E. J. Quel

Towards an instrumental harmonization in the framework of LALINET: dataset of technical specifications

The Latin American Lidar Network (LALINET) is the aerosol lidar network operating over South America. LALINET is now an operative network performing a schedule of routine measurements and, currently, is composed by 9 stations distributed over South America. The main objective of LALINET is to generate a consistent and statistically relevant database to enhance the understanding of the particle distribution over the continent and its direct and indirect influence on climate. The creation of an un-biased spatiotemporal database requires a throughout review of the network on two pillars: instrumentation and data processing. Because most of the LALINET systems are not series-produced instruments and, therefore, present large differences in configuration and capabilities, attempts for network harmonization and, consequently, optimization are mandatory. In this study a review of the current instrumental status of all LALINET systems is done and analyzed in detail in order to assess the potential performance of the network and to detect networking weaknesses.

New differential absorption lidar for stratospheric ozone monitoring in Patagonia, South Argentina

As part of environmental studies concerned with measurements of the stratospheric ozone layer, CEILAP has developed a new differential absorption lidar (DIAL) instrument. Since the initial construction of the first DIAL instrument, the Lidar Division of CEILAP has made important financial and scientific investments to upgrade this initial prototype. The new version has a bigger reception system formed by four Newtonian telescopes, each of 50 cm diameter, and a larger number of detection channels: four different wavelengths are detected simultaneously and six digital channels record the Rayleigh and Raman backscattered photons emitted by a ClXe excimer laser at 308 nm and the third harmonic of a Nd–YAG laser at 355 nm. A number of different changes have been made to increase the dynamic range of this lidar: a mechanical chopper was installed together with a gated photomultiplier in the high-energy detection channels to avoid the detector being overloaded by strong signals from lower atmospheric layers. This new version was installed inside a shelter, giving the possibility to make field campaigns outside CEILAP laboratories, for example the SOLAR campaign made in the Argentine Patagonian region during 2005 and 2006 spring periods. In this paper a full description of the instrument update is given. Intercomparisons with the ozone sonde and satellite platform instrument are presented. The results show agreement better than 10% in 16–38 km altitude range when the same airmasses are sampled. The comparison with five quasi-coincident sondes launched in Punta Arenas during spring 2005 shows good agreement between both types of measurement, with relative differences inside 1σ deviation of the lidar measurement. The comparison of the integral of height integrated lidar profiles with total ozone column measured with a Brewer photometer shows good agreement, with relative differences less than 10%.

LALINET: The First Latin American–Born Regional Atmospheric Observational Network

AbstractSustained and coordinated efforts of lidar teams in Latin America at the beginning of the twenty-first century have built the Latin American Lidar Network (LALINET), the only observational network in Latin America created by the agreement and commitment of Latin American scientists. They worked with limited funding but an abundance of enthusiasm and commitment toward their joint goal. Before LALINET, there were a few pioneering lidar stations operating in Latin America, described briefly here. Biannual Latin American lidar workshops, held from 2001 to the present, supported both the development of the regional lidar community and LALINET. At those meetings, lidar researchers from Latin America met to conduct regular scientific and technical exchanges among themselves and with experts from the rest of the world. Regional and international scientific cooperation has played an important role in the development of both the individual teams and the network. The current LALINET status and activities are...

The first ALINE measurements and intercomparison exercise on lidar inversion algorithms

The first coordinated effort to perform simultaneous lidar measurements in Latin America was carried out as a pilot campaign between 10 and 14 September 2012. Four lidar stations contributed to the campaign measurements: Manaus, Sao Paulo, Concepcion and Buenos Aires. Data from all four contributing stations were manually screened and a 1-h average cloud-free profile was selected from each one. These four elastic profiles were analyzed by four of the groups using their own elastic lidar algorithm. Here, the results for the particle backscatter coefficient are compared and discussed. We show that after five stages, the results have an agreement better than the typical uncertainty in the retrieval. Systematic errors found in different algorithms during the five stages of the exercise emphasize the need for analysis, measurements and data quality protocols. Difficulties involved in the coordination of the campaign and in the collaborative analysis are also highlighted.

