What is the measurement of volume of water flow equivalent to 1 million cubic meters per second called?

The correct term for the measurement of water flow equivalent to 1 million cubic meters per second is "Sverdrup." This unit is named after the Norwegian oceanographer Harald Sverdrup and is commonly used in oceanography to quantify ocean currents.

One Sverdrup is precisely defined as a volumetric flow rate of one million cubic meters of water per second. The concept is particularly significant in the study of large-scale oceanic circulation, as it provides a way to express the immense volumes of water that move through ocean currents.

The other options—Cubestream, Flowrate, and Gyre—do not specifically represent a unit of measurement equivalent to 1 million cubic meters per second. "Flowrate" is a general term that refers to the volume of fluid that passes a point in a system per unit time, but it is not associated with the specific value of one million cubic meters per second. "Cubestream" is not a recognized term in the field of oceanography, and "Gyre" refers to a large system of rotating ocean currents and does not measure volume flow. Thus, Sverdrup is the precise and correct measurement for this query.