世界最大冰山在海洋陷阱中旋轉

A23a is an extraordinary iceberg that has captured the attention of scientists and researchers around the world. This iceberg is the largest in the world, with a flat, table-like surface that stretches endlessly across the horizon. It is located just north of Antarctica, and for several months, it has been spinning in place instead of moving along with the powerful ocean currents that usually carry icebergs away. Scientists have discovered that A23a is sitting atop a massive rotating column of water, a phenomenon known as a Taylor Column. This unique situation means that A23a might remain in this location for many years to come. Typically, icebergs are known for drifting away and eventually breaking apart, but A23a is proving to be quite resilient. Professor Mark Brandon, a polar expert, remarked, 'A23a is the iceberg that just refuses to die,' highlighting the unusual nature of this iceberg's journey. The history of A23a is quite remarkable. It broke free from the Antarctic coastline back in 1986, but shortly after, it became stuck in the muddy bottom of the Weddell Sea. For three decades, it remained stationary, earning the nickname 'ice island. ' It wasn't until 2020 that A23a finally re-floated and began to drift again, initially moving slowly before heading north toward warmer waters. While the edges of the iceberg may be crumbling, its main body remains largely intact. In early April of this year, A23a entered the Antarctic Circumpolar Current (ACC), a powerful current that moves an immense volume of water around the globe, far surpassing the flow of all the world's rivers combined. Scientists anticipated that this would propel A23a quickly into warmer waters, but instead, it has remained in the same spot, just north of the South Orkney Islands, spinning in an anti-clockwise direction at a rate of about 15 degrees per day. This unusual behavior is delaying its melting and eventual demise. A23a is not grounded on the ocean floor; there is at least a thousand meters of water between its underside and the seabed. The iceberg is being held in place by a type of vortex that was first described by the brilliant physicist Professor Taylor in the 1920s. He was a pioneer in fluid dynamics and contributed to the Manhattan Project, where he modeled the stability of the first atomic bomb test. Professor Taylor explained how a current that encounters an obstruction on the seafloor can separate into two distinct flows, creating a rotating mass of water between them. In this case, the obstruction is a 100-kilometer-wide bump on the ocean floor known as Pirie Bank. The vortex formed above this bank is currently keeping A23a trapped in its swirling waters. The iceberg covers an area of 3,600 square kilometers, which is approximately 1,400 square miles. Professor Mike Meredith from the British Antarctic Survey expressed his fascination with this phenomenon, stating, 'The ocean is full of surprises, and this dynamical feature is one of the cutest you'll ever see. ' He noted that Taylor Columns can also form in the atmosphere, such as in the movement of clouds over mountains. They can vary in size from just a few centimeters in a lab to enormous formations like the one surrounding A23a. Scientists are eager to learn how long A23a will continue its spinning routine. When Professor Meredith placed a scientific buoy in a Taylor Column above another underwater bump, he observed interesting patterns. A23a serves as a perfect example of the importance of understanding the shape of the ocean floor. Underwater mountains, canyons, and slopes significantly influence the movement and mixing of ocean waters, as well as the distribution of nutrients that support marine life. This understanding is also crucial for the climate system, as the movement of water helps distribute heat energy around the planet. A23a's behavior can be explained by the well-mapped ocean floor just north of the South Orkney Islands, but many other areas of the ocean remain poorly surveyed. Scientists are working diligently to improve our understanding of these regions, as they play a vital role in the health of our oceans and the overall climate.