Broadband albedo is a very important geophysical parameter in the Earth surface–atmosphere interaction in either global climate change or hydrological cycle and snowmelt runoff studies. To derive the broadband albedo accurately from satellite optical sensor observation at limited bands and at a single observation angle, the bidirectional reflectance factor (BRF) has to be specified quantitative...

We show that the errors due to atmospheric refraction are present in the magnitudes determined with the Difference Images Analysis method. In case of single, unblended stars the size of the effect agrees with the theoretical prediction. But when the blending is strong, what is quite common in a dense field, then the effect of atmospheric refraction can be strongly amplified to the extent that s...

During the ALOHA-90 campaign a novel comparative study was made between near infrared wave structure imaged in the zenith using a CCD camera and that detected at infrared wavelengths by a Fourier Transform Spectrometer. Coincident measurements were made briefly on several occasions and for an extended period on 31 March. The temporal variations imaged in the near infrared structure during this ...

[1] We use the Polar Wind Outflow Model (PWOM) to study the geomagnetically quiet conditions in the polar cap during solar maximum. The PWOM solves the gyrotropic transport equations for O, H, and He along several magnetic field lines in the polar region in order to reconstruct the full 3D solution. We directly compare our simulation results to the data based empirical model of Kitamura et al. ...

Using photochemical models for the validation of NO2 satellite measurements at different solar zenith angles A. Bracher, M. Sinnhuber, A. Rozanov, and J. P. Burrows Institute of Environmental Physics and Remote Sensing (IUP/IFE), University of Bremen, 28334 Bremen, Germany Received: 2 April 2004 – Accepted: 29 August 2004 – Published: 21 September 2004 Correspondence to: A. Bracher (bracher@uni...

Cherenkov telescope observations at zenith angles > 70o are capable of providing large collection areas. This improves the detection efficiency for photons at very high energies. In order to understand the telescope’s performance extended Monte Carlo studies have been made taking the first HEGRA Cherenkov telescope CT1 as an example. First results of these studies will be presented.