Five statistical and dynamical tropical cyclone intensity guidance techniques available at the National Hurricane Center during the 2003 and 2004 Atlantic and Eastern North Pacific seasons were evaluated within three intensity phases: (I) formation; (II early intensification; and (III) decay. During the formation phase, the Decay Statistical Hurricane Intensity Prediction (DSHIPS) technique was the best technique in both basins. When the forecast errors during formation exceed +/- 10 kt, the statistical techniques tend to over-forecast and the dynamical models tend to under-forecast. Whereas DSHIPS was also the best technique in the Atlantic during the early intensification stage, the Geophysical Fluid Dynamics Laboratory model was the best in the Eastern North Pacific. All techniques under-forecast periods of rapid intensification and the peak intensity, and have an overall poor performance during decay-reintensification cycles in both basins. Whereas the DSHIPS was the best technique in the Atlantic during decay, none of the techniques excelled during the decay phase in the eastern North Pacific. All techniques tend to decay the tropical cyclones in both basins too slowly, except that the DSHIPS performed well (13 of 15) during rapid decay events in the Atlantic. Similar error characteristics had been found in the western North Pacific.

TRACT (maximum 200 words) The Northern Oscillation Index (NOI), an atmospheric climate index relating climate variations in the tropical Pacific and Northeast Pacific was used to selectively average output from the Parallel Ocean Climate Model (POCM 4C) for 1979-1998. Composites, or smart climatologies, were made representing El Nino (EN) and La Nina (LN) conditions, as well as a long term mean (LTM) average or traditional climatology, for November to March. Conditions in the California Current System (CCS) in the smart climatologies were consistent with large scale features noted in previously published studies of EN and LN. Overall, the patterns of anomalies (POCM 4C Smart Climatology minus POCM 4C Traditional Climatology) in salinity, temperature, and currents were opposite in sign and magnitude between the EN and LN composites. This was expected for opposite phases of the same climate variation, and many of the model's EN/LN differences were found to be statistically significant. Therefore, POCM 4C smart climatologies provide better estimates of ocean state and circulation patterns than traditional climatology. Such smart climatologies offer improved environmental information to Naval operational and strategic planners. They are also useful for studying climate variations, and in improving boundary and initial conditions for ocean and atmosphere models.

Extended Range Munitions (ERMs) are gun-launched rocket-boosted munitions having an effective range ocer 27 km. In accordance with Sea power 21 and the Marine Corps's requirements for sea-based fire support, three ERMs are being developed. The purpose of this work is to increase the range and lethality of these munitions by applying environmental effects when computing the projectiles' trajectory. A broad review of artillery and munitions literature reveals that historically 66% of ballistic error can be attributed to meteorological factors. The most important factors are wind (speed and direction), temperature, and pressure. It has also been shown that global atmospheric numerical weather presictions (NWP) data typically outperforms the traditional radiosonde data and is suitable for use in ballistic corrections. Forecasted NWP products provided by the Fleet Numerical Meteorology and Oceanographic Center (FNMOC) are integrated using the Joint Meteorology and Oceanographic (METOC) Broker Language (JMBL) into a Five Degree of Freedom (5DOF) aerodynamic model within the Autonomous Unmanned Vehicle (AUV) Workbench producing a ballistic correction (BALCOR) for the munition. This new capability can significantly enhance naval gunfire effectiveness since the BALCOR increase the munitions' range and the ability apply kinetic energy onto the target rather than using it to maneuver to the target.

Cirrus cloud forecasting is of particular importance to various Department of Defense programs. This thesis takes a case study approach to study Air Force Weather Agency Mesoscale Model 5 (AFWA MM5) skill in forecasting cirrus clouds, which are not represented explicitly by the model (ice water mixing ratio is used as a surrogate.) Two cases are selected for study. For each case, an initial forecast time of interest is determined which serves as the beginning point for the case study. GOES data and 3-hourly MM5 data are then obtained at 3- hourly intervals to coincide with model forecast time steps between the initial time through the 30-hour forecast. A standard analysis is performed on all data to determine general atmospheric structure for each case at each 3- hourly point. Following this, the model's relative humidity with respect to ice, explicit ice water content, vertical velocity, and other fields are considered to determine if the model possesses the proper dynamical factors for cirrus formation. Finally, model coverage of ice cloud is compared to the ABL cloud mask results to determine how well the model s ice cloud forecasts verify against each 3-hourly observed ice water field taken from the GOES data. Results indicate that the MM5 underforecasts cirrus coverage, and that the 90% relative humidity field with respect to ice may be a better approximation of observed cirrus coverage than the ice water field.

model-derived wind gusts determined by each method are then compared to wind reports from the Storm Prediction Centerâ s severe storm reports archive and reports from observing stations. Model-derived wind gusts are then compared to the observed wind gusts for varying times of day and observed wind gust ranges. Wind gust frequency plots are examined for each wind method to determine accuracy and to characterize any patterns. The T1 method was the most accurate overall for this study, but was shown to be less sensitive to varying atmospheric conditions. The T2 method was the least accurate of the three methods during all situations. The WINDEX method performed well in most situations and was nearly as accurate as the T1 method, while WINDEX also proved to be the most sensitive of the three to varying mesoscale conditions.

