reply to post by Mushussu
Sorry for the delay in replying. Had dinner, then had to get some animated gifs made up to show the pattern of outflow. I don't think there is a
cycle but the images will show it better than I can tell it.
In the following images, the brown line represents the mean (average), the blue or red line is the actual flow. (Blue line means “recorded”, red
line is “estimated”.) Please note that the graphs do not all use the same scales. I couldn’t do much about that. The thing to watch for, though,
is if the blue/red line is above or below the brown line.
I hope all these images will work…I set the animations to run fairly slowly so it won't be too hard on the eyes for older folks like me.
This first one is for the seven-year period from Jul 01, 1988 to Jun 30, 1995. I set them up this way so that winter is in the middle of the graph and
so it’s easier to follow what happens:
And here is the graph for the three-month period in each year, in the format Nov 01 1988 to Jan 31 1989, Nov 01 1989 to Jan 31 1990, and so on to Jan
31 1995:
You can see that in this seven-year period the outflow did not deviate much above the mean in the key period we’re concerned with, namely December
into January.
Now for the next seven years, from Jul 01 1995 to Jun 30 2002:
This time there is a four-year stretch with outflow above the mean, but the flow appears to be higher for most of the entire year in each case. Here
is the 3-month series, on the same date-basis as the previous one, years 1995 -- 2002:
The final series covers the (less than) seven-year period from Jul 01 2002 to Jan 10, 2009:
And here is the three-month, Nov to Jan series for the same period:
(
Credits: All original images from USGS. Published for informational purposes only. Individual images have not been altered in any way. The
animations are not from USGS. Images converted to animated gif format courtesy of Gickr.com. )
Summary:
Although there have been some years where the levels have also been above the trend for this time of year, it is difficult to determine whether there
were other factors involved in those cases, as we suspect may be the situation now. In short…more research is needed!
(Now didn’t you just
know I was gonna say that?
)
Mike
PS If any gifs are in the wrong place lets me know and I'll try and fix them. They should be okay but it's getting on in the evening here so I might
have messed something up.
Errm..Edited to fix a bad animation.
[edit on 11/1/09 by JustMike]