to significantly reduce the emission of MB in the atmosphere. The research programs are carried out in parallel with demonstration projects, aimed at transferring in practical applications the results achieved. The research program is carried out at DI.VA.P.R.A., Patologia vegetale Università di Torino and the demonstration are carried out at Centro Regionale di Sperimentazione e assistenza tecnica, Albenga, Savona.