2011 - Cooperative Institute for Research in Environmental Sciences ...

SARAH LANCE
A stream of water droplets are generated with a piezo electric device,
each with a diameter of about 30 microns and with a high degree of
uniformity.
Contact freezing on demand:
Measurement of contact nuclei with a
novel instrument using single droplets
levitated in an optical trap
Sara Lance (CIRES/ESRL CSD),
Margaret Tolbert (CIRES) and Josh Gordon (NIST)
Freezing of cloud droplets in the temperature range 0°C
to -40°C depends on the properties of aerosol particles acting
as ice nuclei (IN). “Contact nucleation,” which occurs when a
supercooled liquid droplet and IN particle collide, can occur at
much warmer temperatures than other freezing mechanisms
and may, therefore, have great importance for the phase partitioning
of clouds. The researchers are developing an instrument
for laboratory experiments of contact nucleation, based
on the precise control and detection of individual contact
events, which will provide the basis for establishing a program
to investigate this ice-formation mechanism.
A test of the role of mixotrophy
in regulation of nitrogen fixation
by cyanobacteria
James H. McCutchan, Jr. (CIRES)
and William M. Lewis, Jr. (CIRES)
Cyanobacteria (blue-green
algae) are important primary producers
in aquatic environments and
dominate photosynthetic production
in the open ocean and in many
lakes. Through the work proposed
here, the researchers seek to better
understand some of the factors controlling
cyanobacterial nitrogen fixation
in lakes. Information derived
from this work will be particularly
important as demand grows for
production of algal biofuels, and a
better understanding of controls on
nitrogen fixation also will contribute
to the knowledge of the global nitrogen
cycle and nutrient limitation
in aquatic ecosystems.
Anabaenopsis elenkenii,
which dominated Little
Gaynor Lake in 2007–2008.
The little ball at the end
of each string of cells is a
heterocyst, which is where
nitrogen fixation occurs.
Recently, Little Gaynor Lake
has been dominated by
Arthrospira, which is also a
member of the cyanobacteria
but lacks heterocysts.
Marrying a frequency-agile Fe Doppler
lidar with a multi-frequency etalon-based
edge-filter for profiling the whole
atmosphere wind and temperature
Xinzhao Chu (CIRES), John A. Smith (CIRES
student) and Wentao Huang (CIRES)
Collaborators: Mike Hardesty (CIRES/ESRL-CSD)
and Hanli Liu (NCAR)
The investigators plan to install a narrowband lidar
receiver in a mesosphere/lower thermosphere (MLT) to
extend measurements of wind, temperature and perhaps
aerosol concentration to the stratosphere and troposphere.
It’s hoped that this novel receiver design, in conjunction
with 3-frequency resonance fluorescence measurements of
the MLT, will evolve into a receiver capable of performing
routine measurements of wind and temperature through
the entire neutral atmosphere. Such measurements promise
to greatly expand our understanding of the coupling and
dynamics of atmospheric regions.
Horns Rev Offshore Wind Farm near Denmark
VATTENFALL
Developing a lower boundary layer radar
for renewable energy research
Christopher R. Williams (CIRES),
Laura Bianco (CIRES), Paul E. Johnston (CIRES),
Daniel C. Law (ESRL CSD) and Scott E. Palo
(CU Aerospace Engineering)
This project will develop a Lower Boundary Layer (LBL)
radar capable of estimating the horizontal wind and turbulence
from 20 m to over 1 km above ground level with a
10-m vertical resolution. This new radar will use Linear Frequency
Modulated Continuous Wave (LFMCW) radar technology
enabling fine vertical resolution close to the ground.
The researchers call this radar a LFMCW-LBL radar.
CIRES Annual Report 2011 79