Data Services Newsletter

Volume 18 : No 1 : Spring 2016

DMC TA Meteorological Subarray: a Reference Data Set

As of February 2016, the Transportable Array (TA) component of the USArray/EarthScope project 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).

Map of 25 neighboring USArray TA stations
Map and table show 25 neighboring USArray TA stations (shown by blue dots) that form a meteorological subarray.

The above stations are also equipped with infrasound sensors (BDF) and, therefore, the data gathered by the meteorological and acoustic channels of these stations provide a suitable data set for analyzing the relation between wind and temperature variations and the changes in barometric pressure noise. To facilitate such an analysis, the new IRIS DMC TA Meteorological Subarray Reference Data Set data product (ds.iris.edu/ds/products/ta-met-subarray/) has been assembled. This data set uses a standard methodology to highlight variations in wind speed, wind direction, temperature and barometric pressure and their potential relation for the deployment days in 2013 and 2014 in both graphical and textual formats.

Normalized histograms of the monthly distribution of wind speed
The normalized histograms of the monthly distribution of wind speed at station TA.T57A 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.

Ambient infrasound noise vs wind speed 2013-2014
The ambient infrasound noise (microbaroms at 0.1 to 0.3 Hz) at station TA.T57A 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.

by Manoch Bahavar and Chad Trabant (IRIS Data Management Center)