We study the non-parametric covariance estimation of a stationary Gaussian field X observed on a lattice. To tackle this issue, we have introduced a model selection procedure in a previous paper [Ver09]. This procedure amounts to selecting a neighborhood m̂ by a penalization method and estimating the covariance of X in the space of Gaussian Markov random fields (GMRFs) with neighborhood m̂. Such ...

The German geoscience satellite CHAMP (CHAllenging Minisatellite Payload, launched on July 15, 2000, Reigber et al., 2002) is in orbit now for more than 2 years. CHAMP's measurements are used to determine Earth's gravity and magnetic field and to derive precise information about vertical temperature, humidity and electron density distribution on a global scale using the innovative GPS radio occ...

The results presented in this thesis have in part already been published in Refs. [1, 2, 3, 4, 5] listed overleaf (page v). We consider physics beyond the Standard Model which implies the existence a of long-lived electromagnetically charged massive particle species (CHAMP) which we denote by X ±. We discuss in detail the unique sensitivity the early Universe exhibits on the mere presence and o...

The relevance of water vapour in atmospheric physics and climate research contrasts strongly with the availability of humidity data in the Arctic. The most extensive humidity data set is based on approx. 80 radiosonde stations north of 60°N, but suffers from two major problems: Sensor diversity and sensor limitations under Arctic conditions, on the one hand, and lacking radiosonde launch sites ...

[1] The satellite CHAMP in its low-altitude polar orbit, and with its high-resolution magnetic field measurements, provides the opportunity to investigate ionospheric currents in great detail. In this study we focus on average features of equatorial current systems during day time. Considering quiet time observations from the period Aug. 2000 to Oct. 2004 we determined the mean spatial structur...

In this paper we estimate zonal plasma drift in the equatorial ionospheric F region without counting on ion drift meters. From June 2001 to June 2004 zonal plasma drift velocity is estimated from electron, neutral, and magnetic field observations of Challenging Mini-satellite Payload (CHAMP) in the 09:00–20:00 LT sector. The estimated velocities are validated against ion drift measurements by t...

Performance of a recently proposed technique for gravity field modeling has been assessed with data from the CHAMP satellite. The modeling technique is a variant of the acceleration approach. It makes use of the satellite accelerations that are derived from the kinematic orbit with the 3-point numerical differentiation scheme. A 322-day data set with 30-s sampling has been used. Based on this, ...

Despite clear and consistent clinical-trial evidence that secondary-prevention medical therapies reduce mortality in patients with established coronary artery disease, these therapies are underutilized in patients receiving conventional care. To address this issue, a Cardiac Hospitalization Atherosclerosis Management Program (CHAMP) focused on initiation of aspirin, cholesterol-lowering medicat...

The Defense Meteorological Satellite Program (DMSP) launches and maintains a network of satellites to monitor the meteorological, oceanographic, and solar-terrestrial physics environments. In the past decade, geomagnetic field modelers have focused much attention on magnetic measurements from missions such as CHAMP, Ørsted, and SAC-C. With the completion of the CHAMP mission in 2010, there has ...