Lag-time effects on a naturally ventilated large thermometer screen
Lag-time effects on a naturally ventilated large thermometer screen
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DOI：
10.1002/qj.745
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发表时间：
2011-01-01
影响因子：
8.9
通讯作者：
Harrison, R. G.
中科院分区：
文献类型：
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作者：
Harrison, R. G.
在夏季条件下，使用校准良好的铂电阻温度计，研究了标准大型木制温度计屏幕内系统自然通风对测量温度的影响。在低通风量条件下(2 m风速u(2) < 1.1 m s(-1))，屏幕对白天气温的估计略低，但对夜间气温的估计过高0.2℃。屏幕滞后时间L随着风速的减小而延长，L与u(2)呈反幂律关系。对于u(2) > (2) m s(-1)， L近似于2.5 min，当风平浪静时，L增加到至少15 min。由于风速的滞后变化，筛网对气温波动的光谱响应特性也随风速的变化而变化。由于滞后效应和太阳能加热，通风效果在较高的温度下（bb0 - 25摄氏度）尤为明显。对于风速随白天温度升高而降低的地点，温度计屏幕温度在较高温度下可能显示较大的不确定性。在强烈的太阳直射束辐射（> 850瓦米（-2））下，辐射效应可能小于0.4摄氏度
Systematic natural ventilation effects on measured temperatures within a standard large wooden thermometer screen are investigated under summer conditions, using well-calibrated platinum resistance thermometers. Under low ventilation (2 m wind speed u(2) < 1.1 m s(-1)), the screen slightly underestimates daytime air temperature but overestimates air temperature nocturnally by 0.2 degrees C. The screen's lag time L lengthens with decreasing wind speed, following an inverse power law relationship between L and u(2). For u(2) > 2 m s(-1), L similar to 2.5 min, increasing, when calm, to at least 15 min. Spectral response properties of the screen to air temperature fluctuations vary with wind speed because of the lag changes. Ventilation effects are particularly apparent at the higher (> 25 degrees C) temperatures, both through the lag effect and from solar heating. For sites where wind speed decreases with increasing daytime temperature, thermometer screen temperatures may consequently show larger uncertainties at the higher temperatures. Under strong direct beam solar radiation (> 850 W m(-2)) the radiation effect is likely to be < 0.4 degrees C. Copyright (c) 2011 Royal Meteorological Society