Rainfall variability and relations with satelite, radar and raingauge mesurements during the WETAMC/LBA / A variabilidade da precipitação e suas relações com as medidas por satélite, radar e divergência do vento em altos níveis durante o LBA - WETAMC

AUTOR(ES)
DATA DE PUBLICAÇÃO

2001

RESUMO

Radiosonde, satellite data, TOGA radar 2 km CAPPI and rainfall collected from the TRMM-WETAMC/LBA experiment are used to investigate the diurnal cycle of the tropical convection, the relationship between brightness temperature and precipitation and the use of the high level wind divergence to estimate precipitation and convective cloud cover. GOES satellite images were used to describe the diurnal modulation of the total/high/convective cloud fraction. Radar 2km CAPPI were used to describe the diurnal cycle of the rain fraction for different thresholds. An average over the four networks rain gauge was applied to describe the average hourly rainfall. The cloud drift winds from water vapor images was used to compute the upper air wind divergence. High and convective clouds area reach their maximum some hours after the maximum rainfall detected by rain gauge and radar 2 km – CAPPI. The minimum cloud cover occurs only a few hours before the maximum precipitation and the maximum cloud cover occurs during the night. These results suggest the following mechanism controlling the diurnal cycle: in the morning, cloud cover decreases as the solar flux increases. In the beginning of the afternoon convection rapidly develops, high and convective clouds fraction increase rapidly and the maximum precipitation. The relationships between the brightness temperature and the radar reflectivity were also verified. Precipitation was estimated based on linear equations integrated in the time interval of 1, 3, 6, 24 hours, it was observed improvements in the estimate when was used larger scales of time. Finally, the diurnal cycle of the upper air wind divergence is very close to the diurnal cycle of the precipitation. The upper air divergence can be used to forecast the convective cloud cover or to evaluate the convective rainfall.

ASSUNTO(S)

divergência precipitação meteorologia cobertura de nuvens convection meteorology precipitation divernce convecção vento (meteorologia) satélite cloud cover satallite wind (meteorology)

ACESSO AO ARTIGO

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