ALARO-0 experience in Romania

Diana-Corina BOSTANdiana.bostan@meteoromania.ro

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!