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.

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

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 Meteorological, Climatological 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