This Major Research Instrumentation (MRI) Program grant supports the development of a continuous, real-time, low latency Global Positioning System (cGPS) and collocated meteorological sensing package (temperature, barometric pressure, relative humidity, surface wind speed) array in Mexico for atmospheric, climatic, and seismotectonic research in the Americas. The network has been coined TLALOCNet, after the Aztec God of rain fertility and water. TLALOCNet will entail the construction of six new GPS/Met stations located in the Sierra Madre Occidental of northern Mexico, islands in the Pacific off central Mexico and two sites on island in the Bay of Campeche, Gulf of Mexico. An additional 18 existing cGPS sites along the western Coastal and interior regions of central Mexico proximal to the Mexico subduction zone will be upgraded with modern GPS receivers and choke ring antennas, upgraded power and telecommunication systems, meteorological sensors, and enclosures to bring the full network to the standards of the other tectonic geodesy GPS networks (e.g., EarthScope Plate Boundary Observatory). TLALOCNet data will be openly and freely available and discovery via UNAVCO web services. TLALOCNet data will offer the potential to transformably advance understanding of atmospheric dynamics in a region that is impacted seasonally and annually with large fluxes of atmospheric moisture from the Pacific, the Gulf of Mexico and the Caribbean. GPS/Met enables the derivation of total precipitable water (TPW) in the Earth's atmosphere in a cone above GPS/Met stations by using the delay time of multiple frequency GPS satellite signals that are influenced by the integrated amount of atmospheric moisture from the top of the atmosphere to the receiver antenna. GPS-Met observations of TPW complement other measurements of the vertical and horizontal spatial and temporal distribution of water vapor in the atmosphere through satellite remote sensing methods and weather balloon launched radiosonde meteorological sensors. The real advantage of GPS-Met is that it is an all-weather observation that can cost-effectively provide increased spatial and temporal coverage at scales necessary to improve understanding of the causation and evolution of mesoscale convective systems (MCS). MCS give rise to spectacular volumes and intensity of precipitation in the tropics, especially as that moisture cools and precipitates in response to the atmosphere's dynamic interaction with mountainous terrain. MCS may account for between 50-70% of total precipitation annually in northwestern Mexico and the southwestern U.S. during the North American Monsoon. Seasonal and annual TPW in this region is likely to be sensitive to changing climate and resultant hydrometeorological impacts are likely to present large scale societal hazards (e.g., floods, landslides) and have significant water resource management implications for both Mexico and the southwestern U.S. TLALOCNet will also sustain and enhance continued detailed studies of subduction zone dynamics and the earthquake cycle in Western Mexico. Real-time, high rate GPS observations in this region will advance studies of the subduction earthquake cycle, including studies of coseismic rupture processes, postseismic fault afterslip and viscoelastic rebound, episodic tremor and slip (in conjunction with ancillary but contemporaneous seismic observations) , and interseismic elastic strain.
