What type of data is primarily analyzed by the DIFAR sonobuoy?

The DIFAR (Directional Frequency Analysis and Recording) sonobuoy is specifically designed to analyze the frequency and direction of underwater sound. It employs a hydrophone that can determine the direction from which a sound is coming, alongside its frequency components. This capability is crucial for anti-submarine warfare, as it enables the detection and localization of submarines and other underwater threats by examining the acoustic signature they generate.

In the context of the other options, wave patterns pertain more to the physical movement of water, which is not the primary focus of a sonobuoy designed for acoustic analysis. Temperature variations are relevant to oceanography but are not the core function of the DIFAR sonobuoy. Sound intensity levels may provide some data but do not encompass the directional capabilities that are essential for effective submarine detection, which is why frequency and direction are the primary data types the DIFAR sonobuoy analyzes.