| Ce |
calibrated Brillouin frequency shift strain coefficient of the fiber ( T−1) |
| Cp(θ) |
soil heat capacity (ML2T−2Θ−1) |
| cS and caS |
Constants related to laser power and responsiveness of the DTS detectors (ML2T−2) |
| CT |
calibrated Brillouin frequency shift temperature coefficient (Θ−1 T−1) |
| Δα |
difference in attenuation factors between Stokes and anti−Stokes (L−1) |
| Δε |
change in strain (dimensionless, LL−1) |
| ΔvB |
change in Brillouin frequency (T−1) |
| ΔT |
change in temperature (Θ) |
| γ(θ) |
soil thermal conductivity (MLT−3Θ−1) |
| ħ |
reduced Planck’s constant (ML2T−1) |
| IaS |
measured photon intensity of anti−Stokes (ML2T−2) |
| Is |
measured photon intensity of Stokes (ML2T−2) |
| k |
Boltzmann constant (ML2T−2Θ−1) |
| λS and λaS |
wavelengths of the Raman shifted returning light (L) as discussed by Farahani and Gogolla (1999) |
| Ω |
frequency difference between Stokes and anti−Stokes scattering in typical fiber (T−1) |
| ρ |
water density (ML−3) |
| θ |
soil volumetric water content (dimensionless, (L3L−3) |
| z |
distance along the optical fiber (L) |
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