Diagnosis of Spatial Patterns Across Microclimatic Gradients Through Synergistic Use of Mobile and Fixed Measurement Platforms

Vital connections between microclimate and ecological systems have been documented for many decades. More recently, the relevance of microclimate to microrefugia has been highlighted in relation to survival of endangered species and relict habitats under changing large-scale climate forcing and anthropogenic habitat loss. At the smallest scales, the structure, phenology, and behavior of vegetation canopies (forest, woodland, shrub, grassland) impact and interact with radiative, wind, and evapotranspiration processes to modulate and drive site microclimate. Aside from purely altitudinal gradients related to adiabatic cooling and precipitation, local terrain is recognized to influence microclimate by slope aspect control on solar radiation during day, “cold air pool” effects during night, and modulation of turbulent mixing processes. Local moisture sources and water bodies may influence microclimate in complex ways that can be expected to be more pronounced in locations characterized by drier surroundings and light winds. Cold air pool effects may be observed to varying degrees in forest clearings, valleys, and topographic depressions (closed basins) under conditions of light winds and a radiative deficit such as often occurs nocturnally under clear skies.

While a few sites and cases have been well documented with extensive research projects, there remain a wide spectrum of scales, shapes, surface conditions, and geographic variables that have been minimally investigated from both observational and numerical modeling frameworks. Besides the locally extreme cold of “frost pockets”, sinkholes and sheltered valleys may provide habitat to isolated populations of bryophytes, ferns, arthropods, and glacial relict forests. Near small water bodies and wetlands, few data are available to address the extent to which water vapor from local evapotranspiration is transported, mixed, or accumulated spatially. Similar effects may occur due to ephemeral wet soils, floodwaters, and isolated forest patches.

We have begun the initial phase of a series of microscale measurements of temperature, humidity, and radiation using a pedestrian mobile system previously developed for CHEESEHEAD and strategically located stationary sensors over a variety of environments. The initial five sites are located in upland and floodplain areas of Mississippi. Areas of greater topographic relief will be investigated in Maryland, Missouri, and other states to be determined.