A Case Study of Four Atmospheric River Events Over the Pacific West Coast of the United States

Atmospheric Rivers (AR) are moisture phenomena related to cyclones which bring moisture and large amounts of precipitation to areas of enhanced elevation along coastal areas. These events bring much of the rain received by the state of California, and the past winter was no exception, as many AR events brought much-needed rain to the region. Four different events from the 2016 fall through 2017 spring seasons are examined to better identify the relative roles of long-range moisture transport versus local moisture fluxes in AR events. Cross-sections of areas and times of interest during each event are generated, along with trajectory analyses which will aid in determining the origin of the moisture being moved. Both the cross-sections and trajectory analyses are taken from the CFSR (Climate Forecast System Reanalysis) model. It is expected that the results of these processes will support the findings of Dacre et al. (2015), which show that the moisture anomaly present during AR events is not actually due to moisture transport directly along the AR. Rather, the AR is the result of moisture convergence from a combination of the warm conveyor belt forcing the ascent of moisture over the warm front and the trailing cold front forcing ascent as it moves eastward. The importance of this research is evident on the US West Coast, as water conservation in this naturally dry region is extremely important to the ever-expanding cities and communities present there and requires long-term planning, which is aided by our increased understanding of AR events

Quantifying Sensible Weather Forecast Variability

Sensible weather occurs on small scales and the development and evolution of these small scale features depends strongly on the larger scale environment. Synoptic scale variability is represented by the individual members in a well-designed ensemble modeling system. The objective of this research is to quantify the local scale variations in sensible weather elements, like fog, due to larger scale variability. The sensitivity of selected weather elements to synoptic scale background variance will be quantified to identify when local scale predictability may be high or low

A Case Study of Four Atmospheric River Events Over the Pacific West Coast of the United States

Atmospheric Rivers (AR) are moisture phenomena related to cyclones which bring moisture and large amounts of precipitation to areas of enhanced elevation along coastal areas. These events bring much of the rain received by the state of California, and the past winter was no exception, as many AR events brought much-needed rain to the region. Four different events from the 2016 fall through 2017 spring seasons are examined to better identify the relative roles of long-range moisture transport versus local moisture fluxes in AR events. Cross-sections of areas and times of interest during each event are generated, along with trajectory analyses which will aid in determining the origin of the moisture being moved. Both the cross-sections and trajectory analyses are taken from the CFSR (Climate Forecast System Reanalysis) model. It is expected that the results of these processes will support the findings of Dacre et al. (2015), which show that the moisture anomaly present during AR events is not actually due to moisture transport directly along the AR. Rather, the AR is the result of moisture convergence from a combination of the warm conveyor belt forcing the ascent of moisture over the warm front and the trailing cold front forcing ascent as it moves eastward. The importance of this research is evident on the US West Coast, as water conservation in this naturally dry region is extremely important to the ever-expanding cities and communities present there and requires long-term planning, which is aided by our increased understanding of AR events

Improving Tactical Environmental Support in Data Denied Areas: Applications of Machine Learning (ML)

NPS NRP Executive SummaryImproving Tactical Environmental Support in Data Denied Areas: Applications of Machine Learning (ML)N2/N6 - Information WarfareThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Improving Tactical Environmental Support in Data Denied Areas: Applications of Machine Learning (ML)

NPS NRP Executive SummaryImproving Tactical Environmental Support in Data Denied Areas: Applications of Machine Learning (ML)N2/N6 - Information WarfareThis research is supported by funding from the Naval Postgraduate School, Naval Research Program (PE 0605853N/2098). https://nps.edu/nrpChief of Naval Operations (CNO)Approved for public release. Distribution is unlimited.

Evolution of Low-level Flow Patterns in Littoral Regions when Extratropical Marine Cyclones Encounter Coastal Mountains

LONG-TERM GOALS: The long term goal of this project is to understand the interaction of slightly different large scale flows interaction with complex coastal topography to produce both regions of enhanced and diminished near surface winds.Award Number: N0001499WR3012

Dependence of Mesoscale Coastal Predictability on Data Assimilation and Distribution of Observations

The long term goal of this project is to determine the mesoscale atmospheric predictability and how it relates to synoptic scale uncertainty due to sampling and data assimilation of incomplete samples on the larger scale.Award Number: N0001401WR2003

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

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

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 1993-98 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