Interpreting seasonal convective mixing in Devils Hole, Death Valley National Park, from temperature profiles observed by fiber‐optic distributed temperature sensing

Hausner, Mark B.; Wilson, Kevin P.; Gaines, D. Bailey; Tyler, S. W.

doi:10.1029/2011wr010972

Cited by 14 publications

(12 citation statements)

References 24 publications

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“…Temperature measurements to -34 m in DH indicate that cold surface waters sink during the winter months, causing vertical convective mixing (11). This finding, however, is hardly relevant for our model because the roof collapse that opened DH to the surface occurred 60,000 years ago (12); thus, modern winter conditions in DH are not analogous to the conditions that existed during TII.…”

mentioning

confidence: 41%

Response to Comments on “Reconciliation of the Devils Hole climate record with orbital forcing”

Moseley

Dublyansky

Edwards

et al. 2016

Science

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Winograd and Coplen question the thorium-230 distribution model proposed to explain the age bias observed with increasing depth during Termination II. We have evaluated both criticisms and find that all samples display virtually identical fabrics, argue that the modern setting is not analogous to the conditions during Termination II, and reiterate the robustness of our age models. Our conclusions remain unchanged. In their Comments on our Report (1), Winograd (2) and Coplen (3) Th onto calcite at the cave walls thus results in increasingly erroneously old 230 Th ages with depth. Similar to the oceans, it is possible that changes with time in the total sediment flux affected the radionuclide flux (5, 9) and intensity of scavenging (9), hence providing a mechanism for the greater age biases observed during glacial terminations (1).Winograd Th concentration with depth (2), whereas Coplen questions the steepness of the 230 Th gradient (3). Winograd's qualitative arguments are based on (i) temperature surveys in DH that suggest that convection occurs in winter and stratification in summer along with "horizontal groundwater flow" (11); (ii) low vertical thermal gradients characteristic of upward flow of geothermal water within fault zones; (iii) chemical homogeneity between 5 and 37.5 m depth (12); (iv) the difference between air and water temperatures; and, finally, (v) a statement about water transit times. Several lines of reasoning argue against these points.Temperature measurements to -34 m in DH indicate that cold surface waters sink during the winter months, causing vertical convective mixing (11). This finding, however, is hardly relevant for our model because the roof collapse that opened DH to the surface occurred 60,000 years ago (12); thus, modern winter conditions in DH are not analogous to the conditions that existed during TII. DH-2, which remains relatively enclosed with only two small (several m 2 ) openings, provides the closest modern analog for TII conditions; however, detailed studies of the water column have not yet been conducted. Observations in DH during the summer, when the air temperature is closer to that of the water, are thus the closest available analog to TII conditions, and these indicate very precisely the presence of a stable, stratified water column with a temperature gradient of 0.005°C m −1 (11) (i.e., no convective mixing). Winograd et al. (10) estimated the transit time of water recharging~80 km away and discharging at DH to be less than 2000 years. Based on these numbers, the transit time between the caves (5 years) was calculated to be within 230 Th age uncertainties (1); hence, differences in age for a specific event are unlikely to be caused by leads and lags in the arrival of the water. The transit time between the two caves may, however, be variable, and had it ever exceeded 230 Th age uncertainties (1), then the d 18O time series for DH, which is downstream, should lag DH-2 [note that the flow direction is incorrect in (2)]. In fact, the data demonstrate the exact oppos...

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mentioning

confidence: 41%

Response to Comments on “Reconciliation of the Devils Hole climate record with orbital forcing”

Moseley

Dublyansky

Edwards

et al. 2016

Science

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“…For each time step, the following calibration was applied to the raw data ( T raw ):

T_{calib} ((), l) = T_{raw} ((), l) - ((), η \frac{x - x_{0}}{L_{s e p}} + ξ)

where

ξ = true {\overset{T}{true}}_{raw} ((), l_{1 a} \leq italic l \leq l_{1 b}) - T_{logger}

