Jasmine Report 4

R/V Ron Brown

Indian Ocean/Bay of Bengal

C. Fairall

Hello again. Just to fill you in on things here. Monday was our rainiest day yet (68 mm) and Tuesday was our least rain (15 mm) since Friday. However, Tuesday was the windiest (average 25 kts with gusts to almost 40 kts). I think the rain and storms are on the decline now, but it will probably take a day or so to be sure. From the satellite pictures, it looks like the center of convective activity is moving further north in the Bay. Right now we are working in 10 ft waves and the ride is pretty bumpy when our course takes us into them. Some people are having trouble sleeping because of the motion, but I usually sleep well. It's like rocking in your crib. In the 5 days we have been at the location of this star pattern, the ocean has cooled 0.7 C because of the strong wind-induced evaporation and the clouds blocking the sun.

Tonight at 6 pm we will complete the star survey at 11 N, 88 W and start the long journey back. We will set a course for 5 deg. South and 94 deg. W. It will take us 4 days to get there; then we will turn to the west and head for Darwin. That will take 8 more days. Our major data gathering activities will cease when we reach -5, 94 so we will have about a week to process data and compare notes, discuss what we have found, and write up some preliminary reports.

Based on your last two messages, I will expect one more forecast. I will send a last set of data back tomorrow night.

Regards, CF

Answers to your questions:

1. With reasonable care, we are not in any danger in monsoon conditions. The people working on deck handling the CTD system wear a life vest and a hardhat. When conditions get rough, they wear a belt with a line attached to the ship so they can't get washed overboard. When it gets really rough, then they don't let you walk around on the wet decks. The conditions we experience in the monsoon (25- 30 kt winds) are not considered very hazardous for a vessel of this size. The ship has very carefully planned procedures for fire, man overboard, and abandon ship situations. We have 2 drills a week where everyone goes to an assigned location and awaits instructions. We have had several briefings about various emergency procedures and equipment.

2. If lightning actually hits an instrument, you usually just throw it away. We have spares for almost all of our sensors. More commonly, you get small electrical discharges from the ship that are not direct lightning strikes. These can blow power supplies and sensitive components. In some cases they can be replaced. A lot of our stuff has surge protectors, which help in these cases (they don't help much for direct lightning strikes). My laboratory operates a very tall meteorological tower (1000 ft) back near Boulder and we have a lot of problems with lightning in the summer.

3. The biggest surprise so far has been strong day-night difference in rainfall. We have received 75% of our rain at night. This is a much stronger diurnal variation than we observed in previous studies in the tropical western Pacific warm pool (where El Nino originates). We assume it has something to do with the influence of land, even though we are a long way out to sea.

4. The squid seen around here are quite large by my personal observations of 6 inch long squid in the western Pacific and back in Monterey, California (where I used to live). Apparently they fishermen have seen some in the 18 inch size range.

5. My sea legs are ok as long as it doesn't get too rough. It only takes a day or two and your sense of balance adapts to the uncertainty of the floor. It is still a bit of a pain taking a shower while holding on with one hand or having to sit down to put on a shirt.

Note added on Friday.

I just received your last comments. Thursday was mostly sunny with fairly strong winds and Friday is sunny with winds finally declining. Right now plans for a party in Darwin are in the works, but we are not sure what we are doing. The aussies on board we trying to get the Australian Met Offfice to do a barbecue, but we are not sure that can be arranged. Otherwise, people will celebrate in their own fashion. A few may even imbibe alcoholic beverages. Attached is more data for your group. I am glad this project was interesting for the students and I hope we can do a better job next time. Right now cruise plans for next year are uncertain, but 2001 is shaping up as a biggie.

Regards,. CF