Ballons [Balloons! pardon my french]

How fast are the winds blowing, high above us? How warm are they, and how much moisture do they carry? The best way to find that out is with a balloon! We attach a thermometer, a humidity sensor, a GPS tracker, and a radio antenna (all integrated in a small lightweight box) to a helium-filled balloon, and release it. The instrument (called a radiosonde) rises up ~300 meters every minute, into thinner and colder layers of the atmosphere, often reaching up to 20’000 meters (65’000 feet) above us. The high-quality latex balloon expands up to 4-5m across, before it eventually pops! (and invariably falls somewhere..). The sonde transmits data, valuable especially over the oceans, back in real time.

Mooring adrift

How much heat does the ocean supply to the atmosphere? And how much water evaporates in the Bay of Bengal? Both are critical for the dynamics of the monsoon, and the rainfall over land. One of the instrument platforms deployed to answer these questions is a drifting “mooring”: a floating buoy tethered to a long line with a weight at the end. The buoy is decked out with gauges measuring weather conditions at the surface. Below the water, attached to the long line, are instruments measuring ocean currents, temperature, salinity, and turbulence at many different depths, from right at the surface to 200 m below. Normally such a mooring is held in place by a heavy weight sitting at the bottom of the ocean (often old railroad wheels!) for a year. However this mooring needs not to stay for an entire year, and also not stay precisely at one point. So a much easier solution was found: instead of anchored to the seafloor, it is “anchored” to the slow currents at 200 m depth, by large x-shaped wings that get dragged by the water. So even if the winds are howling at 15 m/s, or 30 knots, the buoy won’t be sailing away, but is stuck in place with the much slower moving deep ocean. Check out its current location and live data, courtesy of the Upper Ocean Processes group at the Woods Hole Oceanographic Institution:

call sign KTDQ

Speed over ground: ~12 knots. Heading: East. Destination: active weather of the summer monsoon, to shed some light on the murky interactions at the boundary between warm sea and tropical atmosphere.

A suite of instruments probing the atmosphere above the ship: far left on the railing is a microwave sounder, inside the open container a W-band radar, and hosted on the center mast are direct-covariance flux instruments.

Preparations in Port

The first two days on the ship reminded me of moving into a new home—lots of unpacking, assembling, and cleaning. However, instead of building IKEA furniture for your living room, we were assembling instruments and lab spaces. Enjoy some photos from the two days at port in Chennai, India, and stay tuned for more updates from sea!   J.H.

Welcome aboard!

Welcome to the MISO-BoB (Monsoon Intra-seasonal Oscillation in the Bay of Bengal) pilot cruise aboard the R/V Thomas G. Thompson! For the next three weeks we will chase rains and winds, making measurements between ocean and atmosphere in the Bay of Bengal. As a team of oceanographers and meteorologists we aim to better understand the monsoon over the northern Indian Ocean, producing better forecasts in the future!

This blog is a purely personal notebook with contributions from a few students and researchers on board, to offer family, friends, and curious visitors a window into the excitement and day-to-day life at sea on board a research ship. We hope you enjoy!

Wispy early morning clouds over the  R/V Thompson docked in the port of Chennai, India