1. ASYM subWG1 – Feedback from the splinter meeting
Status:
STD validation BENCH leads by M. Kakmarik
Future plans:
STD validation BENCH
° Results based on the same configuration (cutoff 7°)
° Tests of the cutoff angle (compare STD for the same range of low elevation) + test mapping function
° Validation of STD using external observations
 recommendation
Post-fit residuals (influence of the multipath; pattern antenna) GFZ, ROB, TUV, CNAM, GOP, WUELS leads by ???
STD during severe weather & impact of hydrometeors on IF TS (implementation of flag) leads by H. Brenot

2. WG2: TOMO subgroup
Contributors of GRADIENTS/STD to the benchmark campaign
AUSTRIA (Gregor Möller, Robert Weber, TU Vienna)
Development of a tomography software (based on LSQ and MART)
Retrievals of refractivity fields for two test domains (one flat East; one in mountainous West of Austria)
Input: SWD derived from GNSS observations of the EPOSA network
Validation of the improved refractivity fields with passive radiometer data in the Innsbruck valley
Some assimilation tests using the operational weather forecast model AROME operated at ZAMG (May/June 2013)
BELGIUM (Hugues Brenot, BIRA)
Cross-validation of GNSS tomography and methodological improvement using data from CORS Australian network
(collaboration with TUO, WUELS and RMIT)
 impact of uncertainty of STD
 interest of pseudo-STD
Preparation of the tomography for HyMeX (collaboration with Météo-France / ENSTA / IGN)
Case studies using GNSS tomography in Poland (collaboration with WUELS).
CZECH REPUBLIC (Michal Kačmařík, TUO) using BERNESE (DD) and G-Nut/Tefnut (PPP)
(collaboration with BIRA, WUELS and RMIT)
 statistical + visualisation tools for tomography retrievals

3. WG2: TOMO subgroup
Contributors of GRADIENTS/STD to the benchmark campaign
FRANCE (Laurent Morel et al., Oliveir Le Coz, CNAM/ESGT)
Installation of 3 stations in the city of Le mans (France) + 2 collocated meteo data logger
Development of tomographic software.
 Impact on low troposphere retrievals using tests of the parametrisation + impact on low troposphere retrievals
° with and without gradients
° sensivity of ZHD estimations from model or hydrostatic formulation
° importance of apriori condition
° configuration of network
POLAND (Witold Rohm, WUELS)
Working on the TOMO-NRT for Poland, running but validation in progress will be ready by June
Working on a paper: storms location and 3D water vapour distribution using GNSS tomography, lightning location and GEO cloud images
Cross-validation of GNSS tomography and methodological improvement using data from CORS Australian network
(collaboration with BIRA, WUELS and RMIT)
AUSTRALIA (Toby Manning, RMIT)

4. Outlook
Jan wrote
“Are there any plans to use Benchmark for tomo? In particular, are there interest to have slants for all/part of Benchmark?”
Witold answered
“Of course, this is good material to run tomography especially that we have some sections with higher density and terrain undulation - we were discussing that in previous meetings.
Let us think about the study we can run using benchmark campaign. I'm sure at the workshop Hugues may present some idea on how to use it.
Additionally I would like to ask your opinion on the use of Benchmark data for tomography - would you be interested to process the case study using your models? Should we study first the solution using ray-traced slants, then real observations and in the end provide data for assimilation?”
Hugues think
“It could be good to set two network for two period (quiet and severe):
- one with low contrast of altitude and a network as dense as possible
- one with high contrast of altitude”
I agree with synthetic tomography using STDs already available for these 2 networks and 2 periods. We could look at the impact of the degradation or the improvement of the density of a network using several tomography models”
 choice of networks, periods and configuration of tomography required
 choice of obs. dataset required
 choice of synthetic dataset required
 need of external obs. for validation (WVR, RS, RO, IASI-A&B…)
 exchange of between TOMO and BENCH