Acceleration of ions transverse to the local magnetic field is ultimately necessary for gravitationally bound ionospheric plasma to escape out to the magnetosphere. Transversely accelerated ions (TAI's), which take the form of upflowing "conical" ion distributions, are not completely understood and are the subject of this thesis. TIDE and TIMAS are highly sensitive ion mass spectrometers carried by NASA's Polar spacecraft and capable of exceptional temporal, spatial, and energy resolution. Polar's elliptical orbit allows these instruments to sample auroral outflows at low altitudes near common source regions of transverse energization and also at high altitudes where conics are rarely reported. Four conic events observed by both TIDE and TIMAS are compared with several possible acceleration mechanisms. Low altitude conics are found to be the result of resonant wave-particle heating, while high altitude transverse distributions appear to arise from acceleration through small-scale electromagnetic structures.

The spatial distribution of water in all its three phases is an important factor in determining the climate. The interactions among temperature, water vapor, infrared emission and solar radiation form a series of feedback mechanisms, which play a very important role in the climate system. In order to trace moisture flow through the climate system and examine its impact on climate, a parameterization for the computation of moisture transport and precipitation is developed, one that will eventually be incorporated into a coupled energy balance climate-thermodynamic sea ice model (the CCSI model). This parameterization is tested by comparing computed energy transports and precipitation rates with available observations and by evaluating its sensitivity to variations in the values of specified parameters. The results of these studies indicate that the moisture parameterization is somewhat sensitive to variations in wind speed, surface air temperature and moisture flux, while it is relatively insensitive to changes in relative humidity. In general this parameterization does a good job in simulating the seasonal cycle and latitudinal distribution of the wind speed, moisture transport and precipitation when compared to the observed data and general circulation model (GCM) results.

I report here on preliminary work incorporating transient effects from lightning into a global thunderstorm electricity model. First, E, the electric field produced by a lightning return stroke, is analytically derived. Second, a determination is made of the model's ability to handle the quickly varying fields produced by lightning. In solving for the conduction current and other quantities of interest in the atmosphere the contribution to E from the vector potential is ignored. This approximation is most likely to be invalidated by the electric fields associated with lightning. We calculate the electric field component due to the vector potential, and the conduction current this electric field drives. The conduction current driven by the lightning flash is small compared to the other currents present for the time scales of importance in the model, and can be ignored. Therefore the model is able to include the effect of lightning on the global electric circuit even though the radiation component of the lightning is explicitly absent. A test of the model's accuracy, the continuity of current test, shows the model's results are self-consistent to within 9%-17%, depending upon the region being studied.

Observations of the surface of Mars suggest a high probability of surface water activity in that planet's past. Consequently, many studies of Mars' early atmosphere have attempted to estimate the carbon dioxide level by requiring that surface temperatures be high enough to support surface liquid water. In the main, these studies have employed one-dimensional, radiative-convective climate models capable of considering only a single solar zenith angle, typically chosen to represent a global and annual average. Such models are hence not well suited for considering meridional variations in the temperature profile, which are affected by variations in the orbital obliquity and the meridional redistribution of heat by dynamic processes. I describe modifications to a more complex model, the multi-level energy balance model designed at NASA's Goddard Laboratory for Atmospheric Sciences, which make it suitable for study of an atmosphere with varying carbon dioxide levels. Vertically and meridionally defined, the model includes heating and cooling by radiation, mean meridional circulation, large-scale (baroclinic) and small-scale (convective) eddies, and surface turbulent flux. I present annually-averaged results for an examination of potential atmospheres of early Mars, given that its carbon dioxide level may range from 0 to 500 Pa and the orbital obliquity from 0$\sp\circ$ to 50$\sp\circ.$ These results are compared with those obtained from a radiative-convective model.

Globally representative atmospheric electric field and current data have been obtained from two sites at Amudsen-Scott South Pole Station at ground level (3 m) with 1 Hz time resolution. The average diurnal variation has been calculated for individual months and seasons, and well known features of the Carnegie curve observed. Amplitude ratios for seasonal curves range between 30-43%, in agreement with other studies. The Northern hemisphere winter is found to be a minimum for global convective-electrical activity and summer a maximum, in contradiction to the original 1929 Carnegie results. Seasonal phase shifts observed in previous studies of the diurnal variation of deep convective activity (DCA) in the tropics also appear in the results of this study. Good correlations between low amplitude peaks suggest our data are highly accurate and could be useful in detecting changes in weather patterns as might occur with global warming.

We develop a stochastic spatial-temporal model of the wind field in Houston, Texas, using wind data collected at pollution monitoring stations scattered about the area. This model is intended to be used as an input to an air pollution model, since wind is a very important part of modeling pollution transport. Since wind is naturally bivariate, in our case east and north wind components, we develop a method that assumes the wind is the gradient of some smooth, latent, univariate potential field. The mean and covariance functions of this potential field then induce the mean and covariance functions for the wind field. The advantage to this approach is that developing a scalar-valued covariance model for the potential field is much easier than developing a general, matrix-valued covariance model for the wind directly. We develop the mathematics for this gradient process model, and in particular explore the structure that arises when the underlying potential has an isotropic covariance. This structure allows us to develop variogram-like functions that can be estimated from the data in a way very similar to standard variogram estimation. For the data analysis, we propose a model of the wind following Breckling's 1989 time-series study: the wind is decomposed into a geostrophic term, a diurnal term, and an error term. The geostrophic term is constant over space, since the spatial scale we are working on is small compared to pressure systems, and captures the long-range time dependence caused by these pressure systems. The diurnal term is allowed to vary over space and time, is periodic with a period of 24 hours, and captures the sea-breeze oscillations. We adjust for errors in the data that are caused by local features, such as buildings and trees, that prevent the "true" wind from being measured. We explore the nature of the sea-breeze, and find that rotating the components of the wind allows the sea-breeze to be captured in a single component that is perpendicular to the sea coast. We fit the elements of the model using the variogram and maximum-likelihood estimation.

A model describing a thunderstorm's interaction with the global electric circuit is presented. The model includes a thunderstorm, the surrounding atmospheric and ionospheric region, and the magnetically conjugate atmospheric and ionospheric region. The model is time-dependent, and includes lightning and thundercloud evolution. A method of using experimental data to more accurately simulate observed thunderstorms has been developed. Of the upward current generated by a thunderstorm, about 50% flows through the Earth's magnetosphere to the conjugate hemisphere. This percentage is fairly constant over the storm's active life, and varies little with storm size or structure. Infrequent lightning activity (less than one flash/minute) within a thunderstorm does not appear to greatly affect the thunderstorm's efficiency in transferring separated charge to the global circuit. Lightning does limit the magnitude of the electric fields and resulting currents within and below the storm.

No description available.

No description available.

No description available.