The 327th and 331th Observations at the East China Sea

Ship-based observations were carried out to investigate the atmosphere and sea at the East China Sea. A student, Kyouhei YAMADA joined this observation and reports about it.

Kyouhei YAMADA, Radiation & Climate Physics Laboratory,
Center for Atmospheric and Oceanic Studies,
Graduate School of Science, Tohoku Univ

During June 21-23, 2011 and July 21-30, 2011, ship-based observations with radiosonde and XBT were carried out to investigate the atmosphere and sea at the East China Sea, especially over the area from Nagasaki to Naha and around the Iriomote Island.
Kyouhei YAMADA joined this observation and reports about it.

(Fig1. Non-Iriomote non-wild cats of the Island of Ishigaki)

The observation is operated under a cooperation between a ground-based radar and a ship, Nagasakimaru, of the Faculty of Fisheries of Nagasaki

(Fig2. Nagasakimaru Mk 3 with a maximum speed of 16.2kt)
Observation by Radiosonde

The observation by radiosonde was performed to investigate the upper-troposphere. The radiosonde consists of a thermometer, a hygrometer, and a barometer.

>Reference: About the aerological observation of the Meteorological Agency(Link to The Meteorological Agency)

The Japan Meteorological Agency operates regular observations by radiosonde at 0 UTC and 12 UTC (9 and 21 local time in Japan). However, during this voyage, we launched a radiosonde every hour at some area and one every 6 hours at some area.


1 hour before the release of a balloon
Synchronizing a radiosonde and a satellite, a battery should be set in the radiosonde, the perform ance is checked using a receiver, and the radiosonde is kept at open space, e.g., a deck.
15 minutes before the release of a balloon
A balloon is blown up by helium. This balloon is elastic but so fragile if touching a floor or wall. There fore a balloon should not be bump against wall, and caution is needed to strong wind on ship.

5 minutes before the release of a balloon
An inflated balloon is tied to the radiosonde by string. This string is wound to ease the tension.

(Fig3.Inflating a balloon. In this picture, we used a balloon of 100g. However, we sometimes used 350g one.)


(Fig4. Releasing the balloon)
Release of a balloon

A balloon, a spool of string , and radiosonde are released in the correct order. A receiver starts to operate when radiosonde is released.

Sensors on radiosonde, especially a hygrometer, can be influenced by rain drops. So that we were carefull not to expose the radiosonde to rain.

Observation by XBT

Observation by XBT (Expendable Bathythermograpgh) is normally cooperated with observation by radiosonde.

XBT consists of the barrel, a probe (a sensor and a sinker), and an enameled wire. The thermistor of the probe measures the temperature of sea water.

>Reference: About XBT(Link to the information department of Japan Coast Guard)

The connection part is sensitive to moisture and can be rusted. So it is important to keep it dry. For example, the probe should be always set on the XBT, except when  exchanging probes.

Observation by Assmann Psychrometer

This psychrometer measures temperature and humidity on the ground or sea. The humidity is known by the difference between wet- and dry-bulb thermometers.

The 327th observation was my first ship-based observation, and I got seasick, which obstructed me from eating and kept me in bed. But I did not get seasick at the 331th observation. Eating not too much may be a good behavior for comfortable voyage. It was my first observation, but the cruise members kindly helped me. I thank a lot of people of Nagasaki Univ, Hirosaki Univ, Mie Univ, JAMSTEC, and the sailors of Nagasakimaru, and so on.

(Fig5. False Killer Whale at the Okinawa Churaumi Aquarium. He can spit out well.)