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DeWolf, S, Walker KT, Zumberge MA, Denis S.  2013.  Efficacy of spatial averaging of infrasonic pressure in varying wind speeds. Journal of the Acoustical Society of America. 133:3739-3750.   10.1121/1.4803891   AbstractWebsite

Wind noise reduction (WNR) is important in the measurement of infrasound. Spatial averaging theory led to the development of rosette pipe arrays. The efficacy of rosettes decreases with increasing wind speed and only provides a maximum of similar to 20 dB WNR due to a maximum size limitation. An Optical Fiber Infrasound Sensor (OFIS) reduces wind noise by instantaneously averaging infrasound along the sensor's length. In this study two experiments quantify the WNR achieved by rosettes and OFISs of various sizes and configurations. Specifically, it is shown that the WNR for a circular OFIS 18m in diameter is the same as a collocated 32-inlet pipe array of the same diameter. However, linear OFISs ranging in length from 30 to 270m provide a WNR of up to similar to 30 dB in winds up to 5m/s. The measured WNR is a logarithmic function of the OFIS length and depends on the orientation of the OFIS with respect to wind direction. OFISs oriented parallel to the wind direction achieve similar to 4 dB greater WNR than those oriented perpendicular to the wind. Analytical models for the rosette and OFIS are developed that predict the general observed relationships between wind noise reduction, frequency, and wind speed.

Landro, M, Zumberge M.  2017.  Estimating saturation and density changes caused by CO2 injection at Sleipner - Using time-lapse seismic amplitude-variation-with-offset and time-lapse gravity. Interpretation-a Journal of Subsurface Characterization. 5:T243-T257.   10.1190/int-2016-0120.1   AbstractWebsite

We have developed a calibrated, simple time-lapse seismic method for estimating saturation changes from the CO2-storage project at Sleipner offshore Norway. This seismic method works well to map changes when CO2 is migrating laterally away from the injection point. However, it is challenging to detect changes occurring below CO2 layers that have already been charged by some CO2. Not only is this partly caused by the seismic shadow effects, but also by the fact that the velocity sensitivity for CO2 change in saturation from 0.3 to 1.0 is significantly less than saturation changes from zero to 0.3. To circumvent the seismic shadow zone problem, we combine the time-lapse seismic method with time-lapse gravity measurements. This is done by a simple forward modeling of gravity changes based on the seismically derived saturation changes, letting these saturation changes be scaled by an arbitrary constant and then by minimizing the least-squares error to obtain the best fit between the scaled saturation changes and the measured time-lapse gravity data. In this way, we are able to exploit the complementary properties of time-lapse seismic and gravity data.

De Groot-Hedlin, CD, Hedlin MAH, Walker KT, Drob DP, Zumberge MA.  2008.  Evaluation of infrasound signals from the shuttle Atlantis using a large seismic network. Journal of the Acoustical Society of America. 124:1442-1451.   10.1121/1.2956475   AbstractWebsite

Inclement weather in Florida forced the space shuttle "Atlantis" to land at Edwards Air Force Base in southern California on June 22, 2007, passing near three infrasound stations and several hundred seismic stations in northern Mexico, southern California, and Nevada. The high signal-to-noise ratio, broad receiver coverage, and Atlantis' positional information allow for the testing of infrasound propagation modeling capabilities through the atmosphere to regional distances. Shadow zones and arrival times are predicted by tracing rays that are launched at right angles to the conical shock front surrounding the shuttle through a standard climatological model as well as a global ground to space model. The predictions and observations compare favorably over much of the study area for both atmospheric specifications. To the east of the shuttle trajectory, there were no detections beyond the primary acoustic carpet. Infrasound energy was detected hundreds of kilometers to the west and northwest (NW) of the shuttle trajectory, consistent with the predictions of ducting due to the westward summer-time stratospheric jet. Both atmospheric models predict alternating regions of high and low ensonifications to the NW. However, infrasound energy was detected tens of kilometers beyond the predicted zones of ensonification, possibly due to uncertainties in stratospheric wind speeds. (C) 2008 Acoustical Society of America.