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 ideniz@beun.edu.tr, cmekik@hotmail.com, gokhanngurbuz@gmail.com ES1206 Workshop, Reykjavik, 8-10 March 2016

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.

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.

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

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

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

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

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

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

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

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

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

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

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.

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.

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

Acquisition of PWV from TUSAGA-Active stations in the north west of Turkey 1 August 2013 from June 2013 to June 2014 mPWV=±0.50-1.32mm 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.

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).