Statistical analysis of stratospheric temperature and ozone profile data for trends and model comparison

Work performed during the project period July 1, 1990 to June 30, 1992 on the statistical analysis of stratospheric temperature data, rawinsonde temperature data, and ozone profile data for the detection of trends is described. Our principal topics of research are trend analysis of NOAA stratospheric temperature data over the period 1978-1989; trend analysis of rawinsonde temperature data for the period 1964-1988; trend analysis of Umkehr ozone profile data for the period 1977-1991; and comparison of observed ozone and temperature trends in the lower stratosphere. Analysis of NOAA stratospheric temperature data indicates the existence of large negative trends at 0.4 mb level, with magnitudes increasing with latitudes away from the equator. Trend analysis of rawinsonde temperature data over 184 stations shows significant positive trends about 0.2 C per decade at surface to 500 mb range, decreasing to negative trends about -0.3 C at 100 to 50 mb range, and increasing slightly at 30 mb level. There is little evidence of seasonal variation in trends. Analysis of Umkehr ozone data for 12 northern hemispheric stations shows significant negative trends about -.5 percent per year in Umkehr layers 7-9 and layer 3, but somewhat less negative trends in layers 4-6. There is no pronounced seasonal variation in trends, especially in layers 4-9. A comparison was made of empirical temperature trends from rawinsonde data in the lower stratosphere with temperature changes determined from a one-dimensional radiative transfer calculation that prescribed a given ozone change over the altitude region, surface to 50 km, obtained from trend analysis of ozonsonde and Umkehr profile data. The empirical and calculated temperature trends are found in substantive agreement in profile shape and magnitude

A Note on likelihood estimation of missing values in time series

Missing values in time series can be treated as unknown parameters and estimated by maximum likelihood, or as random variables and predicted by the expectation of the unknown values given the data. The difference between these two procedures is illustrated by an example. It is argued that the second procedure is, in general, more relevant for estimating missing values in time series

Convergence of Semi-discrete Stationary Wigner Equation with Inflow Boundary Conditions

Making use of the Whittaker-Shannon interpolation formula with shifted sampling points, we propose in this paper a well-posed semi-discretization of the stationary Wigner equation with inflow BCs. The convergence of the solutions of the discrete problem to the continuous problem is then analysed, providing certain regularity of the solution of the continuous problem.Comment: 14 page

A Note on likelihood estimation of missing values in time series.

Missing values in time series can be treated as unknown parameters and estimated by maximum likelihood, or as random variables and predicted by the expectation of the unknown values given the data. The difference between these two procedures is illustrated by an example. It is argued that the second procedure is, in general, more relevant for estimating missing values in time series.ARIMA models; Interpolation; Mean Square Error;

Senior women leaders in higher education overcoming barriers to success

The purpose of this study was to obtain a deeper understanding of what it takes for women to succeed as cabinet-level higher education administrators. The findings not only offer a wealth of strategies for career success and for overcoming professional and personal challenges, but also shed new light on critical factors that affect women’ experiences at work. This qualitative, phenomenological study was based primarily on confidential interviews with nine senior women leaders. Two informants are presidents, six are vice presidents, and one serves as a senior executive officer of their universities. Before assuming their current posts, they worked in a variety of leadership capacities ranging from department head to president at various institutions. All interviews were transcribed verbatim, analyzed, and compared for salient themes. To ensure the credibility of this research endeavor, triangulation was used by incorporating all informants and an independent outside auditor to validate the accuracy, objectivity, and plausibility of the results drawn from this study. Six major themes emerged from this research: effective leadership strategies: earning your place at the table; tests and trials; maintaining focus and political savvy; numbers matter: the rules change; gender as a two-edged sword; and competing as a woman: prepared and ready. The results revealed that to succeed as top-level executives, women must constantly overachieve, maintain good relationships with others, hold onto personal and institutional values to do the right things, expand themselves constantly, and utilize strong mentors’ assistance as well as sponsorship. When faced with implicit and explicit challenges such as unequal treatment, gender bias, resistance, political joggling, or personal struggles, they rely on private confrontation, emotional intelligence, and tenacity, as well as all possible support and resources to survive and thrive. The most important finding was the contrast between women leaders’ token experiences versus their experiences as an equal social group in leadership teams. The results confirmed Kanter’s (1993) theory about the impact of the proportion of women on management culture and on individual leaders’ experiences. Obviously, placing more women in powerful leadership positions will foster a more diversified, inclusive management culture and improve executive women leaders’ experiences at work