Vertical Profiles Of Air Temperature Research Articles

Variation of 222Rn Concentration in Outdoor Air due to Variation of the Atmospheric Boundary Layer

Variation of 222Rn concentration in outdoor air, returns of a monostatic acoustic sounder and sensible heat flux are simultaneously observed at Okayama-shi in Japan. The sensible heat flux is measured with an eddy correlation method using a sonic anemometer and a copper-constantan thermocouple thermometer. Using height of a surface-based inversion layer obtained by the acoustic sounder returns and two 222Rn concentrations during the presence of the surface-based inversion layer, the exhalation rate of 222Rn at this site is estimated to be about 0.01 Bq.m-2.s-1, which agrees well with the exhalation rate of 222Rn estimated at Nagoya-shi in Japan. Using the estimated exhalation rates of 222Rn and the variation of the 222Rn concentration in the daytime, heights of mixing layers are estimated. These heights of the mixing layers are larger than the height of the mixing layer estimated using the sensible heat flux and the representative vertical profile of the autumnal night time air temperature in this area.

Modelling the energy exchange processes between plant communities and environment

A steady-state, one dimensional simulation model based on the gradient diffusion approach is designed to predict the microclimate and properties of energy exchange processes between plant communities and their ambient environment. The architecture of the model is comprised of formulations of turbulent transfer, radiation distribution, and plant community energy balance. The driving forces are meteorological observations above the canopy and the necessary inputs are several geometrical, optical and ecophysiological properties of the community. The model output includes the vertical profiles of radiation, wind velocity, air and leaf temperature, humidity, source strength of heat and water vapor, and total sensible and latent heat fluxes, throughout the community. The results of simulation agree reasonably well with two sets of field measurements reported by other researchers.

DYNAMIC MODELING OF THE MICROCLIMATE OF A GREENHOUSE CUCUMBER ROW-CROP PART I. THEORETICAL MODEL

ABSTRACT A theoretical model of greenhouse microclimate was developed for describing heat and mass transport processes in a greenhouse row-crop stand, including radiation transfer, energy balance, transpiration and CO2 exchange. The canopy was described as a series of parallel rows with pseudo-rectangular cross-sections and variable architectural parameters. Radiation transfer, convective transport processes, and plant responses to environmental factors were formulated as functions of plant architecture, greenhouse structure and state variables of bulk air above the canopy. Each of the individual submodels was parameterized from experimental data for a dense row cucumber crop. The general theoretical considerations were assembled into a dynamic simulator by applying energy and mass balances simultaneously over differential strata of plant leaves and greenhouse air. Outputs of the simulator included both diurnal courses and vertical profiles of leaf temperature, air temperature, humidity and CO2 concentration in addition to energy and mass exchange.

The Microclimate and Transpiration of a Greenhouse Cucumber Crop

ABSTRACT Point source sensors and plant growth variables were used to characterize the microclimate of a greenhouse grown cucumber crop. Diurnal cycles and/or vertical profiles of solar radiation, air movement, leaf and air temperature, humidity, transpiration rate, and stomatal resistance, as well as plant architectural parameters were reported. Canopy leaf temperature with high solar radiation was found considerably lower than greenhouse air temperature due to high transpiration rate.

都市内河川が周辺の温熱環境に及ぼす効果に関する研究

This paper describes the results of field observation about the micro-climate in and around the Ota River flowing through Hiroshima City. Meteorological elements - air temperature, humidity, wind direction and velocity were measured at several stationary points, moving around the river by automobile or bicycle, and moving on foot within the river section along the bridge. These observations were conducted in each season at two sites having different river width and structure (with floodplain or not). According to the vertical profiles of air temperature from the water surface to the bridge, the river is considered as the heat source in cooler seasons and as the heat sink in warmer seasons to the air within the river section. The appearance of the obvious difference between air temperature on the bridge and surrounding built-up area is restricted in warmer seasons. Namely, the river seemingly acts only as the heat sink to the adjacent field in urban area. The drop in air temperature above the river in warmer seasons is proportional to the surface temperature difference between river water and asphalt pavement, and is also affected by the direction and velocity of the wind. Above the floodplain, the air temperature decreases sooner than in surrounding built-up area after sunset, so it is a suitable place to get a comfortable feeling of the evening cool in summer. The results of detailed air temperature measurement at a height of 1.5m along the street, which lies at right angle to the river, show that the discernible reduction in air temperature may be spread to the extent about 150〜500 m from the river. However, the most variation in air temperature occurs within about 10 m from the edge of water.

