Office of
Biological and Environmental Research Weekly Report
March 16, 2009
Remote Detection of Drizzle
from Low Altitude Clouds. DOE scientists developed a
novel remote sensing method to detect drizzle from low-altitude water clouds
using the Atmospheric Radiation Measurement (ARM) program millimeter wave cloud
radar (MMCR). Low-altitude water clouds
have a significant influence on earth’s climate through their interaction with
radiation to and away from the earth. It
has been a major technical challenge to remotely determine if low-altitude
clouds do or do not rain because of the low thermal contrast between these clouds
and earth’s surface. ARM investigators
found that cloud drizzle is dictated by the vertical variation of rain drop
size and total cloud water. Drizzling
clouds usually exhibit a decreasing trend of rain droplet size with altitude,
while non-drizzling clouds have an opposite trend. Both theoretical analyses and observations suggest
that drizzle drops can significantly increase in size near the bottom of a
cloud layer. These findings help improve remote sensing of precipitation
amounts and understanding of aerosol effects on clouds, associated rain, and
climate.
Reference:
Chen, R, R Wood, Z Li, R Ferraro,
and F Chang, 2008: "Studying the vertical variation of cloud droplet
effective radius using ship and space-borne remote sensing data." Journal
of Geophysical Research 113, doi:10.1029/2007JD009596.
Media Interest: No
Contact: Kiran Alapaty, SC-23.1, (301) 903-3175
Estimating Fossil Energy-based
CO2 Emissions from US
Croplands: DOE supports research to understand mechanisms of carbon
sequestration in managed ecosystems. An important part of that research
is knowing the sources of carbon emissions. Scientists from Oak Ridge National Laboratory
report a method to estimate both on- and off-site fossil energy-based CO2 emissions (FCE)
associated with crop production. FCE was found to differ by crop and
region because of changes in energy requirements for crop production driven by
environmental differences, e.g., soil texture, soil chemistry, and
climate. Changes in policies (e.g., Farm Bills) and abrupt changes in
annual weather patterns (e.g., droughts and wet years) have also resulted in annual
shifts in FCE. This new method is important because estimates of
fossil-fuel consumption for cropping practices and the associated CO2 emissions enable (i) monitoring of energy and emissions
with changes in land management and (ii) calculation and balancing of regional
and national carbon budgets.
Reference: Nelson, R.G., C.M. Hellwinckel, C.C. Brandt, T.O.
West, D.G. De La Torre Ugarte, G. Marland. 2009. Energy Use and Carbon Dioxide
Emissions from Cropland Production in the United States, 1990-2004. Journal of
Environmental Quality 38: 418-425.
Media interest: No
Contact: Mike Kuperberg, SC-23.1, (301) 903-3511;