Leaf Temperature Measurement I. Thermocouples*

Pieters, Guido; Schurer, K.

doi:10.1111/j.1438-8677.1973.tb00878.x

Cited by 21 publications

(5 citation statements)

References 6 publications

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“…These thermocouples were chosen because of their low cost, accuracy, and rapid response time (Tanner 1963), which was about one tenth that of the recorder. An added advantage of these sensors is their very small radiation error (Pieters and Schurer 1973), which largely eliminates the usual requirement for aspiration, particularly since temperature measurements were made during time periods when the lichens were wet, usually during cloudy conditions after rain.…”

Section: The Largestmentioning

confidence: 99%

Studies on lichen-dominated systems. VIII. The instrumentation of a raised-beach ridge for temperature and wind speed measurements

Field¹,

Larson²,

Kershaw³

1974

Can. J. Bot.

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KERSHAW. 1974. Studies on lichen-dominated systems. VI1I. The instrumentation of a raised-beach ridge for temperature and wind speed measurements. Can. J. Bot. 52: 1927Bot. 52: -1934. The instrumentation of a research site on a raised-beach ridge, 5 km inland from Hudson Bay, is described. Fine thermocouples and hot-film anemometers were used to measure air and thallus temperature, and wind speeds, respectively. Replicate sensors were monitored throu h automatic stepping switches of new design and strip chart recorders. The circuit diagram of tEe stepping switch is described. The satisfactory operation of the entire system indicates that it is not difficult to maintain this type of electronic equipment in remote sites and opens up considerable possibilities for ecological work in fairly inaccessible areas. FIELD, G., D. W. LARSON et K. A. KERSHAW. 1974. Studies on lichen-dominated systems.VlII. The instrumentation of a raised-beach ridge for temperature and wind speed rneasurements. Can. J. Bot. 52: 1927-1934. Les auteurs dCcrivent l'instrumentation d'une station de recherche situCe sur la cr&te d'une plage surClevCe situCe k 5 km du rivage de la baie #Hudson. Des thermocouples et des anCmomktres k film chauffC ont Ct C utilisCs pour mesurer respectivement la tempkrature de l'air et des thalles, ainsi que la vitesse du vent. Les lectures de senseurs multiples ont Ct C automatiquernent enregistrkes par des commutateurs k trCbuchet d'une conception nouvelle, ainsi que par des enregistreurs graphiques. Le dia amme du circuit d'un commutateur k trCbuchet est prCsentC.Le bon fonctionnement de tout $ systkme indique qu'il n'est pas difficile de rnaintenir ce type d'kquipement Clectronique dans des endroits CloignCs et offre d'intkressantes possibilitks pour les travaux Ccologiques dans les rCgions difficilernent accessibles.[Traduit par le journal] IntroductionThus any attempt to understand the physioIn a previous paper of this series (Kershaw and logical ecology of the two dominant speciks of Rouse 1973) the position of the Clndina alpestris these associations, Alectoria nitiduh and Clnditza association and the Alectoria nitiditla association nlpestris, necessitates, at least, measurements of was shown to be markedly correlated with posi-metabolically critical variables such as wind tion on older raised-beach ridges at the-Pen speed, thallus temperature, and air temperature Island research site.across the ridge profile under conditions of The variables controlling net CO2 assimilation diffuse radiation. in lichens are summarized in Fig. 1 . The largestAn important methodological consideration is proportion of assimilation occurs during and that the differential effects of these environmental after periods of rain when radiation is all diffuse parameters over the ridge profile will have been as a result of a heavy cloud cover. Under these integrated over a considerable time span, and if conditions there is little variation of radiation the gbsolute differences between t h e im~ortant across the ridge profile. The oth...

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Section: The Largestmentioning

confidence: 99%

Studies on lichen-dominated systems. VIII. The instrumentation of a raised-beach ridge for temperature and wind speed measurements

Field¹,

Larson²,

Kershaw³

1974

Can. J. Bot.

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“…However, errors may adse from thermal effects at the sensing junctions. Pieters and Schurer (1973) monitored artificial leaf temperatures in a ventilated and nonventilated chamber and found that radiative errors could be reduced to 0.1 K using wire of 0.025 mm diameter, and convective errors could be made less than 1 K by applying a slight constant force on the sensor.…”

Section: Thermocouples -----------------mentioning

confidence: 99%

Techniques for Thermocouple Placement and the Automation of Temperature Measurements in the Microenvironment of Kentucky Bluegrass¹

