For how long is the Alfa index considered valid?

The Alfa index is considered valid for 72 hours. This time frame is established based on the expected changes in environmental conditions that could impact acoustic performance and oceanographic measurements. Data related to sound speed profiles and other critical parameters can vary significantly due to factors like temperature, salinity, and currents. A validity period of 72 hours allows for a reasonable window to maintain accuracy in acoustic modeling and operations while ensuring that the data reflects relatively current conditions. This approach balances the need for up-to-date information with practical considerations in planning and execution of operations, making the Alfa index a reliable resource during that span.