“APAF” Stand-Alone Test-Case Torben Schüler and Eva Krueger ...

Tropospheric Modelling Efforts
Objectives
and Results
from the
“APAF”
Stand-Alone
Stand Alone
Test-Case Test Case
Torben Schüler and Eva Krueger
University FAF Munich
Antonio Martellucci and Giulio Blarzino
ESTEC
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL

Motivation ...
Tropospheric refraction limits
Galileo positioning accuracy!
2.4 metres vertical ▪ 24 metres @ 5° elevation
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
Poor performance of
RTCA MOPS
(Standard WAAS Model)
Enhanced corrections by
use of numerical weather
models ...

Numerical
Weather
Fields
Data layout:
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
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Refractivity profile can be
extracted.
Precise computation of
tropospheric delays by
numerical integration.
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NWM-based NWM based delays
provided as Core Product.

Galileo
Standard
Correction
Model
Goal:
Develop improved standard (default) tropospheric model
to be implemented right at receiver level.
Characteristics:
- No explicit input parameters required (“blind” model)
- Derived from numerical weather fields
- Input of surface meteorological quantities possible
- Global coverage; biases kept to minimum
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL

Galileo
Standard
Correction
Model
University FAF Munich ESA/ESTEC
NOAA NCEP GDAS FNL
3.5 years of data
1° x 1° resolution
“TropGrid TropGrid” ” and “TropSite “ TropSite”
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
ECMWF Re-Analysis Re Analysis ERA15
15 years of data
1.5° x 1.5° resolution
“ESA”

Galileo
Standard
Correction
Model
TropGrid Model Parameters:
Parameter Seasonal Diurnal
Partial water vapour pressure
Vapour lapse rate
Mean vapour temperature
Mean temperature lapse rate
University FAF Munich ESA/ESTEC
NOAA Total NCEP pressure GDAS FNL
3.5 years Dry temperature of data
1° x 1° resolution
Temperature lapse rate
“TropGrid TropGrid” ” and “TropSite “ TropSite”
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
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�
�
�
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�
ECMWF Re-Analysis Re Analysis ERA15
�
15 years �of
of data
�
1.5° x 1.5° �resolution
resolution
“ESA”

RTCA MOPS [15° Lat.]
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
Resolution:
15°, only in
latitudinal
direction
Symmetry:
assumed for
northern and
southern
hemisphere

GTN [15° Lat. x 30° Lon.]
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
Resolution:
15° latitude
30° longitude
Symmetry:
northern and
southern
hemisphere
modelled
separately

GSTB TropGrid [1° x 1°]
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
Resolution:
1° latitude
1° longitude
Symmetry:
northern and
southern
hemisphere
modelled
separately

GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
Zenith Path Delay

BLIND
MODEL
NUMERICAL
WEATHER MODEL
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
Validation
VALIDATION
RADIOMETER
METEO SENSOR
GPS
RADIOSONDE

RMS [mm]
60,0
50,0
40,0
30,0
20,0
10,0
0,0
14,0
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
Accuracy of Models
RMS of ZPD - Validated by IGS Data
(2002)
24,5
NWM TropSite
+ Meteo
Input
36,7
TropSite
Blind
37,6
42,6
TropGrid ESA-
Model
2.0
54,1
MOPS-
Model

Outstanding
Issues
Storage Size, Processing Load:
Models not yet optimised for minimum storage size ...
- Compression of data layers
- Increased/decreased resolution vs. incr./decr incr./ decr. . load
(adaptive resolution?)
Statistics:
Some statistical analysis still to be completed, e.g.
- Analysis of statistical distribution
- Time-dependent Time dependent error analysis
- Confidence intervals and inflation factors
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL

GSTB Core Products
Data of 1° x 1° weather model:
RINEX METEO
"Surface Data"
RINEX METEO
"Full Data"
CORE PRODUCTS
SINEX TRO
Data
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL
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Pressure
Temperature
Relative Humidity
Temperature lapse rate
Mean Temperature of the
atmosphere
Mean temperature lapse rate
Water vapour lapse rate
Total Tropospheric Zenith
Delay (ZPD)
Zenith Hydrostatic Delay
(ZHD)
Zenith Wet Delay (ZWD)

GSTB Core Products
Data of 1° x 1° weather model:
Availability of Tropospheric Core Products:
Availability of Tropospheric Core - Pressure Products:
- Temperature
- Relative Humidity
Access via GSTB Server (DSF/GPC) or
- Temperature lapse rate
- Mean Temperature of the
http://www.kn.nz.dlr.de
atmosphere
> Projects > GSTB-V1 > Request
- Mean temperature lapse rate
- Water vapour lapse rate
Point of contact: eva.krueger@unibw-muenchen.de
- Total Tropospheric Zenith
RINEX METEO RINEX METEO SINEX TRO
Delay (ZPD)
"Surface Data" "Full Data" Data
- Zenith Hydrostatic Delay
(ZHD)
CORE PRODUCTS
- Zenith Wet Delay (ZWD)
GSTB Workshop ▪ 16 April 2004 ▪ ESTEC, NL