Victoria E. Cachorro Revilla

Optical calibration facility at the Izaña Atmospheric Research Center

During the last years a new optical calibration facility has been developed and deployed at the Izana Observatory for the calibration and characterization of the radiation measuring instruments within research activities. These activities require a traceable Quality Assurance & Quality Control system. This new facility allows the absolute, spectral and cosine response calibration. At present there are six set-ups running at the laboratory for radiance calibration, angular response determination, spectral response characterization, slit function determination and absolute irradiance calibration (vertical and horizontal set-ups). Each method and procedure has required the development of the corresponding protocol. These systems, as well as some examples of instrument calibrations, are presented in this work.

CALIPSO and sunphotometer measurements of Saharan Dust events over Camagüey

Large volumes of Saharan dust particles are transported each year from northern Africa to the Americas, through Atlantic Ocean, reaching during the northern hemisphere summer the Wider Caribbean and Cuba in particular. Since the installation in October 2008 of a sun photometer type CIMEL CE-318, operated by Atmospheric Optics Group of Camaguey, numerous Saharan dust events have been registered. The most significant events for this AERONET measurement site were registered during July 2009. The highest AOD value with a magnitude greater than 0.6 was reported on July 6. The longest event for this period occurred between 15 and 20 July, with maximum AOD values above of 0.6. Measurement performed with lidar aboard CALIPSO satellite, for coincident measurement on July 19, distant 22.6 km to west of sun photometer site, provide information about the space-temporal distribution of this event. The AOD registered values of 0.35 and 0.32 for both, CALIPSO and MODIS, respectively, have equal magnitude than CIMEL measurement for the same day. The intercomparison between instruments, with different measurement principles, has corroborated its complementarity. CALIPSO, MODIS and AERONET data available at global scale are used, in conjunction with transport models and backtrajectories, for investigating the Saharan dust plume dispersion.

Characterizing aerosol optical depth measurements and forecasts of Saharan dust events at Camagüey, Cuba, during July 2009

Se comparan las mediciones del espesor optico de aerosoles (AOD) de polvo del Sahara realizadas en Camaguey, Cuba, durante Julio del 2009 con valores pronosticados de AOD por el modelo SKIRON y con mediciones de AOD realizadas por los satelites MODIS. Las diferencias entre las medias diarias del AOD pronosticado por SKIRON y medido por MODIS (tanto Terra como Aqua) son menores que las diferencias entre los maximos diarios. Los resultados demuestran la capacidad de desarrollar un sistema de alerta y seguimiento de los eventos de polvo del Sahara a traves del Atlantico.

Cloud optical depth measurements with sunphotometer in Camagüey, Cuba

One year of Cloud Optical Depth (COD) measurements obtained with the radiometer (sunphotometer Cimel CE - 318), in Camaguey, Cuba, from June 2010 to May 2011, are presented. As the first step an evaluation method is proposed, in order to confirm that a cloud was measured. This method is based on the complementary cloud information derived from the actinometrical observations. In the second step of the work, the statistical results from the first year of the COD measurements in Camaguey were analyzed. The results show the high quality of COD measurements at Camaguey. The analysis of the COD frequency showed two peaks at the intervals centered in 2.5 and 17.5. Similar behavior occurred each month. The COD mean value for the entire period was 24.8, with a standard deviation of 31.7. The mean monthly minimum and maximum value of COD occurred in December, 2010 and May, 2011, respectively. The diurnal cycle of the mean hourly COD values showed an increase in the afternoon hours. At the same time, the number of measured cases decreased. There was correspondence between the COD data obtained with sun-photometer and CALIOP lidar, for the COD values below 5. The results showed in this paper constitute the first report of such measurements in Cuba.