What is Remote Sensing?
Remote sensing is acquisition of information without directly contacting the features being observed. It provides an extraordinary tool for helping scientists and non-scientists alike understand and characterize condition and change of the natural and built environment. In New York State (NYS), remote sensing analysis is applied in areas such as land cover and land use inventory or change analysis, urban growth planning, vegetation dynamics, emergency response and water management. With access to imagery archives dating back decades from various online resources, such as the NYS GIS Clearinghouse, Earth Explorer and Global Visualization Viewer, researchers have significant opportunities to explore NYS from this birds-eye view.
- What is remote sensing? (reference)
What is Landsat?
Landsat is a joint effort of the U.S. Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA), and comprises a series of satellites that have been collecting data since 1972. A survey by NYView sought to understand current applications of remote sensing data within NYS and found that Landsat is one of the most frequent used data sources. Three quarters of the survey participants reported Landsat was often used in their fields, which includes ecology, geology, geography, phenology, education, forestry and agriculture.
- Landsat—Earth observation satellites (reference)
The Goal of Landsat Change Pair Images
Observing different Landsat images of a common region across different time periods, reveals natural and cultural change. Through use of the 40+ year Landsat archive we can observe changes in seasonal, annual and even decades. The change pairs in this collection focus on New York State and aim to highlight the range of analysis scenarios where remote sensing has application to state residents. We characterize these images based on the observation time period and function.
Descriptions of Change Pair Categories
- Seasonal — Changes happen in different seasons within one year.
- Annual — Changes happen more than one year but within 10 years.
- Decadal — Changes happen with a gap more than 10 years.
- Cities — Changes related to urban areas, such as sprawl, land use change, interchange of urban and other land uses.
- Land Features — Significant land feature changes, like agriculture or forest.
- Natural Disasters — Monitor impact of natural disaster including hurricane and drought.
- Water and Ice — Change pairs relevant to water bodies, such as river flooding, winter storms, or ice cover.
- Special Images — Change pairs that cannot be characterized into one of the above mentioned categories.