Small CW-rotating cyclonic vortex near/on the equator

[AJC3]

Just thought I'd point out something sort of neat to the group. Check out the NHEM satellite image at:

http://wwwghcc.msfc.nasa.gov/cgi-bin/ge ... color=gray

(time-sensitive)

I was checking out the large mass of ITCZ convection to the north of NE Brazil...what caught my eye was the tiny CW rotating vortex to the S-SSW of the convection, roughly due north of Fortaleza Brazil. At first glance I though it was a bit north of the equator, but having looked at a map of the region, it appears to be pretty much right on the equator - which is impressive nonetheless. I don't know whether this was a leftover MCV, but I suspect it may have been given how small the feature is.

I point this out because this subject has come up many times on the list. We know that the planetary coriolis parameter is very small within 5 degrees of the equator and zero at the equator, and also becomes very small when talking about smaller atmospheric scales such as single thunderstorms (And while we're on the subject...NO, coriolis does NOT determine how the vortex in your toilet bowl spins!)

You can still get cyclonic spin very close to the equator provided you have the right dynamical processes going on. For instance, in smaller atmospheric scales, you can easily get these types of circulations when the when the flow is cyclostrophic (i.e coriolis is zero/negligible, and pressure gradient and centrifugal forces balance each other out).

In any event, enjoy it while it lasts.

[wjs3]

Really neat. Thanks for pointing that out. It sure looks like an MCV.

[Derek Ortt]

I fixed it on GARP at .3 north

[Derek Ortt]

question about cyclostrophic,

at a scale fo 70km (which is the diameter that I fixed on GARP), wouldn't that be too large for cyclostrophic balance? Shouldn't cyclostrophic balance be on even smaller scales?

[lrak]

Wow, it is turning the other direction! Thats a first for ME.

Thanks.

[Dean4Storms]

Very interesting, it appears TStorms are developing around this feature as well.

[AJC3]

question about cyclostrophic,

at a scale fo 70km (which is the diameter that I fixed on GARP), wouldn't that be too large for cyclostrophic balance? Shouldn't cyclostrophic balance be on even smaller scales?

In higher latitudes, sure. However, since we're talking about a system that's very close to the equator, the areal extent of the circulation isn't going to matter, given how small (negligible) the coriolis parameter is.

[Ed Mahmoud]

Makes the disturbed area to its North look huge by comparison.

[AJC3]

MODIS imagery from 1250 UTC:
http://rapidfire.sci.gsfc.nasa.gov/real ... T081791250

Check it out on the 250M res at:
http://rapidfire.sci.gsfc.nasa.gov/real ... 0.250m.jpg
(broadband warning...this is a huge file)

[Chacor]

It's really weird to see a clockwise cyclonic spin north of the equator. I'm used to tracking Southern Hemisphere cyclones but this is quite something.

[Category 5]

That is really cool.

[dizzyfish]

That's wild! Thank you so much for posting this.

[Category 5]

Just a thought.

Wouldn't it be hilarious if it became Bertha?

I'm trying to picture the NHC Discussion.

[Cyclone1]

That is unreal! I'm saving some SWF's and AVI's of the loop right now.

[HURAKAN]

[Cryomaniac]

Just a thought.

Wouldn't it be hilarious if it became Bertha?

I'm trying to picture the NHC Discussion.

I would love that to happen, if only to appease my sense of the bizarre.

[vbhoutex]

Wow!! I have never seen that before. Thanks for posting this. And C5 I can only imagine the discussion!!! In their shoes I might be tempted to ignore the fact it is rotating the "wrong way" and just talk about the rest of the synoptic features.

[Derek Ortt]

for those met students

check out the third chapter of holton for how this comes about. You can also do a simple scale analysis of the equations of motion as well

[whereverwx]

Here's a cool discussion on it with loops: http://cimss.ssec.wisc.edu/goes/blog/archives/675

[HurricaneBill]

The closest to the equator that an Atlantic storm formed was Isidore in 1990. Isidore formed at 7.2N.