Models for the atmosphere of Mars based on the Mariner IV occulation experiment Scientific report nos. 2 and 15

Mars atmospheric models based on Mariner IV OCCULTATION experimen

The two-frequency, bistatic radar-occultation method for the study of planetary ionospheres scientific reports no. 1 and no. 7

Method for study of planetary ionospheres based on radio wave propagation between earth and spacecraf

The atmosphere of Venus as studied with the Mariner 5 dual radio-frequency occultation experiment, part 1 Final report

Differential Doppler measurement analysis for Mariner 5 Venus occultation experimen

The bistatic radar-occultation method for the study of planetary atmospheres scientific report no. 5

Bistatic radar-occultation method for planetary atmosphere stud

GPS radio occultation with GRACE: Atmospheric profiling utilizing the zero difference technique

Radio occultation events recorded on 28-29 July 2004 by a GPS receiver aboard the GRACE-B satellite are analyzed. The stability of the receiver clock allows for the derivation of excess phase profiles using a zero difference technique, rendering the calibration procedure with concurrent observations of a reference GPS satellite obsolete. 101 refractivity profiles obtained by zero differencing and 96 profiles calculated with an improved single difference method are compared with co-located ECMWF meteorological analyses. Good agreement is found at altitudes between 5 and 30 km with an average fractional refractivity deviation below 1% and a standard deviation of 2-3%. Results from end-to-end simulations are consistent with these observations.Comment: 17 pages, 4 figure

A non-linear optimal estimation inverse method for radio occultation measurements of temperature, humidity and surface pressure

An optimal estimation inverse method is presented which can be used to retrieve simultaneously vertical profiles of temperature and specific humidity, in addition to surface pressure, from satellite-to-satellite radio occultation observations of the Earth's atmosphere. The method is a non-linear, maximum {\it a posteriori} technique which can accommodate most aspects of the real radio occultation problem and is found to be stable and to converge rapidly in most cases. The optimal estimation inverse method has two distinct advantages over the analytic inverse method in that it accounts for some of the effects of horizontal gradients and is able to retrieve optimally temperature and humidity simultaneously from the observations. It is also able to account for observation noise and other sources of error. Combined, these advantages ensure a realistic retrieval of atmospheric quantities. A complete error analysis emerges naturally from the optimal estimation theory, allowing a full characterisation of the solution. Using this analysis a quality control scheme is implemented which allows anomalous retrieval conditions to be recognised and removed, thus preventing gross retrieval errors. The inverse method presented in this paper has been implemented for bending angle measurements derived from GPS/MET radio occultation observations of the Earth. Preliminary results from simulated data suggest that these observations have the potential to improve NWP model analyses significantly throughout their vertical range.Comment: 18 (jgr journal) pages, 7 figure

Preliminary results of the Mariner IV radio occultation measurements of the upper atmosphere of Mars

Mariner IV radio occultation measurements of Mars upper atmospher

Administration of remote computer networks

Today's computer networks have gone from typically being a small local area network, to wide area networks, where users and servers are interconnected with each other from all over the world. This development has gradually expanded as bandwidth has become higher and cheaper. But when dealing with the network traffic, bandwidth is only one of the important properties. Delay, jitter and reliability are also important properties for the quality of network connection. This is because different applications has different needs, and therefore require different properties from the network. System administrators are in an increasing degree involved with the troubleshooting of solving network problems concerning the quality of service for the different applications. This thesis analyzed techniques for measuring, analyzing, presenting and interpreting the different properties for the administration of remote computer network. In this way system administrators can benefit from this thesis when administrating their remote computer networks.Master i nettverks- og systemadministrasjo

Preliminary results of the Mariner IV OCCULATION measurement of the atmosphere of Mars

Mariner IV radio occultation measurement of Mars atmospher

Global monitoring of tropospheric water vapor with GPS radio occultation aboard CHAMP

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 retrieval of vertical refractivity, temperature and water vapor profiles from GPS RO observations. CHAMP RO data are available since 2001 with up to 200 high resolution atmospheric profiles per day. Global validation of CHAMP water vapor profiles with radiosonde data reveals a bias of about 0.2 g/kg and a standard deviation of less than 1 g/kg specific humidity in the lower troposphere. We demonstrate potentials of CHAMP RO retrievals for monitoring the mean tropospheric water vapor distribution on a global scale.Comment: 7 pages, 4 figure