Abstract
         The Global Navigation Satellite System (GNSS) techniques have transformed positioning, navigation and time, becoming indispensable in many activities of daily living. Apart from commercial and civilian applications already known GNSS technology can be used as atmospheric observation system, since it has been demonstrated its ability to estimate the content of water vapor in the atmosphere from suffering tropospheric delay propagation signal in the satellite-receiver direction.
         The distribution and evolution of water vapor is critical for the functioning of climate and weather atmospheric, being one of the essential climate variables systematic observation currently defined System Global Climate Observing System (GCOS Global Climate Observing System). The behavior of the atmospheric water vapor is essential for studies of climate change, since it is the main greenhouse effect gas that affects global warming. It is also a major component in the vertical stability of the atmosphere, actively involved in the evolution of storm systems.
         Until recently, this variable was not well defined atmospheric in the absence of measures with sufficient resolution to represent their high spatial and temporal instability. The increase in recent years of permanent GNSS reference stations worldwide, is a major breakthrough for monitoring the amount of water vapor or precipitable water (PW).
         One of the main characteristics that define the rainfall within the Valencia is the variability, but an interesting aspect is the extraordinary rainfall intensity shown in some episodes. In the Levant area torrential rainfalls affects relatively often to the point of considering characteristics of this region. PW also occurs in this region with greater variability and instability, which is intrinsically linked to the heavy rainfall.
         The objective of this thesis is to analyze the behavior of the water vapor content determined from atmospheric observations made ??in GNSS reference stations located in Valencia, establishing a system of observation and atmospheric monitoring in the study area.
         After verifying the methodology used for the determination of water vapor, we analyze the influence of precipitable water over the most significant rain events occurred in Valencia in the last 11 years (time series data available), to establish the criteria to predict weather events, since this new product GNSS provides information of spatial and temporal variability of rapid moisture in the troposphere. The PW relations with meteorological variables atmospheric pressure and precipitation, is also described, evaluating the trend and variability of atmospheric water vapor when heavy rainfall events ocurred, characterizing graphically for every month of the year, normal conditions in the pressure-PW combination in the study area.