IEEE Geoscience and Remote Sensing Magazine - March 2013 - 70

role in NASA's Cyclone Global Navigation Satellite System
(CYGNSS), a new mission that aims to improve extreme
weather prediction. Prof. Garrison is a member of the science team, responsible for the development of measurement noise models and compression algorithms.
Geomatics Engineering:
Surveying to Mobile Mapping
Current activities in Geomatics at Purdue span the fields
of photogrammetry (terrestrial, aerial, space), laser scanning
(terrestrial, aerial), geodesy, geographic information systems, and surveying. A common thread throughout the program is the mathematical modeling of sensors and the reconciliation of observed data with those models. Estimation
and error propagation are essential tools for addressing all
these tasks. Recent projects have ranged from development
of a geo-positioning algorithm for high resolution satellite
imagery to building extraction from laser point clouds, with
applications as diverse as accident reconstruction via forensic
photogrammetry and mapping of storm damaged structures.

vertical strata, canopy height and the relative complexity of
the understory (Fig. 4). Acoustic data are being processed as
maps and traditional remote sensing analytical approaches,
such as segmentation and pattern recognition, are being used
to quantify acoustic patterns in soundscape data. Over 30 TB
of soundscape data are now stored in the Purdue Soundscape
Archive (www.purdue.edu/soundscapes).
The National Science Foundation is also funding a Global Sustainable Soundscape Network project, led by Purdue,
which involves ecologists, social scientists, engineers and
musicians who visit different soundscapes around the
world where work on their sustainability is ongoing.

Sensing Atmospheric Chemistry
Purdue's Prof. Paul Shepson and his tropospheric chemistry group have been studying chemistry above the Arctic
Ocean since 1988.
The Shepson Tropospheric Chemistry Group has focused
on developing an understanding of the dramatic complete
depletion of surface level ozone that occurs each spring over
the Arctic Ocean. It has been known for about 20 years that
this is caused by reaction of ozone with bromine atoms,
Remote Sensing of Soundscapes
which are ultimately derived from the ocean. However, idenRemote sensing research at Purdue has expanded to include
tification of the specific source of those bromine atoms, e.g.
the integration of in situ, stationary environmental sensor
organic compounds emitted from phytoplankton, or chemdata streams with airborne and satellite-based multispecistry on sea salt aerosols (that contain NaBr), or reactions on
tral and LIDAR data.
the surface of the salty ice (that also contains NaBr), has reResearchers in the Department of Forestry and Natural
mained elusive. A major step forward came with the advent
Resources have embarked on research in soundscape ecology,
of satellite remote sensing of BrO, which is produced from
the study of biological (biophony), geophysical (geophony)
the reaction of Br atoms with O3. Those data showed that
and anthropogenic (anthrophony) sources of sounds in landscapes. Automated acoustic recorders deployed in the field by
BrO exists in fairly large-scale clouds (typically ~10,000 km2)
Prof. Bryan Pijanowski and his students collect continuous
over the Arctic Ocean. However, these satellite data provide
data (weeks to years) that are then combined with spatial inno vertical scale information, so it was not known whether
formation about land use derived from Landsat, vegetation
those BrO clouds were in the stratosphere (~15 km up), or
characteristics from MODIS, and vegetation structure from
somewhere closer to the sea ice surface.
LIDAR. In work at the La Selva Biological Station, Pijanowski
To resolve the issue, Shepson and collaborators from the
and his team have shown that soundscape composition is
University of Heidelberg installed a scanning UV/VIS specmore complex in forests with complex vertical structure;
trometer on the belly of his airplane, the Purdue Airborne
acoustic entropy correlates positively with the number of
Laboratory for Atmospheric Research (ALAR), and flew to
Barrow, Alaska in March of 2012 to
make vertical profile measurements
of BrO over the frozen ocean. Those
ALAR flights proved that most of the
BrO and thus ozone depletion is occurring in a very shallow (~100 m
deep) layer next to the frozen surface.
That in turn told them that the bromine came from the sea ice surface
itself. This knowledge is important
to understanding and predicting how
the chemistry of the atmosphere will
change over the Arctic Ocean, as the
sea ice recedes due to climate change.
(a)
(b)
Photographs and stories from the trip
are available at http://shepsonbromex.
FIGURE 5. Indian Pine (1992) AVIRIS data; (a) RGB image of bands 25,16,7 and (b) ground
blogspot.com/.
reference information.
70

ieee Geoscience and remote sensing magazine

march 2013

http://www.purdue.edu/soundscapes http://shepsonbromex http://www.blogspot.com/

Table of Contents for the Digital Edition of IEEE Geoscience and Remote Sensing Magazine - March 2013