Detecção remota da coluna de ozono recorrendo a irradiâncias espectrais medidas à superfície

O trabalho realizado tem como objetivo principal a determinação dos valores da coluna de Ozono Atmosférico sobre Évora a partir de irradiâncias espectrais medidas à superfície. O instrumento utilizado foi um radiómetro espectral (Multi-Filter Rotating Shadow Band Radiometer YES MFR-7), instalado no Observatório do Centro de Geofísica de Évora. O estudo realizado compreendeu os anos de 2005 a 2008 em determinados períodos de cada ano, não tendo sido utilizadas medições contínuas devido a falhas do instrumento. Utilizaram-se também dados do instrumento OMI localizado a bordo do satélite AURA, com uma periodicidade diária, de modo a comparar com os valores obtidos com a metodologia apresentada aqui, utilizando observações de superfície. A comparação realizada evidenciou a concordância na evolução anual e sazonal do conteúdo da coluna total de Ozono anualmente e sazonalmente. Os resultados obtidos revelaram uma correlação linear significativa entre ambas as séries (O3_OMI e O3_MFR-7) e coeficiente de correlação, R=0.8.; ### ABSTRACT: The purpose of the study is to determine the total ozone column content over Évora, from spectral irradiances measured at the surface. The instrument used was a spectral radiometer, (Multi-Filter Rotating Shadow Band Radiometer YES MFR-7), installed in the Observatory of the Évora Geophysics Centre. This study was carried out for four years, 2005 to 2008, in some distinct periods each year, due to lack of data in the rest of the time. Satellite data from the Ozone Monitoring Instrument (OMI) onboard AURA satellite, were used too. Satellite remote sensing values are obtained once a day in order to compare with the corresponding daily mean calculated from the surface instrument. A comparison of the evolution of the total ozone column was done per year and per season. The results of this study reveal a strong linear correlation between the two series (O3_OMI e O3_MFR-7), with a correlation coefficient R=0.8

Transport of the smoke plume from Chiado’s fire in Lisbon (Portugal) sensed by atmospheric electric field measurements

The Chiado’s fire that affected the city centre of Lisbon (Portugal) occurred on 25th August 1988 and had a significant human and environmental impact. This fire was considered the most significant hazard to have occurred in Lisbon city centre after the major earthquake of 1755. A clear signature of this fire is found in the atmospheric electric field data recorded at Portela meteorological station about 8 km NE from the site where the fire started at Chiado. Measurements were made using a Benndorf electrograph with a probe at 1 m height. The atmospheric electric field reached 510 V/m when the wind direction was coming from SW to NE, favourable to the transport of the smoke plume from Chiado to Portela. Such observations agree with predictions using Hysplit air mass trajectory modelling and have been used to estimate the smoke concentration to be ~0.4 mg/m3. It is demonstrated that atmospheric electric field measurements were therefore extremely sensitive to Chiado’s fire. This result is of particular current interest in using networks of atmospheric electric field sensors to complement existing optical and meteorological observations for fire monitoring

Interactions lake-atmosphere: The ALEX 2014 field campaign and numerical simulations

The ALqueva hydro-meteorological EXperiment, ALEX 2014, was an integrated field campaign with measurements of chemical, physical and biological parameters in water and air at different experimental sites in the region of the Alqueva reservoir, a 250 km2 man made lake, in the southeast of Portugal. The Field campaign took place from June 1 to September 30, 2014 and comprises an Intensive Observation Period (IOP) of three days (22 to 24 July). During the four months, the over water fluxes of momentum, heat and mass (H2O and CO2) were obtained with an integrated Open-Path CO2 /H2O Gas Analyser and 3D Sonic Anemometer, mounted on a floating platform, where radiative fluxes were also measured, as well as the water temperature profile. Eight near surface weather stations were operating in the area and air quality, atmospheric electrical field (Potential Gradient) and radon (222Rn) concentration were continuous monitored. Along this period, in situ measurements, water samples and biological elements were monthly collected from three fixed platforms placed in the lacustrine zone and from selected sites in the margins. During the IOP, radiosondes were launched every tree hours, allowing a characterization of the atmospheric boundary layer and its evolution. In 10 occasions Geigersondes were coupled to the radiosondes in order to obtain the atmospheric ionization profile. The boundary layer was characterized with a Ceilometer and the vertical distribution of O3 and NO2 were obtained from a Spectrometer. A GPS network of 15 GNSS stations was installed in order to map the water vapour. The sky brightnesson the nights of July 24 and 25, was measured using a Sky Quality Meter. The lake-atmosphere interactions and its impact in the boundary layer structure and in the local circulations are studied using data collected during the ALEX 2014 POI together with results from numerical simulations performed with the non-hydrostatic Meso-NH french model

Comparison of total ozone column content given by satellite and retrieved from ground-based remote sensing

The purpose of the study is to determine the total ozone column content from spectral irradiances measured at the surface and compare these values with the corresponding obtained from satellite remote sensing. The spectral irradiances measured at the surface are acquired by the Multi-Filter Rotating Shadow Band Radiometer YES MFR-7, installed in the Observatory of the Geophysical Centre of Évora and the satellite remote sensing values are obtained from the Ozone Monitoring Instrument (OMI), onboard AURA satellite, once a day

DETECÇÃO REMOTA DA COLUNA DE OZONO RECORRENDO A IRRADIANCIAS ESPECTRAIS MEDIDAS À SUPERFÍCIE

In the present study the main goal is to estimate the total ozone content of the atmosphere. The data refers to spectral irradiances measured, at the surface, by a Multi-Filter Rotating Shadow Band Radiometer YES MFR- 7, installed in the Geophysics Centre of Évora. The results achieved will be validated through comparison with independent results

ALEX2014: The Alqueva Hydro-Meteorological Experiment

During the four months of the ALEX 2014, the over water fluxes of momentum, heat and mass (H2O and CO2) were obtained with an integrated Open-Path CO2 /H2O Gas Analyser and 3D Sonic Anemometer, mounted on a floating platform (Fig.1) belonging to the Portuguese Environment Agency. The short and long wave, up and down, radiative fluxes were measured at the same place, as well as the water temperature profile. Eight near surface weather stations were operating during the field campaign, two in floating platforms and one in a little island. The air quality, the atmospheric electrical field (Potential Gradient) and the radon (222Rn) concentration were continuous monitored. The solar direct normal irradiation (DNI) as well as other solar radiation components were also measured. Along this period, in situ measurements, water sam-ples and biological elements were monthly collected from three fixed platforms placed in the lacustrine zone and from selected sites in the margins. In each campaign, the vertical profiles of temperature, dis-solved oxygen (mg DO L-1 and %), pH, oxidation-reduction potential, turbidity and solar inwater irra-diation were taken. Simultaneously, water samples were collected at three depths for nutrient determina-tion and microscopic and molecular characterization of cyanobacteria. Diatoms were collected from artificial substrates placed in the platforms and Chironomid pupal exuviae were sampled from two selected sites on the reservoir margins During the IOP, 18 balloons with meteorological radiosondes were launched. In 10 occasions Geigersondes were coupled to the radiosondes in order to obtain the atmospheric ionization profile. The boundary layer was characterized with a Ceilometer and the vertical distribution of O3 and NO2 were obtained from a Spectrometer. A GPS network of 15 GNSS stations was installed in order to map the water vapour. The sky brightness on the nights of July 24 and 25, was measured using a Sky Quality Meter