Archive for July 28th, 2011

Changing currents from one hour to the next

Thursday, July 28th, 2011

Hey All!


Well Challenger has been continuing on it way south while combating the draw of a number of eddies. 

The above picture is where Challenger 1 surfaced Monday, with a sea surface height overlay. After a few days of strenuous battle, Challenger 1 was almost completely clear of the Eastern eddy field's influence (next picture is of yesterday's update with a sea surface temperature overlay).

We have sailed along the Western edge of the eddy for roughly 112km (70miles) and are slowly inching our way out of its pull. And what's to our South? Southernly heading currents for the time being! The HYCOM does not reveal it but it seems as if there is another eddy Southeast of our position. If the past repeats itself, there will be more storms ahead for Challenger 1 and hopefully bring us fast flowing currents past any hurdles.

Currents and everything that affects them are a curious thing. Just as I update Google Earth, a hour after my previous statement yesterday, the currents end up looking like this. They are all facing completely north and there does not seem to be any relief to our West or East, be we shall keep pressing on!

Today, July 27th, the currents aren't looking much better, still all completely North and no relief is in immediate sight.

And just like that, the currents have changed a little since the last hour. Now we have a little room for maneuvering, even though these currents do seem a little powerful.

The image above was provided by Antonio and shows sea surface height of our journey ahead. We have a solar system of eddies ahead of us, but we have a number of defeated eddies under our belt already, so they should be no sweat.  We will just need to keep an eye on our surfacings to make sure we don't get dragged full circle around one of the stronger ones.

To try and make more accurate predictions about what the currents will be doing, I overlayed the currents provided to us by ULPGC on top of the geostrophic currents from HYCOM.  In the figure below, we can see how there are some similarities and differences between what each of the models are showing.

U. Las Palmas Gran Canaria Currents overlayed with HYCOM geostrophic currents and sea surface height model relative to Challenger's latest position

Looking at the weather conditions, we see what may be causing the discrepancies between the models.  It looks like there is a strong wind system blowing directly north courtesy  of  the jet stream.  There also seems to be another storm headed our way which will undoubtedly add more mixing to the direction of the currents between the movements of the eddies.

It looks like there is a long road ahead of us but I have no doubt Challenger will fight valiantly.

Oliver & Nilsen