{"title":"Accuracy of daily extreme air temperatures under natural variations in thermometer screen ventilation","authors":"R. Giles Harrison, Stephen D. Burt","doi":"10.1002/asl.1256","DOIUrl":null,"url":null,"abstract":"<p>Accurate air temperatures underpin environmental research. Most professional meteorological air temperature measurements still expose thermometers within traditional, naturally ventilated screens. Their representation of true air temperature depends on screen airflow, and therefore local winds. Accuracies of daily maximum (<i>T</i><sub>max</sub>) and minimum (<i>T</i><sub>min</sub>) air temperatures are assessed by comparison between a naturally ventilated large conventional screen and a co-located aspirated reference screen. In over 1200 days' data, the naturally ventilated <i>T</i><sub>min</sub> and <i>T</i><sub>max</sub> both showed small (median < 0.06°C) cold bias, but, in 1% of cases, warm <i>T</i><sub>max</sub> bias and cold <i>T</i><sub>min</sub> bias >|1°C|. The <i>T</i><sub>min</sub> cold bias is associated with calm clear nights, and the <i>T</i><sub>max</sub> warm bias events with calm winter days at low sun angles, allowing solar heating of the screen. The prevalence of poor natural ventilation, potentially affecting <i>T</i><sub>min</sub> and <i>T</i><sub>max</sub>, is estimated across European sites. Poor ventilation occurred at <i>T</i><sub>min</sub> for 12% of values, and at <i>T</i><sub>max</sub> for 4%. Climatological averaging will reduce these effects, but, without corroborating wind data, statistical changes in <i>T</i><sub>min</sub> or <i>T</i><sub>max</sub>, including identifying “Tropical Nights” (<i>T</i><sub>min</sub> > 20°C) or occurrences of winter extremes, may have limited value. Wider adoption of aspirated thermometer screens, with an initial overlap period, will largely eliminate these effects.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"25 10","pages":""},"PeriodicalIF":2.0000,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1256","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Atmospheric Science Letters","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/asl.1256","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"METEOROLOGY & ATMOSPHERIC SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Accurate air temperatures underpin environmental research. Most professional meteorological air temperature measurements still expose thermometers within traditional, naturally ventilated screens. Their representation of true air temperature depends on screen airflow, and therefore local winds. Accuracies of daily maximum (Tmax) and minimum (Tmin) air temperatures are assessed by comparison between a naturally ventilated large conventional screen and a co-located aspirated reference screen. In over 1200 days' data, the naturally ventilated Tmin and Tmax both showed small (median < 0.06°C) cold bias, but, in 1% of cases, warm Tmax bias and cold Tmin bias >|1°C|. The Tmin cold bias is associated with calm clear nights, and the Tmax warm bias events with calm winter days at low sun angles, allowing solar heating of the screen. The prevalence of poor natural ventilation, potentially affecting Tmin and Tmax, is estimated across European sites. Poor ventilation occurred at Tmin for 12% of values, and at Tmax for 4%. Climatological averaging will reduce these effects, but, without corroborating wind data, statistical changes in Tmin or Tmax, including identifying “Tropical Nights” (Tmin > 20°C) or occurrences of winter extremes, may have limited value. Wider adoption of aspirated thermometer screens, with an initial overlap period, will largely eliminate these effects.
期刊介绍:
Atmospheric Science Letters (ASL) is a wholly Open Access electronic journal. Its aim is to provide a fully peer reviewed publication route for new shorter contributions in the field of atmospheric and closely related sciences. Through its ability to publish shorter contributions more rapidly than conventional journals, ASL offers a framework that promotes new understanding and creates scientific debate - providing a platform for discussing scientific issues and techniques.
We encourage the presentation of multi-disciplinary work and contributions that utilise ideas and techniques from parallel areas. We particularly welcome contributions that maximise the visualisation capabilities offered by a purely on-line journal. ASL welcomes papers in the fields of: Dynamical meteorology; Ocean-atmosphere systems; Climate change, variability and impacts; New or improved observations from instrumentation; Hydrometeorology; Numerical weather prediction; Data assimilation and ensemble forecasting; Physical processes of the atmosphere; Land surface-atmosphere systems.