Kaipara Harbour entrance and rain radar

[dudduddud]

What causes this to happen? It's there all the time and seems to stream out of the harbour. It's marked on the screenshot with a thin red arrow.

http://i46.tinypic.com/24m81lu.png
:confused:

[Tarq57]

I've seen this before, on the old ATC radar (which wasn't a weather radar, but would pick up weather when set to do so reasonably well), wherever a strong tidal flow occurred within radar range.
It's probably waves due to tidal flow.

[Tarq57]

dont think its possible with the doplers used as the precip is picked up to a height of 0.5km above the radar station out to 50km ( higher the furthur out) and not below
Rain radar that does not pick up precip below ~1500ft??
That would be surprising.
What's your source for that info?

[Tarq57]

Thanks for the info, MMArdmore.

I think you might possibly find that in the real world, the surface might be seen at such a range.
Just guessing.

I know that on the Marconi radar that was at Wellington, we could see the surface/sea clutter for quite a distance from the radar head.

[Lancair70]

While we're one the subject of radar returns, a while back I was flying skydivers and was asked by BN-CTR if I could see anything about 13-15miles off the coast SE of BNA. When I looked there was what looked very much like an Aircraft Carrier. when I advised CTR thats all I can see, he replied that must be the radar return he's seeing moving south at about 25kts. I was surprised as they often dont/can't see light aircraft below about 500' in the circuit at BNA, but can see a ship, approx 18-20miles further away from their radar site in the hills behind the GC ?

[BurntheBlue]

I think you might possibly find that in the real world...

...in the real world I think you'll find all sorts of things going on that don't line up with what you learned in CPL Met.

What you see here is simply sea spray kicking up on a windy day, usually (but not always) found in conjunction with a strong tidal flow (ideal conditions for breaking swell).

That clause on metflights site is an arse covering exercise, doesn't mean the radar cant actually see to surface level. For example, the Te Weraiti SSR on the Kaimais can see transponders down to 4500ft around GIZ and NPR on a good day (don't know why but certain atmospheric conditions help). That's way below direct line of sight. How? I don't know, the point is it does.

[framer]

What you see here is simply sea spray kicking up on a windy day, usually (but not always) found in conjunction with a strong tidal flow (ideal conditions for breaking swell).
I´m no radar guru but I find it hard to believe that the harbour inlet and tidal flow cause waves and spray out to 40km offshore. Is that what you're saying?

[BurntheBlue]

That's what i'm saying.

Take a look at the countrywide rain radar plot on a windy day, you usually get this happening around New Plymouth, Mahia, Cook Straight, Clarence River etc etc... All similar spots for orographic wind funneling (and sometimes strong water currents).

I will concede though, that Kaipara Harbour gets it more often than perhaps it should. Maybe some other anomaly at play in this instance.