PBL AEROSOL
RADIOMETER OBSERVATION
RADIOMETER
PHOTO GALLERY
INSTRUMENTATION
DETAILS
ESSC scientists are measuring the downwelling
thermal infrared radiation from the atmosphere, using two ventilated
Kipp & Zonen CG4 pyrgeometers atop a twelve-foot tower on the NSSTC
Annex rooftop. The two sensors are initially collocated to inter-calibrate
their relative responsivity over a wide range of air temperatures, sky
conditions, and sky temperatures. Collocation also allows the scientists
to determine with a high degree of confidence that any unusual measurement
features are due to changes in sky condition or sky temperature, and
not due to instrument artifacts. David Bowdle, ESSC Research Scientist
is the lead investigator on the pyrgeometer measurements; Danielle Nuding
and Stephanie Long, ESSC Undergraduate Research Technicians, are the
junior investigator and instrument technician, respectively. The
prygeometer activity is part of a larger measurement/modeling project
to diagnose and quantify the radiative warming due to aerosol injection,
trapping, and hygroscopic growth in the nocturnal boundary layer. The
next step in the nocturnal forcing project is to compare measured and
modeled nocturnal sky radiation, where the model alternately includes
and excludes measured aerosol profiles from the collocated MIPS ceilometer.
Results from these preliminary experiments will be used to design a field
project near Huntsville in late summer or early fall, when nocturnal
radiative forcing from aerosols is expected to be maximized. In this
field experiment, the intercalibrated radiometers can either be separated
or operated as uplooking/downlooking pair to measure the net thermal
radiation from the sky and the earth surface. UAH collaborators in the
larger project include Richard McNider (Principal Investigator), Michael
Newchurch (RAPCD), Kevin Knupp (MIPS), Sundar Christopher (satellite-based
aerosol observations), Kirk Fuller (aerosol optical properties), and
Udaysankar Nair (RAMS, radiative transfer modeling).
|
Figure A: Time series of downwelling infrared
irradience for May 21, 2007. A clear sky was present from midnight-midnight
local time.
|
|
Figure B: Time series difference
in downwelling infrared irradience for two collocated pyrgeometers
for the same conditions as in figure A. |
|