The Madden-Julian oscillation (MJO) is the dominant mode of variability in the tropical atmosphere on intraseasonal timescales and planetary spatial scales. Despite the primary importance of the MJO and the decades of research progress since its original discovery, a generally accepted theory for its essential mechanisms has remained elusive. Here, we present a minimal dynamical model for the M...

Using idealized distributions of surface moisture, it is shown that with a significant synoptic prevailing flow over these regions of surface variability, dispersion is generally enhanced over heterogeneous surfaces as compared to horizontally homogeneous conditions. The importance of the heterogeneity becomes less, however, as the large scale wind speed increases and/or the spatial scale of th...

The occurrence of major avalanche episodes in the Eastern Pyrenees (NE Spain) is estimated by means of the Poisson and the negative binomial distributions, assuming that they are rare events. The differences observed in their spatial distribution along the seven regions in which Eastern Pyrenees have been divided, suggests us to look for spatial variations in the relationship between extreme av...

The character of fog at Cape Town International Airport (CTIA), South Africa, is investigated, using 13 yr of historical hourly data during the period 1997–2010. Hourly surface observations are used to identify fog types that most frequently affect CTIA, by using an objective fog-type classification method that classifies fog events according to their primary formation mechanisms. Fog-type char...

the aim of this research is recognizing synoptic patterns of the level 500 hp occurrence of late spring freezes over kurdistan province during 1965-2005. after determining freeze temporal-spatial threshold, 22 freezing days spreading over the region were extracted. then, level 500 hp height data located in a scope of 25-60 northern latitude and 30-60 eastern longitude was formulated as an s-mod...

Most of the existing methods we know to tackle datasets of XML documents directly work on the trees representing these XML documents. We investigate in this paper the use of a different kind of representation for the manipulation of XML documents. Our idea is to transform the trees into sets of attribute-values, so as to be able to apply various existing methods of classification and clustering...