# What is the (average) velocity of ocean currents?

Does anybody know where to find statistical (average, standard deviation) data on velocities of ocean currents, such as

• Equatorial countercurrent North of Madagascar
• Agulhas current
• East Australia current
• Gulf stream East of Florida is about $2\,\frac{m}{s}$ (the only figure I have found)
• South equatorial current North of South America
• Kuroshio current
• Antarctic circumpolar current (Strait of Magellan)
• North equatorial (Philippines)
• etc.

I have found time series data by NOAA (link), but no "postprocessed" values. Is such data available?

• Usually, when dealing with currents, we talk about transport rather than velocity. As currents are intrinsically three dimensional, it makes more sense that way. You can divide the transport by the average depth at that location to get average velocity. A good description of these currents can be found at: oceancurrents.rsmas.miami.edu/atlantic/atlantic-arrows.html – arkaia Jul 22 '18 at 14:39
• @arkaia: These pages are a great resource. Velocities for some currents are given. However, for some others I would need the width of the current as well in order to obtain the averaged velocity of the current. – Simon Jul 22 '18 at 20:02
• That is the tricky part. In some cases, like the Florida Current (Gulf Stream) it is easier because most of it goes between Florida and Bahamas. In other places it's way more challenging and more variable. – arkaia Jul 22 '18 at 20:50
• @arkaia OSCAR data (svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=3958) is a great source of near-surface current speeds. However, if I understand correctly currents change positions, therefore just cell averaging of that data would not be very useful. Would it? Also I don't know how representative near-surface speed is for the whole 3D current. – Camilo Rada Sep 27 '18 at 22:16
• @CamiloRada Usually, the easiest way to get at this is to get the transport published in the literature and then divide by the total depth of the current at that location. – arkaia Sep 27 '18 at 22:49

## 1 Answer

This is not meant to be a comprehensive answer:

Sometimes the easiest way to calculate the velocity of an ocean current is to take the published transport of the current and divide by the total depth of the current.

For instance, for the Agulhas Current, you can take Figure 2 from Casal et al. (2009) (below) and extract the velocities based on the depth of each area. Also in their Figure 6, there are several vertical sections of velocity across the current.

Also, you can obtain vertical sections of velocity for the same current (Agulhas) in earlier publications: Bryden et al. 2005 (Figure 8 and 9). Or in newer publications: Beal & Elipot (2016).

The main issue is that you will need to do a bit of digging around for each of the currents you list.

• Thanks,+1. However, I assume, velocities obtained using the beam of an ocean current are subject to larger uncertainties compared to actual velocity measurements. – Simon Sep 30 '18 at 20:57