Feasibility of soil moisture monitoring with heated fiber optics

Sayde, Chadi; Gregory, Christopher; Gil-Rodríguez, María; Tufillaro, Nick; Tyler, S. W.; Giesen, Nick van de; English, Marshall; Cuenca, Richard H.; Selker, John S.

doi:10.1029/2009wr007846

Cited by 194 publications

(205 citation statements)

References 42 publications

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“…Applications vary from temperature profiling of the subsurface: borehole observations (Freifeld et al, 2008), soils (Ciocca et al, 2012;Jansen et al, 2011;Sayde et al, 2010;Steele-Dunne et al, 2010); water: estuaries (Henderson et al, 2009), surface/groundwater (Lowry et al, 2007;Mamer and Lowry, 2013), solar ponds , streams (Selker et al, 2006;Vogt et al, 2010;Westhoff et al, 2007Westhoff et al, , 2011 and lakes (Vercauteren et al, 2011;van Emmerik et al, 2013); rocks (Read et al, 2013), ice caves (Curtis and Kyle, 2011), forests (Krause et al, 2013) and infrastructure: dam surveillance (Dornstadter, 1998), sewers , electric transmission cables (Yilmaz and Karlik, 2006) and gas pipelines (Tanimola and Hill, 2009).…”

Section: Introductionmentioning

confidence: 99%

Fiber optic distributed temperature sensing for the determination of air temperature

2015

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Abstract. This paper describes a method to correct for the effect of solar radiation in atmospheric distributed temperature sensing (DTS) applications. By using two cables with different diameters, one can determine what temperature a zero diameter cable would have. Such a virtual cable would not be affected by solar heating and would take on the temperature of the surrounding air. With two unshielded cable pairs, one black pair and one white pair, good results were obtained given the general consensus that shielding is needed to avoid radiation errors (WMO, 2010). The correlations between standard air temperature measurements and air temperatures derived from both cables of colors had a high correlation coefficient (r 2 = 0.99) and a RMSE of 0.38 • C, compared to a RMSE of 2.40 • C for a 3.0 mm uncorrected black cable. A thin white cable measured temperatures that were close to air temperature measured with a nearby shielded thermometer (RMSE of 0.61 • C). The temperatures were measured along horizontal cables with an eye to temperature measurements in urban areas, but the same method can be applied to any atmospheric DTS measurements, and for profile measurements along towers or with balloons and quadcopters.

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Section: Introductionmentioning

confidence: 99%

Fiber optic distributed temperature sensing for the determination of air temperature

2015

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“…[3] Recent applications of DTS include lake bottom temperatures, mine shaft temperature profiles, glacier air snow interface profiles, lake air water interface temperatures, borehole circulation [Freifeld et al, 2008], snow hydrology , soil moisture studies [Sayde et al, 2010;SteeleDunne et al, 2010], land surface energy exchanges, and temperature distributions along streams [Selker et al, 2006a]. Additionally, these DTS data have been used to quantify groundwater inflows in streams [Selker et al, 2006b], test temperature model predictions [Westhoff et al, 2007], measure snowpack base temperatures , and measure the groundwater component of a tidal system on a salt marsh [Moffett et al, 2008].…”

Section: Introductionmentioning

confidence: 99%

Solar radiative heating of fiber‐optic cables used to monitor temperatures in water

