22
BAMOS
Dec 2018
Event
summary
Remote sensing workshop
Nick Grosfeld
Remote sensing of the natural environment has expanded
immensely in recent years, yielding countless benefits for
meteorology and climate science as well as other environmental
fields. On Thursday, October 25 many of our colleagues
gathered in Melbourne to share their insights into these
exciting developments. Satellite-based sensing and Radar were
the main technologies discussed, though other platforms such
as ground-based sounding and remotely controlled drones
were also covered.
John Le Marshall (Bureau) opened proceedings with a tour
through the history of the use of satellites in meteorology,
commencing with the visual imagery provided by TIROS-1 in
1962. Next came the incorporation of satellite measurements
of MSLP and 1000 hPa–500 hPa thickness in numerical weather
prediction efforts in the 1970’s. Modern meteorological remote
sensing has expanded to include infra-red sounding of the
atmosphere (from both satellites and ground), retrieval of
atmospheric motion vectors from satellites such as Himawari-8,
and obtaining vertical profiles of temperature via the refraction
of GPS signals. John concluded with some key areas of future
progress, noting the study of the moisture cycle, measurement
of greenhouse gas concentrations by satellite and geostationary
ultra-spectral sounding.
Ian Grant (Bureau) continued the broad overview, outlining the
environmental remote sensing services provided by the Bureau.
Products to support the aviation industry include observations
of volcanic ash, fog and low-level cloud, as well as upper level
icing potential for aircraft. Observations of the ocean aid the
conservation of tropical reefs with measurements of sea-
surface temperatures as well as water sediment and chlorophyll
levels. Land surface vegetation can be studied with imagery of
false colour and other specialised band combinations, as well as
the Normalised Difference Vegetation Index (NDVI). Ian finally
described how satellite-derived measurements of solar energy
at the surface can assist the development of renewable energy
projects.
After morning tea, Leon Majewski (Bureau) honed the focus in
on weather forecasting at very short time scales (‘nowcasting’).
Nowcasting has traditionally relied heavily on the extent
of Radar coverage, and while Australia has a relatively high
number of weather Radars, significant areas of land gaps
remain. The geostationary satellite Himawari-8 is now being
utilised to support nowcasting, and Leon hopes that a
geostationary satellite-based Radar will become available to
support Australia’s nowcasting in the future.
Yi Huang (Monash University) then explored the study of clouds
by satellite, noting the importance of condensation as an
energy source to the upper atmosphere, and the contribution
of cloud feedbacks to climate projection uncertainty. Yi showed
that active sensing, particularly in the microwave bands, has
significantly improved the study of clouds beyond traditional
passive imagery. This is currently provided by such satellites
as TRMM, Cloudsat and Calypso, and will be extended by the
EarthCARE mission.
After lunch Claire Krause (Geoscience Australia) showcased the
land observation capabilities of Geoscience Australia, focusing
on bodies of water. New methods can determine the area of tidal
inundation at the coast, as well as monitor areas of mangroves.
A new dataset is also available to monitor the surface area of
all permanent water bodies across NSW, providing real-time
information on the extent of drought. This dataset will hopefully
be extended to cover all of Australia in the future.
Clare Richards (ANU) then walked us through the vast collection
of remote sensing data maintained at the NCI, with a volume
exceeding 10 Petabytes. This data can be accessed through the
GSKY interface, and Clare invited users to share their iPython
notebooks in the open toolkit at http://gsky.nci.org.au.
Joshua Soderholm (Bureau) returned us to the world of Radar
with an introduction to observing extreme weather systems
such as thunderstorms. After noting that horizontal Radar
beams are best suited to detecting falling raindrops, while
vertical beams are adept at revealing ice and hail stones, Joshua
explained the benefits of dual-polarity Radar, which combines
both. Joshua then related his involvement in a field-test of
a portable dual-polarisation Radar to observe micro-scale
dynamics surrounding a bushfire in Victoria, before concluding
with the news that Australia will have a dual-polarisation Radar
network rolling out nationwide over the next 10 years.