Welterlen¹,

Watschke

1981

Agronomy Journal

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A Kentucky bluegrass (Poa pratensis L.) sward is comprised of many closely spaced, minute plants forming a dense, low canopy. Measurements of soil and basal tiller temperatures require careful placement of many small sensors. The objectives of this research were to develop expedient methods for obtaining precise point measurements of tiller, thatch, and soil temperatures with thermocouples in the field. Measurements were made in ‘Touchdown’ Kentucky bluegrass mowed to 5 cm. Throughout the study, Chromel‐Alumel thermocouples were used. A 40‐channel, microprocessor‐based data acquisition system and a computer compatible nine‐track magnetic tape were used for uninterrupted data collection. Irradiance, measured approximately 1 km from the experimental site, and air temperature, sensed by an aspirated thermocouple located 1.5 m above the turf, were recorded simultaneous with sod temperature measurements. Thermocouples [20 AWG (0.81 mm)] placed horizontally and vertically, thermocouples [40 AWG (0.076 mm)] placed vertically, and thermocouples [40 AWG] fastened to 0.6 cm diameter wooden dowels were placed 2 cm below the thatch‐soil interface and compared for precision and placement expedience. Vertically placed fine‐gauged thermocouples (the most expedient means of installation) were as precise as the other methods. Although gauge did not influence precision in this test, in some situations (particularly vertical placement) the potential for error may exist due to heat flow along the wire. Two methods of thermocouple (40 AWG) placement into basal tillers were compared for expedience of placement and relative precision. In one method, thermocouples were threaded through the tiller base leaving the thermocouple bead inside the tiller with lead wire connection on opposite sides. The other method involved direct insertion into a hypodermic puncture in the tiller base. The inserted thermocouple method was found to be the most expedient, and no significant temperature differences were found between the methods. Tiller base temperatures measured in the field on a cloudy afternoon on 11 June 1979 ranged from 16.8 to 21.1 C, with a maximum difference of 0.6 C between the two methods (insignificant at the 0.05 level). The coefficients of variation for each method were not greater than 10.6. Temperatures measured during a clear afternoon on 12 June 1979 ranged from 23.1 to 31.5 C. At 1500 hours, the difference between the methods of placement was greatest (3.3 C) but was not significant at 0.05. The maximum coefficient of variation was 15.3 and 13.7 for the inserted and threaded thermocouples, respectively. Throughout the day, the threaded method had generally lower coefficients of variation.

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“…surface emissivity). Third, a large part of the thermocouple junction is exposed, leading to radiative and convective heat exchange with the environment and resulting in systematic errors up to several degrees, even for tiny 0.1 mm diameter junctions (Pieters & Schurer, 1973; Tarnopolsky & Seginer, 1999). Fourth, thermocouples sample only a small part of each given leaf, and large temperature gradients have previously been shown (Leigh et al ., 2017).…”

Section: Introductionmentioning

confidence: 99%

‘Dual‐reference’ method for high‐precision infrared measurement of leaf surface temperature under field conditions

et al. 2021

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Summary Temperature is a key control over biological activities from the cellular to the ecosystem scales. However, direct, high‐precision measurements of surface temperature of small objects, such as leaves, under field conditions with large variations in ambient conditions remain rare. Contact methods, such as thermocouples, are prone to large errors. The use of noncontact remote‐sensing methods, such as thermal infrared measurements, provides an ideal solution, but their accuracy has been low (c. 2°C) owing to the necessity for corrections for material emissivity and fluctuations in background radiation Lbg. A novel ‘dual‐reference’ method was developed to increase the accuracy of infrared needle‐leaf surface temperature measurements in the field. It accounts for variations in Lbg and corrects for the systematic camera offset using two reference plates. We accurately captured surface temperature and leaf‐to‐air temperature differences of needle‐leaves in a forest ecosystem with large diurnal and seasonal temperature fluctuations with an uncertainty of ± 0.23°C and ± 0.28°C, respectively. Routine high‐precision leaf temperature measurements even under harsh field conditions, such as demonstrated here, opens the way for investigating a wide range of leaf‐scale processes and their dynamics.

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Leaf Temperature Measurement I. Thermocouples*

Cited by 21 publications

References 6 publications

Studies on lichen-dominated systems. VIII. The instrumentation of a raised-beach ridge for temperature and wind speed measurements

Studies on lichen-dominated systems. VIII. The instrumentation of a raised-beach ridge for temperature and wind speed measurements

Techniques for Thermocouple Placement and the Automation of Temperature Measurements in the Microenvironment of Kentucky Bluegrass¹

‘Dual‐reference’ method for high‐precision infrared measurement of leaf surface temperature under field conditions

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Leaf Temperature Measurement I. Thermocouples*

Cited by 21 publications

References 6 publications

Studies on lichen-dominated systems. VIII. The instrumentation of a raised-beach ridge for temperature and wind speed measurements

Studies on lichen-dominated systems. VIII. The instrumentation of a raised-beach ridge for temperature and wind speed measurements

Techniques for Thermocouple Placement and the Automation of Temperature Measurements in the Microenvironment of Kentucky Bluegrass1

‘Dual‐reference’ method for high‐precision infrared measurement of leaf surface temperature under field conditions

Contact Info

Product

Resources

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Techniques for Thermocouple Placement and the Automation of Temperature Measurements in the Microenvironment of Kentucky Bluegrass¹