Nowcasting cloud fields for U.S. Air Force special operations

Nowcasting is a trending subset of numerical weather prediction that aims to produce a highly accurate analysis of current conditions along with a short-term forecast. One of the greatest challenges to a nowcast system operating in data-sparse regions is that of accurately forecasting clouds. Clouds significantly impact a variety of operations, particularly intelligence, surveillance and reconnaissance. A prototype nowcast system is developed and tested on a case of summertime stratus clouds over the Monterey Bay in California. This system ingests high-resolution geostationary satellite data and mesoscale model fields to produce gridded 06-h forecasts of cloud reflectance and probability of cloud. A statistical post-processing technique is applied using Bayesian estimation to train the system from a set of past predictor variables and observed imagery. This approach demonstrates skill over a climatology-based approach and shows an ability to accurately forecast non-typical cloud patterns. It proves to be very computationally feasible for nowcasting. This study lays down the initial framework for a highly accurate nowcast system that can operate anywhere in the world to enable mission success while reducing costs.http://archive.org/details/nowcastingcloudf10945529571st Lieutenant, United States Air ForceApproved for public release; distribution is unlimited

Aerial Surveys of the Ocean and Atmosphere off Central California

The long-term goal is to enhance our understanding of airsea interaction in the littoral zone by means of applying simple dynamical theories to high-quality observations obtained in the field. The Monterey Bay serves as our natural laboratory for these purposes. The grant is one of a continuing series of programs to study the bay funded by the National Ocean Partnership Program NOPP and the ONR Naval Ocean Modeling and Prediction NOMP Program.Grant #s: N0001403WR20002, N0001403WR20006, N0001403WR2020

Genome Sequence of the Chestnut Blight Fungus Cryphonectria parasitica EP155: A Fundamental Resource for an Archetypical Invasive Plant Pathogen.

Cryphonectria parasitica is the causal agent of chestnut blight, a fungal disease that almost entirely eliminated mature American chestnut from North America over a 50-year period. Here, we formally report the genome of C. parasitica EP155 using a Sanger shotgun sequencing approach. After finishing and integration with simple-sequence repeat markers, the assembly was 43.8 Mb in 26 scaffolds (L50 = 5; N50 = 4.0Mb). Eight chromosomes are predicted: five scaffolds have two telomeres and six scaffolds have one telomere sequence. In total, 11,609 gene models were predicted, of which 85% show similarities to other proteins. This genome resource has already increased the utility of a fundamental plant pathogen experimental system through new understanding of the fungal vegetative incompatibility system, with significant implications for enhancing mycovirus-based biological control

Coastally Trapped Wind Reversals: Progress toward Understanding

Coastally trapped wind reversals along the U.S. west coast, which are often accompanied by a northward surge of fog or stratus, are an important warm-season forecast problem due to their impact on coastal maritime activities and airport operations. Previous studies identified several possible dynamic mechanisms that could be responsible for producing these events, yet observational and modeling limitations at the time left these competing interpretations open for debate. In an effort to improve our physical understanding, and ultimately the prediction, of these events, the Office of Naval Research sponsored an Accelerated Research Initiative in Coastal Meteorology during the years 1993â 98 to study these and other related coastal meteorological phenomena. This effort included two field programs to study coastally trapped disturbances as well as numerous modeling studies to explore key dynamic mechanisms. This paper describes the various efforts that occurred under this program to provide an advancement in our understanding of these disturbances. While not all issues have been solved, the synoptic and mesoscale aspects of these events are considerably better understood.Most of the authors were supported through the Office of Naval Research Coastal Meteorology Accelerated Research Initiative, one of the authors (WTT) was supported by Program Element 0601153N, Naval Research Laboratory

Kelvin Waves and Internal Bores in the Marine Boundary Layer Inversion and Their Relationship to Coastally Trapped Wind Reversals

Detailed observations of a coastally trapped disturbance, or wind reversal, on 10–11 June 1994 along the California coast provide comprehensive documentation of its structure, based on aircraft, wind profiler, radio acoustic sounding system, and buoy measurements. Unlike the expectations from earlier studies based on limited data, which concluded that the deepening of the marine boundary layer (MBL) was a key factor, the 1994 data show that the perturbation was better characterized as an upward thickening of the inversion capping the MBL. As the event propagated over a site, the reversal in the alongshore wind direction occurred first within the inversion and then 3–4 h later at the surface. A node in the vertical structure (defined here as the altitude of zero vertical displacement) is found just above the inversion base, with up to 200-m upward displacements of isentropic surfaces above the node, and 70-m downward displacements below. Although this is a single event, it is shown that the vertical structure observed is representative of most other coastally trapped wind reversals. This is determined by comparing a composite of the 10–11 June 1994 event, based on measurements at seven buoys, with surface pressure perturbations calculated from aircraft data. These results are compared to the composite of many events. In each case a weak pressure trough occurred between 2.4 and 4.0 h ahead of the surface wind reversal, and the pressure rose by 0.32–0.48 mb between the trough and the wind reversal. The pressure rise results from the cooling caused by the inversion’s upward expansion. The propagation and structure of the event are shown to be best characterized as a mixed Kelvin wave–bore propagating within the inversion above the MBL, with the MBL acting as a quasi-rigid lower boundary. If the MBL is instead assumed to respond in unison with the inversion, then the theoretically predicted intrinsic phase speeds significantly exceed the observed intrinsic phase speed. The hybrid nature of the event is indicated by two primary characteristics: 1) the disturbance had a much shallower slope than expected for an internal bore, while at the same time the upward perturbation within the inversion was quasi-permanent rather than sinusoidal, which more closely resembles a bore; and 2) the predicted phase speeds for the ‘‘solitary’’ form of nonlinear Kelvin wave and for an internal bore are both close to the observed intrinsic phase speed

