ALARO-0 experience in Romania
Diana-Corina [email protected]
National Meteorological AdministrationROMANIA
Outlook
Precipitations forecast is one of the most difficult problems for forecasters.
In general, Numerical Weather Prediction models, regardless of resolution, have deficiencies in precipitations field simulation, concerning:
- the structure;- evolution and - maximum quantity forecasted.
ALARO had presented a continuous improvement of the parametrization of wet process. The change to ALARO-0 baseline determined the improvement of the precipitations forecast.
Most of forecasters believe that, in terms of precipitations, ALARO-0 baseline is the best choice. Therefore, this presentation will be focused on forecast of 24 hours precipitations.
ALARO-0 configuration setup for Romania
Precipitation simulation analysis for July and August 2014
Specific cases
Content
since 10th of February 2010
ALARO-0 49 levels, 240x240 grid points (Δx=6.5
km), Lambert projection;
Model version: Cy35T1; later Cy36T1;
Dynamical adaptation mode, DFI
initialisation;
2TL Semi-lagrangean scheme; Δt=240s,
Vertical finite differenced;
Arpège LBC; 3 hours coupling frequency
forecast range.
since 1st of January 2014
ALARO-0 baseline 60 levels, 240x240 grid points (Δx=6.5
km), Lambert projection;
Model version: Cy36T1 + modifications
for ALARO-0 baseline;
Dynamical adaptation mode, DFI
initialisation;
2TL Semi-lagrangean scheme; Δt=240s,
Vertical finite element;
Arpège LBC; 3 hours coupling frequency
forecast range.
ALARO-0 configuration setup for Romania
July: a rainy month, significant rainfall, flooding in more regions. Precipitation (area and intensity): In most of the cases, the model has
indicated intense precipitation nuclei, but they are slightly shifted from the real position
Precipitation forecast - July 2014
ALARO-0 baseline – 24 h cumulated precipitation
OBSERVATION (synop + pluvio + hydro) – 24 h cumulated precipitatiopn
07.03.2014 07.10.201407.08.2014 07.15.2014 07.23.2014
August: a month with less precipitation Precipitation: light precipitation - generally underestimated;
intense precipitation - simulated nuclei position is slightly offset , in respect with those of observed nuclei
ALARO-0 baseline – 24 h cumulated precipitation
Precipitation forecast - August 2014
OBSERVATION (synop + pluvio + hydro) – 24 h cumulated precipitatiopn
08.02.2014 08.04.201408.03.2014 08.12.2014 08.14.2014
Synoptic situation Maxim 100 l/mp Maxim 103 l/mp
ALARO model forecasted a nucleus of maximum intensity in the north; the nucleus is displaced in the central region.
Rainfall on the night of July 22, amounted up to 103 l/mp in the mountain area of Bacau County and produced flooding in several towns.
Floods in Moldavia region
MSLP: low pressure field in S-E of Europe, including Romania;
At 500 hPa, a trough situated over eastern Europe, including northern and eastern parts of Romania.
MSLP analysis: 07.22.2014, 12 UTC (from MetOffice UK)
22 - 23 of July 2014 – high instability
ALARO-0 baseline - 24 h cumulated precipitations
Observation – 24 h cumulated precipitations
h 12:00 UTC h 15:00 UTC h 18:00 UTC h 21:00 UTC h 23:00 UTC
Last hour cumulated precipitation simulated with Alaro-0 baseline
Comparative analysis shows a good agreement from 12:00 UTC to 15:00 UTCM. After this time, convective systems from the central part have a quasi-stationary displacement and the model did not captured the event.
22 - 23 of July 2014OHP (One Hour Precipitation) radar estimation - Barnova (Iasi)
Synoptic situation Maxim 105 l/mp Maxim 98 l/mp
Simulated quite accurately the precipitations, regarding the position and intensity.
Floods in Oltenia region
MSLP: A Mediterranean cyclone formed on 07.27.2014, evolved from Gulf of Genoa to western part of Romania.
At 500 hPa, a trough situated over central Europe; his ascending part including western regions of Romania.
MSLP analysis: 27.07.2014, 18 UTC (from MetOffice UK)
27 - 28 of July 2014
ALARO-0 baseline - 24 h cumulated precipitations
Observation – 24 h cumulated precipitations
Synoptic situation Maxim 100 l/mp Maxim 100 l/mp
Simulated the precipitation was better over southern regions and the mountains
The model predicted quite well the precipitable areas and most of the intense precipitation nuclei.
MSLP: low pressure field in the south of Europe and high pressure in the north.
At 500 hPa, weak geopotential field.
MSLP analysis: 06.08.2014, 00 UTC (from MetOffice UK)
6 of august 2014 – afternoon convection
ALARO-0 baseline - 24 h cumulated precipitations
Observation – 24 h cumulated precipitations
h 12:00 UTC h 13:00 UTC h 14:00 UTC h 15:00 UTC h 16:00 UTCOHP (One Hour Precipitation) radar estimation - Barnova (Iasi)
Last hour cumulated precipitation simulated with Alaro-0 baseline
Analysis of rainfall simulated by the model and OHP (Barnova radar), indicates a good correlation on hourly rainfall occurrence.
6 of august 2014
Maxim 100 l/mp Maxim 150 l/mpA cold front crossed the country from NW to SE in the afternoon and reached SE of the country at night on 00 UTC.
Floods in Constanta, RO
MSLP analysis: 17.08.2014, 00 UTC (from MetOffice UK)
16 - 17 august 2014 – cold front
ALARO-0 baseline - 24 h cumulated precipitations
Observation – 24 h cumulated precipitations
It rained torrentially and only in 2 hours in Constanta were gathered 74 l/m2 .
Simulated the precipitation over the south-eastern part of Romania: not sufficient accurate position of precipitation nuclei.
Maxim 50 l/mp Maxim 66 l/mpA cold front passage over the northern half of the country, which has passed from west to north-east. The front passed during the day.
Simulated the precipitation were well placed in space;
A good estimation of precipitation nuclei
MSLP analysis: 27.08.2014, 12 UTC (from MetOffice UK)
MSG – visible
27 of august 2014 – cold front (during the day)
ALARO-0 baseline - 24 h cumulated precipitations
Observation – 24 h cumulated precipitations
Maxim 150 l/mp Maxim 72 l/mp
A cold front passed during the night, nearly 24 hours after running the model;
Simulated the precipitation over the south part of Romania: subestimation precipitation and not sufficient accurate position of precipitation nuclei
MSLP analysis: 23.07.2014, 18 UTC (from MetOffice UK)
23 - 24 of august 2014 – cold front (during the night)
ALARO-0 baseline - 24 h cumulated precipitations
Observation – 24 h cumulated precipitations
Globally better forecast:
the fraction of correct forecasted events is higher for all precipitation classes and scores are better for the first day
the very light [0.1 – 2 l/mp/24h] unrealistic precipitation was reduced, but there are still underestimated for almost 50% cases
the more intense precipitation [10 – 200l/mp] scores are better for the first day but the position of precipitation nuclei are shifted.
subjective evaluation of the forecasters: ALARO provides a good precipitation forecast, especially for severe situations.
in case of crossing fronts, model performances decrease as the forecast range increases.
Conclusions
ALARO-0 baseline Verification of precipitation
Thank you!
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