Engineering topics

Stolarski, Richard S.

Publications and source records attributed to Stolarski, Richard S..

84 records · Page 5

NASA NTRS1989

The sensitivity of total ozone and ozone perturbation scenarios in a two-dimensional model due to dynamical inputs

The sensitivity of the total ozone distribution in the Douglass et al. (1989) photochemical model to the dynamical inputs of ozone and the zone perturbation scenarios was investigated by computing the residual circulation from three sets of heating rates (used in computing the advection field). The model ozone results were compared to solar backscattered UV ozone data (SBUV). It was found that, depending on the dynamical inputs, the modeled global average total ozone varied up to 10 percent (with even more substantial seasonal and latitudinal variabilities), indicating that total ozone in the middle to high latitudes is very sensitive to the advection field below 100 mbar, the region where the heating rates are most uncertain. The modeled total ozone showed better agreement with solar SBUV climatology when computed horizontal eddy diffusion was used.

Jackman, Charles H.↗

NASA NTRS1989

The 1988 Antarctic ozone depletion - Comparison with previous year depletions

The 1988 spring Antarctic ozone depletion was observed by TOMS to be substantially smaller than in recent years. The minimum polar total ozone values declined only 15 percent during September 1988, compared to nearly 50 percent during September 1987. At southern midlatitudes, exceptionally high total ozone values were recorded beginning in July 1988. The total integrated southern hemispheric ozone increased rapidly during the Austral spring, approaching 1980 levels during October. The high midlatitude total ozone values were associated with a substantial increase in eddy activity as indicated by the standard deviation in total ozone in the zonal band 30-60 deg S. Mechanisms through which the increased midlatitude eddy activity could disrupt the formation of the Antarctic ozone hole are briefly discussed.

Schoeberl, Mark R.↗

NASA NTRS1989

Impact of heterogeneous reactions on stratospheric chemistry of the Arctic

The possible depletion of ozone due to heterogeneous reactions occurring in Arctic polar stratospheric clouds (PSCs) is fundamentally different from the Antarctic situation. PSCs in the Arctic are relatively short-lived and occur over limited regions of the Arctic stratosphere. The Arctic situation is examined using a model which calculates photochemical processes as a function of longitude in air circulating with fixed velocity around the pole at fixed pressure level and latitude. The model allows sunlight to vary diurnally and PSCs to occur in specified subregions of the domain. Measurements of chemical species including HCl, ClO, NO2 and HNO3 downwind from a PSC should show obvious changes compared to measurements in air unaffected by clouds. These species concentrations are found to be sensitive to sticking coefficients, cloud characteristics including particle number density and surface area, and to the PSC exposure time.

Douglass, Anne R.↗

NASA NTRS1988

The 1987 Antarctic ozone hole - A new record low

In 1987 the Antarctic springtime total ozone as measured by TOMS was substantially lower than in any previous year. Polar ozone levels began decreasing significantly after a mesoscale transient minimum developed over the Weddell Sea on September 5-7. The total ozone over most of the Antarctic continent decreased to less than 200 DU on September 19, and a region where total ozone was less than 125 DU developed on September 30. The lowest level observed was 109 DU on October 5 near the South Pole, a value 29 DU less than the 1985 previous record low. Compared with previous years the 1987 October zonal mean total ozone is substantially lower poleward of 60 S. Antarctic total ozone in 1987 also showed the greatest rate of ozone decrease as well as the longest persistence of the ozone hole.

Krueger, Arlin J.↗

NASA NTRS1988

Watching a disappearing shield

The remote-sensing techniques used to monitor atmospheric ozone levels are reviewed, and recent results are discussed. The importance of the ozone layer as a shield for UV radiation is stressed, and the impact of human activities generating ozone-destroying compounds is considered. Ground-based, airborne, balloon-borne, and satellite remote-sensing methods are shown to complement each other to provide both global coverage and detailed structural information. Data obtained with the Nimbus-7 TOMS and solar-backscatter UV instruments are presented in graphs and briefly characterized.

Stolarski, Richard S.↗

NASA NTRS1988

Variations of total ozone in the north polar region as seen by TOMS

Data from the TOMS instrument has been used to follow the course of development of the Antarctic ozone springtime minimum since 1979. Addressed is the question of possible north polar region changes which might be deduced from the nine years of TOMS measurements of total ozone. Total ozone is a much more variable quantity in the Northern Hemisphere than in the Southern Hemisphere. This makes the search for trends more difficult and the interpretation of results more uncertain. The 9-yr time series of TOMS data at high latitudes in the Northern Hemisphere is examined. Because the TOMS measurements have drifted by 3 to 4 percent with respect to closely collocated Dobson measurements, it was chosen in this study to adopt the Dobson normalization and adjust the TOMS measurements accordingly. The difference between the last two years (1986 and 1987) of the TOMS record, and the first two years of the record (1979 and 1980) are shown. The difference in percent is given as a function of latitude and time of year. The Antarctic springtime decrease is clearly seen as well as a smaller change which extends to about 50 degrees south latitude at all seasons. Changes in the Northern Hemisphere are less dramatic and are concentrated near the polar night where solar zenith angles are very large. These data are now being examined in more detail and updated results will be presented at the Workshop.

