(meteorobs) Re: Solar activity and meteors (reply)

To: Rainer Arlt <100114.1361@compuserve.com>
Subject: (meteorobs) Re: Solar activity and meteors (reply)
From: Marco Langbroek <marcolan@stad.dsldot nl>
Date: Tue, 12 May 1998 19:22:07 +0000 ()
Cc: Meteor Observers List <MeteorObs@latrade.com>
In-Reply-To: <199805111427_MC2-3CA2-2653@compuserve.com>
Reply-To: meteorobs@latrade.com
Sender: owner-meteorobs


Hello Rainer and others,

Perhaps "well established" was not the right word indeed (sometimes it is 
difficult when English is not your native tongue), but what I meant with 
it is that it was not just a 'rumour', but that some serious research has 
been done on the topic which really suggests that these things are going 
on. At least in the Meteorobs message to which I responded, that seemmed to 
be a little bit the flavour that talk about rate variation due to solar 
activity had never been substantiated in any way. That, however, has been 
done, as I replied.

Future analysis on this topic are indeed very welcome. You rightly 
identified the need for long term correlations due to the rather long 11 
year cycle in solar activity.

Yet, I also think that you should be extremely carefull with sporadic 
data in the sense that you should keep in mind what might be obscuring 
any rate variation, e.g. variation in observer sample if you do not 
normalize for perception differences. The rate variations which we are 
discussing are rather small.

-Marco



Op Mon, 11 May 1998, Rainer Arlt schreef:

> Marco,
> 
> Thank you for the note about the connection of meteor rates to solar
> activity. I don't think I was telling there is no relation, I just noted
> that the height of the ionosphere may not affect meteor rates, whereas the
> air density does, and this is what you also indicated citing several
> papers. I find "well established" a little exaggerated when talking about
> observational evidence. We have to bear in mind that it is always only one
> solar activity period which is covered by a single publication. Several of
> them together indeed hint on a consistent picture. I tried to extract
> sporadic rates from the VMDB 1984-1997, and I only used those obtained
> between 2200 and 0200 hours local time and those noted in July, since this
> a month covered by many observations and is not affected by a major shower.
> I did not find any correlation. Here is the data:
> 
> Year  sporadic hourly rate
> 1984  14.8
> 1985  12.6
> 1986  15.6
> 1987  18.0
> 1988  12.8
> 1989  13.9
> 1990  14.7
> 1991  15.7
> 1992  18.0
> 1993  15.1
> 1994  14.8
> 1995  15.3
> 1996  17.6
> 1997  15.3
> 
> (By the way, I was satisfied by the overall constancy of the rates, which
> does not support the suspicion about rates inflating during the last
> years.)
> 
> Of course, this is just a quick look in the data, more can certainly be
> done. Nevertheless, we don't have much more than one cycle either. When
> looking at the graphs of PER and ORI in Peter Jenniskens' article, I would
> like to know how other shower behaved. I guess enough data should also be
> available for the Geminids, eta-Aquarids and Southern delta-Aquarids
> according to Table 3a.
> 
> The analysis will be an interesting task using a long series of visual
> observations (more than 2 solar cycles). I am keen on seeing more on this.
> 
> Best wishes, Rainer
>