Neilson

Hatch

Ban

et al. 2010

Water Resources Research

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[1] In recent years, applications of distributed temperature sensing (DTS) have increased in number and diversity. Because fiber-optic cables used for DTS are typically sheathed in dark UV-resistant materials, the question arises as to how shortwave solar radiation penetrating a water column influences the accuracy of absolute DTS-derived temperatures in aquatic applications. To quantify these effects, we completed a modeling effort that accounts for the effects of radiation and convection on a submersed cable to predict when solar heating may be important. Results indicate that for cables installed at shallow depths in clear, low-velocity water bodies, measurable heating of the cable is likely during peak solar radiation. However, at higher velocities, increased turbidity and/or greater depths, the effects of solar heating are immeasurable. A field study illustrated the effects of solar radiation by installing two types of fiber-optic cable at multiple water depths (from 0.05 to 0.8 m) in the center and along the sidewall of a trapezoidal canal. Thermistors were installed at similar depths and shielded from solar radiation to record absolute water temperatures. During peak radiation, thermistor data showed small temperature differences (∼0.003°C-0.04°C) between depths suggesting minor thermal stratification in the canal center. DTS data from cables at these same depths show differences of 0.01°C-0.17°C. The DTS differences cannot be explained by stratification alone and are likely evidence of additional heating from solar radiation. Sidewall thermistor strings also recorded stratification. However, corresponding DTS data suggested that bed conduction overwhelmed the effects of solar radiation.

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“…Additionally, for active deployments the fiber-optic cable must have metal components to enable thermal resistance heating via application of electrical currents. The voltage may be applied either across the steel armor or across supplementary copper wires (Freifeld et al, 2008;Sayde et al, 2010). Heating of the fiber-optic cable via the steel armor is suitable for short fiber-optic cable sections up to 250 m, whereas heating via copper wires is suitable for longer fiber-optic cable sections.…”

Section: Cable Considerationsmentioning

confidence: 99%

“…They may be employed to investigate hydrologic systems (Selker et al, 2006a), stream dynamics (Selker et al, 2006b), groundwater-surface water interactions (Slater et al, 2010), atmospheric processes (Keller et al, 2011;Thomas et al, 2012) or soil moisture (Sayde et al, 2010;SteeleDunne et al, 2010;Striegl and Loheide II, 2012). Fiber-optic temperature measurements may also be used in engineering, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…This provides additional information, not only on (i) the background temperature of the fiber-optic cable prior to its heating, but on (ii) its heating and cooling behavior, which again reflects the conditions in the environment of the fiber-optic cable. So far, this technique has been used to investigate dam stability (Etzer et al, 2012), soil moisture (Sayde et al, 2010), and hyporheic zone processes (articles in preparation).…”

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confidence: 99%

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Autonomous distributed temperature sensing for long-term heated applications in remote areas

Kurth

Dawes

Selker

et al. 2013

Geosci. Instrum. Method. Data Syst.

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Abstract. Distributed temperature sensing (DTS) is a fiberoptical method enabling simultaneous temperature measurements over long distances. Electrical resistance heating of the metallic components of the fiber-optic cable provides information on the thermal characteristics of the cable's environment, providing valuable insight into processes occurring in the surrounding medium, such as groundwater-surface water interactions, dam stability or soil moisture. Until now, heated applications required direct handling of the DTS instrument by a researcher, rendering long-term investigations in remote areas impractical due to the often difficult and time-consuming access to the field site. Remote control and automation of the DTS instrument and heating processes, however, resolve the issue with difficult access. The data can also be remotely accessed and stored on a central database. The power supply can be grid independent, although significant infrastructure investment is required here due to high power consumption during heated applications. Solar energy must be sufficient even in worst case scenarios, e.g. during long periods of intense cloud cover, to prevent system failure due to energy shortage. In combination with storage batteries and a low heating frequency, e.g. once per day or once per week (depending on the season and the solar radiation on site), issues of high power consumption may be resolved. Safety regulations dictate adequate shielding and ground-fault protection, to safeguard animals and humans from electricity and laser sources. In this paper the autonomous DTS system is presented to allow research with heated applications of DTS in remote areas for long-term investigations of temperature distributions in the environment.

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Feasibility of soil moisture monitoring with heated fiber optics

Cited by 194 publications

References 42 publications

Fiber optic distributed temperature sensing for the determination of air temperature

Fiber optic distributed temperature sensing for the determination of air temperature

Solar radiative heating of fiber‐optic cables used to monitor temperatures in water

Autonomous distributed temperature sensing for long-term heated applications in remote areas

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