Just DO it. Dendroclimatology NEEDS you!

Cheers — Pete Tillman
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“Gentlemen, you can’t fight in here — this is the War Room.”
– Dr. Strangelove (Stanley Kubrick)

During the period Oct – April inversions are common between winter storms. Winter storms coming in from the West or SW produce minimal precip with somewhat higher snow level and lots of wind and mix out the inversion. Storms coming down from the north (and even the odd retrograde cut off low coming in from the northeast or east) have less wind and produce more precip due to the fact they don’t have the cross the Sierra Nevada (and incur the rainshadow). Years where the northerly Siberian Express sets up (classic examples, last year and the year before) tend to keep the snow cover on the ground longer (both between the storms and overall) and the snow pack can last until June or July. Mammoth Mtn Ski Area (not in the Whites, but nearby, on the East slope of the Sierra) can be open on the 4th of July more often than not. Years where the Siberian Express does not set up result in an earlier melt off and if there is not an El Nino, a deficient snow pack. A highly unusual climate with large variations in temps and precip on all time scales.

Check out the Reno NWS site every few days for a year and you’ll get a sense of how the climate in the Whites works.

The possible reasons for these differences could be endless, w/higher temps = greater growth not apparently among them.

Climatic stations White Mountains 1 and White Mountains 2 operated from ~1950 to 1980. WM1 at 10150′ (3100 m) and WM2 at 12470′ (3800 m). WM1 had mean annual temperature of +2.3 deg C and 31 cm precipitation; WM2 had average temperature of -2.4 deg C and precipitation of 36.5 cm. Obviously cold and dry. Local gradients (up) would be therefore about -0.67 deg C/100 m and +0.8 cm/100 m, although I’m sure that this varies a lot in the different microclimates.

The key control on growth seems to be soil moisture, which remains above critical levels for longer at higher altitudes. I’ve got a post in the works on this.

Re: #11:

Unless you are using a lapse rate with which I am not familiar, I think you need to either drop a zero from the height (so it says .6 deg C/100 m), or move the decimal to the right for temperature (so it says 6 deg C /1000 m).

And could you clarify the lapse rate to which you were referring? We usually discuss three. The first two are associated with the expansion air as it ascends:

Dry Adiabatic Lapse Rate (for unsaturated air–relative humidity less than 100%): about 10 deg c/ 1000 m

Wet Adiabatic Lapse Rate (for saturated air–RH = 100%): about 6 deg c/ 1000 m; greater at cold temps, less at warm temps

The other rate is the observed, or “environmental” lapse rate. On average it is 6.5 deg C / 1000 m, though it is rarely exactly this value through any given layer of the atmosphere or for a prolonged period. Obviously with inversions, this lapse rate would be negative, because the temperature increases with height.

As related to normal environmental and adiabatic processes, you would expect the upper site to be 1 to 1.5 deg C cooler than the lower site. You would also expect the upper site to be slightly more moist, unless the lower site was windward and the higher site leeward.

Anyway, I would appreciate a clarification so I can better follow your argument.

Thanks.

This ties into an interesting bias in nearly all tree ring width series. You may recall prior discussion of sampling bias – tree ringers do not sample small trees. Melvin, a student of Briffa’s, mentioned 5 mm diameter as a typical minimum. In the 20th century, tree lines have been rising but sampling has not (due to minimum sample girth). We’re seeing very big differences in ring width over rather short elevation intervals. So the absence of samples from the higher elevations has to bias the sample somehow. Note again that medieval treelines were typically higher than modern treelines and these higher trees were sampled in the medieval period. (discussed in connection with Polar Urals – see Category right frame)

In all of the sites, the graph of the upper site shows anomalous growth in the last century.

The “crossing at Timber Gap” is an artefact. Of the sites shown, only at Timber Gap does the lower site (as expected) have wider ring width than the upper site. However, during the anomalous upper site growth of the last century, they reverse positions.

The question you pose, as I understand it, is how can we possibly uutilize sites where upper site ring width is greater than lower site ring width as a temperature proxy? This is a critical question. One hopes they might discuss this stuff.

w.

I can’t figure out what would cause the crossing at Timber Gap – that seems pretty weird to me.

A working hypothesis would be temperature. To my eye the upper and lower series could be negatively related. This is esp visibile in Pearl Peak data, when one goes up the other goes down. This is to be expected from the physiology if the upper and lower are on different sides of the inverted ‘U’ curve. Judged against this model 20th century behaviour seems anomolous.