Thermal infrared survey of Aberdeen City: data processing, analysis and interpretation

Abstract The survey procedure and subsequent development of a microcomputer processing and analysis system adopted for a thermal survey of Aberdeen City is described. Thermal shadows on the imagery are shown to reflect air-mixing patterns at ground level and the sheltering effects of natural windbreaks, whereas canopy temperatures are related to vertical air-temperature profiles, thus enabling identification of frost hollows. Determination of heal loss from buildings was found to be problematical. The technique allows pollution sources and water-mixing patterns in river estuaries and nearshore zones to be identified.

安定接地気層の乱流構造の観測

The turbulent structure under stable conditions in the atmospheric boundary layer (ABL) has been investigated by tower measurements, of the turbulent fluctuations and vertical mean profiles of wind velocity and air temperature. The results are summarized as follows:(1) For the parameter of thickness of the turbulent ABL under stable conditions, the height hq at which turbulent heat flux disappears is a more reasonable choice than the height hθ derived from the potential temperature profile, and hq has linear relation to the Monin-Obukhov stability length.(2) Unlike the constant flux layer near the ground, the absolute values of vertical heat flux (q) and momentum flux (u*) decrease with height in the stable ABL.According to these results, the ABL model proposed by Yokoyama et al. (1977, 1979) is applied to the turbulent ABL under stable conditions. We conclude that the vertical profiles of q and u* are approximated by the power function ζm andζn, respectively (where, ζ=1-z/hq, z: height, hq: thickness of the layer, m _??_3/2, n _??_1/2) and the same relations which described the turbulence quantities, temperature and wind velocity gradients in the constant flux layer are valid for whole stable ABL by replacing surface values of q and u* by their local values.

Heat and Momentum Transfers under Strong Stability in the Atmospheric Surface Layer

Abstract Transfers of heat and momentum under strongly stable conditions in the atmospheric boundary layer have been studied through measurements of the turbulent fluctuations and vertical mean profiles of wind velocity and air temperature. As the local gradient Richardson number increases, intermittent turbulence appears, especially in temperature fluctuations. The ratio of the eddy conductivity to the eddy viscosity decreases with increasing Richardson number and tends to zero at high stabilities. The local value of the dimensionless shear function for wind velocity does not exceed a limit of about six. These results imply that the eddy viscosity for very stable conditions does not take the infinitesimally small value predicted from extrapolation of the so-called log-linear profile, and that the flux Richardson number has a limit in the range of 0.1–0.4, although the gradient Richardson number can become indefinitely large. It is also shown that the divergences of both the radiative and turbulent heat f...

Variations in oceanic net long-wave radiation caused by atmospheric thermal structure

Observations of clear sky net long-wave radiation at sites off Oregon and off northwest Africa were compared with vertical profiles of air temperature. Atmospheric thermal inversions appeared to reduce the net long-wave radiation by at least 0.02 cal cm−2 min−1. If empirical formulas are used to estimate the irradiance, account should be taken of this effect in regions with persistent inversions.

Topographic effects apparent in nocturnal temperature profiles in a conifer canopy

Vertical profiles of air temperature were measured through the canopy at a location on a forested mountain slope for two summer nights with light or no cloud cover, together with associated nocturnal sky radiation and windspeed. The temperature profiles show a local maximum well within the canopy. The behavior of this maximum on one of the nights with alternate cooling and warming on the slope indicates that it is due to subsidence heating caused by topographically induced divergence of the density flow in the canopy. The position and magnitude of the maximum are in approximate agreement with the estimated distribution of net radiation loss in the canopy and the measured windspeed.

