The Corvallis, OR. USCRN Site: A Natural Laboratory – Part Two

Written by Dr Jerry L Krause (Chemistry) on November 20, 2018. Posted in Current News

Since I composed the previous essay I have learned a little which is a lot.  Since we live about 50 miles from this natural laboratory, my wife suggested that we go to the William L Finley National Wildlife Reserve to see what we had not seen before.

One question to which I wanted to learn the answer was: Is the tall grass seen in this photo of my previous essay still there?

[Warning:  If you do not have a pressing desire to learn something, do not waste your time reading further.  For learning requires a significant effort.]

After learning about the location of the USCRN meteorological station from Jeremiah Maghan, the U.S. Fish & Wildlife Service’s (FWS) Fire Management Officer at the Reserve, I was extremely surprised to learn there were two meteorological stations instead of just one. This fact obviously made this site an even better natural laboratory.

Photo B.  This is not an actual photo of the FWS Remote Automated Weather Stations (RAWS) at the Finley Reserve but the grass seen here is very similar to that we saw.  So the tall grass was no longer present.

As I inspected this unexpected second station of the FWS I noticed that it had a horizontal tube (seen in the left image) positioned about a foot above the ground, which the USCRN station did not have.  And the wind sensors mounted at 10 meters above the ground rather than at the 1.5 meters above the ground of USCRN station could not be missed.  And no wind data is reported for the USCRN station for it is commonly observed that any ‘light’ wind measurements at the 1.5 meter has any relationship to those much stronger measured at the 10 meter altitude.

A historical fact is that decades earlier I had read in C. Donald Ahrens’ Meteorology Today 3rd Ed. (1988):

“However, on a windless day, this form of heat exchange is slow and a substantial temperature difference usually exists just above the ground.  This explains why joggers on a clear, windless, summer afternoon may experience air temperatures of over 50C (122F) at their feet and only 32C (90F) at their waist.”

Hence, I suspected that this tube instrument was measuring the air temperature a foot above the ground as well as were other sensors at about1.5 meter above the ground conventionally measuring the air’s temperature and the air’s relative humidity.

To learn what this tube instrument actually was I emailed Jeremiah.  And he replied:

“The tube shaped Sensor measures 10 hour fuel moisture.  When you look at the RAWS data it will be under Fuel Moisture Mean Percent. Nice meeting you good luck with your research.”

From which I did not learn much (anything) because I had no understanding as to what the ’10 hour fuel moisture’ actually was except that seemed clear it was not a temperature.

So I wrote back for more information and Jeremiah replied.

“The fuel moisture and fuel temperature (FT) is measured through the same stick.  I replace that sensor annually.  Here is a brief description of the sensor.”

Which I have made briefer by editing to:

“The FS-3 provides an electronic measurement of the internal temperature (FT) and humidity of a wooden dowel. Based upon a 10-hour fuel stick algorithm, these measurements are used to indicate the moisture content of naturally occurring fuels in the vicinity of the weather station. The FS-3 dowel is manufactured from clear kiln-dried ponderosa pine with 10-14 annual growth rings per inch. The dowel is hollowed with a machine ream to ensure precise repeatability between sensors.  Fuel temperature is monitored by a precision thermistor, and fuel moisture by a capacitive humidity sensor.”

At our home we have a weather station (cost about $35 US) which has an outside sensor with a thermistor to measure air temperature and a capacitive sensor to measure the air’s relative humidity.  Its measurements are transmitted to the base station inside our house just as the measurements of these two meteorological stations are transmitted to a base station.  I review this so you can see how simple (at this modern time) and elementary this fuel stick sensor actually is.

However, in the case of the fuel stick’s reported data, the measured relative humidity is converted to a ‘fuel moisture content’ (FMC) by the “10-hour fuel stick algorithm”.  Just as the (air) temperature and relative humidity measured at 1.5 meter above the surface by the FWS station is converted into the atmospheric ‘dew point temperatures’ (ADPT) by the dew point temperature algorithm.

The FMCs and the ADPTs are compared in Figure A so that the relationship between these two factors can be seen.

