SOME RELATIONSHIPS BETWEEN SOME RELATIONSHIPS BETWEEN MESOSCALE CONVECTIVE SYSTEMS MESOSCALE CONVECTIVE SYSTEMS

LIFE CYCLE AND OBSERVED LIFE CYCLE AND OBSERVED RAINFALL OVER DEL PLATA BASINRAINFALL OVER DEL PLATA BASIN

Daniel Vila Daniel Vila 1,21,2, Luiz Augusto Toledo , Luiz Augusto Toledo Machado Machado 22, Ines Velasco , Ines Velasco 33

11 Instituto Nacional del Agua Instituto Nacional del Agua, Ezeiza, Buenos Aires, Argentina, Ezeiza, Buenos Aires, Argentina

22 DSA, CPTEC-INPE, Cachoeira Paulista, BrasilDSA, CPTEC-INPE, Cachoeira Paulista, Brasil

33 DCAyO, FCEN, UBA, Buenos Aires, ArgentinaDCAyO, FCEN, UBA, Buenos Aires, Argentina

• OUTLINESOUTLINES

• THE FORTRACC TECHNIQUE

• USED DATA BASE

• MAIN ALGORITM CHARACTERISTICS

• TECHNIQUE APPLICATION: IGUAZU BASIN

• CONCLUSIONS

• OUTLINESOUTLINES

• THE FORTRACC TECHNIQUE

• USED DATA BASE

• MAIN ALGORITM CHARACTERISTICS

• TECHNIQUE APPLICATION: IGUAZU BASIN

• CONCLUSIONS

• DATADATA : GOES 8 (75º W, 0º ) imagery - channel 4 (10.7 μm, thermal infrared), - spatial resolution: 4 km x 4 km - temporal resolution: ½ hour (*) provided by Centro de Previsión del Tiempo y Clima (CPTEC) .

• PeriodPeriod: December 2002 – January and February 2003

• RegionRegion: SHEM (Southern Hemisphere Scan)

• OUTLINESOUTLINES

• THE FORTRACC TECHNIQUE

• USED DATA BASE

• MAIN ALGORITM CHARACTERISTICS

• TECHNIQUE APPLICATION: IGUAZU BASIN

• CONCLUSIONS

Conex space generation (“clusters”). Temperature threshold T 235 K – Minimun Area AMIN 150 pix

(a) Regular tracking (continuity), (b) split y (c) merge.

White MCS: t - Purple MCS: t+Δt

Tracking MethodologyTracking Methodology

• Based on overlapped area between consecutive images (1/2 hour)

• Minimum MCS size: 150 pixels

• MCS displacement estimation

• MCS growing evolution estimation

TECHNIQUE VALIDATION OF INTERPOLATED TECHNIQUE VALIDATION OF INTERPOLATED IMIMAAGENS: GENS: NOWCASTING USENOWCASTING USE

TECHNIQUE VALIDATION OF INTERPOLATED TECHNIQUE VALIDATION OF INTERPOLATED IMIMAAGENS: GENS: NOWCASTING USENOWCASTING USE

Evolución temporal de la cantidad de píxeles pronosticados y observados para el tiempo de pronóstico de 30 minutos (izquierda) y 120 minutos (derecha) para el periodo 6 al 11 de enero de 2003

• OUTLINESOUTLINES

• THE FORTRACC TECHNIQUE

• USED DATA BASE

• MAIN ALGORITM CHARACTERISTICS

• TECHNIQUE APPLICATION: IGUAZU BASIN

• CONCLUSIONS

Monthly rainfall and mean number of pixels per image with temperature below 235 K

Iguazu river basin: green dots are raingauge stations (daily accumulation)

Rain event from raingauge measurement:

• RR > 25 mm/day - minimum area = 50000 km2

or

• RR > 75 mm/day in (at least) one raingauge.

• 17 day were selected

Rain event from satellite detection:

• For those days classified as rain event from raingauge measurement, were selected all MCS (“famlies’) that affect the raingauge stations with rr > 25 mm/day

• 32 families were selected

Mean brightness temperature (left) and brightness temperature anomaly (right) for selected cases.

Mean trajectory of composite (32 MCS families). Green circle correspond to initial stage, box to maturity (maximum extension) and star to dissipation.

Relative frequency of life time for rainy and non-rainy MCS (left) and life time – maximum extent scatter plot for rainy and non-rainy MCS.

DIURNAL CYCLEDIURNAL CYCLE

MCS area expansion rate (in s-1*106) and minimum temperature diurnal cycle.

