Satellite data that are used to model the global gravity field of the Earth are typically corrupted by correlated noise, which can be related to a frequency dependence of the data accuracy. We show an opportunity to take such noise into account by using a proper noise covariance matrix in the estimation procedure. If the dependence of noise on frequency is not known a priori, it can be estimate...

Using magnetic field data obtained by the Challenging Minisatellite Payload (CHAMP), we show global and frequent appearance of small-amplitude (1 to 5 nT on the dayside) magnetic fluctuations with period around a few tens of seconds along the satellite orbit in middle and low latitudes. They are different from known phenomena, such as the Pc3 pulsations. The following characteristics are presen...

the recent dedicated satellite gravimetry missions have provided huge amount of high quality gravity data with global coverage. from computational point of view, estimation of the unknown gravity field parameters is a highly demanding task due to the sheer number of observations and the unknown coefficients. different computational schemes have been proposed to tackle the problem. since the ear...

Ambitious satellite constellation projects by commercial entities and the ease of access to space in recent times have led a dramatic proliferation low-Earth traffic. It jeopardizes safety long-term sustainability, necessitating better domain awareness (SDA). Correct modeling uncertainties force models orbital states, among other things, is an essential part SDA. For objects orbit (LEO) region,...

Family-based interventions with children who are affected by HIV and AIDS are not well established. The Collaborative HIV Prevention and Adolescent Mental Health Program (CHAMP) represents one of the few evidence-based interventions tested in low-income contexts in the US, Caribbean and South Africa. This paper provides a description of the theoretical and empirical bases of the development and...

In this paper we describe the behaviour both in time and in space of an induction eld created by an imposed high frequency alternating current around a solid conductor. To do this, we introduce two time scales and we decompose the induction eld in a mean eld and an oscillating eld. With the help of singular perturbations theory and multiple scales method we obtain two uncoupled models; one for ...

Challenging Minisatellite Payload (CHAMP) radio occultation (RO) observations during a two-week period are assimilated into global analyses using the National Center for Environmental Prediction (NCEP) three-dimensional variational (3D-Var) system with a recently improved observation operator for assimilating GPS bending angle data. The NCEP 3D-Var system used in this research is suboptimal sin...

The paper deals with application of GPS radio occultation (RO) measurements aboard CHAMP for the retrieval of tropospheric water vapor profiles. The GPS RO technique provides a powerful tool for atmospheric sounding which requires no calibration, is not affected by clouds, aerosols or precipitation, and provides an almost uniform global coverage. We briefly overview data processing and retrieva...

Knowledge about the gravity eld allows an insight into the structure and dynamics of the earth. It provides the geoid as the most important physical reference surface in geodesy and oceanography. Since 2000, the CHAMP (CHallenging Mini-satellite Payload) mission detects the structure of the global gravity eld, followed by the launch of GRACE (Gravity Recovery And Climate Experiment) in 2002. In...