retreat 2015 28.04.-30.04. miesenbach daniel landskron - my previous and upcoming research...
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Retreat 2015 Daniel Landskron
Retreat 2015 28.04.-30.04.Miesenbach
Daniel Landskron-
My previous and upcoming research
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Overview
Work together with Armin and Johannes
• Calculating tropospheric delays through ray-tracingcarried out by Armin‘s ray-tracing program RADIATE
• Modeling of tropospheric delays o Mapping functions
- site-augmented improvement of GPT2w
- temporal improvement of VMF1
o Azimuthal asymmetry
- new treatment of gradients
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Part 1
Part 1:
Research in Mapping Functions
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Improvement of GPT2w
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ah vs. T plot for WETTZELL 2011
Shows a clear correlation
If the user measures T => improve ah
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Improvement of GPT2w
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If user measures also e => improve zwd
zwd vs. e plot for WETTZELL 2011
Shows a clear correlation
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Improvement of GPT2w
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Comparison of mfh for WETTZELL first half of 2011, T from NWM
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Improvement of GPT2w
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Comparison of mfh for WETTZELL first half of 2011, T from NWM
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Improvement of GPT2w
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Mapping Function
Δshd [cm] T (NWM)
Δzwd [cm]T (NWM)
GPT2w 1.3 2.6Additional
measurement of T 0.9 2.5Additional
measurement of T, e 0.9 1.7
Comparison slant hydrostatic delays w.r.t. VMF1:e = 5°; averaged for 18 VLBI stations from 2011-2014, zwd from ECMWF
=> GPT2w well suited for site-augmented approach using in situ measurements of
T, p and e
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Improvement of GPT2w
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Geographical variation of the coefficient M2
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Improvement of VMF1 (1)
Calculation of new mapping function coefficients:
• For CONT11
• From ray-traced delays using RADIATE
=> No clear improvement in BLR
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Improvement of VMF1 (2)
Higher temporal resolution of NGS data
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Improvement of VMF1 (2)
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Part 2
Part 2:
Research in Azimuthal
Asymmetry
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Azimuthal asymmetry
Standard gradient formula (Chen and Herring, 1997):
Tropospheric delays vary for different azimuths because
• Atmosphere thicker at the equator
• E.g. weather fronts affect delay
Effect is significant for low-elevation observations
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Azimuthal asymmetryNew gradient formulas:
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WESTFORDResiduals of total slant delays
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Azimuthal asymmetry
Gradient formulas can be used:
1. as a priori gradients– gradients determined for every NWM epoch and provided in a text file
– use of the new gradient formulas improves the resulting delays
2. for estimating gradients in VLBI analysis– in vie_lsm, together with zwd, station coordinates, source coordinates,..
– Use of the new gradient formulas does not yield improvement
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Azimuthal asymmetry
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A priori gradients (a) (b)none 1.20 1.07
standard gradient formula 1.10 1.05
extended formula (1) 1.09 1.03
extended formula (2) 1.09 1.04
BLR comparison for CONT11 in [cm]:(a) Only using a priori gradients(b) Additionally estimating gradients using standard gradient formula
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Part 3
Part 3:
teaching activities
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Teaching activities
• 124.026 “Geodetic Space Techniques - project handling and data processing“ exercise
– takes place every even winter semester
– group work
– scheduling and Simulation in VieVS
– final presentation of the results
• Willingness to do more teaching
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Part 4
Part 4:
Outlook
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Outlook
• Collaboration with Gregor
• Find a way to map delays below 3° elevation as well
• Make everything operational, include in VieVS
• Make research for longer time periods
• Find a way to provide gradients on a grid
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