Using UAV Technology to Collect Vertical Temperature and Relative
Humidity Profiles over a Tropical Montane Rainforest
Abstract
Unmanned aerial vehicles (UAV) have been increasingly used for field
data collection and remote sensing purposes. Their ease of use, ability
to carry sensors and cameras, low cost, and precise maneuverability and
navigation makes them a versatile tool for a field researcher.
Procedures and instrumentation to use UAVs in the field are largely
undefined, especially for atmospheric and hydrologic applications. A
field study was conducted to test the UAV’s ability to collect
atmospheric data in order to locate and analyze the canopy boundary
layer (CBL) above a Costa Rican tropical montane rainforest. This study
aims to give further insight on the changes of the CBL throughout the
day and for atmospheric comparison to land development. Through the
study, it was found that there was little previously defined procedures
and preferred instrumentation that directly applied to the UAV field
study. Because of this, the methodology of using an UAV for atmospheric
and CBL remote sensing and data collection was developed and refined by
testing and comparing precision and performance of sensors and executing
systematic flight patterns throughout the day. The UAV allowed for quick
and specific access to sampling locations and for all of the variables
to be measured by sensors over vertical profiles. Flights were scheduled
at different locations throughout the day over the Texas A&M Soltis
Center and surrounding forest in San Isidro, Costa Rica. Vertical
profiles were also measured over the Soltis Center grounds to determine
how development has affected the presence of the CBL. The UAV was
successful in gathering data above the forest canopy and the Soltis
Center at varying elevations during clear and cloudy conditions. The
procedure produced reliably consistent vertical profiles over small
domains in space and time, validating the general approach. The
technique also identified unique profiles at spatially and temporally
distinct sample sites including response to meteorological events. These
findings suggest a healthy ability to diagnose CBL characteristics of
interest. It was also found that there is a distinct increase in
temperature and dew point over land development when compared to over
forest. Future studies include flights at other locations and
determining preferred instrumentation for UAV atmospheric data
collection.