Sunday, Nov. 19, 2006

R/V MIRAI

"westward propagation system"

Rain, later cloudy. At night, we had rain again.
North-westerly prevailed whole day, and its speed changed from 10 m/sec in the morning to 5 m/sec in the afternoon.
Significant wave height was 2m.

Observations:

Radiosonde observation, CTD casting, and other routine observations have been carried out.
Videosonde was launched at 08:23 LST.
In the morning, it was overcasted with organized cloud (photo-1). While the lower tropospheric wind had north-westerly component, precipitation systems moved westward. In the afternoon, rain was stopped for a while, but westward propagating cloud systems brought rain again at night (Fig. 1).
Today, SST decreased whole day and it did not exceed 29.0 degC.

Remarks:

Wind direction in the lower troposphere changed from easterly to north-westerly. Satellite-based cloud image shows large-scale cloud area over the entire the tropical Indian Ocean. Their center of convective area seems to be shifted eastward a little bit.
Photo-2 shows that marine technicians enjoyed to sample the water to analyze dissolved oxygen. Usually, one or two guys analyze it. But, today they examined the sampling performance all together.
We had 12th MIRAI seminar as the last one. He introduced preliminary results of radiosonde and Doppler radar observations during the current cruise (photo-3).