R/V Mirai: The Mirai Radar

One of the key instruments on R/V Mirai is THAT: The weather radar.

The first figure is the outlook of the radar antenna. Actually the antenna is inside the ball, called “radome”, and rotates to scan three-dimensional structure of the cloud.

You already saw examples in this blog: An highlight in this cruise is yesterday’s vortex. These two parameters, radar reflectivity (alias of rain intensity) and radial velocity (index of wind) has been obtained from the very beginning of the launch of R/V Mirai in 1998. The radar equipped motion sensors and precise antenna controlling system to cancel the ship motion to stabilize the antenna. The radar never gets sea sick.

The radar was renewed in 2014. Among many upgrades, an epoch is the ability of “polarimetric” measurement. It provides the information about the “shape” of the precipitating particles, to be utilized to identify the kind of the particles (rain, snow, graupel, …), and to better estimate the rainfall amount.

The second and third figures are the identical vertical cross section seen by the different parameters. On the radar reflectivity, a classic parameter, is tend to be high below 5-km height where the particles are liquid (i.e. rain). On the other hand, a “polarimetric” parameter called “KDP” detects heavy rain part in the left-most part of the cloud (as seen by green/yellow). In addition, the strong signal is also found in the upper right of the panel, where the height is above 6-km and temperature is subzero. The data tells that a lot of “horizontally-elongated” ice crystals, such as plane, column, etc. existed. By combining other “polarimetric” parameters, we will investigate further detail of the internal structure of the cloud.

Actually, the Mirai radar is the world’s first shipboard polarimetric radar. We have been trying and trying to make data in better quality. Our colleague Dr. Biao Geng (see 4th photo, when he is controlling and monitoring the radar) is the key personnel to do the work. His work is in progress even during onboard over rough sea condition. He may have his own powerful stabilizer, like the radar. With his work, we are going to reveal inside of clouds, not only over Maritime Continent but also over the world where Mirai goes.

(reports by M.K.)

R/V Mirai: vortex !

We just captured a vortex in between Mirai and Bengkulu !

First figure, named “reflectivity”, means radar reflectivity, an alias of the rainfall intensity. You can see the circular pattern between Mirai (small blue/red circle in lower-left) and Bengkulu site (red marker on the right).
Second image, named “velocity”, is the velocity of the air motion in the radial direction from Mirai. Red (positive) means the motion away from Mirai, while blue (negative) means motion toward Mirai. The pair of the red and blue means there is a vortex.

After that, the vortex moves southeastward. I guess Bengkulu experienced heavy rain and strong wind. In contrast, around Mirai, we have no precipitation under the weak wind.

It is very beautiful image (for us meteorologist), but we need further analyses the mechanism of the vortex.

(reports by M.K.)


Dr. Takanori HORII (JAMSTEC researcher) is a roommate of Motesaku. He is a specialist on the research using ocean buoys over the Indian Ocean. During this cruise, he is in charge of the TurboMAP operation in the daytime. It is really fun to discuss on the observation profiles everyday. This is so nice photo showing we are naturally discussing on something, isn’t this? By the way, there are three unnatural things that are not related to the YMC. Can you find them? If you could, please do not tell anyone it and it would be a secret between you and me.


Wonderful tonight

Christmas dolphin made a fantastic night rainbow just above CTD. “Oh my dolphin, you’re wonderful, tonight…” I had a feeling that I was listening to Eric Clapton’s guitar sounds and time passes slowly on the most wonderful night ever.


Hello, miKitty!

Hello, Mikitty! Thank you for the TurboMAP operation in the daytime. Ms. Miki TAWATA is the new hope of marine technician who positively asks questions on researchers’ presentations at the seminar inside the vessel and well communicates with us. We appreciate your good job, and count on Mikitty.


How to enjoy on Christmas Eve

Merry Christmas! How are you tonight on Christmas Eve? I imagine there are so many twinkling illuminations everywhere over cities and we are doing our observation as usual at the corner of this world.

We ate a piece of a roll, discussed on data analyses at the seminar room, were carefully trouble shooting, and we all contributed to own roles for keeping the data high quality.

Christmas presents for us are not given by someone. Those will be created for someone.

The two staffs in the photo are Takeda-san and Fukuda-san who are doing water sampling by the bucket. By pulling the rope up for sampling 10 liter sea water, we can keep a lot of sampling bottles for many analysis items every 6 hours.
You can see the large CTD winch behind them. They can quickly do the bucket water sampling for the time when CTD is going down between 200 m and 300 m because they have another jobs after the CTD coming back.

Each 300 m CTD profiling takes about 1 hour (90 minutes for 500 m once per day) and the 3 hourly CTD operation is continued without any data lost.

Motesaku gets so excited at each profile and says “Wow! Salinity is getting lower! Oooops! Temperature is getting 0.1 degree higher! Hey, hey, hey, … current direction has been changed!”

How do you think it? Why not join us on future Christmas days?

Qoosaku MOTEKI

Light up the sky

Between dusk and dawn, a green light to the dark sky becomes visible on the R/V Mirai and gives a sword to Orion.

The light is a part of the Mirai LIDAR. In the sky, particles (sea salt, dust, cloud droplet, rain drop, etc.) glint with the light. The lidar collects these glints to shed light on the sky condition during day and night.

On a clear night, the lidar collects extra gleams from water vapor and nitrogen molecules.

So, I enjoy very much the green illumination of the stargazing night.

(K.T., photo by S.S.)

“Yuhi” & Yu-hi

Today’s “Yuhi” NAKAMURA (U. Tokyo, 2nd degree of Master course) and Yu-hi (meaning “the setting sun” in Japanese) were different from those till yesterday.

Today’s Yu-hi (evening sun) lighted up the rear of well-organized precipitation clouds having 90 mm/day till this morning in darker red than usual.

Today’s “Yuhi” (a good radiosonde operator) enjoyed the evening sky observation taking more time than usual because today was stopping hourly high frequent radiosonde operation and in usual 3 hourly one.

Motesaku (strange as usual) was reporting.

The efficient use of silica gel

Friday, Dec. 22, 2017

Recently, we launch three kinds of GPS radiosonde at the same time. Then, many silica gels contained in packages of radiosonde are left. Since throwing away all silica gels is wasteful, a part of them is reused for snacks :)  (tk)


His name is…

Daisuke TAKASUKA (U. Tokyo, 1st degree of PhD student). I like his working with a confident look. Many thanks for the radiosonde operation on the nightshift.

Qoosaku MOTEKI