This is an amazing accomplishment
and will allow us to wonderfully track airflows against theoretical models. This will hugely increase confidence in the
modeling. I look forward to seeing this
applied to thunderclouds and tornado.
With this level of processing and
resolution, there is not much left that needs to be done in terms of imaging
the changing atmosphere and that means testable models can be easily assembled
and run.
This is good news for even
climate science as we will finally be able to say specific things about cloud
behavior in particular. We may even be
able to measure cloud cover properly.
High-resolution radar can detect individual raindrops
07:52 June 29, 2012
A high-resolution Doppler radar can detect individual raindrops over
0.5 mm in diameter (Photo: James
Jordan)
A high-resolution Doppler radar has the ability to detect individual
hydrometeors, such as atmospheric raindrops, over 0.5 mm in diameter research
led by the Naval Research Laboratory has revealed. The discovery should further
understanding of the structure and behavior of clouds, and could lead to more
accurate forecasting of severe weather.
A Doppler radar sends focused microwave signals towards a target and
listens for the reflection. By analyzing the doppler effect, the changes in
frequency of the reflected microwaves, the radar is able to ascertain the
target's velocity.
Though the principle is identical to that used by a police speed gun,
the technology that comprises the high-resolution radar is rather more
powerful. The 3 MW radar emits microwaves with a 0.22-degree beam-width, which
allows it to interrogate a 14 cubic-meter (500 cubic foot) volume of cloud for
individual raindrops from a range of 2 km (1.25 miles) at a "world's
best" resolution of 0.5 m (1.6 ft). The radar was previously put to use
tracking debris coming away from NASA space shuttles during launch.
The detection of raindrops is in part made possible due to the fact
that these larger drops are highly reflective but occur in much lower
concentrations than the much smaller particles from which clouds are mainly
comprised. Cloud droplets are on average only 10-15 micrometers in diameter.
Though researchers had intended to study clouds in detail, the
ability to see individual raindrops came as a complete surprise. "The
signal processing of the radar returns revealed that these cloud details led to
the unanticipated observations of individual raindrops - a first ever
observation through remote sensing means," said Dr. Mark Anderson, a
scientist at the Naval Surface Warfare Center Dahlgren Division, which
contributed to the research.
The results mean that weather systems can be monitored as a whole, and
right down to individual raindrops, nearly simultaneously using a single piece
of equipment, and may pave the way to research into more advanced weather
radar.
The findings were published in Proceedings of the National Academy of Sciences. See the sources
below for the full list of contributing researchers.
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