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  • An Extraordinary Voyage - Exploratory Upper-air Sounding over the South China Sea (Part II)

  • Tuesday, 11th August 2015


2015.6.15    Fine becoming cloudy
After a day of cruising, the ship had reached southwest of Xisha, about 800 km from Hong Kong. Armed with experience from the previous two balloon launches, and with assistance from crew members, the launching work became smoother. We could finish up and send the data back to the Observatory within 3 hours every time. KC and I took turns to have breakfast and looked after the data reception. We could also spend some time to observe the cumulus clouds. They were cool with very sharp edges at the bottom parallel to the sea surface, like being chopped by a sharp knife (Figure 11).

Figure 11

Figure 11      A leisure moment on board to observe the clouds - Cumulus with rain shaft (left)
and sharp cloud edges at the bottom (right).

The sea state was better than we expected. The crew said that the weather and sea state would usually be the best from April to June in the South China Sea, with calm seas like a mirror. This is quite different from what we normally think of. We thought the southwest monsoon would be active in May and June, hence a wavy sea. We lost the chance for wave and swell watching, but fortunately we did not have to take sea-sick pills! The mobile phone rang at night, probably because there were oil-rigs nearby. It was signal from Vietnam. There was even a cold call from Hong Kong. Of course I would not answer as it was a roaming one!

2015.6.16    Cloudy with rain
As usual, when I got up in the morning, KC had everything ready. The ship already traveled to south of 10 N and west of 110 E, about 1500 km from Hong Kong. Mobile phone signal had totally lost. Radio noise was also dead, which meant this was the best time for launching radiosonde! It was cloudy today and there were heavy showers in the afternoon. The seas were moderate (Figure 12) but we hardly felt it on board. The experience gained at King's Park tells us that the balloon may burst earlier if it is raining. It is because moisture can stick onto the balloon surface and becomes ice when the balloon rises to upper atmosphere. The tension of the balloon may then be affected, leading to an early burst. This was proven again by the balloon launch on that night. The balloon passed through a thick layer of clouds (Figure 13, relative humidity reached 100% between 4 to 7 km height) and could not pass 100 hPa level, which was about 16 km high. This was the 'worst' launch during the whole voyage.

Figure 12

Figure 12      Waviest moment in the voyage with white horses.

Figure 13

Figure 13      Upper-air meteorological information on the night of 16 June. Balloon passed through
cloud layer at about 4-7 km high and burst at around 16 km height.

2015.6.17    Partly cloudy becoming fine
It was about 600 km from our destination, Singapore, in the early morning. KC and I prepared for the last balloon launch in the morning. There would be no further launch at night as the crew would be busy preparing for mooring when the ship headed closer to landmass. The weather turned better today. Twilight sneaked out from the cloud deck and crepuscular rays blessed the Earth from the cloud gaps (Figure 14). It was such a beautiful picture together with the waves generated by the ship. Launching a balloon became an enjoyable task and it was concluded almost perfectly. Following the Third Officer, we had a walk on the deck. It swept away all the dull feeling being stuck inside the cabin in the past few days. Of course we took the good opportunities to take photos down under the mast in the bow.

Figure 14

Figure 14      Twilight (left) and crepuscular rays (right).

The marine traffic had become busy after dinner. Ships were seen traversing orderly on the navigation radar. Though not far from Singapore, the crew was paying extra attention tonight. It was because an oil tanker was hijacked in nearby waters just a week ago and communication equipment on board was damaged. The tanker and the crew were all towed away (see related news). The crew ought to be in high alert when they were on duty for the "Pirate Shift". As pirates normally ride on speed boats and board the ship from the stern, the crew had to pay particular attention to the sound of speed boat engines. As told by the crew, oil tankers were the usual targets as they contained millions of US dollars of oil or diesel. The pirates would pump them away or ask for a ransom. Merchant ships, on the other hand, only have goods and they are too heavy to be taken away. That is why the pirates normally take the easier targets, namely the oil tankers.

2015.6.18    Fine
The ship entered the Singapore Strait slowly after midnight. The smell of pandan cake was in my dreams. I took the opportunity in the morning to thank Captain Duan with a set of the Observatory souvenir stamps for his great hospitality and assistance during the past few days (Figure 15). With the assistance from the local agent, we passed the customs and immigration and entered Singapore. That concluded the amazing 6-night / 5-day balloon launching voyage.

Figure 15

Figure 15      The author (left) thanked Captain Duan Shaoda (right) for his support of the exploratory launch.

We are now analyzing the data obtained during this voyage to see if there are any potential benefits to weather forecasting. In any case, if upper-air sounding can be made over the South China Sea, it should assist typhoon prediction and also contribute positively to the navigation safety on the "One Road" [2].

Last but not least, we would like to express our sincere gratitude to Orient Overseas Container Line Ltd. for their full support. Special thanks go to Captain Duan Shaoda and his team for their kind assistance and endurance. Also big thanks to the cook for the delicious meals so that we did not feel home-sick on board!

David Lam


[2] "One Road" means 21st Century Maritime Silk Road in the "One Belt One Road" initiative.

Last revision date: <09 Nov 2015>