Turbulence theory for troposphere delay modelling in VLBI

01.01.2008 - 31.12.2010
Scholarship
State-of-the-art modelling of tropospheric delays in the analysis of space geodetic techniques uses elevation-dependent mapping functions and azimuth-dependent gradients. However, recent simulations for VLBI2010 dealing with the improvement of geodetic VLBI revealed that that these models are not sufficient to achieve an accuracy of 1 mm for baselines of several thousand kilometers. In this project turbulence theory is applied to improve the modelling of the wet delays in VLBI analysis. Spherical harmonics are fitted to the turbulent delays generated with a Monte Carlo simulator to account for the distinct delay patterns which cannot be covered by mapping functions and gradients only. Meteorological parameters from numerical weather models driving the turbulence (height of wet troposphere, wind velocity) are used to specify the set of spherical harmonics that need to be estimated and to assess the constraints on their respective coefficients. Wet troposphere delays from the turbulence model are characterized by spatial and temporal correlations. Thus, the application of correlation matrices as a priori information for the least squares adjustment will be assessed in the project, too. Starting from station-wise investigations in stand-alone programs, all these procedures will be implemented in the VLBI analysis software package OCCAM at a later stage of the project where they will be applied on simulated VLBI2010 networks and schedules. The validation of these tests is straightforward because the wet delays provided from the Monte Carlo simulator are always known. Final goal of the project is to apply the procedures to real VLBI observations and determine the impact on geodetic results. For external validation the application to GNSS will be considered, too.

People

Project leader

Institute

Grant funds

  • Vereine, Stiftungen, Preise Type of funder Vereine, Stiftungen, Preise Specific program Österreichische Akademie der Wissenschaften DOC-FFORTE

Research focus

  • Beyond TUW-research focus: 20%
  • Environmental Monitoring and Climate Adaptation: 80%

Keywords

GermanEnglish
Troposphäretroposphere
Turbulenztheorieturbulence theory
VLBIVLBI
VLBI2010VLBI2010

Publications