Electric atmospheric activity in Argentina, a study for estimating the annual death rate by lightning

The information about lightning activity is fundamental to atmospheric surveillance. Few countries in the world have their own lightning detection networks which allow monitoring the lightning activity inside their national borders. The World Wide Lightning Location Network (WWLLN) provides global lightning data, which was already used to characterize the lightning activity in several regions of the world. The aim of the present work is the use of the lightning data obtained by the WWLLN to make an analysis on the lightning activity over Argentina between the years 2005-2012. These data are used to estimate the annual death rate by lightning in the region. The estimation is based on a model proposed by Chandima Gomes, and Ab Kadir [1]. The obtained results could help to promote protective behaviors in the population.

The incidence of erythemal and UV solar irradiance over Buenos Aires, Argentina

Measurements are presented of UV solar irradiances at 305, 320, 340 and 380 nm and erythemal irradiance on clear-sky days in the city of Buenos Aires, Argentina. These values are compared with data calculated from a radiative atmospheric transfer model. Two quantities of major importance in this model are the ozone and aerosol atmospheric contents. Different values are assigned to them in order to estimate their relative importance in the solar UV irradiance reaching this geographical location. Complementary data on ozone profiles, obtained with the DIAL technique at the same location, are also presented. These spectral and erythemal irradiances are of importance in relation to the biological effects induced in humans by solar UV radiation.

Monitoring of Cirrus, Clouds and Planetary Boundary Layer in Southern Hemisphere at Buenos Aires (34.6 S, 58.5 W) for Climate Application

A new lidar station is now implemented at Buenos Aires (34.6 S, 58.5 W) since September 1994 for climate application and studies of regional processes taking place at southern mid-latitudes. Chiefly, the objective is to monitor the cloud properties, especially cirrus, and planetary boundary layer (PBL) structure on long term. The lidar operates at 532 nm, making easy a direct comparison in optical properties with other data bases available around the world. The station is in operation since late 1994, during daytime and nighttime, so a sufficient amount of data has been already collected to fulfill our primary goal. For further analysis, descriptions of the various synoptic situations and the relevant meteorological variables are available from the nearby meteo-station, along with satellite data. At present, the lidar data set is made of time series for geometrical and optical characteristics for clouds, and time series for PBL height recorded on a day-by-day basis. The station is now operated on a routine basis several days a week. A preliminary climatology for clouds, cirrus and PBL will be presented at the conference, with examples of applications as presented below.

Monitoring volcanic ash in the atmosphere

Fil: Chouza, Fernando. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Instituto de Investigaciones Cientificas y Tecnicas para la Defensa. Centro de Investigacion en Laseres y Aplicaciones; Argentina

Biomass burning aerosol detection over Buenos Aires City, August 2009

At the end of August 2009, a biomass burning aerosol intrusion event was detected at the Laser and Applications Research Center, CEILAP (CITEFA-CONICET) (34.5° S – 58.5° W) at Villa Martelli, in Buenos Aires, Argentina. This center has a sunphotometer from the AERONET-NASA global network, UV solar radiation sensors, a meteorological station and an aerosol lidar system. The aerosol origin was determined by means of back-trajectories and satellite images. This work studies the aerosol air mass optical characterization and their effect in UV solar radiation.

Characterization of the atmospheric aerosols in the Buenos Aires area using sun photometer measurements

An analysis of aerosols optical parameters is made using the sun photometer measurements taken at CEILAP in 2000. The sun photometer deployed in the Buenos Aires suburb is part of AERONET. Using the present data set, time series of key optical parameters such as the optical depth at 500 nm and Angstrom coefficient of the wavelength scaling law are derived. Clustering the observations by mean of a statistical analysis we can infer the pollution episodes in the Buenos Aires area. They can be either of local or regional origins, depending on the meteorological conditions prevailing over central Argentina.