This study investigates the impact of the synoptic-scale flow on the propagation and intensity of the sea breeze front at Eglin Air Force Base. The 925 mb wind direction and speed from the 12 UTC Tallahassee sounding was used to categorize 509 summer days as having an offshore, onshore, or coast parallel synoptic-scale flow regimes. Days with similar synoptic-scale flows were then composited together to create hourly surface analyses for each regime. Sea breeze frontogenesis, location and intensity were analyzed on hourly plots of temperature, winds and frontogenesis. Results indicate that the most intense sea breeze fronts formed under 3-5 1 ms- offshore, 7-9 1 ms- coast parallel easterly, and 3-5 1 ms- coast parallel westerly synoptic-scale flow while the weakest fronts formed under 0-3 1 ms- onshore and coast parallel westerly flow. The inland penetration of the sea breeze front was restricted under offshore flow but propagated through the Eglin Range Complex under onshore flow. The intensity of the sea breeze front was found to be a balance between convergence (frontogenetic) and turbulent mixing (frontolytic). Under onshore flow the sea breeze front formed late in the afternoon when convergence at the front was maximized and turbulent mixing decreased. Under offshore flow, the strongest sea breeze fronts formed early in the afternoon due to strong convergence between offshore and onshore winds and weak turbulent mixing.

The Air Force Weather Agency (AFWA) version of the Advanced Research Weather Research and Forecasting (ARW) model with a moving 4-km nested grid is examined for 10 track and intensity predictions of six western North Pacific tropical cyclones during 2005. In three of the 10 integrations, the ARW vortex tracker algorithm based on the 500-mb height minimum failed to appropriately move the nest and thus lost track of the storm vortex. For the other seven cases, the ARW track forecasts are more skillful than the AFWA MM5 forecasts and (except at 12 h) the CLIPER-type forecasts. The ARW intensity forecasts were less skillful than the MM5 and CLIPER-type forecasts at all forecast intervals, and were severely degraded by a large negative bias at the initial time. The deficiency in these intensity forecasts is shown to be related to model spin-up (lasting 12-54 h) problems caused by the lack of a bogus vortex and a cold start initialization from the interpolation of the NCEP Global Forecast System (GFS) analysis to the 12- km and 4-km grids. Thus, a more appropriate initial vortex representation will be required to improve intensity forecasts.

During the 1979 Atlantic hurricane season a tropical wave left the west coast of Africa and continued westward where satellite and ship observation indicated strengthening to a tropical depression from which Hurricane Frederic developed. This particular tropical disturbance has an interesting history. In its westward progression it intensified to hurricane strength lasting less than 24 hours followed by a weakening east of the Lesser Antilles. Continuing westward, this disturbance became extratropical over Southeast Cuba, but quickly reintensified to hurricane strength over Northwest Cuba, tracking through the warm Gulf waters and eventually making landfall near Mobile, Alabama. A number of experiments were carried out on a multi-level primitive equation (PE) model, a one-level PE model, and a higher resolution multi-level PE model (T63) in order to simulate the progression and intensification from a wave to a hurricane over a specified limited domain. Although previous experiments using this model with its comprehensive physical processes exhibit a reasonable predictive rate of success, the early experiments during this case study produced poor results. The most successful forecasts will be examined carefully and discussed entirely. There is strong indication that for mesoscale features a higher resolution model would achieve better results. / Typescript. / "Submitted to the Department of Meteorology in partial fulfillment of the requirements for the degree of Master of Science." / Advisor: T. N. Krishnamurti, Professor Directing Thesis. / Includes bibliographical references (leaves 165-167).

Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 122-126.

This study uses a very high resolution numerical weather prediction (NWP) model to investigate the complex structure and behaviour of cold fronts along the New South Wales coast during the warmer months of the year, the complex interaction between the wind flow and coastlines and elevated areas as well as the lee-trough effect, particularly the way it affects waters off the east coast of Tasmania, The study also investigates the utility of the higher resolution NWP model to better predict wind fields compared to a lower resolution model. The University of New South Wales very high resolution model (HIRES), nested in the Australian Bureau of Meteorology's coarse NWP model (GASP), was run at various horizontal resolutions (from 15 to 25km) in order to investigate the above-mentioned features. It was found to bave very good skill in resolving the features and was also found to be very accurate in the prediction of surface wind fields for various yacht race events out to at least four days ahead. It can be concluded that there is considerable skill in the ability of high-resolution NWP models such as HIRES, to predict the major features of the wind fields over the ocean out to several days ahead. Moreover, it was also able to more accurately simulate the complex structure of the summer-time cool change as it progressed along the NSW coast than the lower resolution model runs. The influence of coastlines, particularly ones with complex topographical features, on the wind flow was demonstrated to a limited extent throughout the study. Finally the following concepts were also verified as a result of the study: - air flow takes the path of least resistance - the shape of topography can help generate local turbulence - the orientation of the wind flow to a mountain range is important in determining turbulent effects. - under certain airflow and stability situations, standing wave activity and a lee trough can be observed in the lee of mountains, hills or even high coastal cliffs.