Natural ventilation effects on temperatures within Stevenson screens

Harrison, Richard G.

doi:10.1002/qj.537

Cited by 29 publications

(35 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The values of T z t are subtracted from T sa , giving T bias , which during nighttime periods (no solar radiation) is calculated to be 2 • C. The nighttime bias is removed from T bias , which is then regressed against the incoming shortwave radiation (K down ) within a www.the-cryosphere.net/11/2897/2017/ The Cryosphere, 11, 2897-2918, 2017 set of given ranges of measured wind speed (see below). The rationale here is that, for a given K down , the higher the wind speed, the more efficient the natural ventilation of the sensor, leading to smaller T bias (e.g., Harrison, 2010). The linear regression, applied on the 2012 data, yields the following relationship between T bias and K down :…”

Section: Uncertainty Analysismentioning

confidence: 99%

Evaluation of different methods to model near-surface turbulent fluxes for a mountain glacier in the Cariboo Mountains, BC, Canada

et al. 2017

View full text Add to dashboard Cite

Abstract. As part of surface energy balance models used to simulate glacier melting, choosing parameterizations to adequately estimate turbulent heat fluxes is extremely challenging. This study aims to evaluate a set of four aerodynamic bulk methods (labeled as C methods), commonly used to estimate turbulent heat fluxes for a sloped glacier surface, and two less commonly used bulk methods developed from katabatic flow models. The C methods differ in their parameterizations of the bulk exchange coefficient that relates the fluxes to the near-surface measurements of mean wind speed, air temperature, and humidity. The methods' performance in simulating 30 min sensible-and latent-heat fluxes is evaluated against the measured fluxes from an open-path eddycovariance (OPEC) method. The evaluation is performed at a point scale of a mountain glacier, using one-level meteorological and OPEC observations from multi-day periods in the 2010 and 2012 summer seasons. The analysis of the two independent seasons yielded the same key findings, which include the following: first, the bulk method, with or without the commonly used Monin-Obukhov (M-O) stability functions, overestimates the turbulent heat fluxes over the observational period, mainly due to a substantial overestimation of the friction velocity. This overestimation is most pronounced during the katabatic flow conditions, corroborating the previous findings that the M-O theory works poorly in the presence of a low wind speed maximum. Second, the method based on a katabatic flow model (labeled as the K Int method) outperforms any C method in simulating the friction velocity; however, the C methods outperform the K Int method in simulating the sensible-heat fluxes. Third, the best overall performance is given by a hybrid method, which combines the K Int approach with the C method; i.e., it parameterizes eddy viscosity differently than eddy diffusivity. An error analysis reveals that the uncertainties in the measured meteorological variables and the roughness lengths produce errors in the modeled fluxes that are smaller than the differences between the modeled and observed fluxes. This implies that further advances will require improvement to model theory rather than better measurements of input variables. Further data from different glaciers are needed to investigate any universality of these findings.

show abstract

Section: Uncertainty Analysismentioning

confidence: 99%

Evaluation of different methods to model near-surface turbulent fluxes for a mountain glacier in the Cariboo Mountains, BC, Canada

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Using the methodology described in detail previously (Harrison, 2010), an experiment to compare temperatures measured inside a large thermometer screen with those measured in the adjacent open air was undertaken during summer 2010 at the Reading University Atmospheric Observatory. In brief, a fine wire platinum resistance thermometer system (Harrison and Pedder, 2001;Harrison and Rogers, 2006) was standardized to the large thermometer screen sensor using 5 min average values over at least two diurnal cycles.…”

Section: Outline Methodologymentioning

confidence: 99%

“…• C (Harrison, 2010). Differences, T diff , between the open-air thermometer temperature, T open , and screen temperature, T scrn , were determined, together with coincident colocated measurements of wind speed † at 2 m, u 2 , direct beam irradiance, S b , and global solar irradiance, S g .…”

Section: Outline Methodologymentioning

confidence: 99%

“…In part this may arise from the effect of ventilation on screen lag time, slowing the response of the screen thermometer sufficiently to prevent it responding accurately to air temperature variations. Hence, at sites having low wind speeds around the diurnal minimum in air temperature, screen minimum temperatures may not fall to the actual air temperature minimum, which presents a systematic effect slightly modifying both the diurnal temperature range observed and the derived mean temperature (Harrison, 2010).…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Lag‐time effects on a naturally ventilated large thermometer screen

Harrison

2011

Quart J Royal Meteoro Soc

Self Cite

View full text Add to dashboard Cite

“…Even if they were, any calibration adjustment documentation is either unavailable or not easily accessible. Even the present day standard of a screened thermometer may still contain biases compared to the "true" WMO recommended standard of shaded free air temperature (WMO, 1992(WMO, , 1998Harrison, 2011Harrison, , 2010. However, for analysis of changes in climate, achieving this WMO standard is less important than the long-term continuity of a given station and its practices.…”

Section: Introductionmentioning

confidence: 99%

A framework for benchmarking of homogenisation algorithm performance on the global scale

Willett

Williams

Jolliffe

et al. 2014

Geosci. Instrum. Method. Data Syst.

View full text Add to dashboard Cite

Abstract. The International Surface Temperature Initiative (ISTI) is striving towards substantively improving our ability to robustly understand historical land surface air temperature change at all scales. A key recently completed first step has been collating all available records into a comprehensive open access, traceable and version-controlled databank. The crucial next step is to maximise the value of the collated data through a robust international framework of benchmarking and assessment for product intercomparison and uncertainty estimation. We focus on uncertainties arising from the presence of inhomogeneities in monthly mean land surface temperature data and the varied methodological choices made by various groups in building homogeneous temperature products. The central facet of the benchmarking process is the creation of global-scale synthetic analogues to the real-world database where both the "true" series and inhomogeneities are known (a luxury the real-world data do not afford us). Hence, algorithmic strengths and weaknesses can be meaningfully quantified and conditional inferences made about the real-world climate system. Here we discuss the necessary framework for developing an international homogenisation benchmarking system on the global scale for monthly mean temperatures. The value of this framework is critically dependent upon the number of groups taking part and so we strongly advocate involvement in the benchmarking exercise from as many data analyst groups as possible to make the best use of this substantial effort.Published by Copernicus Publications on behalf of the European Geosciences Union.

show abstract

Natural ventilation effects on temperatures within Stevenson screens

Cited by 29 publications

References 15 publications

Evaluation of different methods to model near-surface turbulent fluxes for a mountain glacier in the Cariboo Mountains, BC, Canada

Evaluation of different methods to model near-surface turbulent fluxes for a mountain glacier in the Cariboo Mountains, BC, Canada

Lag‐time effects on a naturally ventilated large thermometer screen

A framework for benchmarking of homogenisation algorithm performance on the global scale

Contact Info

Product

Resources

About