North Brazil Current - Characteristics

Characteristics

The general speed of the current is between 60 and 100 centimeters per second. A peak recorded speed of 110 centimeters per second was recorded about 100 m below the surface of the ocean, in the vicinity of where the NBC merges with the SEC. Average temperatures are in the range of 22°C to 28.5°C, and tend to be warmest during the northern hemisphere’s summer.

The strength of the current is dependent on the season. During the northern hemisphere's spring, there is a minimum of 13 Sv in the current, which jumps to 36 Sv as the easterlies strengthen. The average is about 26 Sv for the whole year.

The average salinity of the current occurs at about 5°S, where the more saline SEC merges with the NBC. Both are quite warm, so the densities are similar, and the currents mix and create water with a salinity of 37.1 psu. The salinity will then decrease to around 36.5 psu as the current moves northward toward the equator and into the presence of the Intertropical Convergence Zone (ITCZ). The rainfall produced at the ITCZ works to dilute the salt content of the water.

The depth of the NBC is dependent on the depth of the thermocline, as well as the depth of the continental shelf. Closer to the shore, and especially where the depth of the water is less than 400 m, the sea floor acts as the lower limit to the current. If the depth is greater than 400 meters, the thermocline acts as the lower limit, and represents the boundary of the NBC and the colder, eastward moving Atlantic North Equatorial Undercurrent (NEU). Since the NEU is colder than the NBC, they will have different densities and not mix, allowing each to flow past each other mostly uninhibited.