Research

multispectral drone remote sensing can monitor water quality in coastal waters (2020)

Unoccupied aircraft systems (UAS, or drones) equipped with off-the-shelf multispectral sensors originally designed for terrestrial applications can be used to derive water quality properties with improved spatial and temporal resolution that is needed to monitor rapidly changing environments such as an estuary. Failure to accurately account for surface reflected light can significantly influence remote sensing reflectance, resulting in inaccurate water quality estimates once algorithms are applied. The objective of this research is to evaluate the efficacy of methods that remove surface reflected light from total UAS radiance measurements in order to derive accurate remote sensing reflectance retrievals and scientifically valuable in-water constituents. More information can be found in this StoryMap.

Publications:

Windle, A. E., & Silsbe, G. M. (2021). Evaluation of unoccupied aircraft system (UAS) remote sensing reflectance retrievals for water quality monitoring in coastal waters. Frontiers in Environmental Science9, 182.

The Use of drone imagery for tidal wetland vegetation monitoring: a case study at poplar island, md (2019-2020)

Tidal wetlands, existing at the nexus of land and water, are amongst the most vulnerable environments to climate and anthropogenic change. Environmental monitoring is critical to assess and better understand the fate of extant and restored tidal wetlands. High resolution drone imagery provides the temporal and spatial scales needed to study critical processes such as wetland vegetation changes. I am currently conducting drone flights with a multispectral sensor over a restored wetland cell at the Paul S. Sarbanes Ecosystem Restoration Project at Poplar Island. Wetland vegetation species (primarily Spartina alterniflora and Spartina patens) will be classified using NDVI and texture layers and used to study marsh migration over time.

Evaluation of Atmospheric Correction Algorithms in Chesapeake Bay Waters for the OLCI Ocean Color Sensor (2019-2020)

The optical complexity of Chesapeake Bay waters can confound the accuracy of atmospheric correction algorithms, leading to erroneous water quality retrievals. I am evaluating four atmospheric correction algorithms using data collected by the Ocean and Land Color Instrument (OLCI) onboard Sentinel 3A and 3B satellites. A matchup analysis with satellite derived remote sensing reflectance (Rrs) and in situ Rrs measurements is used to identify the best performing AC algorithm. This research aims to improve remote sensing of coastal waters and advance water quality monitoring and management in Chesapeake Bay. I presented this research at the 2020 Ocean Sciences Meeting.


Using Unoccupied Aerial Systems (UAS) remote sensing to monitor intertidal oyster reef habitat (2017-2019)

Funded through North Carolina Sea Grant/Space Grant, we researched how to effectively monitor intertidal oyster reef habitat using unoccupied aircraft systems (UAS, or drones). We used a variety of different UAS aircraft and sensors to assess oyster reef condition. By analyzing UAS imagery, we were able to nondestructively estimate critical oyster reef metrics such as reef area and height. More information can be found on this interactive ESRI story map.

Publications:

Windle, A. E., Poulin, S., Puckett, B., Hubert, K., Johnston, D.W., Ridge, J.T. In Prep: Using spectral and structural characteristics from unoccupied aircraft systems (UAS) to estimate intertidal oyster reef density.

Ridge, J. T., Gray, P. C., Windle, A. E., & Johnston, D. W. (2019). Deep learning for coastal resource conservation: automating detection of shellfish reefsRemote Sensing in Ecology and Conservation.

Windle, A.E., Poulin, S.K., Johnston, D.W., Ridge, J.T. (2019). Rapid and Accurate Monitoring of Intertidal Oyster Reef Habitat Using Unoccupied Aircraft Systems and Structure from Motion. Remote Sens.11, 2394.


Autonomous terrestrial rovers enable high resolution light pollution sampling at sea turtle nesting beaches (2017-2018)

For my Master’s Project at the Nicholas School of Environment at Duke University, I used a terrestrial rover to quantify artificial nighttime light, or light pollution, on beaches in North Carolina. I compared light pollution measurements to sea turtle nesting trends to study the effect on female nest site selection and hatchling orientation. I concluded that there were fewer nests occurring in areas of high light pollution. I presented this research at the North Carolina Museum of Natural Sciences.

Publications:

Windle, A. E., Hooley, D. S., & Johnston, D. W. (2018). Robotic vehicles enable high-resolution light pollution sampling of sea turtle nesting beaches. Frontiers in Marine Science5, 493.


The effects of sand characteristics on the hatching success and clutch survival of Loggerhead sea turtles (2015-2016)

I completed my undergraduate thesis at Washington College in Chestertown, Maryland on data collected during a summer NOAA internship at the Rookery Bay National Estuarine Research Reserve in Naples, Florida. I collected sand samples taken from sea turtle nests and analyzed sand grain size, porosity, and total water holding capacity to determine if different sand characteristics affected the hatching success of sea turtle nests located in Southwest Florida.