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<br />complicated and diverse situation. But I think we have to.. . obviously water that comes down as
<br />snow and rain is where this whole thing starts from, and 1've been asked a number of times how
<br />unusual is the current drought? And this is some work with _? _ and Nolan Doeskin, showing
<br />a fraction of Colorado drought using the 48 month SDI, so it's a relatively long-term drought, and
<br />what you see here which I'll stand aside.. .they emphasize, I think very effectively, that since 1980
<br />up to a couple of years ago, we were in a very wet period, in fact one of the wettest periods ofthe
<br />past 110 years or so. In contrast, there were periods of significant drought, the '30' s and the '50' s,
<br />and then a much shorter one in the '70's, one back here 1980's, early 1900's. So even looking at
<br />this figure we can see that the duration ofthe current drought is far shorter than what we're seeing
<br />in the historical record. So that message suggests that this is not a usual one. Klaus Walters has
<br />provided some resources for us to do further analysis of this, and I have some very preliminary
<br />results that show you... what we're doing is taking the climate divisions that Klaus has proposed,
<br />and we're looking at stations within these divisions to look at how the current pattern relates to
<br />what has occurred historically. And one of the ways we're looking at this data is to do a plot. Let
<br />me explain this. This is a spaghetti diagram, basically we go to a given year, and you say what are
<br />the departures from the mean actual temperature, and what's the departure in terms of
<br />precipitation. So this is for Rocky Ford. So you start here, for example, and you ask, what
<br />happened the following year? And say it was this value. And then you go to the following year,
<br />and so forth. And you track this to see how persistent drought is, how persistent wet periods are,
<br />and so forth. Because in the upper left hand box here is warm actual temperatures on average to
<br />draw it. So one dry, over here is one wet, down here is cold and wet, here it's cold and dry. And
<br />by looking at how these cluster, you can get an idea of what is sort of the average condition, and
<br />you have a lot of extreme values here, a lot of them clustered, not that far from the mean, but
<br />they're actually slightly more and slightly dryer than the average to the mean, and the mean is
<br />slightly different, is what it implies.
<br />
<br />We're looking at this also in the context of bar graphs, this is precipitation deficit, for Rocky Ford
<br />in 2001, and you can see the wet periods that we had very recently, and you can see the dry period
<br />back here in the '30s and so forth. Nothing stands out as saying this drought is anything unusual.
<br />It's nothing atypical, it's part of Colorado's semi-arid climate, and the only difference probably is
<br />the fact the impacts are broader now than they were in the past. We're also looking at this in
<br />terms of accumulated deficit, and this is again Rocky Ford, going back to 1890, and when the
<br />curve goes up it means there's an excess of precipitation, when it's sort of flat it means you sort of
<br />have the average, and then when it drops you have a dry period. So here's the 1930's drought,
<br />with its drop here, then you see actually, how there was a rather long term dryness for several
<br />decades that occurred in Rocky Ford, where until very recently, where the precipitation was above
<br />average, and wet. So there's this long-term variation of the precipitation and temperature
<br />superimposed on this near armual variability, and it put.. . droughts happen, of course, you get the
<br />superposition of multi-years, the driest superimposed on this decade-long below- average type of
<br />precipitation. This pattern, by the way is relatively consistent, it's the data sites that we've looked
<br />so far, but again, we're exploring that, but again it just reinforces that we.. . and what's recently
<br />been in a wet period, and that I think has misled us to assuming this drought is particularly
<br />unusual. We're also analyzing, this is hard to see, but let's just take one of these curves that's
<br />readable, it's the idea that's important. This is a 6-month SDI in the second curve here, starting in
<br />1950, and we're just tracking at Rocky Ford, how does it vary over the past 51 years, we want to
<br />extend this back to 1890, that's work we have to do yet, but again, it shows dry periods here in the
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