Atmospheric Ozone

The Atmospheric Ozone group carries out research and long-term monitoring of the ozone layer, and atmospheric pollutants. Measurements of the total ozone content and ozone vertical profile by the Umkehr method at Belsk by means of Dobson spectrophotometer had started in 1963, long before the depletion of the ozone layer became great challenge for research community and the policy makers. In 1991 a Brewer spectrophotometer with a UV-B monitor was installed. The length and the high quality of the ozone data made it very useful for trend detection. It is worthy to note that the problem of the trend detection in geophysical variables turns out to be the key issue in investigation of the global climate changes.

Belsk ozone series
Because the high quality of ozone data is crucial in the analysis of the ozone variability the quality control and quality assurance of the measurements of the total ozone content is a major concern of the ozone group. The Belsk ozone data were revaluated on a reading-by-reading basis, taking into account the calibration history of the instrument and were also several times compared with external sources of data, the TOMS (Total Ozone Mapping Spectrometer) included. The method of the Belsk series revaluation was recommended by Ozone Commission of the World Meteorological Organization as ”the best method of revision” of the ozone data.

Daily total ozone data at Belsk station

The series was also a base for an intensive study of the ozone variability. The ozone variability and determination of the impact of human activities on the ozone layer is essential because of the coupling of the ozone layer and the global climate system. The changes in the ozone layer over middle altitudes are examined in connection with changes in the dynamic factors characterizing the atmospheric circulation in the troposphere, the lowermost stratosphere, and the stratospheric overworld. The study is focused on the role played by the dynamical factors in ozone variability, because natural dynamical processes in the Earth’s atmosphere can perturb the recovery of the ozone layer.

The ozone data are submitted to World Ozone Data Center, and Institute cooperates with WMO Northern Hemisphere Daily Ozone Mapping Centre operated by the Laboratory of Atmospheric Physics at the Aristotle University of Thessaloniki (Greece).

Daily UV-B data at Belsk station

The continuing depletion of the ozone layer gives raise to increasing interest in ultraviolet radiation, because of the inverse correlation between the ozone column amounts and biologically active ultraviolet (UV-B) irradiance. Energy of ultraviolet radiation represents only a small fraction of the energy of the solar global radiation, reaching the surface of the Earth, however it plays fundamental role in the processes in the upper atmosphere, which control ozone budget, and in photobiological processes in the biosphere, because it is absorbed by living tissues and can inflict severe damage on them. The Belsk UV data series is the longest time series of UV measurements in Europe and similarly to ozone series is a subject of intensive study. In the studies of the UV-B variability advanced statistical methods such as wavelet decomposition and multivariate adaptive regression spline are used. In addition to ozone content and cloudiness the aerosol optical depth is also an important parameter in determining the aerosol effect on UV-B radiation transfer. Method of retrieving aerosol optical depth values over Belsk, from the Brewer spectrophotometer direct sun observations is examined.

Measurements of concentrations of gaseous air pollutants – ozone, nitrogen oxides, sulfur dioxide and carbon monoxide have been measured at Belsk since 1991. In 2007, additionally the measurements of concentration of carbon dioxide and particulate matter (PM10) have been added to the measurement program. Measurement place is located far away from urban and industrial areas so the measurements of individual trace gases are performed in the natural, relatively clean environment. Measurements results are used in basic research in the field of atmospheric chemistry and physics, as well as for investigation of the influence of urban and industrial agglomeration on the air quality level. Belsk’s measurements data sets are the ones of the longest in Poland (especially ozone and nitrogen oxides) and are used for the trend analysis of the trace gases.

In order to study the properties and concentration of iron containing atmospheric aerosol the Mössbauer effect is used.

Atmospheric Electricity

Parameters of the atmospheric electricity have been recorded at the Świder Observatory since 1958. Currently the potential gradient, vertical current density, air conductivity of positive and negative polarity and concentration number of condensation nuclei are measured. Measurements of gaseous and radioactive air pollutants and routine meteorological measurements are also conducted.

The electric field (potential gradient) has been systematically measured since 1986 at Hornsund Polar Station (Spitsbergen, Svalbard), and Arctowski Antarctic Station (South Shetland Islands) since 2013.

Warsaw atmospheric electricity group continues also activities in the field of thunderstorm electricity observations and lightning research. Observations of lightning-related electric field changes of the first and subsequent return strokes (RS) in cloud-to-ground (CG) flashes in summer thunderstorms over the 100×100 km area monitored around Warsaw by single-point reference station with low frequency (LF) and Maxwell current antennas have been conducted. The observations allowed to determine new time characteristic of the recorded RS waveform signatures.

In 2007 special research project entitled “Multiple cloud-to-ground lightning flashes - their development, parameters, hazard for people and risk of damages” was started in the frame of COST (European Co-operation in the Field of Scientific and Technical Research) P18 program with the cooperation of Warsaw University of Technology, Institute of Meteorology and Water Management and Space Research Centre of Polish Academy of Sciences.

In recent thunderstorm season several cases of CG flash events with their electric field signatures containing the continuing current (CC) component were collected. Although the CC changes are not so frequent components of CG flashes as for example the RS ones, the possible application of their dynamic spectra properties for CC detection and location by network lightning systems could be a considerable progress in lightning protection against their powerful and harmful effects on ground objects or forests.