Editor's note
On November 1, organized by the Ministry of Natural ResourcesThe 40th Chinese Antarctic ExpeditionFrom within the country. From now on, the "China Natural Resources News" will open a special column entitled "Antarctic Chronicle" to publish what the special reporters of this newspaper have seen, heard, thought and felt during their participation in the Antarctic scientific expedition with the "Snow Dragon".
Ke Changqing, a member of the expedition team, controls a drone to carry out observations
On the evening of December 10, the routine maintenance of lifting materials from the "Snow Dragon" was carried out, and the unloading operation was suspended. Taking advantage of this "gap" in the sky, Ke Changqing, a member of the expedition team, used a drone to carry out a lidar aerial remote sensing experiment on the sea ice around the "Snow Dragon" after reporting to the expedition team. This is one of the scientific survey projects carried out by the 40th Chinese Antarctic Expedition during the unloading operations at Ferry and Zhongshan Station. Ke Changqing is a professor at the School of Geography and Ocean Sciences at Nanjing University, and has long been engaged in satellite remote sensing observation and research of Antarctic sea ice and plateau glaciers and lakes. He participated in the Antarctic expedition this time, and the main task was to carry out the on-site investigation and research of the remote sensing inversion of the albedo of Antarctic sea ice and its long-term change trend, a national natural science project. Ke Changqing said that through the interpretation and analysis of satellite remote sensing data, data such as the area and thickness of Antarctic sea ice can be calculated, so as to analyze the impact of global climate change on sea ice change. For example, Arctic sea ice has been decreasing, in tandem with global warming. Antarctic sea ice extent showed a slight increase before 2015, which did not keep pace with global warming. However, since 2016, Antarctic sea ice has been decreasing year by year, and the reason for this is that there is currently a scientific concern in the world. The purpose of the field survey is to verify the estimation results of the satellite data and calibrate the parameters, so as to make the future estimation more accurate. As early as November 25, after the "Snow Dragon" sailed through the westerly wind belt into the ice floe area, Ke Changqing began to observe the ship's sea-based sea ice. Every hour, he travels to the wheelhouse and deck to record the characteristics of the sea ice in accordance with internationally accepted observation rules. These days, when Ke Changqing was observing, I asked him for some knowledge about sea ice. Sea ice density, for example, is the percentage of sea ice area per unit area. At the beginning of the ice floe area, the sea ice density was less than 50%, and then gradually increased, and near Zhongshan Station, the sea ice density reached more than 90%. For example, the types of sea ice can be classified by size, as well as by the time and characteristics of formation. According to the classification of size, as big as a small town is called huge ice floe, as big as a golf course is called big ice floe, as big as a block in a city is called medium ice floe, as large as a warehouse is called small ice floe, as large as a volleyball court is called a block of ice floe, as big as a billiard table is called cake ice, and less than two meters in size is called crushed ice floe. According to the time and characteristics of the formation, it has just begun to freeze, mixed with scattered ice crystals, ice needles, and bornechips, and has no fixed shape called new iceThe new ice continues to freeze, and the Nile ice that has a preliminary shape but a smaller thickness is called Nile ice;The edge of the bottom of the Nile ice continues to condense and thicken, and the ice changes color, and when it reaches a thickness of 10 to 30 cm, it is called the first ice;Sea ice developed from the first ice, with a thickness of 30 cm to 2 m, and only one winter growth period, is called one-year iceSea ice that has not completely melted after at least one summer is called multi-year ice. Most of the multi-year ice in Antarctica is found in the West Wildel Sea, the Belingsgaujin Sea and the Amundsen Sea, while the rest of the sea is dominated by annual ice and is relatively thin. In dense ice floes, the sea is white because the sea ice is covered with snow. Sometimes the snow is so thick that it pushes all of the ice into the sea, or even a part of the snow doesn't go into the sea. The depth of snow on the surface of sea ice is also something that Ke Changqing needs to observe and record. After the "Snow Dragon" arrived in the sea near Zhongshan Station, it stopped the ship and began unloading operations. Ke Changqing, with the assistance of his teammates, went to the ice to carry out field investigations. One survey is to drill ice, select some points, drill the ice surface with a drill pipe, obtain accurate sea ice thickness, water height (freeboard height) and other data, and compare and verify the thickness calculated from satellite data. Another survey was to measure the albedo of sea ice with a spectrometer. Albedo is an important factor affecting the rate of sea ice melting, and the higher the albedo, the less heat absorbed by the sun and the slower it will ablate. The albedo measured in the field can provide a basis for calibrating the estimated parameters. Unmanned aerial vehicles (UAVs) are able to expand the scope of observation, which corroborates human field measurements. The drone is equipped with a lidar detector and an optical lens that can be used to estimate sea ice thickness from the lidar data, and an optical lens that can take clear images and calculate sea ice area. Ke Changqing moved the drone to the foredeck platform, when the weather was fine and the wind was light, which was suitable for operation. After setting the parameters, the quadrotor drone takes off and makes observations over Antarctica. It took more than an hour for Ke Changqing to complete the observation of three survey areas and obtain valuable data. Next, when the "Snow Dragon" continues to sail, Ke Changqing will continue to carry out sea ice observations. Of course, this Antarctic expedition will also improve the accuracy of his observation of sea ice with the "eye in the sky". Chief Reporter: Wang Shaoyong.
Text editor: Zhao Ning.
New ** Editor: Qu Bingjie (Xi).
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