Alfonso Nunez

Combining meteorological radar and network of rain gauges data for space–time model development

SUMMARY Technological developments and the trend to go higher and higher in frequency give rise to the need for true space–time rain field models for testing the dynamics of fade countermeasures. There are many models that capture the spatial correlation of rain fields. Worth mentioning are those models based on cell ensembles. However, the rain rate fields created in this way need the introduction of the time variable to reproduce their dynamics. In this paper, we have concentrated on addressing the time domain effects while we have relied on existing spatial rain field models for creating initial fields, which are propagated (advected) according to proposed models and assumptions, some of which have been drawn from a combined use of a concurrent weather radar and a network of rain gauges. The dynamic modeling presented simulates the advection of a synthetically generated rain field according to dynamic, spatially correlated advection fields extracted from the analysis of weather radar images. Experimental data and model fits have been presented as well. Further ideas on how to improve the realism of the generated dynamic fields have also been presented. Furthermore, the limitations of radar data, especially those related to their limited time resolution, for the required space–time models have been pointed out. These can be overcome by using data from a network of rain gauges. However, it is important to be aware of the similarities and differences between these two sources. A comparative study of these two data sets has also been presented. Copyright r 2009 John Wiley & Sons, Ltd.

Rain-Cell Identification and Modeling for Propagation Studies from Weather Radar Images

This study aims to characterize and model the rain fields for propagation studies from weather radar images of the northwest coast of Spain. The study includes the modeling of these images according to two well-known rain-cell models, EXCELL and HYCELL. For this analysis, a procedure for detecting rain field-s and an algorithm for identifying rain cells within the images is presented. This work is part of an ongoing activity, trying to develop dynamic space-time models of rain fields for simulating rain-induced effects on millimeter-wave communication systems.

On the spatial structure of rainfall rate: Merging radar and rain gauge data

This paper extends some first steps given in merging radar and rain gauge data for a better understanding of rainfall rate spatial structure. The study has been performed analyzing spatial correlation between sites within a densely meshed rain gauge network and also with their corresponding pixels in weather radar images.

Cellular automata for predicting three-state rain rate and rain attenuation field dynamics

A straightforward linkage between rain cell dynamics in terms of reflectivity Z (dBz) or its equivalent rain rate R (mm/h) and satellite or terrestrial radiolink attenuation can be performed. This work focuses on the presentation of an approach for assessing and characterizing rain cell dynamics based exclusively on the analysis of the radar reflectivity scans recorded in weather radar image, and without an a priori assumption on the structure of rain cells. This research has been addressed by using cellular automata. Rain cell dynamics are simulated by using probabilistic cellular automata rules and tracking vectors which indicate a global advection direction and velocity.

Radar Rain Cell Identification and Modeling in the North-West of Spain

This study aims to characterize and model the rain fields in the North-West of Spain from Weather Radar Images. The study includes the modeling of these images according to two well known rain cell models: EXCELL and HYCELL. For this analysis, a procedure to detect rain fields and an algorithm for identifying rain cells within the images is presented. This work is part of an on-going activity trying to develop dynamic space-time models for rain fields for simulating rain induced effects on millimeter wave communication systems.