From csage@eden.rutgers.eduWed Apr 12 16:04:58 2000 Date: Mon, 10 Apr 2000 22:08:37 -0400 From: Sage Lichtenwalner To: sage@arctic.rutgers.edu Subject: Fw: Measurements see significant Arctic ozone loss Status: OR [The following text is in the "iso-8859-1" character set] [Your display is set for the "US-ASCII" character set] [Some characters may be displayed incorrectly] -------------------------------------------------------------- -----Original Message----- From: JPLNews@jpl.nasa.gov To: undisclosed-recipients:; Date: Wednesday, April 05, 2000 10:07 PM Subject: Measurements see significant Arctic ozone loss >MEDIA RELATIONS OFFICE >JET PROPULSION LABORATORY >CALIFORNIA INSTITUTE OF TECHNOLOGY >NATIONAL AERONAUTICS AND SPACE ADMINISTRATION >PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011 >http://www.jpl.nasa.gov > >Contacts: >Lynn Chandler, NASA/Goddard Space Flight Center, Greenbelt, Md >(301) 614-5562 >Mary Beth Murrill, JPL (818) 354-6478 > >FOR IMMEDIATE RELEASE April 5, 2000 > >NASA-EUROPEAN MEASUREMENTS SEE SIGNIFICANT ARCTIC OZONE LOSS > > Ozone losses of more than 60 percent have occurred in the >Arctic stratosphere near 60,000 feet (18 kilometer) in one of the >coldest winters on record. This is one of the worst ozone losses >at this altitude in the Arctic. > > Investigations into the Arctic stratosphere have provided >better insights into the processes that control polar ozone. >These insights considerably add to scientists' ability to predict >ozone levels in the future as chlorine levels decline as a result >of the Montreal Protocol, and as greenhouse gases increase. >Climate change in the stratosphere will likely enhance ozone >losses in the Arctic winter in the coming decades, even as the >amount of chlorine introduced into the atmosphere is decreased, >researchers say. > > This winter, the NASA sponsored SAGE III Ozone Loss and >Validation Experiment (SOLVE) and European Union sponsored Third >European Stratospheric Experiment on Ozone (THESEO) obtained >measurements of ozone, other atmospheric gases, and particles >using satellites, airplanes, large, small and long duration >balloons, and ground-based instruments. > > Scientists from the United States joined with scientists >from Europe, Canada, Russia and Japan in mounting the biggest >field measurement campaign yet to measure ozone amounts and >changes in the Arctic stratosphere. The activities were conducted >from November 1999 through March 2000. The total amount of >information collected by the international campaign this winter >is greater than the information collected in any past polar >measurement campaign. Most of the measurements were made near >Kiruna, Sweden with additional measurements being made from >satellites and a network of stations at mid- and high- northern >latitudes. > > During the winter of 1999-2000, large ozone losses were >observed in the Arctic lower stratosphere, measured by a number >of instruments and techniques, including a National Oceanic and >Atmospheric Administration ozone instrument aboard the high >altitude NASA ER-2 aircraft, a civilian variant of the U-2 >reconnaissance plane. > > "Measurements from the NASA ER-2 show ozone in the Arctic >region decreasing by about 60 percent between January and mid- >March," said ER-2 co-project scientist Dr. Paul A. Newman of >NASA's Goddard Space Flight Center, Greenbelt, Md. > > These measurements are comparable to the large chemical >losses at this altitude observed in several winters in the mid- >1990s. The effect on total column ozone was slightly mitigated by >the fact that reductions in ozone were smaller above 20 >kilometers (66,000 feet). Spacecraft observations by NASA's Total >Ozone Mapping Spectrometer-Earth Probe showed a clear ozone >minimum over the polar region during February and March. The >average polar column amounts of ozone for the first two weeks of >March were 16 percent lower than observed in the early 1980's. > > High altitude clouds (at about 18 kilometers or 60,000 feet) >that exist only at the poles are called "polar stratospheric >clouds" or PSCs. They play a unique role in atmospheric ozone >loss. The visually beautiful, opalescent clouds form only at the >cold temperatures found at the poles. These clouds help trigger >the conversion of chlorine from relatively non-reactive forms to >a form (chlorine monoxide, or ClO) that, in combination with >sunlight, destroys ozone. > > PSCs were observed to extend widely over the Arctic region >from early December to early March. "We were somewhat surprised >to see PSCs so early in December," said Dr. Mark Schoeberl, who >was the SOLVE co-project scientist for observations made from >NASA's DC-8 aircraft. "Some of the PSC types and their locations >which we observed in December did not fit within our current >understanding." The last PSCs were observed on March 8 by >instruments aboard the DC-8, and on March 15 by satellite. > > The polar stratosphere temperatures were extremely low over >the course of this last winter. PSCs can only form in these low >temperature regions. At 20 kilometers (66,000 feet) on Jan. 28, >the area covered by temperatures low enough to form PSCs was 14.8 >million square kilometers (5.7 million square miles), which is >larger than the United States. This is the largest-area coverage >recorded in more than 40 years of Northern Hemisphere >stratospheric analyses. > > "The polar stratospheric clouds covered a larger area, and >persisted for a longer period of time, than for any other Arctic >winter during the past 20 years. These conditions heighten our >concern regarding possible couplings between climate change and >stratospheric ozone depletion," said ozone researcher Dr. Ross >Salawitch of NASA's Jet Propulsion Laboratory, Pasadena, Calif. > > The mixing of polar air into middle latitudes, both during >the winter and as the polar circulation broke down in late March, >influences ozone levels over the populated middle latitudes. >Dilution of ozone-depleted air into latitudes is a major >contributor to the long-term mid-latitude decline. These mixing >processes have been studied during SOLVE/THESEO-2000 and detailed >analysis of these processes continues. > >For further information visit the SOLVE web site at >http://cloud1.arc.nasa.gov/solve/ . For supporting images see: >http://svs.gsfc.nasa.gov/imagewall/solve.html . > > JPL is managed for NASA by the California Institute of >Technology, Pasadena. > > ##### >#2000-032 >4/5/00 MBM >--------------------------------------------------------------- >You are subscribed to JPL's news mailing list. To unsubscribe, >please send an e-mail to JPLNews@jpl.nasa.gov and in the body >of the message include the following line. > >unsubscribe news > >Please do not reply to this e-mail. >For help, send a message to listmaster@www.jpl.nasa.gov.