As of February 2016, TA has deployed total of 32 stations equipped with meteorological sensors: wind speed (channel = LWS), wind direction (LWD) and outside temperature (LKO). Although these stations are deployed in various regions (the southeast US, Canada, New Mexico), 25 are spaced approximately 90 km apart and therefore could be considered a meteorological subarray (Figure below). The data gathered by these 25 stations provide an opportunity to analyze the relation between wind and temperature variations and changes in barometric pressure noise, as recorded by the infrasound sensors (channel = BDF).
Map showing the 25 neighboring USArray TA stations (blue dots) that form the meteorological subarray.
Table showing operating time of the USArray TA meteorological subarray stations.
For the TA infrasound sensors, wind and microbaroms, infrasonic waves generated in marine storms, are often the dominant sources of noise that may mask infrasound signals or result in false positives in automated detection systems such as TAID. This data product aims to compile a reference data set based on the data collected by these 25 stations, to highlight potential interdependencies between these quantities. The links below show plots of variations in wind speed, wind direction,temperature and barometric pressure for 2013 and 2014 (see table above), using a common methodology.
Normalized monthly histograms of wind speed, 2013-2014 (click to show/hide)
The following normalized histograms show monthly distribution of the wind speed at each station during 2013 & 2014. Histograms are obtained using 0.5 m/s bins. For each histogram, distribution fitting is performed and the resulting mean and standard deviation are noted in the legend.
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Monthly wind direction histograms, 2013-2014 (click to show/hide)
The following histograms show monthly distribution of the wind direction at each station during 2013 & 2014. Histograms are obtained using 12° bins. The grid lines show number of samples in bins.
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Seasonal wind speed/direction statistics, 2013-2014 (click to show/hide)
The following plots show summary of seasonal wind statistics at each station during 2013 & 2014. These statistics excludes winds with speeds less than ~1 km/h that are considered as “calm” winds. Plots to the left are histograms of mean hourly winds speed during each season with the vertical axis representing number of hours station experienced that particular wind speed. The rose diagram to the right show the wind direction and speed:
- Spring – from March 1 to May 31;
- Summer – from June 1 to August 31;
- Fall – from September 1 to November 30; and,
- Winter – from December 1 to February 28 (February 29 in a leap year).
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Monthly HVSR, 2013-2014 (click to show/hide)
The HVSR curve, computed for a seismic station represents station’s site response.The following plots show plots of computed monthly HVSR for a given station (BH? channels) based on the PSDs/PDFs available from IRIS’s MUSTANG data quality metrics web service:
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Normalized monthly histograms of the outside temperature, 2013-2014 (click to show/hide)
Bellow normalized histograms show monthly variation of the outside temperature at each station during 2013 & 2014. Histograms are obtained using 0.5 °C bins. For each histogram distribution fitting is performed and the resulting mean and standard deviation are noted in the legend.
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Hourly Power spectral densities 2013-2014 (click to show/hide)
Below are plots of the hourly PSDs during each month with 50% overlap between consecutive 1-hour windows. Monthly median, 5 and 95 percentile values are shown by sold red, orange and yellow curves respectively. PSDs that fall between 5% and 95% curves are shown in green. PSDs that cross these limits are shown in gray. The dashed red, orange and yellow lines are the computed median, 5 and 9 percentiles for all times (2013-2014) respectively.
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Ambient infrasound noise (0.1 – 0.3 Hz) vs wind speed 2013-2014 (click to show/hide)
The following plots of the ambient infrasound noise (microbaroms at 0.1 to 0.3 Hz) are obtained by filtering the infrasound channel data (2013-2014) with a 0.1 – 0.3 bandpass filter. The filtered traces are then decimated to 1Hz (the same sampling rate as the LWS channel). The resulting samples are used to create the plot below.
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Monthly mean and standard deviation of wind speed vs median, 5 and 95 percentile PSDs , 2013-2014 (click to show/hide)
The following plot shows the monthly (2013 & 2014) mean and standard deviation of the wind speed (blue, left axis) and the monthly microbaroms (at 0.1 to 0.3 Hz) median, 5 and 95 percentile PSDs (green, right axis) for a station.
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
Monthly mean and standard deviation of the outside temperature (red) and median PSD and 5 and 95 percentiles (green), 2013-2014 (click to show/hide)
Plot below shows the monthly mean and standard deviation of the outside temperature at a station during 2013 & 2014 (red, left axis) and the corresponding monthly microbaroms (at 0.1 to 0.3 Hz) median, 5 and 95 percentile PSDs (green, right axis).
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
All-time Power spectral density 2013-2014 (click to show/hide)
Below are plots of the hourly PSDs during each month with 50% overlap between consecutive 1-hour windows. Monthly median, 5 and 95 percentile values are shown by SOLID red, orange and yellow curves respectively. PSDs that fall between 5% and 95% curves are shown in green. PSDs that cross these limits are shown in gray. The dashed red, orange and yellow lines are the computed median, 5 and 9 percentiles for all times (2013-2014) respectively.
- Hover over station names to view plots for the corresponding station
- Click on station names for larger view
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