PROGRAM TITLE:	Polar Ozone Depletion/Ultraviolet Radiation 
ACTIVITY STREAM:	Process, Observe, Model, Data
SCIENCE ELEMENT:	Biogeochemical Dynamics, Ecosystem Dynamics


SCIENTIFIC MERIT:  Since the surprising discovery in 1985 of an annual 
springtime "ozone hole" in the stratosphere above Antarctica, research has 
focused on understanding its causes.  It is very important to understand fully 
the causes of this phenomenon, because stratospheric ozone filters out 
biologically damaging solar ultraviolet (UV) radiation, and also since the 
polar chemical and dynamic processes which cause it are harbingers of future 
similar ozone depletion at more temperate latitudes.  It is known that the 
chemical processes which destroy the ozone are driven mainly by chlorine 
from chlorofluorocarbons, but there is still much to be learned.  This requires 
laboratory studies of detailed chemical processes, field observation of 
concentrations and distribution of chemical species, and improvements in 
modeling of stratospheric chemistry and dynamics. 
The stratospheric "ozone hole" has allowed increased penetration of UV 
radiation to the earth's surface in polar regions where it has been historically 
low.  Research is focused on understanding the effects of enhanced UV 
radiation on marine, freshwater and terrestrial biota and on ecosystem 
structure and function. Efforts are directed towards measurements and 
modeling efforts to predict UV penetration through the atmosphere to the 
Earth's surface and into aquatic systems.  The NSF supported and operated 
polar UV monitoring network which is located at several permanent stations 
in arctic, antarctic and sub-antarctic regions provides high resolution surface 
data which facilitates research in several disciplines.  This program has 
established a (polar) UV data base that for the first time has calibrated long-
term stability.  Data from the last few years is readily available in CD-format.  
This has been used to demonstrate (i) the increase in biologically active UV 
dosages in spring (20%) due to a reduction of ozone (-8%), (ii) a reduction in 
phytoplankton photosynthesis of 6-12% in the "ozone hole", and (iii) marine 
organism defense mechanisms.  However, CFC residence times are ten years 
or more, and therefore, this program must continue for a decade to reduce the 
uncertainty and map the future reductions and recoveries.
STAKEHOLDERS:  The study of polar ozone depletion is of interagency 
interest with NOAA and NASA playing a major role, along with NSF. The 
study of UV radiation and its effects in polar regions has been concentrated 
within NSF, with increasing interest in other agencies.  The general world-
wide interest in UV radiation-related research has resulted in plans to 
establish a US Interagency In-situ UV Monitoring Network, a national UV 
instrument calibration facility and national data network.  This involves 
USDA, DOE, EPA, DOI, NASA, NOAA, NIST and NSF. International 
cooperation includes joint efforts in both ozone depletion and UV radiation 
POLICY RELEVANCE:  Field, laboratory, and theoretical/modeling efforts 
will aid understanding of the effects of human activity on global ecosystems.  
This research also continues to support policy decisions aimed at the control 
of the use of halocarbons.  Recent public debate has emphasized the rapid 
phase-cut of CFC's and some have questioned the scope of the problem.  This 
program is needed to assess these issues and to monitor the impact of the 
Montreal Protocol.
PROGRAM CONTACTS:  Polly Penhale and Dennis Peacock, Office of Polar