1. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
Ilke Deniz, Cetin Mekik, Gokhan Gurbuz
Bulent Ecevit University, Department of Geomatics Engineering, Zonguldak, Turkey
ES1206 Workshop, Reykjavik, 8-10 March 2016

2. Aims of this project are
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
Recent studies on GNSS Meteorology in Turkey
The Project titled "The Estimation of Atmospheric Water Vapour Using GPS " is supported by The Scientific and Technological Research Council of Turkey (TUBITAK).
MAY 2013-OCTOBER 2015
Aims of this project are
to determine the total zenith delays and the precipitable water vapor accurately and reliably from TUSAGA-Active (CORS-TR),
to produce the numerical models based on time and position.

3. factor Q for each profile.
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
Distribution of radiosonde stations in Turkey providing atmospheric profile data
In this context, a radiosonde analysis algorithm has been developed to define empirical model of the weighted mean temperature Tm and the conversion
factor Q for each profile.

4. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
The weighted mean temperature Tm model

5. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey

6. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
The conversion factor Q models
TΔ= Ts-Tavg
Eq.1
Eq.4
Eq.2
Eq.5
Eq.6
Eq.3
Coefficients
Model
Eq.1
Eq.2
Eq.3
Eq.4
Eq.5
Eq.6
Value
RMSE a0
6,259
0,002
5,387
0,043
6,032
0,035
5,273
0,031
5,705
5,959
0,016 a1
-0,016
0,000
0,022
0,001
-0,011
0,024
-0,007 a2
0,091
0,115 a3
0,190
0,006
0,093
0,013 a4
0,057
0,192
0,083
0,084 a5
0,070
0,003
0,071 a6
0,120
mQ=± 0,0924
mQ=±0,1064
mQ=± 0,0815
mQ=± 0,0764
mQ=± 0,0684
RMS(%)
1,48
1,98
1,35
1,45
1,20
1,15

7. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
For the purpose of validating the PWV models developed, ZTD and IWV are estimated from the GNSS stations established in Istanbul and Ankara using Bernese and GAMIT/GLOBK software (PWVGNSS), and compared with those from the collocated radiosonde stations (PWVRS).
Geodetic network used in PWV estimation

8. PWV estimation with Tm model
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
PWV estimation with Tm model
Differences between PWVGNSS and PWVRS at Istanbul station, r=0.90

9. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
Differences between PWVGNSS and PWVRS at Ankara Ankara station, r=0.87

10. Statistics of the developed Tm model
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
GNSS Station
Min. (mm)
Max. (mm)
Avg. (mm)
RMSE of Avg.
RMSE of ∆PWV (mm)
GANM
Ankara
743 profiles
-4.60
6.35
2.02±0.06
±1.60
GISM
Istanbul
671 profiles
-4.74
6.45
2.33±0.07
±1.72
Statistics of the developed Tm model

11. PWV estimation with Qhybrid model
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
PWV estimation with Qhybrid model
Differences between PWVGNSS and PWVRS at Istanbul station, r=0.90

12. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
Differences between PWVGNSS and PWVRS at Ankara Ankara station, r=0.87

13. Statistics of the developed Qhybrid model
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
GNSS Station
Min. (mm)
Max. (mm)
Avg. (mm)
RMSE of Avg.
RMSE of ∆PWV (mm)
GANM
Ankara
743 profiles
-5.24
6.12
1.62±0.06
±1.68
GISM
Istanbul
671 profiles
-5.50
6.14
1.75±0.07
±1.76
Statistics of the developed Qhybrid model

14. Numerical modelling of PWV from TUSAGA-Active (CORS-TR)
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
Numerical modelling of PWV from TUSAGA-Active (CORS-TR)
Continuous meteorological observations are made at less than 10% of TUSAGA-Active stations. However, there are many meteorological stations surrounding TUSAGA-Active stations.
It is required to determine the meteorological parameters of TUSAGA-Active (CORS-TR) accurately and reliably for PWV estimation.
For this purpose, a study area was chosen.

15. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
meteorological parameters for these stations (temperature, pressure and humidity) were derived by applying spherical harmonics modelling and interpolation to the above-mentioned meteorological parameters measured by meteorological stations surrounding TUSAGA-Active stations.

16. Spherical Harmonics Modelling
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
Meteorological Data
In the computations, the Tikhonov regularization algorithm is used to solve for the ill conditioned problem occurring in small areas.
It has been found that the precision of modeling and interpolation depends on the measuring accuracy of meteorological data, density and distribution of meteorological station network.
Reduction to Geoid
Spherical Harmonics Modelling
Interpolation for TUSAGA-Active stations
elevation to the station height
Results of spherical harmonics modelling and interpolation from June 2013 to June 2014 yield the average precision of ±1.74 K in temperature, ±0.95 hPa in pressure and ±14.88 % in humidity.
ZHD
ZWD=ZTD-ZHD
PWV=ZWD*K(Tm)-1

17. Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
1 August 2013
from June 2013 to June 2014
mPWV=± mm
To compute PWV in near-real time or by GNSS observation reprocessing, spherical harmonics modelling and interpolation yield sufficient accuracy for the estimation of meteorological parameters (temperature, pressure and humidity) of TUSAGA-Active stations from the surrounding meteorological stations.
Spherical harmonics modelling and interpolation can be considered as a suitable method for the automation of data processing.

18. We would like to thank Dr. SZALBOLCS RÓZSA
Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey
We would like to thank
Dr. SZALBOLCS RÓZSA
for his invaluable help in our project which is supported by the Scientific and Technological Research Council of Turkey (TUBITAK).