USNI PROCEEDINGS: Wired for Sound in the Near Seas
China is deploying an ocean-floor surveillance network to strengthen its antisubmarine-warfare capability.
As China’s naval modernization program has shifted into high gear in recent years, numerous defense analysts, both inside and outside China, have rightly pointed to the People’s Liberation Army Navy’s (PLAN’s) quite obvious weaknesses in antisubmarine warfare (ASW) as a persistent Achilles’ heel of the evolving force. Although the 2012 introduction of the Type 056 light frigate, which has subsequently been produced at an unusually rapid clip, may represent a significant step toward increasing ASW prowess, there appears to be a long road ahead for Chinese development in this realm. This is made more likely given the profound paucity of operational experience in the PLAN, as well as the apparently long-time neglect of maritime-patrol aircraft and ship-borne helicopters.
Defense analysts who follow Chinese military literature closely, however, will have noticed over the past several years that the massive Chinese military-industrial complex has now come around to the great importance of ASW, and China’s substantial military and science-research energies have shifted accordingly. The fruits of these major research efforts are now gradually coming into view. Most startling is the revelation in numerous Chinese scientific and strategy publications since 2012 that China has deployed fixed ocean-floor acoustic arrays off its coast, presumably with the intent to monitor foreign submarine activities in the “near seas.” While it may be nearly impossible to fully assess the effectiveness of these ocean-bottom arrays in enhancing Chinese ASW capabilities, here we endeavor to at least outline in general terms the parameters of these deployed systems that have been revealed in various recent Chinese writings on the subject.
Before exploring in detail the substance of new Chinese revelations, it will be worthwhile to review, albeit briefly, what is known in the open realm regarding the significance of ocean-floor acoustic arrays to the historical development of ASW, and especially its role in the Cold War. According to an authoritative analysis of U.S. Navy ASW development during the Cold War by Owen Coté, ocean-floor arrays commonly known as SOund SUrveillance System (SOSUS) played an immensely important role. First deployed off the Bahamas in 1951, the system was expanded through the 1950s along both coasts of the United States. Coté explains, “SOSUS arrays consisted of hydrophones spaced along undersea cables laid at the axis of the deep sound channel roughly normal to the direction that the array was to listen.” The results were stunning, and SOSUS is famously said to have tracked the first George Washington –class nuclear-powered ballistic-missile submarine (SSBN) all the way across the Atlantic Ocean in 1961. Suggestive of the system’s revolutionary capabilities, it is claimed that a SOSUS array in Barbados accomplished the extraordinary feat of detecting the first Soviet nuclear submarine to enter the Greenland-Iceland-U.K. gap in 1962.
A so-called “happy time” for American ASW followed as SOSUS capabilities were paired with maritime-patrol aircraft squadrons to establish a formidable counter to the growing Soviet submarine fleet. Certain challenges, however, arose surrounding the use of these new systems. First was the imperative, familiar from the use of ULTRA intelligence in World War II, not to reveal the system’s locations and capabilities to the adversary. Second, it was clear that Soviet efforts at submarine quieting could eventually undermine the effectiveness of the system. Third, the happy time of the U.S. advantage in passive acoustics afforded partly by the revolutionary SOSUS capabilities partly came to an end when Moscow radically increased the range of its submarine-launched missiles, allowing them to remain in “bastions” near the Soviet coast, and thus avoid NATO ASW barriers.
According to Coté, the U.S. Navy met these challenges by deploying both Fixed Deployable Systems (FDS) wider afield, as well as developing the Surface Towed Array Surveillance System (SURTASS), but he concludes that the end of the Cold War had a “saved-by-the-bell” aspect to it, as submarines were once again gaining the upper hand over ASW forces. Thus, it is clear that SOSUS played a highly critical, but also somewhat contingent role in the Cold War at sea. Chinese naval analysts have ample awareness regarding the nuances in this important history. 1
Signs that Beijing’s naval planners had more than a passing interest in ocean-floor surveillance networks go back well over a decade. For example, a researcher at the Chinese navy’s Institute 715 published a survey of “ocean surveillance technologies” in 2001 that included a detailed discussion of the American SOSUS program. 2 As revealed here later, it is probably not at all coincidental that the eastern maritime province of Shandong is home to the PLAN’s first nuclear submarine base and that one of the most detailed discussions of Chinese undersea sensor networks appeared in the journal Shandong Science in 2010. This article was not especially coy regarding its significant military applications and also demonstrated a high level of awareness among Chinese scientists regarding various similar U.S. programs. Moreover, it also observed that, given China’s vast coastline, there is enormous potential for the country to develop an ocean-surveillance network. 3
However, Shandong was apparently not the only coastal area pushing forward with ocean-floor sensor research. Farther to the south and located near Shanghai at the mouth of large Hangzhou Bay, a recently established “East Sea Ocean Floor Observation Test Station” was discussed extensively by Chinese researchers in an article appearing in Science Bulletin in 2011. Focusing on the collection of a variety of oceanographic information—tidal and current data, for example—experimentation with sonars appears to be ongoing at the station. The wireless data-collection system began its operations in April 2009 at the Xiaoqushan Station. 4
Although that specific article does not explicitly discuss military applications, another article by several of the same authors appearing in late 2012 discussed the station and military applications for the ocean-floor sensors, alongside civilian uses, including environmental protection, navigation, and disaster prevention. The latter article compares different configurations for ocean-floor sensor networks, including linear, circular, and “tree-type” designs, evaluating both cost and also security and reliability implications. It also mentions the Xiaoqushan Station as the basis for a larger “East Sea Ocean Floor Sensor Network” that will be completed by 2016. It is finally perhaps noteworthy that this discussion also explicitly mentions “undersea mobile sensor stations,” as well as fixed sensors. 5