η = true {\overset{T}{true}}_{raw} ((), l_{2 a} \leq italicl \leq l_{2 b}) - true {\overset{T}{true}}_{raw} ((), l_{1 a} \leq l \leq l_{1 b})

x refers to length along the fibre‐optic cable and x 0 is the appropriate offset for the beginning of the coiled data with respect to the sections of cable in the calibration bath. Following the recommendations of Hausner et al (), the raw forward and reverse Stokes and anti‐Stokes data were inspected for step losses caused by cable damage. Some natural step losses were observed along the cable at the expected locations where there is a clear temperature contrast such as the boundary between air‐exposed and water‐exposed portions (Hausner et al, ).…”

Section: Methodsmentioning

confidence: 99%

Improved spatial delineation of streambed properties and water fluxes using distributed temperature sensing

Halloran

Roshan

Rau

et al. 2016

Hydrological Processes

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A new method was developed for analysing and delineating streambed water fluxes, flow conditions and hydraulic properties using coiled fibre-optic distributed temperature sensing or closely spaced discrete temperature sensors. This method allows for a thorough treatment of the spatial information embedded in temperature data by creating a matrix visualization of all possible sensor pairs. Application of the method to a 5-day field dataset reveals the complexity of shallow streambed thermal regimes. To understand how velocity estimates are affected by violations of assumptions of one-dimensional, saturated, homogeneous flow and to aid in the interpretation of field observations, the method was also applied to temperature data generated by numerical models of common field conditions: horizontal layering, presence of lateral flow and variable streambed saturation. The results show that each condition creates a distinct signature visible in the triangular matrices. The matrices are used to perform a comparison of the behaviour of one-dimensional analytical heat-tracing models. The results show that the amplitude ratio-based method of velocity calculation leads to the most reliable estimates. The minimum sensor spacing required to obtain reliable velocity estimates with discrete sensors is also investigated using field data. The developed method will aid future heat-tracing studies by providing a technique for visualizing and comparing results from fibre-optic distributed temperature sensing installations and testing the robustness of analytical heat-tracing models.

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“…Field data were collected 23–24 June 2010, using a fiber‐optic DTS and meteorological monitoring equipment. DTS instrumentation has been used extensively in hydrological studies (Selker et al 2006; Westhoff et al 2011; Suárez et al 2011b), and DTS data have informed previous models of convection in engineered systems (Suárez et al 2011a) and in Devils Hole (Hausner et al 2012). The meteorological data were compared with a meteorological monitoring station operated onsite by the National Park Service.…”

Section: Methodsmentioning

confidence: 99%

The shallow thermal regime of Devils Hole, Death Valley National Park

Hausner

Wilson²,

Gaines³

et al. 2013

Limn Fluids and Environments

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Lay Abstract Devils Hole is an open, water‐filled fault in Ash Meadows National Wildlife Refuge that is home to the world's only population of endangered Devils Hole pupfish (Cyprinodon diabolis). In 1995, the population of Devils Hole pupfish began to decline, and to date no single cause for this decline has been identified. This article examines the influence of water temperature on the Devils Hole pupfish population by considering a part of the habitat that is critical to the pupfish's reproductive cycle: the shallow shelf at the south end of the pool. A mathematical model of the shallow shelf is used to examine the daily patterns of water flow and temperature change that result from the daily cycles of air temperature and solar radiation. The model matches well the data collected during this and other studies and shows that the shallow shelf of Devils Hole will respond to small changes in air temperature. Over the past 30 years, the southwestern United States has experienced an increase of up to 2 °C in average air temperature, and this increase has the potential to negatively affect the population of Devils Hole pupfish. The changes in local climate over this time period may have contributed to the decline of the Devils Hole pupfish population.

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Interpreting seasonal convective mixing in Devils Hole, Death Valley National Park, from temperature profiles observed by fiber‐optic distributed temperature sensing

Cited by 14 publications

References 24 publications

Response to Comments on “Reconciliation of the Devils Hole climate record with orbital forcing”

Response to Comments on “Reconciliation of the Devils Hole climate record with orbital forcing”

Improved spatial delineation of streambed properties and water fluxes using distributed temperature sensing

The shallow thermal regime of Devils Hole, Death Valley National Park

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