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Abstract: The aim of this paper is to present the partial trends of rainy days and total precipitation in Córdoba Province, Argentina, during the period 1960–2010 and the full range of precipitation for the Córdoba Observatory station, which has the longest measurement record in Argentina, 1873–2010, and to show the relationship between these variables and solar activity. A strong association is shown between break points when the trend changes for both the number of rainy days and the total precipitation, and the occurrence of maxima in the sunspot cycle, indicating that these variables are modulated by the solar Hale cycle and probably by the influence of cosmic rays. [Copyright &y& Elsevier]

Abstract: Conventional surface data and quantitative estimations of precipitation are used to document the occurrence and spatial distribution of severe weather phenomena associated with deep moist convection over southeastern South America. Data used in this paper are 24-hour rainfall, maximum hourly gusts and present weather reports from the surface station network for Argentina to the north of 40°S and cover the period 2000–2005. Hourly rainfall estimated with the CMORPH technique (CPC MORPHing technique, R. J. Joyce et al., 2004) is included in the analysis in order to increase the density of the precipitation database from January 2003 to December 2005. Extreme events are detected by means of a 95th-percentile analysis of the 24-hour rainfall and wind; values greater than 30mm and 25ms−1 respectively are considered extreme in the study area. These results are related to the presence of deep convection by considering the 235K and 218K cloud shield evolution in Geostationary Operational Environmental Satellite-12 Infrared (GOES-IR) imagery evaluated by the Forecasting and Tracking of Cloud Cluster (FORTRACC) technique. Rainfall above 30mmday−1 and present convection-related weather events tend to occur in the northeast of the country. Finally, an analysis is made of the relationship between severe phenomena and the location and lifecycle of Mesoscale Convective Systems (MCSs) defined by the 218K or 235K levels. According to the reports, favorable locations for severe weather concentrate to the northeast of the cloud shield anvil centroid although most of the cases are found in the northwest. This feature can be seen in systems with anvil areas larger than 250,000km2 in association to the predominant mid-level wind shear direction from the northwest over the area. Moreover, systems with centers located north of 30°S present a more circular shape while those to the south are more elongated with a NW–SE main axis clearly related to the presence and interaction with frontal zones over the area. Most of the events occur previous to the moment when the systems reach their maximum extension, between 2 and 10h after the initiation of the system depending on the size of the MCSs. [Copyright &y& Elsevier]

Abstract: This paper presents PWV estimates from GPS data computed at four continuously operated GPS stations in Argentina established at Buenos Aires, Córdoba, Rosario and Salta over a 1 year period (2006–2007). The objective is to analyze the behaviour of the GPS PWV estimation using mean tropospheric temperature () values from the Bevis model, Sapucci model and obtained by a numerical integration of variables provided by the operational analysis of the National Centre of Environmental Prediction (NCEP). The results are validated using PWV values from nearest radio soundings. Moreover, a comparison between PWV values determined from microwave sensors deployed on the NOAA-18 satellite and PWV from GPS observations is also presented. From the analysis we can see that the computation of GPS PWV using the from the Bevis model, originally deduced for the northern hemisphere, shows similar behaviour to the respective computation using a Sapucci model inside 0.5mm. The differences between the T m values computed from the Sapucci model and the numerical integration of NCEP variables are of the order of 15K, although it does not represent a significant error in PWV. Nevertheless, differences in bias are imperceptible during the dry period and they are as big as 3mm during the moist or high precipitation period. This behaviour could not represent an improvement when comparing radio soundings with respect to the GPS PWV values using different estimations of T m . Thus, we conclude that the usage of T m estimated from the Bevis model is the best choice for regional studies, considering the simplicity and dissemination of the method, unless some more studies taking into account the geographical and climatological characteristic of the region are performed. As expected, GPS PWV values show very good agreement with radio sounding determinations, small differences can be observed especially during extreme precipitation periods. In general the NOAA PWV values denote an over estimation of the available water vapour. It is important to note that the determination of PWV is not the mean product of the NOAA-18 satellite mission. These results show the potential of such a product although a preliminary calibration using GPS PWV is still necessary. [Copyright &y& Elsevier]