Figure B is similar to Figure 5 of the previous essay with the addition of the fuel temperature and the conventional air temperature measured by the FWS meteorological station.

I first direct your attention to the difference I see between Figures A and B.  Which difference is the data of A is not near as regular as that of B during these 5 days.  Except when I look more closely I see that maximum values of the temperatures of Figure B are regularly decreasing (not constant).  Which decrease I had previously considered to be related to the slight, regular decrease of the values of the incident solar radiation seen in Figure 1 of the previous essay.

If you have read my warning you either want to make an effort to learn or you have ignored my warning because it does not matter if you waste your time.  I hope the reason you are reading this it is the former but either makes no difference to me as I review what Richard Feynman taught his students during the first day of The Feynman Lectures on Physics. “Each piece, or part, of the whole of nature is always merely an approximation of the complete truth, or the complete truth as far as we know it. …  The principle of science, the definition, almost is the following:  ‘The test of all knowledge is experiment.“  The result of experiment is the data measured by these two meteorological stations and this data must be studied if we are to begin to learn about the approximation of nature to which they direct our attention.

The fuel temperature and the fuel moisture content measured by the simple (low tech) fuel stick is vitally critical to allow Jeremiah, a Fire Management Officer, to successfully perform his duties.  And a study of the artificial system defined by this simple fuel stick sensor is vitally critical to what we might learn about the natural system which you and I are trying to better understand (learn).

Before having access to the fuel stick’s data, the USCRN’s surface temperature data, as measured with an IR thermometer device, was a matter of reasoned question.  The fact that the fuel temperatures measured with the fuel stick sensor, and the surface temperatures measured with an IR thermometer, track so closely (Fig. B), removes the question about the validity of the surface temperature measurements.

For who can question the direct measurement of the FT by a precision thermistor?  While the temperatures being measured are of two completely different systems, it seems difficult to rationally reason (argue) there can be no relationship between these two temperatures because the observed tracking is merely a coincident.

I had a problem as I previously tried to understand (learn about) a natural system when the formation of dew or frost on surfaces occurred during the nighttime.  A question was:  From where did the water vapor, which had condensed, come?  From the atmosphere or from the moisture content of the soil beneath the ground’s surface?

The position of the fuel stick about a foot above the ground eliminated the latter possibility.  Because even if it came from the ground, it got to the exterior surface of the fuel stick as atmospheric water molecules.

Now, in the case of the fuel stick, an obvious question should be:  How do water molecules in the atmosphere get to the interior of the wooden dowel, or vice versa?  Clearly the data (Fig A) shows that such a transfer between the stick’s exterior and interior must occur.

Einstein is said to have stated:  “The only source of knowledge is experience.”  For my thesis research I did experiments involving the diffusion of cadmium and lead ions in highly purified, solid, single crystals of sodium chloride or potassium chloride.  So my answer to this last question is that the water molecules diffuse through the ‘solid’ wood between the fuel stick’s exterior and interior.  Now a fact is I have never read about the diffusion of water vapor through the atmosphere.

This should not imply that I consider that no one has never written about such a diffusion of water vapor.  But based upon my experience I can state with absolute confidence that water molecules are continuously evaporating from water surfaces and then diffusing upward to fill the space of the atmosphere with more water molecules.  Which might condense to form clouds which eventually precipitate to return these water molecules to the earth’s surface.  Which if the latter precipitation mechanism did not occur, the moisture content of the atmosphere would continually increase as the ocean levels decreased.

In Figure A we can see that the fuel stick’s interior moisture content does not continually increase but instead diurnally can (does) oscillate between a maximum value and a minimum value which appears to have a significant range.

The data known as the atmospheric dew point temperature is common.  A problem is many seem not to understand what this temperature is, or represents.  Because of the importance of the claim I must document the facts which led me to this conclusion.

Feynman at his first lecture taught (second paragraph):  “Surprisingly enough, in spite of the tremendous amount of work that has been done for all this time it is possible to condense the enormous mass of results to a large extent­—that is, to find laws which summarize all our knowledge.”

