When air is moving downward over the ocean and upward over the sand, it can be inferred that the air over the ocean is cooler than the air over the sand.
This is because air movement is usually caused by differences in temperature and pressure. In this case, the air over the ocean is cooler and denser than the air over the sand, so it sinks and flows towards the lower pressure over the warm sand. Conversely, the air over the sand is warmer and less dense, so it rises and flows towards the higher pressure over the cooler ocean.
This process is known as a sea breeze, which is a type of local wind that occurs near coastal areas where land and water meet. During the day, the land heats up faster than the water, which creates a temperature difference that drives the sea breeze circulation.