ATMOSPHERE & CLIMATE DYNAMICS GROUP

DEPARTMENT OF GEOGRAPHY-HAROKOPIO UNIVERSITY OF ATHENS

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Nowcasting is a form of very short-range weather forecasting (usually up to 6 hours)  based on very fined observational data (Kalnay, 2003). The provided nowcasting information is based on the NOAA's developed Local Analysis and Prediction System (LAPS). It is a mesoscale meteorological data assimilation system that utilizes a suite of observations (e.g. surface meteorological stations, radar, satellite, soundings, and aircraft) to generate a spatially distributed, time-evolving, three-dimensional representation of atmospheric patterns and processes (Albers, 1995).

Currently, LAPS is running on two domains. The coarse one covers the entire Europe, Middle East and North Africa on a horizontal grid increment of 15 km (550x425 grid points) and 43 vertical levels (Fig. 1). The finer one covers Greece on a horizontal grid increment of 3 km (700x320 grid points) and 43 vertical levels, as well. Early and final analyses are provided for both domains on hourly temporal increment. Early analyses are available 30 minutes after the analysis referenced hour and the final analyses about 55 minutes later. Near-to-analysis forecast, valid for the next hour, is also produced for both domains.

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The system is based on the GFS analysis and near-to-analysis forecast data updated every 6 hours (4 forecast cycles on daily basis). It assimilates various types of surface and upper air observations (METAR, SYNOP, RAOBS) and satellite retrievals for the precipitation estimation. LAPS analyses have been evaluated against independent surface observations provided by a dense network of surface stations over Greece (Katsafados et al., 2012).

 

 

 

 

 

 

 

 

 

References

Albers, S., 1995: The LAPS wind analysis. Weather and Forecasting, 10, 342-352.

Kalnay, E., Atmospheric Modeling, Data Assimilation and Predictability. Cambridge University Press, 2003.

Katsafados P., A. Papadopoulos, K. Lagouvardos, V. Kotroni, E. Mavromatidis and I. Pytharoulis: Statistical evaluation of the Local Analysis and Prediction System over Greece. 2nd LAPS Users Workshop, October 23-25, 2012, Boulder CO, USA.

 

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