Walker Branch Watershed Daily Climate: 1993-2008

As part of the long-term Walker Branch project, daily climate data was collected from instruments associated with a meteorological tower located in an upper slope location within the watershed. These measurements were begun in 1993 as part of the Throughfall Displacement Experiment (TDE) in the control (ambient) plot. Measurements include daily integrated or averaged values for incident photosynthetically active radiation, incident total radiation, air temperature, relative humidity, rainfall, and soil temperature at 10-15 cm. Measurements of incoming rainfall, irradiance (Pyranometer sensor, LiCor Inc.) and photosynthetic photon flux density (Quantum sensor, LiCor Inc.) were obtained in a nearby clearing until 1998 when above canopy observations were added to the ambient plot tower. Clearing data were used to represent above-canopy conditions for the experimental site for the years 1993-1997. Sub-canopy air temperature is measured at approximately 1 m of height in a location shielded from direct solar radiation. Soil temperatures are measured at 15 cm depth and 4 locations per plot. All temperatures are measured with thermistors. Climate data are collected as hourly means and logged on data loggers (Li-1000, LiCor Inc.).

Variables included and their units are:

Column 1=Year
Column 2 = Day of year
Day of the year (1-365 or 366)
Column 3 = Quan
Integrated incident photosynthetically active radiation in mol m-2
Column 4 = Pyran
Integrated incident total radiation in MW m-2
Column 5 = Radmean
Mean daily radiation in W m-2.
Column 6 = Rain
Rain in mm. Hourly values summed over each day.
Column 7 = AirTmin
Daily 1 hour minimum air temperature in degrees C
Column 8 = AirTmean
Daily mean 1 hour air temperature in degrees C
Column 9 = AirTmax
Daily 1 hour maximum air temperature in degrees C
Column 10 = RHmin
Daily 1 hour minimum relative humidity in percent
Column 11 = RHmean
Daily mean 1 hour value
Column 12 = RHmax
Daily 1 hour maximum relative humidity in percent
Column 13 = SoilTmin
Daily 1 hour minimum soil temperature (15 cm) in degrees C
Column 14 = SoilTmean
Daily mean 1 hour soil temperature (15 cm) in degrees C
Column 15 = SoilTmax
Daily 1 hour maximum soil temperature (15 cm) in degrees C
Column 16 = Wind (data not available for years prior to 1997)
Wind in m s-1. Hourly values averaged over the day.
Column 17 = LitterTmean (available for some years)
Daily 1 hour mean litter layer (Oi) temperature in degrees C

Publications:

Hanson, P. J., D. E. Todd, M. A. Huston. 2003. Walker Branch Throughfall Displacement Experiment (TDE), In: Hanson, P. J. and S. D. Wullschleger, eds., North American Temperate Deciduous Forest Responses to Changing Precipitation Regimes. Springer, New York, pp. 8-31.

Hanson, P.J. , D.E.Todd and J.S. Amthor. 2001. A six year study of sapling and large-tree growth and mortality responses to natural and induced variability in precipitation and throughfall. Tree Physiology 21: 345-358.