Determination of the geoid with a high accuracy is the main task among researchers in the geodetic community. Precise determination of a regional geoid is usually carried out combining a global geopotential model data with a set of point or mean terrestrial gravity anomalies measured in the region and some topographic information. In this research a primary Iranian gravimetric geoid model has b...

A probabilistic clustering technique is developed for classification of wintertime extratropical cyclone (ETC) tracks over the North Atlantic. We use a regression mixture model to describe the longitude-time and latitude–time propagation of the ETCs. A simple tracking algorithm is applied to 6-hourly mean sea-level pressure fields to obtain the tracks from either a general circulation model (GC...

The aim of this study was to classify the most frequently observed atmospheric circulation anomaly patterns in eastern Africa and the adjacent Indian Ocean. As an example of the usefulness of such a classification, the second objective was to test whether these patterns account for intraseasonal rainfall anomalies in the region. A partitioning algorithm, known as dynamical cluster analysis, was...

AGlobal Vertical Datum (GVD) is naturally defined by the geoid, and there is a well-established consensus to adopt Gauss-Bessel-Listing's definition of the geoid (i.e. as being the level surface of the Earth's gravity field that best fits the undisturbed sea level). Themain problem in defining the geoid is therefore to fix its constant geopotential (W0). Nevertheless, this definition can be int...

Maximum covariance analysis is performed on the fields of boreal summer, tropical rainfall, and Northern Hemisphere (NH) 200-hPa height for the 62-yr period of record of 1948–2009. The leading mode, which appears preferentially in summers preceding the peak phases of the El Niño–Southern Oscillation (ENSO) cycle, involves a circumglobal teleconnection (CGT) pattern in the NH extratropical 200-h...

in this study, the artificial neural networks (anns) and regression models were used to downscale the simulated outputs of the general circulation models (gcms). the simulated precipitation for 25.18 º n to 34.51 º n and 45 º e to 60 º e, geopotential height at 850 mb and zonal wind at 200 mb for 12.56° n to 43.25° n and 19.68° e to 61.87° e data sets as the predictors were extracted from echam...

The International Height Reference System (IHRS) adopted by the IAG in 2015 contains two novelties. First, mean-tide system is for handling permanent tide. Second, reference level of height defined equipotential surface where geopotential has a conventional value W0=62636853.4 m2s-2. This was first determined empirically to provide good approximation global mean sea and then as convention. I an...

Forecasting extreme climate events, for instance heat waves, is key society and a scientific challenge. In this paper we propose novel machine learning approach that successfully forecasts waves up to 45 days before the end of event. The allows dynamical process studies. A message optimal require large amount data. image shows temperature (colors) geopotential height (lines) anomalies typical a...