ATMOSPHERE & CLIMATE DYNAMICS GROUP

DEPARTMENT OF GEOGRAPHY-HAROKOPIO UNIVERSITY OF ATHENS

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Wednesday 28-06-2017 Thursday 29-06-2017
ATHENS 24..33 °C 25..35 °C
THESSALONIKI 25..33 °C 24..35 °C
PATRA 21..30 °C 23..33 °C

Wednesday 28-06-2017 Thursday 29-06-2017
ROME 21..27 °C 22..30 °C
PARIS 16..21 °C 14..21 °C
LONDON 14..18 °C 11..19 °C

nowcast

Current weather conditions over Europe and Eastern Mediterranean are available in the form of thematic maps of the mean sea level pressure, temperature, wind and precipitation.The maps are produced  by the assimilation of various types of surface and upper air observations (METAR, SYNOP, RAOBS) and satellite retrievals for the precipitation estimation. The nowcasts have hourly updated rate.

prec-mslp.d01.000.300x300 prec-mslp-wind.d02.hires.zoom.000.300x300

seasonal forecast

Seasonal prediction’s significance lies on its ability to provide early warnings about oncoming and extreme weather episodes.The provided charts depict a qualitative representation of the atmospheric conditions that are likely to prevail over Europe for the summer 2017 and winter 2018 based on simulations with initial conditions on February 2017. The charts are based on the processed outputs of the ensemble members, a few of them are freely available here.

seasonal forecast

Seasonal prediction’s significance lies on its ability to provide early warnings about oncoming and extreme weather episodes.The provided charts depict a qualitative representation of the atmospheric conditions that are likely to prevail over Europe for the winter 2014-2015. The charts are based on the processed outputs of the ensemble members, a few of them are freely available here.

seasonal-dec2014

January 2015 

 

February 2015

 

Methodology: Seasonal prediction’s significance lies on its ability to provide early warnings about oncoming and extreme weather episodes. The ACDG/HUA seasonal forecasts are obtained from annual ensemble simulations based on the WRF-ARW v3.5 model covering the entire globe. The ensemble simulations performed over a global domain of 720x360 grid points, on 0.5°x0.5° horizontal resolution, with time step of 10min and 32 vertical levels. The simulations were based on a modified version of the lagged average forecast (LAF) formulation introduced by Hoffman and Kalnay (1983). In a short range forecast the LAF method consists of ensemble members that include the latest operational forecast, and also forecasts for the same verification time started a few days earlier than the latest one. Thus each member includes the governing dynamics and it can be considered as a perturbation about the ensemble mean (Katsafados et al., 2014). In accordance to the LAF methodology, WRF annual simulations were initialized by global analyses assuming each analysis as a perturbation of the previous one due to the long lead time of 12 months ahead. Thus, the ensemble consists of 15 members with different initialization dates and different simulation lengths, but with identical end time (September 1st, 2017). In particular, each member was initialized by the Global Forecasting System (GFS) analyses on 00:00 UTC at the period 17-31 August 2016.

USGS DEM database (10x10min) was used for the definition of the domain topography, 16 categories of the FAO (10x10min) for the determination of soil type, and 24 categories of the USGS (10x10min) were used for the vegetation types, which are dynamically updated in the simulation. Real-time global (rtg) analysis data is used for the sea surface temperature (SST) during the initialization stage of each simulation and the monthly climatological NCEP/EMC SST is applied afterwords on a daily update frequency.

How to interpret the charts: In order to assign the estimated temperature anomaly, monthly averaged model outputs were compared against long term monthly means valid for the period of 1971 - 2000, released by the National Center for Environmental Predictions (NCEP) and NCAR (Kalnay et al., 1996). The shaded anomalies are considered as statistically significant in 95% confidence level. Spaghetti plots of the temperature at 850 hPa have been also produced as a guidance provision of each member uncertainty.

♦Consider the freely available charts as an under development research product and not as a guaranteed advisor using it for decision making.

 

  • Hoffman, R. N., and Kalnay, E.: Lagged averaged forecasting, an alternative to Monte Carlo forecasting, Tellus, 35A, pp. 100-118, 1983.
  • Kalnay, E., Kanamitsu, M., Kistler, R., Collins, W., Deaven, D., Gandin, L.,  Iredell, M., Saha, S., White, G., Woollen, J., Zhu, Y., Chelliah, M., Ebisuzaki, W., Higgins, W., Janowiak, J., Mo, K. C., Ropelewski, C., Wang, J., Leetmaa, A., Reynolds, R., Jenne, R., and Joseph, D.: The NMC/NCAR 40-Year Reanalysis Project, Bull. Amer. Meteor. Soc., 77, 437-471, 1996.
  • Katsafados P., A. Papadopoulos, G. Varlas, E. Papadopoulou, and E. Mavromatidis: Seasonal predictability of the 2010 Russian heat wave, Nat. Hazards Earth Syst. Sci., 14, 1531-1542, 2014.

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.

domain1crop

 

 

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.

 

The day-by-day (at 00:00 UTC) simulated distribution of the temperature, the wind speed at 850 hPa and the mean sea level pressure for the period December 1, 2017 up to February 28, 2018.

winter.2017

 

ARIS D01 EXPL T850 12 14 28


ARIS D01 SPAG T850 12 14 28


ARIS D01 PROB 12 14 28 200mm



ARIS D01 EXPL T850 1 14 28


ARIS D01 SPAG T850 1 14 28


ARIS D01 PROB 1 14 28 200mm



ARIS D01 EXPL T850 2 14 28


ARIS D01 SPAG T850 2 14 28


ARIS D01 PROB 2 14 28 200mm

The day-by-day (at 00:00 UTC) simulated distribution of the temperature, the wind speed at 850 hPa and the mean sea level pressure for the period June 1, 2017 up to August 31, 2017.

summer.2017

 

ARIS D01 EXPL T850 6 14 28
 

ARIS D01 SPAG T850 6 14 28

 ARIS D01 PROB 6 14 28 150mm

ARIS D01 EXPL T850 7 14 28

 ARIS D01 SPAG T850 7 14 28

ARIS D01 PROB 7 14 28 150mm

ARIS D01 EXPL T850 8 14 28

ARIS D01 SPAG T850 8 14 28

ARIS D01 PROB 8 14 28 150mm

dust and sea salt forecast

Dust dry deposition72-hr dust forecast is available for the entire Europe, North Africa, Middle East and the Saudi Arabia peninsula. The products are the near surface dust concentration, the dry deposition on the ground level and the total column dust load.

demoThe system is installed in the University Campus (37° 57' 39,55'' N, 23° 42' 27,57'' E) on the meteorological mast at 11 meters height. It detects and tracks thunderstorms up to 500 km away in an updated rate of 30 minutes.It uses a direction-finding antenna to determine the direction of the VLF signal (7-15 kHz). The receiver looks at the signal strength to calculate an approximate distance for the lightning strike. There is additional processing done in software to reduce the effect of strike to strike magnitude variations. Once the receiver recognizes the direction and distance of the strike it plots it on the map. The system is planned to be expanded with 2 more detectors by the end of the year 2014.

lightnings over Greece

latestData is updated every 30 minutes and the detections of the last 2 hours (120 minutes) are shown on the map with different color. The time unit of the map is referred in UTC. Winter time in Greece is UTC+2 and summer time is UTC+3.