Micro-meteorology

First order parameters affecting dispersion stem from meteorological conditions. These, as much as any other consideration, determine how a stack is to be designed for air pollution control purposes. Since the operant transport mechanisms are determined by the micro-meteorological conditions, any attempt to predict ground-level pollutant concentrations is dependent on a reasonable estimate of the convective and dispersive potential of the local air. The following are meteorological conditions which need to be determined ... 

Because of extreme venting conditions assumed, effective stack heights and resultant plumes from both 3- and 5-minute discharge conditions attain heights beyond the micro-meteorological conditions assumed in accepted computation models. It is therefore highly probable there will be considerably further atmospheric dispersion and diffusion of the VCM than predicted in the results shown. That is, the ground level concentration can be expected to be considerably lower than the values shown in Table 6. 

The two approaches give effectively the same results. For example, the average HNO3 deposition velocity measured by micro-meteorological methods above a forest in east Tennessee or on summer... 

To develop our novel micro-meteorological instruments, we used a large cow-pasture east of Pasadena, which gently sloped up toward the San Gabriel mountains. We had a favorite demonstration of katabatic wind. We had a pole with eight wind vanes spaced about every half meter apart. In the afternoon, the sea breeze caused all the wind vanes to point toward the Pacific Ocean. As sunset approached, first the lowest wind vane on our pole turned and pointed toward the mountain as a shallow current of cold air flowed downhill. Somewhat later the second vane turned, then the third, fourth, fifth, sixth, seventh, and finally the eighth turned as the katabatic wind built up to be a deep gentle flow of cold air. Before sunset, we could almost tell the time of day by how many wind vanes pointed uphill. 

We set up the micro-meteorological instruments just above the high-water line on the beach. Part of our job was to explore the area and provide a written report of its terrain and vegetation. It was only a two-man job to read the meters and write down the values so a couple of us would attend to the instruments and the others could hike, fish or swim (swimmers found the water to be cold). Around the harbor there was an unfamiliar and amazing forest of giant eucalyptus trees. A hike up the dirt road that went inland provided us with a view of the owner s house in the distance. We broke into groups to explore and write descriptions of the nearby land. 

The purpose of the Berkeley project was to understand how gas clouds traveled and dissipated over various terrains and micro-meteorological conditions. They developed new instruments to make such studies. If an electrical current flows through a platinum wire, it may become red hot, and its temperature was easily measured. If air flowed over the hot wire, its temperature was lowered, and the faster the air flows the more the temperature is lowered. The Berkeley group measured wind speed by use of this hot-wire anemometer. If air contains some butane, for example, the hot platinum wire burns the butane, and the heat of combustion causes... 

When we arrived at Mt. Shasta, Buck s number one assistant was Clive Countryman, an expert in micro-meteorology and the associated measurements. He was a very quiet fellow but quite smart and 100% devoted to business. He stuttered rather badly which added to his quiet demeanor. Ruben, recognizing his worth, hired him immediately. He stayed with us until after Panama. I cannot find him in the phone book but will see if the forestry department has any record of him. 

I worked only on the micro-meteorological studies. The work for other NDRC workers was not so easy, as illustrated by this write-up by Arthur Pardee ... 

I had a long talk with Jake Nolen. I pointed out that in the fall we had taken micro-meteorological measurements in the meadow and in the forest, but the measurements in the forest were not meaningful since the observations... 

Figure 4.3. Micro-Meteorological Tower, Withlacoochee Hammock, Florida, 1944 5. Picture by Army photographer, July 1944.

Almost without exception the micro-meteorological equipment used on the Project has been designed and furnished by Division 10. Four men from the Division have been busy working with the Meteorological... 

Late in the war, a group tested the dispersion of DDT as an aerosol in the meadows and especially in the forest. We made day and night micro-meteorological measurements for them. 

A. Bob Mills setting up micro-meteorological B. Bob commuting between stations on bike equipment, early morning, long shadows. Dry Lake brush in background. 

As NEP is often small relative to the gross fluxes of photosynthesis and ecosystem respiration, the net flux is sometimes less than the error of measurement. More important than error is bias, and the approach is vulnerable to bias because both the fluxes of CO2 and the micro-meteorological conditions are systematically different day and night. Wind speeds below 17 cm s in a temperate zone forest, e.g., resulted in an underestimate of nighttime respiration (Barford et al., 2001). A similar relationship between nighttime wind speed and respiration in forests in the Brazilian Amazon suggests that the assumption that lateral transport is unimportant may have been invalid (Miller et al., in press). 

Measurements using flux chambers and micro-meteorological techniques are the most numerous (see special section of J. Geophys. Res. 104(017), 1999). As noted in Section 9.04.2, Kinsman and... 

Broecker, W. S., J. R. Ledwell, T. Takahashi et al. (1986) Isotopic versus micro-meteorologic ocean CO2 fluxes a serious conflict. J. Geophys. Res. 91, 10 517-27. 

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