000004269 001__ 4269
000004269 005__ 20190916143757.0
000004269 037__ $$aCTALK-2019-0123
000004269 100__ $$aMorel, L. 
000004269 245__ $$aGlobal validity and behaviour of tropospheric gradients estimated by GPS
000004269 260__ $$c2019
000004269 269__ $$c2019-07-16
000004269 520__ $$aEstimation of tropospheric gradients in GNSS data processing is a well-known technique to improve positioning. Today, they are routinely estimated by several global and regional GNSS analysis centres but they are still not yet used for operational meteorology. We discuss the physical meaning of tropospheric gradients estimated from GPS observations recorded by more than 50 permanent stations located all around the world. We estimated Zenith Total Delay (ZTD) and tropospheric gradients using the software GIPSY-OASIS II version 6.4 in order to retrieve gradient estimations, with a focus on regions with significant relief. We observe that gradient directions are stable over the time and pointed toward the relief for most of the stations selected. Based on these results, we formulate why gradients have this particular direction when stations are closed to high mountains.
000004269 594__ $$aSTCE
000004269 700__ $$aDurand, F. 
000004269 700__ $$aMoudni, O. 
000004269 700__ $$aPottiaux, E. 
000004269 700__ $$aFollin, J.M. 
000004269 700__ $$aDurand, S. 
000004269 700__ $$aVan Baelen, J. 
000004269 773__ $$tInternational Union of Geodesy and Geophysics, Montreal, Canada
000004269 8560_ $$feric.pottiaux@observatoire.be
000004269 906__ $$aContributed
000004269 980__ $$aCTALKCONT