A few years later then Feynman’s lecture, R. C. Sutcliffe, a notable meteorologist, in his book’s, Weather and Climate, introductory chapter wrote:  “Meteorology is not a fundamental physical science, that is to say it is not concerned to develop the basic laws of nature.”  Then, in the 5^th chapter, he wrote:

“These results, obtained first by Wilson and by many later experiments, have a very important bearing on natural meteorology, not because supersaturation [of water vapor] occurs in the atmosphere but cause it does not occur.”

That a supersaturation of the earth’s atmosphere with water vapor (molecules) has never been observed to occur is a fundamental physical science law.  And the result of this law is the factor known as the atmospheric dew point temperature.  Which is the temperature of the atmosphere at which its water vapor content begins to condense.

In Figure A we see the values of measured atmosphere’s dew point temperatures compared with the values of the measured fuel moisture contents in the fuel stick’s interior.  As can be seen, with some effort because of the lack of vertical gridlines, there is a tendency for the fuel moisture content to increase as the atmosphere’s dew point temperature decreases and vice versa.

Nor is it is easy to see that the times of the most rapid changes are shortly after sunrise.  And I point to the last 3 sunrises after which the fuel moisture content decreases from near its maximum value to near its minimum value during a period of only two hours.

I do this so you will not miss how rapidly the water molecules must be diffusing through the solid wood during this brief period. And therefore not consider of how rapidly water molecules might diffuse through the atmosphere relative to through solid wood.  About which mechanism of water vapor transfer through the atmosphere, to beat a dead horse, I have never read.

There is more information to be gleaned from Figure A to which I point to insure you do not miss it. It is that during the last three nights there is a time when the increase of the fuel moisture content abruptly decreases.  We need to ask:  Why?

To answer this question we need to study the data of Figure B and the data of the dew point temperatures of Figure A.  From Figure B it is obvious that both the measured fuel and surface temperatures decrease below the measured dew point temperatures of Figure A.

Hence, we are forced to conclude, because of the law that the atmosphere has never been observed to be supersaturated with water vapor, that dew forms on the surface of the field stick and the other surfaces exposed to a cloudless nighttime atmosphere.  This explains why the dew point temperatures steady decrease as the dew, which forms, removes water vapor from the atmosphere.

So most everything, according to the measured data, fits except why is the data (Figure A) of the first two daytimes and nighttimes obviously different from that of the last three?  We (I) should not walk away from an observed problem like this.

There is abundant evidence (too much to review here) that during 10/14 and 10/15 there was a somewhat consistent, stronger than normal, dry wind which ‘dried out’ the soil’s upper two layers.  Then after this dry wind decreased, it took a day for moisture from the third deeper soil layer’s moisture reservoir to diffuse upward to replenish the moisture content of the top two layers.

Now, we should not forget to note that the decrease of maximum temperatures (Figure B) of the last three days is likely due to the dew which needs to be evaporated during the morning by the solar radiation.  Which (radiation) otherwise could have been warming the surface and the soil beneath.

To summarize the important consequences of these measurements at this natural laboratory would require an extensive historical review of the idea known of the greenhouse effect.  This summary and review will eventually be done in Part 3 if your comments to this essay are not sufficient to accomplish this.

*Diamond, H. J., T. R. Karl, M. A. Palecki, C. B. Baker, J. E. Bell, R. D. Leeper, D. R. Easterling, J. H. Lawrimore, T. P. Meyers, M. R. Helfert, G. Goodge, and P. W. Thorne, 2013: U.S. Climate Reference Network after one decade of operations: status and assessment. Bull. Amer. Meteor. Soc., 94, 489-498.
doi: 10.1175/BAMS-D-12-00170.1

*Bell, J. E., M. A. Palecki, C. B. Baker, W. G. Collins, J. H. Lawrimore, R. D. Leeper, M. E. Hall, J. Kochendorfer, T. P. Meyers, T. Wilson, and H. J. Diamond. 2013: U.S. Climate Reference Network soil moisture and temperature observations. J. Hydrometeorol., 14, 977-988.
doi: 10.1175/JHM-D-12-0146.1

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