Engineering topics

Reinsel, G. C.

Publications and source records attributed to Reinsel, G. C..

5 records

NASA NTRS2004

Comment on "Enhanced upper stratospheric ozone: Sign of recovery or solar cycle effect?"

[01] Steinbrecht et al. [2004] (hereinafter referred to as S4) have discussed the trend in upper stratospheric ozone at 35 -45-km altitude determined from their lidar measurements at Hohenpeissenberg (47.8degN, 11.0degE) from 1987 to 2003. They question the conclusion of Newchurch et al. [2003] (hereinafter referred to as N3) that after approximately 1997 the downward trend of upper stratospheric ozone at 35-45-km altitude has diminished significantly. They argue instead that recent ozone changes are associated with the recent solar maximum (i.e., the solar cycle effect on ozone). In this comment we question their procedure for identifying the solar cycle effect. Moreover, we argue that the solar cycle effect was appropriately accounted for in the N3 analysis, and we buttress our argument by demonstrating that the more extensive data set used by N3 shows that the trend in upper stratospheric ozone has diminished significantly since 1997 and that this is evidence of the first stage of ozone recovery.

Cunnold, D. M.↗

NASA NTRS1992

Comparisons of observed ozone and temperature trends in the lower stratosphere

One result of the ozone assessment (WMO, 1989) is that there is a significant negative ozone trend in the lower stratosphere and upper troposphere from 1970 through 1986. The relationship of this trend in ozone to that of temperature in the same altitude region is examined utilizing a 62-station set of rawinsonde data, and the results are compared to the changes in temperature determined from a radiative equilibrium model calculation. The calculated and observed trends in lower stratospheric temperature indicate substantial agreement in the shape and magnitude of the vertical profiles.

Miller, A. J.↗

NASA NTRS1992

Ozone and temperature trends in the lower stratosphere

It is shown that the pattern of temperature trend with height in the upper troposphere and lower stratosphere is consistent with that calculated from a model incorporating the observed ozone changes. The magnitude of the observed temperature decrease is less than that determined from the numerical model. It is found that the obverse ozone-temperature relationship does not hold. If the temperature at 20 km decreases, this by itself would result in an increase in the ozone values through the inverse temperature sensitivity of the chemical reactions. In the lower stratosphere a positive correlation between ozone and temperature tends to exist through the dynamics. Ozone-rich air moving downward undergoes an increase in temperature through adiabatic compression and vice-versa. That the temperature trends indicate no apparent variation with latitude suggests a nondynamic cause.

Miller, A. J.↗

NASA NTRS1986

A statistical trend analysis of ozonesonde data

A detailed statistical analysis of monthly averages of ozonesond readings is performed to assess trends in ozone in the troposphere and the lower to midstratosphere. Regression time series models, which include seasonal and trend factors, are estimated for 13 stations located mainly in the midlatitudes of the Northern Hemisphere. At each station, trend estimates are calculated for 14 'fractional' Umkehr layers covering the altitude range from 0 to 33 km. For the 1970-1982 period, the main findings indicate an overall negative trend in ozonesonde data in the lower stratosphere (15-21 km) of about -0.5 percent per year, and some evidence of a positive trend in the troposphere (0-5 km) of about 0.8 percent per year. An in-depth sensitivity study of the trend estimates is performed with respect to various correction procedures used to normalize ozonesonde readings to Dobson total ozone measurements. The main results indicate that the negative trend findings in the 15- to 21-km altitude region are robust to the normalization procedures considered.

Tiao, G. C.↗

NASA NTRS1984

Analysis of upper stratospheric Umkehr ozone profile data for trends and the effects of stratospheric aerosols

The effect of stratospheric aerosols on Umkehr estimates of long-term ozone depletion associated with chlorofluoromethanes (CFMs) is considered in a statistical time series trend analysis. Time series models are estimated using monthly averages of Umkehr measurements made over the last 15 to 20 years. The time series regression models incorporate seasonal, trend and noise factors and an additional factor to account for the effects of atmospheric aerosols on the Umkehr measurements. The analysis indicates a statistically significant relation with atmospheric aerosol transmission in the Umkehr layers and implies that the relation is an important factor in any time series trend analysis of Umkehr data. Taking this relation into account, statistically significant negative trends were found in the Upper Umkehr layers. It is pointed out that upper stratospheric ozone could be sensitive to long-term solar variability as well as other possible influences in addition to CFM-induced effects, and therefore the cause or causes of the estimated trend cannot be unambiguously estimated using current Umkehr data.

Reinsel, G. C.↗