Stolarski, Richard S.↗

NASA NTRS1988

The QBO and interannual variation in total ozone

Garcia and Soloman (1987) have noted that the October monthly mean minimum total ozone amounts south of 30 S were modulated by a quasibiennial oscillation (QBO) signal. The precise mechanism behind this effect, however, is unclear. Is the modulation brought about by the circulation-produced QBO signal in the ozone concentration itself, or does the temperature QBO modulate the formation of polar stratospheric clouds (PSCs), leading to changes in the chemically induced Antarctic spring ozone decline rate. Or is some other phenomenon involved. To investigate the means through which the QBO effect occurs, a series of correlation studies has been made between polar ozone and QBO signal in ozone and temperature.

Lait, Leslie R.↗

NASA NTRS1988

The Antarctic ozone hole

Processes that may be responsible for the thinning in the ozone layer above the South Pole are described. The chlorine catalytic cycle which destroys ozone is described, as are the major types of reactions that are believed to interfere with this cycle by forming chlorine reservoirs. The suspected contributions of polar stratospheric clouds to these processes are examined. Finally, the possibility that the ozone hole may be due more to a shift in atmospheric dynamics than to chemical destruction is addressed.

Stolarski, Richard S.↗

NASA NTRS1987

TOMS: The Antarctic ozone hole and ozone trends

The Total Ozone Mapping Spectrometer (TOMS) instrument aboard Nimbus 7 has proved invaluable for the investigation of the recent rapid decline in the springtime total ozone over the Antarctic. The principle problem discussed is that of observing the atmosphere over long periods of time to determine whether or not trends and/or slow oscillations are taking place. Total ozone is an excellent summary parameter for the state of the stratosphere. It responds to temperature changes, and in the long term, is expected to respond to chemical changes. Thus, when changes take place in total ozone, such as the springtime Antarctic decrease it is a clear indication of an important problem, both because of environmental potential and scientific importance. TOMS is actually an overkill for this problem. Significantly more data is taken than is necessary. Tests have shown that maps produced on a 2 by 4 degree grid are essentially equivalent to those produced from the entire gridded data set. Because the critical aspect of the search for changes in ozone is continuous data, reflight of a polar orbiting TOMS is important. Included in the flight should be a stratospheric temperature sensor and, if possible, a modification to obtain some ozone altitude information. A critical aspect of the problem is timeliness of the data. This is the only drawback of the existing TOMS. It is expected that in the very near future the processing will be done within two weeks of real time. This is critical to the process of discovery of phenomena such as the Antarctic ozone hole.

Stolarski, Richard S.↗

NASA NTRS1987

The use of atmospheric measurements to constrain model predictions of ozone change from chlorine perturbations

Atmospheric photochemistry models have been used to predict the sensitivity of the ozone layer to various perturbations. These same models also predict concentrations of chemical species in the present day atmosphere which can be compared to observations. Model results for both present day values and sensitivity to perturbation depend upon input data for reaction rates, photodissociation rates, and boundary conditions. A method of combining the results of a Monte Carlo uncertainty analysis with the existing set of present atmospheric species measurements is developed. The method is used to examine the range of values for the sensitivity of ozone to chlorine perturbations that is possible within the currently accepted ranges for input data. It is found that model runs which predict ozone column losses much greater than 10 percent as a result of present fluorocarbon fluxes produce concentrations and column amounts in the present atmosphere which are inconsistent with the measurements for ClO, HCl, NO, NO2, and HNO3.

Douglass, Anne R.↗

NASA NTRS1986

Diagnostic analysis of two-dimensional monthly average ozone balance with Chapman chemistry

Chapman chemistry has been used in a two-dimensional model to simulate ozone balance phenomenology. The similarity between regions of ozone production and loss calculated using Chapman chemistry and those computed using LIMS and SAMS data with a photochemical equilibrium model indicate that such simplified chemistry is useful in studying gross features in stratospheric ozone balance. Net ozone production or loss rates are brought about by departures from the photochemical equilibrium (PCE) condition. If transport drives ozone above its PCE condition, then photochemical loss dominates production. If transport drives ozone below its PCE condition, then photochemical production dominates loss. Gross features of ozone loss/production (L/P) inferred for the real atmosphere from data are also simulated using only eddy diffusion. This indicates that one must be careful in assigning a transport scheme for a two-dimensional model that mimics only behavior of the observed ozone L/P.

Stolarski, Richard S.↗

NASA NTRS1986

Further interpretation of satellite measurements of Antarctic total ozone

Both dynamical and chemical mechanisms have been advanced to explain the decrease in total ozone in the Antarctic spring. Further analysis of satellite measurements show that during any one year, the September decline in total ozone near the South Pole is compensated by an increase at midlatitudes. The total ozone amount from 44 deg S to the pole remains almost unchanged from August through November even though both the polar and midlatitude values reach extremes during this period. These observations suggest that the variations within the spring season in south polar total ozone are governed by dynamical redistribution rather than chemical processes.

Stolarski, Richard S.↗