Cold Air Drainage on a Forested Mountain Slope

Abstract The nocturnal cold airflow on a small forested slope was studied in an attempt to relate the volume and velocity of flow to the net radiation balance of the slope. The hillside, with an approximately 30% grade, was about 400 m long and covered with an uneven-aged spruce-fir stand of about 20 m height. The location was near Fraser, Colo., at an altitude of 3000 m. The vertical profiles of wind speed and air temperature were measured at various points on a transect approximating a streamline segment down the hill for several nights. Net radiation was measured at the base of the transect. Canopy closure and tree heights and diameters were measured on sample plots along the transect. The vertical profiles of potential temperature deficit and wind speed at the various stations show approximate similarity when scaled by the height of the lowest inversion and by the average velocities and potential temperature deficits below that inversion. The latter varies in a nearly linear manner down the slope, and...

Evaporation from Lake Kasumigaura

Observations on water evaporation were made in three seasons (summer, autumn in 1964, winter in 1965) at about 500m from the shore of Lake Kasumigaura. Data on vertical profiles of air temperature, wind velocity and specific humidity were processed on the basis of the profile method. As a result, estimated value for z0 was 0.22cm during seasons. Bowen's ratio ranged 0.01 to 0.31 in summer and -1.01 to 0.47 in autumn, respectively. The amounts of evaporation were about 10mm/day on Aug. 27, about 3mm/day on Oct. 29. Therefore in the case of Lake Kasumigaura, evaporation was greater in summer than in autumn. In comparison with the result reported by YAMAMOTO as to Lake Towada, our measurements show an inverse phase in the annual course of evaporation. This discrepancy in the phase seemed to be caused by the difference in the storage heat of water body between Towada and Kasumigaura Lakes.

On the Collecting Efficiency of Cloud Particles by Snow Crystals

Cloud droplets collected on snow crystals were observed by means of microscopic photograph method simultaneously with the measurement of size distribution of cloud particles which were suspended in free air at the top of Mt. Teine, Hokkaido in the winter seasons of 1959, 60 and 61. The falling path of snow crystals of various types ware estimated by the use of the vertical profile of air temperature and humidity and by the use of Nakaya's Ta-s diagram. The mean density and size distribution of cloud particles in the cloud through which the particles fell were assumed to be uniform with those which were observed at the mountain.From the data measured, following conclusions were reached : 1) The size distribution of cloud droplets collected on snow crystals always was larger than that in the free air.2) The efficiency of collection of cloud particles by snow crystals seemed to be much smaller than that calculated by Langmuir method.3) snow crystals of needle type showed fairly good efficiency of collection.The discrepancy in the collecting efficiency is considered to be due to the fact that the size distribution was not observed throughout a whole cloud layer but only near the cloud base.

THE MINUTE DIURNAL FLUCTUATION OF AIR TEMPERATURE AND ITS VERTICAL PROFILE IN A BUILT-UP AREA

The use of a thermistor has enabled to make close observation of the vertical profile of air tempera ture with great ease. Characterized with its high sensitivity, however, the instrument is accompanied with the minute fluctuation, which involves many problems in treating the data thus obtained. The author succeeded in drawing a curve of this fluctuation (Fig. 4) based on the frequent observations, and found that the curve was composed of periodic waves, large and small. (The lag of the thermistor is 3.5 seconds.) That is to say, it may be true that the minute fluctuation is caused by the turbulent flow in the lower atmosphere, and that each wave corresponds to respective eddy within the main stream. Thus, he tried to catch the vertical profile of air temperature in a builtup area from the viewpoint of the frequency with these eddies appear. The observation was made on the watchtower (35 meters in height) of the fire station at Takanohashi, Hiroshima City. Each form of the vertical profile of diurnal air temperature variation obtained by using the thermistor can be explained as a process in which the air warmed on the ground is ascending higher forming micro air masses. And the average results of many observations within a difinite time indicate that a.a plane of sudden change of air temperature lies at a height of about 15 meters (Fig. 6). This is due to the high frequecy of the warm micro air masses in the lower atomosphere within 15 meters in height, and may be explained by the influence of buildings (about 8-15 meters in height) and the vertical structure of the surface wind.