Anyone who has participated in one of China’s Antarctic scientific expeditions will never forget the experience of going through the westerlies.
“Westerly winds prevail in the region. Cyclones come one after another. In the past, we relied on satellite cloud pictures for wind information. Whether the icebreakers could go through the westerlies safely mainly depended on luck,” said Jiang Xingwei, Director of the National Satellite Ocean Application Service and chief designer of the HY-2 satel- lite ground application system.
“But now, with the new oceanographic satellite HY-2, the situation has changed. We have real-time, accurate monitoring of the wind and wave conditions on the sea. Thus vessels can make the best choice in route selection,” said Jiang.
The HY-2 satellite is an important part of China’s civil spacecraft program. The satellite is used to monitor ocean wind fields, sea levels and temperatures, waves, currents, tides, and storms in order to provide disaster and weather forecasting information.
The new satellite
The HY-2, which took China Aerospace Science and Technology Corp. 10 years to develop, is China’s first ocean dynamic environmental survey satellite. It was launched at the Taiyuan Satellite Launch Center on August 16, 2011, and was officially put into use by the State Oceanic Administration of China on March 2.
It was another milestone in China’s 30-year history of ocean satellite development, said Jiang in Beijing on March 2.
The ocean plays an extremely important role in China’s social and economic development and national defense efforts. The Chinese mainland has 10 provinces and municipalities and one autonomous region along the coast. With 13.6 percent of China’s territory and 41 percent of its total population, these areas boast more than 60 percent of China’s total wealth.
Currently, the coastal areas are facing prominent challenges in terms of sustainable development of resources. More than 40 Chinese in-shore fisheries are suffering from over-fishing.
The environmental information provided by the HY-2 satellite can inform people of the seasonal changes and the specific layout of fisheries far away from the shore. Thus it can serve as the basis for the government’s fishery policies, said Jiang.
After the United Nations Convention on the Law of the Sea entered into force in 1994, many countries started exploring fisheries in the open seas and oceans. Xu Dezhu, a manager of Rongyuan Fishery Co. Ltd. based in east coastal Shandong Province, said China has 200 boats fishing in the open seas around Fiji. Xu said weather determines when and where they should go fishing in the vast ocean.
In the meantime, with the help of the satellite, people can choose fish breeding areas more rationally, which will help improve the efficiency of the mariculture industry.
On April 11, 2007, China’s second ocean satellite HY-1B was launched. It made up for the shortcomings of HY-1A, optimized technical indicators and improved other functions. With its launch, China achieved realtime dynamic monitoring over the 3-millionsquare-km sea areas under the jurisdiction of China. Also, it got real-time environmental information of the Arctic, the Antarctic and other areas such as the Gulf of Aden.
It has now been joined by HY-2. It cooperates with HY-1B to form a threedimensional monitoring system covering both outer space and underwater areas, through the comprehensive use of microwave and optical observations and a combination of dynamic oceanic environmental monitoring and marine resource detection.
Functions
The new satellite has greatly enhanced China’s ocean monitoring capabilities. Meanwhile, because it can observe nearly 90 percent of the ocean’s wind fields, its observation data is an effective complement to the data of global microwave remote sensing satellites.
To be specific, researchers can determine the environmental information of the fisheries through a combined analysis of the temperature and sea levels monitored by HY-2 and the chlorophyll―an element decisive for marine primary productivity―monitored by HY-1B. Thanks to the joint information, researchers are able to get accurate environmental information about the fisheries.
In addition, devices on the HY-2 can tell the frontal surface and the mesoscale eddies in the ocean. This information provides meteorological support for fishing activities.
The HY-2 satellite can obtain various ocean dynamic parameters across the world, including the wind fields, wave, circulation of the oceans and sea surface temperatures.
It can directly assist in marine environmental monitoring and prediction, oceanographic research, marine pollution monitoring and oceanic environment changes.
The HY-2 contributes significantly to
disaster prevention and mitigation. It can provide information on winds, waves, streams, tides and sea ice for navigation. The satellite effectively monitors changes in the global sea level, the El Nino phenomena, and changes of polar ice caps as well as extreme oceanic phenomena including storms, typhoons, tsunamis and heavy surfs.
The HY-2 will greatly improve the accuracy and timeliness of the marine environmental forecast. Unlike HY-1A and HY-1B, which rely on infrared rays and visible light detection, the HY-2 depends on active and passive microwave remote sensor for detection.
Microwave remote sensing is a new means of observing the Earth from space. Compared with visible light and infrared rays remote sensing, microwave remote sensing has unique advantages because it will not be affected by cloud, thunder and rain―it can work around the clock in all kinds of weather.
“An active microwave remote sensing device is like radar, whose sensor proactively emits electromagnetic waves and receives reflected or scattered electromagnetic waves. Passive microwave remote sensing device is like a camera which receives the electromagnetic wave emitted by the surface of the ocean,” said Jiang Jingshan, chief scientist of the National Space Science Center of the Chinese Academy of Sciences (CAS).
HY-2 carries four main instruments: a radar altimeter, microwave scatterometer, scanning microwave radiometer and correction microwave radiometer. The first two are active microwave remote sensing devices and the last two are passive microwave remote sensing devices. These four instruments, together, play the major role in monitoring and surveying the ocean dynamic environment.
Benefits
China, lying on the west coast of the Pacific, is subject to oceanic disasters such as storm surges. Every year, China suffers big losses due to these disasters. “With typhoons, for example, we could obtain important information only from satellite weather maps, but we could not get accurate information of the changes of wind vector and waves caused by typhoons,” said Jiang of the CAS.
HY-2 can conduct synchronous, real-time and continuous monitoring of a large area of the ocean, and the microwave scatterometer and radar altimeter it carries can solve the problem of monitoring storm surges.
These remote sensors are developed from the multi-molding microwave remote sensor carried by China’s Shenzhou IV unmanned spaceship that was launched on December 30, 2002, and returned on January 5, 2003. The multi-molding microwave remote sensor is an important part of the payload of Shenzhou IV and is China’s first experimental microwave remote system.
“It has achieved a technical breakthrough,” said Jiang. “The four remote sensors on the HY-2 work together to realize a comprehensive remote sensing.”
“China has become the second country that can independently conduct comprehensive microwave remote sensing after the United States,” he said.
The radar altimeter, which operates constantly when the satellite orbits the Earth, has an accuracy of 3-5 centimeters and can measure sea height changes down to the centimeter at an orbit of nearly 1,000 km, said Jiang.
Perhaps for the ordinary people, the technology the professors are developing is irrelevant. But all kinds of oceanographic technology research results are getting closer to the ordinary people. The Outline of the 12th Five-Year Plan for Oceanographic Science and Technology Development (2011-15), which was issued by the State Oceanic Administration and three other ministries, is very much concerned with the livelihood of the people.
In 2003, the State Council approved to launch the 908 Special, a project dedicated to oceanic studies with heavy investment. It covers a wide range of disciplines and adopts the most up-to-date technology. Now the project is coming to a close.
In the past eight years, researchers of the project surveyed the conditions of offshore resources and environment, thoroughly updated the basic statistics of offshore environment and compiled relevant atlas series. It has provided scientific support and necessary references for the exploitation of the ocean for the benefit of the country and the people.
In December 2011, China’s first national-level industry base for the purpose of “exploring the ocean with technology”was formally established in Pudong District, Shanghai. In the first half of this year, China’s first “oceanographic technology demonstration island” will take shape in Zhoushan, east coastal Zhejiang Province, which will be built into a world-class oceanic technology island that takes on such functions as scientific research, entertainment, tourism and ecology.