NUVEM - New methods to Use gnss water Vapor Estimates for Meteorology of Portugal

Wednesday, 17 December 2014
Rui Manuel Silva Fernandes1,2, Pedro Viterbo3, Machiel S Bos1, Joao P Martins3, André Garcia Sá1,4, Hugo Valentim1 and Jonathan Jones5, (1)University of Beira Interior, Covilha, Portugal, (2)Delft University of Technology, Faculty of Aerospace Engineering, Delft, Netherlands, (3)Instituto Port Mar e Atmosfera, Lisbon, Portugal, (4)IPG, Guarda, Portugal, (5)Met Office, Exeter, United Kingdom
NUVEM (New methods to Use gnss water Vapor Estimates for Meteorology of Portugal) is a collaborative project funded by the Portuguese National Science Foundation (FCT) aiming to implement a multi-disciplinary approach in order to operationalize the inclusion of GNSS-PWV estimates for nowcasting in Portugal, namely for the preparation of warnings of severe weather. To achieve such goal, the NUVEM project is divided in two major components:

a) Development and implementation of methods to compute accurate estimates of PWV (Precipitable Water Vapor) in NRT (Near Real-Time);

b) Integration of such estimates in nowcasting procedures in use at IPMA (Portuguese Meteorological Service).

Methodologies will be optimized at SEGAL to passive and actively access to the data; the PWV estimations will be computed using PPP (Precise Point Positioning), which permits the estimation of each individual station separately; solutions will be validated using internal and external values; and computed solutions will be transferred timely to the IPMA Operational Center.

Validation of derived estimations using robust statistics is an important component of the project. The need for sending computed values as soon as possible to IPMA requires fast but reliable internal (e.g., noise estimation) and external (e.g., feedback from IPMA using other sensors like radiosondes) assessment of the quality of the PWV estimates.

At IPMA, the goal is to implement the operational use of GNSS-PWV to assist weather nowcasting in Portugal. This will be done with the assistance of the Meteo group of IDL. Maps of GNSS-PWV will be automatically created and compared with solutions provided by other operational systems in order to help IPMA to detect suspicious patterns at near real time. This will be the first step towards the assimilation of GNSS-PWV estimates at IPMA nowcasting models.

The NUVEM (EXPL/GEO-MET/0413/2013) project will also contribute to the active participation of Portugal at the COST Action ES1206 - Advanced Global Navigation Satellite Systems tropospheric products for monitoring severe weather events and climate (GNSS4SWEC).

This work is also carried out in the framework of the Portuguese Project SMOG (PTDC/CTE-ATM/119922/2010).