Long-term ground based observations in the Great Smoky Mountains and Pigeon Basin

The GSMNP high-resolution rain gauge network includes 44 rain gauges deployed at mid to high elevations (from 1150m to 1920 m) along exposed ridges (Fig. 1). The network is deployed in the western part of the state of North Carolina (USA) in the Southern Appalachians in locations where no previous rainfall observations were ever made, and where complementary existing observations are available at low elevations.

The installation process was done in several steps: a group of 7 rain gauges were installed in the summer 2007 (RG0XX: Fig. 1), another group during summer 2008 (RG1XX: Fig. 1), and a third group in summer 2009 (RG3XX: Fig. 1). The tipping bucket rain gauges used are model TB3 (RG0XX: catchment size of 200 mm; 0.2 mm/tip) and TB3/0.1 (RG1XX: catchment size of 282.8 mm; 0.1mm/tip). Every rain gauge is visited every two-three months for regular maintenance, data collection and scheduled recalibration. Quality control of collected data is performed for each rain gauge, where flags are added to any questionable data.

In addition to the constant precipitation monitoring, intensive observing periods (IOPs) have been conducted in this and surrounding river basins to characterize ridge-ridge and ridge-valley variability of precipitation using radiosondes, tethersondes, Micro-Rain Radars (MRRs), automatic weather stations and optical disdrometers.

Important results from these analyses include the importance of light (<3 mm/hr) rainfall as a baseline freshwater input to the region especially in the cold season, and the high frequency of heavy rainfall and severe weather in the warm season, and illuminate the significant spatio-temporal variability of rainfall in this region.