Mean temporal evolution of families composition: size, minimum temperature and convective area (T < 210 K) for rain events(left) and non-rain events (right)

Initial stage: mean area expansion – cooling rate and total life cycle

Mean area and temperature evolution according to different life cycle duration

24-hour accumulation (left) and size and temperature evolution of selected MCS (right)

Cooling rate Cooling rate ~ 12 K/hour~ 12 K/hour

• OUTLINESOUTLINES

• THE FORTRACC TECHNIQUE

• USED DATA BASE

• MAIN ALGORITM CHARACTERISTICS

• TECHNIQUE APPLICATION: IGUAZU BASIN

• CONCLUSIONS

CONCLUSIONSCONCLUSIONS

• THE MEAN LIFETIME IS AROUND THREE TIMES LARGER FOR RAINFALL-ASSOCIATED MCS’S THAN THAT OF THE GENERAL MCS DATASET.

• THE COOLING RATE DURING THE FIRST STAGES OF LIFE CYCLE (FROM 2-4 TO 6-8 HOURS) IS GREATER THAN THAT OF THE GENERAL DATASET, WHILE THE MINIMUM TEMPERATURE DURING THE FIRST DETECTION STAGE DOES NOT ALLOW TO DISTINGUISH THE EVOLUTION OF A GIVEN MCS.

• AREA EXPANSION RATE AND COLD-TOP GROWTH HAVE A SIMILAR BEHAVIOR TO THE MINIMUM TEMPERATURE EVOLUTION, WITH LARGER VARIATIONS DURING THE PERIOD BETWEEN 2-4 HOURS AND 10-12 HOURS COMPARED TO THOSE OF THE FULL DATASET.

• THE MCS’S REACH THE MINIMUM TEMPERATURE 1 – 2 HOURS BEFORE ACQUIRING THE MAXIMUM EXTENT.

CONCLUSIONSCONCLUSIONS

• THE MEAN LIFETIME IS AROUND THREE TIMES LARGER FOR RAINFALL-ASSOCIATED MCS’S THAN THAT OF THE GENERAL MCS DATASET.

• THE COOLING RATE DURING THE FIRST STAGES OF LIFE CYCLE (FROM 2-4 TO 6-8 HOURS) IS GREATER THAN THAT OF THE GENERAL DATASET, WHILE THE MINIMUM TEMPERATURE DURING THE FIRST DETECTION STAGE DOES NOT ALLOW TO DISTINGUISH THE EVOLUTION OF A GIVEN MCS.

• AREA EXPANSION RATE AND COLD-TOP GROWTH HAVE A SIMILAR BEHAVIOR TO THE MINIMUM TEMPERATURE EVOLUTION, WITH LARGER VARIATIONS DURING THE PERIOD BETWEEN 2-4 HOURS AND 10-12 HOURS COMPARED TO THOSE OF THE FULL DATASET.

• THE MCS’S REACH THE MINIMUM TEMPERATURE 1 – 2 HOURS BEFORE ACQUIRING THE MAXIMUM EXTENT.

CONCLUSIONSCONCLUSIONS

• THE MEAN LIFETIME IS AROUND THREE TIMES LARGER FOR RAINFALL-ASSOCIATED MCS’S THAN THAT OF THE GENERAL MCS DATASET.

• THE COOLING RATE DURING THE FIRST STAGES OF LIFE CYCLE (FROM 2-4 TO 6-8 HOURS) IS GREATER THAN THAT OF THE GENERAL DATASET, WHILE THE MINIMUM TEMPERATURE DURING THE FIRST DETECTION STAGE DOES NOT ALLOW TO DISTINGUISH THE EVOLUTION OF A GIVEN MCS.

• AREA EXPANSION RATE AND COLD-TOP GROWTH HAVE A SIMILAR BEHAVIOR TO THE MINIMUM TEMPERATURE EVOLUTION, WITH LARGER VARIATIONS DURING THE PERIOD BETWEEN 2-4 HOURS AND 10-12 HOURS COMPARED TO THOSE OF THE FULL DATASET.

• THE MCS’S REACH THE MINIMUM TEMPERATURE 1 – 2 HOURS BEFORE ACQUIRING THE MAXIMUM EXTENT.

CONCLUSIONSCONCLUSIONS

• THE MEAN LIFETIME IS AROUND THREE TIMES LARGER FOR RAINFALL-ASSOCIATED MCS’S THAN THAT OF THE GENERAL MCS DATASET.

• THE COOLING RATE DURING THE FIRST STAGES OF LIFE CYCLE (FROM 2-4 TO 6-8 HOURS) IS GREATER THAN THAT OF THE GENERAL DATASET, WHILE THE MINIMUM TEMPERATURE DURING THE FIRST DETECTION STAGE DOES NOT ALLOW TO DISTINGUISH THE EVOLUTION OF A GIVEN MCS.

• AREA EXPANSION RATE AND COLD-TOP GROWTH HAVE A SIMILAR BEHAVIOR TO THE MINIMUM TEMPERATURE EVOLUTION, WITH LARGER VARIATIONS DURING THE PERIOD BETWEEN 2-4 HOURS AND 10-12 HOURS COMPARED TO THOSE OF THE FULL DATASET.

• THE MCS’S REACH THE MINIMUM TEMPERATURE 1 – 2 HOURS BEFORE ACQUIRING THE MAXIMUM EXTENT.