Topic: Where do I mount my ISS..?

[jimnevins]

Question:
I recently purchased a Davis VP2 and am having trouble deciding where to mount the ISS...I'm thinking of extending a plumbing vent on my roof of my 2-story house and using that as my mast for the anemometer. The anemometer will be un-obstructed for 360 degrees. and be 1 meter above the roof peek. this location I believe is high enough to achieve a accurate measurement of wind direction and speed, but if I mount the ISS lower on the mast, I'm concerned about the radiant temperatures from the asphalt roof material. the mast will be on the south aspect of my roof, so during the summer it will be pretty hot.
any comments would greatly be appreciated...

thanks in advance..!!

[saratogaWX]

The anemometer mount on the roof sounds ok.  If possible, the ISS should be mounted at 5.5ft above grass on the ground for best temperature accuracy and good rainfall recordings (if unobstructed for 30' radius).

Mounting the ISS on the pole on the roof will lead to higher temperature readings (due to the root) and possibly decreased rain collection (due to winds), but if that's the only place that has a clear sky view, then it's probably ok.

Check out the siting guide at http://mywebpages.comcast.net/dshelms/CWOP_Guide.pdf and you can see the tradeoffs.

BTW.. I'd removed the duplicate of this post in the "Personal Weather Stations" forum .. this is the right place for this question

Best regards,
Ken

[jimnevins]

thanks for removing that thread...I wasn't sure where to post the question..

thanks for the link, Ken...

Jim

[saratogaWX]

You're welcome, Jim.

I had to make a few compromises on my location too.. the back yard was covered by tree branches.  Side yards too narrow or covered by branches.  Front yard was off limits (by wife), so my only option was the roof of our 1-story ranch-style house.  I'd put my ISS and anemometer on a Davis tripod with a clear sky view, so I only score 17 out of 30 for placement

(http://saratoga-weather.org/station.php )

I am looking at splitting the ISS up and leaving rain gauge and anemometer up, and moving FARS down to North side of house at 5.5 feet to improve the temperature accuracy.  I get about 2 degrees warmer during the day than it should (in bright sun), and 1 to 2 degrees colder at night (as compared to two different thermometers used at 'human height').
Ken

[W3DRM]

Mounting on a plumbing vent is really asking for trouble so I would not suggest attempting such a configuration. Vents tend not to be very stable. Additionally mounting it only 3 feet above the roof will result in your picking up a lot of radiant heat from the roof surface and it will effect your anemometer being so close to the roof peak. You really need to have your ISS at least 5 feet above the roof and the anemometer around 10 feet above the roof to minimize its effects.

I built an eave-mount for mine (see the picture below) and have the supporting mast guyed to the roof for stability. I used three 5-foot sections of tv mast (from Home Depot). The boards are made of 2 x 4's and the clamps are u-bolts to hold the mast. It's been up through two winters now and is steady in 50mph+ winds.