I am still wondering - why is 24,6 degrees chosen as the highest scanning elevation? Couldn´t the cone of silence become smaller and the detection of echo top close to the radar be improved a bit with higher scanning angles?
It could, Birgitte, but there is a trade-off between having that functionality and being able to, within 10 minutes, do a full doppler scan and sweep out the necessary reflectivity scans. It really comes down to what you really want your radar to be able to do.
Birgitte,
I'd also like to add that 24.6 is not way a global constant. In some countries, where they are keen to scan the lowest angles as often as possible, and where they have more emphasis on hydrology than on aviation services, the max angle can be as low as 10 degrees.
In Finland, we basically have 45 degrees at the highest one, but with older radars we have some, where probably the oil gets too thick so when it is colder than -20C we can't run the full volume in needed time so we drop the highest one.
*** Advertisment *** I have written about our scanning schema (and how we selected it) in a paper to be published soon and already available as preprint-pdf at http://www.borenv.net/ in the "forthcoming" -part.
Best regards, Elena
I'd also like to add that 24.6 is not way a global constant. In some countries, where they are keen to scan the lowest angles as often as possible, and where they have more emphasis on hydrology than on aviation services, the max angle can be as low as 10 degrees.
In Finland, we basically have 45 degrees at the highest one, but with older radars we have some, where probably the oil gets too thick so when it is colder than -20C we can't run the full volume in needed time so we drop the highest one.
*** Advertisment *** I have written about our scanning schema (and how we selected it) in a paper to be published soon and already available as preprint-pdf at http://www.borenv.net/ in the "forthcoming" -part.
Best regards, Elena
Thanks for the answers all of you both here and on the mail. I remember Paul Ford mentioned the times used for conventional scans and doppler scans, and the time issue with only 10 minutes available. Though as I had only heard/read of 24 degrees as the highest angle I had wondered if it was due to mechanical limitations of the radar - though I couldn´t image it as an explanation. Therefore my question. It sounds to me like the most common is to scan from 0,3-0,5 up to 24 degrees and not so many chooses to scan higher - as Elena mentions as a possibility - or at least haven´t done until now, as is doesn´t show up in most of the available litterature until now. So it is all a question of available time but also desicion/priority of the most important scan angles chosen.
You're exactly right, Elena. Thanks for pointing that out. It is by no means something that is engraved in stone.