Observation on a fixed point

Monday, June 28, 2021

We are getting close to the end of our fixed-point observations that began on June 16.
At the fixed point, we have been releasing a balloon once every two days with an ozone sonde, a water vapor sonde, sometimes a cloud particle sonde, and several radiosondes attached (all on board). The photo shows an ozone sonde with a water vapor sonde and a cloud particle sonde mounted in the center, and two radiosondes suspended from a plastic plate on top of it.


High-altitude radiosonde observation going well

The high-altitude radiosonde observations using a 3,000-gram balloon are conducted by releasing the balloon shortly before sunset. The balloon receives solar radiation in the troposphere and can pass through the low temperature of -80°C or lower at the tropopause and reaches the stratosphere.

In the stratosphere after sunset, the balloon measures the temperature without being affected by solar radiation and steadily reaches an altitude of 40 km. Currently, we are improving the system by devising a way to obtain more stable data.


Trial and error in high-altitude radiosonde observation

Thursday, June 3, 2021

Since May 27, we have been conducting high-altitude radiosonde observations using a very large 3000g balloon (normally 350-600g) once a day. The purpose of these observations is to observe from the ground to an altitude of around 40 km, and to investigate atmospheric disturbance activities that exist at altitudes above 30 km. When measuring temperatures with the radiosonde, we have been launching at night because we need to correct for solar radiation during the daytime. However, many balloons burst at an altitude of around 20 km. One possible cause is that the balloon cannot withstand the low temperature region at the tropopause.

Then, we launched it during the daytime when sunlight was available, and were able to observe up to 39.8 km. At present, we are planning to launch the balloon near sunset in the upper tropopause, and at night in the stratosphere. We will continue our observations through trial and error.


Observing well

Wednesday, June 2

Since May 27, we have been releasing the ozone sonde and water vapor sonde (SKYDEW) once a day.

So far, we have been able to acquire data beyond 30 km altitude in general smoothly.We have obtained meridional cross sections of ozone and water vapor from the ground to an altitude of about 30 km, and we are looking forward to analyzing them.

On the other hand, we are still in the process of trial and error for high-altitude radiosonde observations. (To be described in another article)


Antenna installation before departure

Tuesday, May 24, 2021

I’ve got on the R/V Mirai today. While the cruise is dedicated mainly to the maintenance of the mooring buoys and one super site, a member from DCOP will join the cruise to conduct special radiosonde observations until early July.
The special radiosonde observation directly measures ozone and water vapor in addition to wind velocity, temperature, relative humidity that can be obtained by standard radiosonde. In addition to these observations, we will also conduct “high-altitude” radiosonde observations using a 3,000g balloon to observe wind velocity and temperature from the ocean surface to an altitude of around 40km.

The purpose of this observation is to observe the material transport associated with the boreal summer monsoon and convective intraseasonal variability. The R/V Mirai will depart from Shimizu Port on May 26 and travel equatorward in the the western tropical Pacific. After that the R/V Mirai will cruise northwestward tendering the mooring buoys at several sites, then she is scheduled to occupy one site around 13.5N, 137E to conduct fixed-point observations for two weeks. The special radiosonde observation will be performed once a day during the cruise and every two days during the fixed-point observation period.

Today, I (SO) set up three antennas for the special radiosonde observations at the rooftop of the aft wheelhouse (next to the GPS dome antenna on the far left).


The intensive observation period of YMC-CSO2021 completed successfully

The last radiosonde was released on 3/8 18Z last night, and the whole schedule of YMC-CSO2021 was over.

Even in Indonesia, there were various obstacles due to Covid-19, which had a considerable impact on the implementation of observations.

Even in such a difficult situation, the BMKG operation staff continued to do a wonderful job until the end.

This was the first remote observation, and no one had the correct answer and/or experience for the trouble.
We are really grateful that everyone worked hard at each place.

Although we had a lot of trouble, the main target of the cold surge occurred more than usual, and we were able to obtain good data.

From now on, we will analyze the data obtained and investigate the air-sea interactions between cold surges and cold tongue, and the relationship between cold surge and extreme severe weather.

The sea surface temperature (SST) in the South China Sea was 1-2 °C lower than usual, so called “cold tongue” in the SST distribution, and it is suggested that this affected the process of strengthening the cold surge that occurred seven times in two months.

On the contrary, a strong cold surge may have an effect on the development of cold tongue, and it is speculated that positive feedback was working between the two.

In addition, heavy rainfall events accompanied by floods occurred on 1/9 and 2/19 due to cold surges, and elucidation of their formation process is strongly required in Indonesia.

A third of IOP has been done smoothly

A third of IOP that is started from 8 January 2021 has been done smoothly.

Today, the photos & movies that are sent from BMKG staff are shown here.

The northerly winds in Indonesia were intensified after the beginning of IOP and rainy/cloudy days were continued everyday.

The movie tells us the wind speed.

We confirmed that 66 mm of large precipitable water vapor was observed with the GNSS station installed at Soekarno Hatta International Airport in the early morning on 9 January.

MOTEKI Qoosaku

Let’s get started!

YMC-CSO2021 has finally started today.

BMKG staff sent us photos and videos of the radiosonde work for 00Z launching this morning.

In Japan, the bomb cyclone passed yesterday, and the cold air outbreak is intensifying.

Cold surge are expected to strengthen in Indonesia in the next few days.

This campaign is exciting from the beginning!

MOTEKI Qoosaku

YMC-CSO2021 will be started!

Cold air outbreaks from the Eurasian continent reach the tropics and affect the climate of the Maritime continent during the Boreal winter.

The variation of the cold air outbreaks which becomes strong or weak are called a “cold surge”.

JAMSTEC/DCOP will conduct a cold surge observation campaign as part of the YMC (Years of the Maritime Continent) in cooperation with Indonesian Agency for MeteorologicalClimatological and Geophysics (Badan Meteorologi, Klimatologi, dan Geofisika or simply BMKG). 

The intensive observation period (IOP) is from January 8 to March 8, 2021.

During this IOP, we will increase the number of upper air sounding in Jakarta and Pangkal Pinang from two to four times a day.

In addition, at Jakarta station, we use the balloons larger than usual to get data up to higher altitudes for 06Z launch.

The cold surge is a phenomenon in the lower layer near the sea/land surface. On the other hand, when convection develops associated with the cold surge, various atmospheric waves in upper layers are excited.

By obtaining observation data at the altitudes higher than 25 km, it is possible to investigate the structure of the waves that are difficult to be detected by usual operational observation.

In addition, a new GNSS sensor has been installed in Jakarta to acquire precipitable water data every 10 minutes.

The pictures show the BMKG staff installing the sensors.

In addition, we can use BMKG’s operational radar network and surface meteorological observations.

It was a lot of work to prepare, but the wonderful staff at BMKG did a great job.

We are looking forward to what kind of data we can get.

MOTEKI Qoosaku

YMC-BSM 2020 has been completed.

The R/V Mirai has returned to Shimizu port from her 45-days cruise in the tropical western Pacific. In addition, enhanced radiosonde soundings at Legaspi/Philippines, Yap/FSM, and Palau have been ended on September 14, 2020.

So, now we have completed our field campaign successfully against the threat of covid-19 pandemic. We really appreciate great support from the local agencies in those islands (PAGASA, Yap Weather Service, Palau Weather Service, and NOAA) and great effort done by all participants.

Hereafter, we will analyze data to see what really happened during the past 1.5 months. Numerical model will also help us to understand those phenomena.

We will also intend to release quality-controlled datasets in timely manner from this YMC data site.

You will see our progress through our websites as well as papers. Bye for now!