Freshwater ecosystems underpin global water and food security, yet are some of the most endangered ecosystems
in the world because they are particularly vulnerable to land management change and climate variability.
The US National Research Council's guidance to NASA regarding missions for the coming decade includes a
polar orbiting, global mapping hyperspectral satellite remote sensing mission, the Hyperspectral Infrared Imager
(HyspIRI), to make quantitative measurements of ecosystem change. Traditionally, freshwater ecosystems have
been challenging tomeasure with satellite remote sensing because they are small and spatially complex, require
high fidelity spectroradiometry, and are best describedwith biophysical variables derived from high spectral resolution
data. In this study, we evaluate the contribution of a hyperspectral global mapping satellite mission to
measuring freshwater ecosystems. We demonstrate the need for such a mission, and evaluate the suitability
and gaps, through an examination of the measurement resolution issues impacting freshwater ecosystem measurements
(spatial, temporal, spectral and radiometric). These are exemplified through three case studies that
use remote sensing to characterize a component of freshwater ecosystems that drive primary productivity. The
high radiometric quality proposed for the HyspIRImission makes it uniquely well designed for measuring freshwater
ecosystems accurately at moderate to high spatial resolutions. The spatial and spectral resolutions of the
HyspIRI mission are well suited for the retrieval of multiple biophysical variables, such as phycocyanin and
chlorophyll-a. The effective temporal resolution is suitable for characterizing growing season wetland phenology
in temperate regions, but may not be appropriate for tracking algal bloom dynamics, or ecosystem responses to
extreme events inmonsoonal regions. Global mappingmissions provide the systematic, repeated measurements
necessary tomeasure the drivers of freshwater biodiversity change. Archival globalmapping missionswith open
access and free data policies increase end user uptake globally. Overall, an archival, hyperspectral globalmapping
mission uniquely meets the measurement requirements of multiple end users for freshwater ecosystem science
and management.
Freshwater ecosystems underpin global water and food security, yet are some of the most endangered ecosystemsin the world because they are particularly vulnerable to land management change and climate variability.The US National Research Council's guidance to NASA regarding missions for the coming decade includes apolar orbiting, global mapping hyperspectral satellite remote sensing mission, the Hyperspectral Infrared Imager(HyspIRI), to make quantitative measurements of ecosystem change. Traditionally, freshwater ecosystems havebeen challenging tomeasure with satellite remote sensing because they are small and spatially complex, requirehigh fidelity spectroradiometry, and are best describedwith biophysical variables derived from high spectral resolutiondata. In this study, we evaluate the contribution of a hyperspectral global mapping satellite mission tomeasuring freshwater ecosystems. We demonstrate the need for such a mission, and evaluate the suitabilityand gaps, through an examination of the measurement resolution issues impacting freshwater ecosystem measurements(spatial, temporal, spectral and radiometric). These are exemplified through three case studies thatuse remote sensing to characterize a component of freshwater ecosystems that drive primary productivity. Thehigh radiometric quality proposed for the HyspIRImission makes it uniquely well designed for measuring freshwaterecosystems accurately at moderate to high spatial resolutions. The spatial and spectral resolutions of theHyspIRI mission are well suited for the retrieval of multiple biophysical variables, such as phycocyanin andchlorophyll-a. The effective temporal resolution is suitable for characterizing growing season wetland phenologyin temperate regions, but may not be appropriate for tracking algal bloom dynamics, or ecosystem responses toextreme events inmonsoonal regions. Global mappingmissions provide the systematic, repeated measurementsnecessary tomeasure the drivers of freshwater biodiversity change. Archival globalmapping missionswith openaccess and free data policies increase end user uptake globally. Overall, an archival, hyperspectral globalmappingmission uniquely meets the measurement requirements of multiple end users for freshwater ecosystem scienceand management.
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