HR: 14:45h
AN: A53C-04 INVITED     [Abstracts]
TI: Seasonal Variability Study of the Tropospheric Zenithal Delay in the South America using regional Numerical Weather Prediction model
AU: * Sapucci, L F
EM: lsapucci@cptec.inpe.br
AF: Instituto Nacional de Pesquisas Espaciais-Centro de Previsao de Tempo e Estudos Climaticos, Rodovia Presidente Dutra, km 40, Cachoeira Paulista, SP 12630-000, Brazil
AU: Monico, J G
EM: galera@fct.unesp.br
AF: Universidade Estadual Paulista-Faculdade de Ciencias e Tecnologia, Rua Roberto Simonsen, 305, Presidente Prudente, SP 19060-900, Brazil
AU: Machado, L T
EM: machado@cptec.inpe.br
AF: Instituto Nacional de Pesquisas Espaciais-Centro de Previsao de Tempo e Estudos Climaticos, Rodovia Presidente Dutra, km 40, Cachoeira Paulista, SP 12630-000, Brazil
AB: In 2010 a new navigation and administration system of the air traffic, denominated CNS-ATM (Communication Navigation Surveillance - Air Traffic Management) should be running operationally in South America. This new system will basically employ the positioning techniques by satellites to the management and air traffic control. However, the efficiency of this new system demands the knowledge of the behavior of the atmosphere, consequently, an appropriated Zenithal Tropospheric Delay (ZTD) modeling in a regional scale. The predictions of ZTD values from Numeric Weather Prediction (NWP), denominated here dynamic modeling, is an alternative to model the atmospheric gases effects in the radio-frequency signals in real time. Brazilian Center for Weather Forecasting and Climate Studies (CPTEC) of the National Institute for Space Research (INPE), jointly with researchers from UNESP (Sao Paulo State University), has generated operationally prediction of ZTD values to South America Continent (available in the electronic address http:satelite.cptec.inpe.br/htmldocs/ztd/zenithal.htm). The available regional version is obtained using ETA model (NWP model with horizontal resolution of 20 km and 42 levels in the vertical). The application of NWP permit assess the temporal and spatial variation of ZTD values, which is an important characteristic of this techniques. The aim of the present paper is to investigate the ZTD seasonal variability over South America continent. A variability analysis of the ZTD components [hydrostatic(ZHD) and wet(ZWD)] is also presented, as such as discussion of main factors that influence this variation in this region. The hydrostatic component variation is related with atmospheric pressure oscillation, which is influenced by relief and high pressure centers that prevail over different region of the South America continent. The wet component oscillation is due to the temperature and humidity variability, which is also influenced by relief and by synoptic events like: the penetration the cold front from Antarctic pole into the continent and occurrence of humidity convergence zones. In South America there are two main convergence zones that has strong influence in the troposphere variability, the ITCZ (Inter Tropical Convergence Zone) and the SACZ (South Atlantic Convergence Zone) zones. These convergence zones are characterized by an extensive precipitation band and high nebulosity almost stationary. The physical processes associated with these convergence zones present strong impacts in the variability of ZWD values. This work aims to contribute with ZTD modeling over South America continent using NWP to identify where and when the ZTD values present lower predictability in this region, and consequently, minimizing the error in the GNSS positioning that apply this technique.
UR: http:satelite.cptec.inpe.br/htmldocs/ztd/zenithal.htm
DE: 0350 Pressure, density, and temperature
DE: 1220 Atmosphere monitoring with geodetic techniques (6952)
DE: 3245 Probabilistic forecasting (3238)
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
DE: 3355 Regional modeling
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly