Which parameter primarily affects the sound velocity in seawater when it increases?

The reason "all of the above" is the correct answer is that sound velocity in seawater is influenced by several interrelated factors. Salinity, depth, and temperature each play a significant role in determining how quickly sound travels through the seawater.

Salinity affects the density and chemical properties of seawater. Generally, as salinity increases, sound velocity also increases. This is due to the added mass and different molecular interactions that occur in saltwater compared to pure water.

Depth also plays a crucial role since, as one goes deeper into the ocean, pressure increases. Higher pressure compresses the water, which tends to increase sound velocity. The relationship is not linear but is an essential factor contributing to overall sound velocity.

Temperature is perhaps the most significant influence among the three. The speed of sound in water increases with rising temperature. This happens because increased thermal energy causes water molecules to move more rapidly, facilitating quicker propagation of sound waves.

Thus, since each of these parameters individually contributes to changes in sound velocity, when all are considered together, it confirms that they collectively affect sound velocity in seawater.