atmometer


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atmometer:

see evaporimeterevaporimeter
, instrument that measures the rate of evaporation of water into the atmosphere, sometimes called an atmometer. Evaporimeters are of two types, those that measure the evaporation rate from a free water surface and those that measure it from a continuously wet porous
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Atmometer

 

(in meteorology), an instrument for measuring evaporation from the surface of bodies of water and from the soil.

A floating atmometer of the GGI-3000 system (developed by the State Hydrological Institute) is used to measure evaporation from bodies of water in the USSR. It is a cylindrical metal vessel with a conical bottom filled with water; the area of the evaporating surface is 3,000 sq cm. During observation a volumetric burette is placed on a tube attached to the center of the vessel. The burette has an opening at the bottom, into which the water passes. The quantity of water evaporated is determined from the difference in the volumes of water taken up by the burette at two successive time intervals. Atmometers are used in the open sea to estimate the extent of evaporation from changes in the concentration of salts in sea water or from differences in its temperature (Shuleikin’s atmometer).

The GGI-500 atmometer is very widely used to measure evaporation from the soil. It consists of two cylindrical vessels, one inside the other, and a water-collecting vessel. The bottom of the inner cylinder has openings; the core sample is placed in it. The quantity of water evaporated is determined from the difference in weight of the sample as measured over two successive observation periods. Evaporating basins set into the ground, with an area of 20 sq m or more, are used to minimize the effect of the walls and bottom on the measurements.

REFERENCES

Sternzat, M. S. Meteorologicheskie pribory i nabliudeniia.Leningrad, 1968.
Kedrolivanskii, V. N., and M. S. Sternzat. Meteorologicheskie pribory.Leningrad, 1953.

S. I. NEPOMNIASHCHII

atmometer

[ət′mäm·əd·ər]
(engineering)
The general name for an instrument which measures the evaporation rate of water into the atmosphere. Also known as atmidometer; evaporation gage; evaporimeter.
References in periodicals archive ?
Landsat 7 with false color composite (bands 4, 3, and 2) indicates the atmometer locations and the nine yellow triangles show corn field sites (b).
Caption: Figure 3: Atmometer mounted in wooden post damaged by mice (a) and mounted on a metal post (b) at Volga site.
Research demonstrated that [ET.sub.r] estimated with atmometers was moderately correlated ([r.sup.2] = [+ or -]0.70) with weighing lysimeters values [35,36], strongly correlated (r = 0.90) with pan evaporation values [37, 38], and strongly correlated ([r.sup.2] = 0.92) with agrometeorological data values, for example, [39-43].
This is where atmometers may serve a purpose since they are simple and intuitive to use.
Atmometers. Three atmometers were used to measure daily [ET.sub.r].
All atmometers were covered with a number 54 green canvas which simulate evaporation rates of alfalfa reference crop.
The [K.sub.c] curves generated in this study for different corn fields (Figure 6) were multiplied by the [ET.sub.r] obtained from atmometers to estimate [ET.sub.a] ([ET.sub.a]-atm) and compare it with [ET.sub.a] estimated with the METRIC model ([ET.sub.a]-METRIC).
Daily values of [ET.sub.r] from atmometers ([ET.sub.r]-atm) varied from 0.5 to 10, 0.5 to 9.5, and 0.5 to 7.6 mm [day.sup.-1] for Brookings, Volga, and Oak Lake, respectively (Figure 4).
In this study METRIC was compared to atmometers, where the relationship between them was good ([r.sup.2] = 0.87) indicating that the METRIC model is a useful tool to estimate [ET.sub.a] at field scale.
Similar results ([r.sup.2] = [+ or -]0.85) were found in [ET.sub.r] measured with atmometers by other researchers [32, 65], although different [ET.sub.r] results (low [r.sup.2] = [+ or -]0.70) were reported by Chen and Robinson [66] and Lamine et al.
The objective was to compare [ET.sub.a] estimated from satellite-based remote sensing METRIC model to [ET.sub.a] estimated with atmometers.
The [ET.sub.a] values derived from METRIC were higher than [ET.sub.a] values estimated with atmometers. However, the [ET.sub.a]-METRIC and [ET.sub.a]-atm correlated well with coefficient of determination ([r.sup.2]) of 0.87 and index of agreement ("d") of 0.84.