New Materials for Photoconductive Terahertz Antennas

In this thesis, we have first introduced a new setup for the reliable characterization of photoconductive antennas to be used in THz time-domain spectroscopy. Using this setup one can benchmark THz antennas with high precision. The intra-day reproducibility error is in the range of 1.9% while the reproducibility within 9 days is 2.6%. This includes not only absolute power stability but also reproducibility of the spectra by eliminating alignment errors that alter the transfer function from sender to receiver. In order to demonstrate the full capabilities of the system, we investigated samples from five LT-GaAs wafers, grown at temperatures between 200°C and 300°C, in a systematic manner. The obtained results are in good agreement with previous studies on the same material system. These results prove that the system allows for quality control of photoconductors with minimum comparison error. We have also investigated the correlation between THz emission strength and the surface properties of the LT-GaAs photoconductive antenna. The THz characteristics were measured with the highly stable setup mentioned above, which allowed exciting a 10-mm long CPS antenna along the gap without changing the alignment of the optical or THz beam path. The surface properties were quantified regarding roughness and grain size. The roughness was extracted from AFM measurements and the grain size from SEM measurements. A comparison of the THz emission strength in form of the peak-to peak THz amplitude and the surface properties showed a strong nonlinear correlation: a smaller grain size and a smoother surface increase the THz amplitude. These results can be used in the future to optimize the performance of THz antennas. Additionally, we have successfully prepared TiN-nanoparticles using ultrasonic and pulsed laser ablation techniques. The two techniques provide with a different distribution of Zeta-potential and particle size. Within our experimental conditions, pulsed laser ablation can give lower particle size and greater Zeta-potential. TiN-nanoparticles prepared by these techniques have a high and flat absorbance in the spectral range 600 -1000 nm. LT-GaAs covered with dispersed TiNnanoparticles has enhanced THz emission when the average particle size is about 62 nm. More investigations are needed on how to develop preparation and deposition techniques in such a way that control the shape, size, distance between the particles. This may lead to a further improvement of the THz power emitted from such devices. Finally, we demonstrated that coating with MnFe2O4 nanoparticles could be used to improve the performance of photoconductive antennas in the THz region. Our experiments demonstrate that coatings with MnFe2O4−particles provided a new approach to increase the photocurrent density on silicon under CW illumination. In order to understand the effect ofMnFe2O4 nanoparticles on photo-excited silicon, a semiconductor model was proposed to describe this phenomenon. We used this model to calculate the transmission amplitudes of THz pulses transmitted through bare silicon substrates and silicon substrates covered by MnFe2O4 nanoparticles under laser irradiation with different powers. Because the effect of MnFe2O4 nanoparticles on silicon significantly provides an enhanced attenuation of terahertz wave, silicon substrates covered by MnFe2O4 nanoparticles have the potential to be used as an optical modulator in the THz region. This may lead to a costefficient component for THz systems operating in transmission mode. Furthermore, MnFe2O4 nanoparticles could be used for the implementation of novel optical devices

USING BAYESIAN STATISTICAL POSTPROCESSING METHODS TO IMPROVE LOCAL WIND FORECASTS

This thesis explores the use of Bayesian statistical postprocessing to rapidly train a highly accurate forecast from a 1 km resolution gridded WRF model forecast over a 100 km by 100 km area. These methods leverage three modeled forecast variables—10 m winds, sea-level pressure, and terrain elevation—in conjunction with downstream observations and prior model runs to identify model inaccuracies. Using only three days of data, a Bayesian corrected forecast is produced and analyzed for accuracy and improvement over the original model run relative to real-world observations. Over 90% of the resulting forecasts saw improvement over the raw model forecasts in root mean squared error, and over 87% of the forecasts saw improvement in mean error over the raw model forecasts. Extreme circumstances saw improvements in accuracy of over 9 knots while overall improvements were reliably seen both in accuracy and precision among Bayesian corrected forecasts. These findings are significant as they suggest that Bayesian statistical postprocessing methods work and should be both employable at rapid rates, and result in more accurate forecasts.First Lieutenant, United States Air ForceApproved for public release. distribution is unlimite

NPS Master Curriculum Chart, September 30, 2016

NPS Master Curriculum Chart listing: School / Curriculum / Degree / Length / Convenes / PO / Refresher / APC / JPME / Dept. / Department Chair / Academic Associate / Program Officer / PhD. Committee Chair / P_Code