Search results for " IR"
showing 10 items of 1350 documents
EVIDENCE OF NON-THERMAL X-RAY EMISSION FROM HH 80
2013
Protostellar jets appear at all stages of star formation when the accretion process is still at work. Jets travel at velocities of hundreds of km s -1, creating strong shocks when interacting with the interstellar medium. Several cases of jets have been detected in X-rays, typically showing soft emission. For the first time, we report evidence of hard X-ray emission possibly related to non-thermal processes not explained by previous models of the post-shock emission predicted in the jet/ambient interaction scenario. HH 80 is located at the south head of the jet associated with the massive protostar IRAS 18162-2048. It shows soft and hard X-ray emission in regions that are spatially separate…
The FRAM robotic telescope for atmospheric monitoring at the Pierre Auger Observatory
2021
FRAM (F/Photometric Robotic Atmospheric Monitor) is a robotic telescope operated at the Pierre Auger Observatory in Argentina for the purposes of atmospheric monitoring using stellar photometry. As a passive system which does not produce any light that could interfere with the observations of the fluorescence telescopes of the observatory, it complements the active monitoring systems that use lasers. We discuss the applications of stellar photometry for atmospheric monitoring at optical observatories in general and the particular modes of operation employed by the Auger FRAM. We describe in detail the technical aspects of FRAM, the hardware and software requirements for a successful operati…
Analysis of the aerosol radiative forcing over a Mediterranean urban coastal site
2014
Abstract The aerosol radiative forcing for the period 2003–2011 has been analyzed in Burjassot, Spain, an urban coastal site on the western Mediterranean, using measurements of global solar irradiance and aerosol properties, as well as simulated data. The aerosol radiative forcing was calculated at 5 minute intervals, and then integrated over 24 h to obtain daily mean values for 200 complete days under cloud-free skies. The monthly mean values of the aerosol radiative forcing showed a clear variation during the year, associated to the annual variability of the aerosol optical depth at 500 nm, ranging from − 6 to − 29 Wm− 2 at the surface, and from − 1.5 to − 3.9 Wm− 2 at the top of the atmo…
The Flux Density of Radiation Energy Originating from the Circumsolar Sky Measured at Groundbased Stations
1983
The aim of this project was the measurement of the radiant energy flux provided by the diffuse radiation of the ring shaped area of the sky around the unmasked sun disk. More than 200 measurements of the irradiance of this circumsolar cloudy or cloudfree sky up to an angular radius of 10° had been taken at Mainz (FRG), Deuselbach (FRG) and Adrano (Sicily). The measurements show that the irradiance of the circumsolar sky radiation may reach an amount of more then 30 % of the direct solar irradiance at the observation site. This means, optical systems combining the direct solar radiation and the circumsolar radiation may compensate — at least partly — the extinction losses of the direct solar…
In search of traceability: two decades of calibrated Brewer UV measurements in Sodankylä and Jokioinen
2016
Abstract. The two Brewer spectrophotometers of the Finnish Meteorological Institute at Jokioinen and Sodankylä have been operated according to the highest levels of the WMO∕GAW (World Meteorological Organization∕Global Atmosphere Watch) recommendations with rigorous quality control and quality assurance. The calibration of the instruments is based on annual recalibrations of primary standard lamps in the VTT MIKES Metrology National Standards Laboratory in Finland and an exhaustive measurement program with measurements of standard and working lamps in the on-site optical laboratories. Over the years, the maintenance of the calibration has produced data sets of approximately 2000 lamp scans …
Influence of air mass history on the columnar aerosol properties at Valencia, Spain
2007
[1] The physical and radiative properties of atmospheric aerosols have been obtained in Valencia (latitude 39.508°, longitude −0.418°, 60 m a. s. l.), a city of the Spanish Mediterranean coast, by the inversion of direct solar irradiance and diffuse sky irradiance measurements made with a CIMEL CE318 system, from January 2002 to July 2005. The data acquired by the CE318 were used to determine the instantaneous values of the aerosol optical depth (AOD), the columnar water vapor content (w) and the Angstrom wavelength exponent (α). The SKYRAD code was used to obtain the size distribution, the asymmetry parameter, the complex refractive index and the single scattering albedo of the aerosols. B…
Detection of Water Stress in an Olive Orchard with Thermal Remote Sensing Imagery
2006
An investigation of the detection of water stress in non-homogeneous crop canopies such as orchards using high-spatial resolution remote sensing thermal imagery is presented. An airborne campaign was conducted with the Airborne Hyperspectral Scanner (AHS) acquiring imagery in 38 spectral bands in the 0.43–12.5 mm spectral range at 2.5 m spatial resolution. The AHS sensor was flown at 7:30, 9:30 and 12:30 GMT in 25 July 2004 over an olive orchard with three different water-deficit irrigation treatments to study the spatial and diurnal variability of temperature as a function of water stress. A total of 10 AHS bands located within the thermal-infrared region were assessed for the retrieval of…
Study of erythemal, UV (A + B) and global solar radiation in Valencia (Spain)
2008
Although ultraviolet B radiation (UVB), the solar radiation band between 280 and 315 nm, is only a small fraction of the extraterrestrial solar radiation, it accounts for 80% of the harmful effects of exposure to the sun. In this work values of erythemal solar irradiance (UVER) measured in Valencia on a horizontal plane in the period between June 2003 and June 2005 are analysed and compared with measures of UV (A+B) and global irradiances on a horizontal plane. UV erythemal (UVER) irradiance has been measured using a YES-UVB-1 broadband radiometer; UV (A+B) irradiance has been measured using a TUVR Eppley radiometer with spectral response between 290 and 385 nm and global irradiance on a ho…
Using HYDRUS-2D model to assess the optimal drip lateral depth for eggplant crop in a sandy loam soil of central Tunisia
2016
The main objective of the work is to assess the optimal drip lateral depth for Eggplant crop (Solanum melongena L.) irrigated with a drip system in a sandy loam soil by means of field measurements and simulation models. Initially, the performance of Hydrus-2D was assessed based on the comparison between simulated soil water contents (SWC) and the corresponding measured in two plots, in which laterals with co-extruded emitters were laid on the soil surface (drip irrigation, DI-0) and at 20 cm depth (subsurface drip irrigation, SDI-20), respectively. In order to identify the optimal position of the lateral, the results of different scenarios, obtained by changing the installation depth of the…
Ground-based measured and calculated spectra of actinic flux density and downward UV irradiance in cloudless conditions and their sensitivity to aero…
2003
Ground-based spectral measurements of actinic flux density (300–660 nm wavelength) and downward UV irradiance (300–324 nm) under cloudless conditions have been compared with the results of one-dimensional radiative transfer calculations employing concurrent airborne vertical profile measurements of aerosol particle size distributions. Good agreement (within ±10%) between measured and calculated spectra was found. The remaining differences were explained by uncertainties inherent in the aerosol particle microphysical input data and the column ozone content. A respective sensitivity analysis of the calculated spectra, which was based on the observed variability of microphysical properties, ha…