Measuring Earth's vital sign-temperature-in four dimensions

Throughout history, humans have instinctively observed temperature. Scientific progress in the earth sciences has leaped forward so that now improvements in the resolution of such observations can be made on spatial and temporal scales, as well as in multiple dimensions. For example, heat transport by groundwater has been used as a tracer to identify surface water infiltration, flow through fractures, and flow patterns in aquifers (Anderson, 2005). Temperature measurements are inexpensive and can be used to evaluate recharge and discharge rates, the interchange with surface water, the hydraulic conductivity of streambed sediments, and basin-scale permeability. Since the 1960s, when the fundamentals of tracing heat transport by groundwater were first published, work at a high resolution with advanced sensing technologies in multiple dimensions has significantly expanded its application to a variety of hydrogeological settings. This presentation will discuss advances in temperature observation based on several studies using a fiber-optic distributed temperature sensing (FO-DTS) system at the Managed Landscapes-Critical Zone Observatory (http://criticalzone.org/iml) and thermal response test (TRT) for geothermal exchange. One of the anticipated discussions during the presentation will be how to represent high-resolution data sets effectively in multiple dimensions (four and higher) for hydrogeology applications.