Digital Commons Network^™

A Hemimysis Driven Novel Ecosystem At A Modified Boulder Breakwall, Eric John Geisthardt

Theses and Dissertations

The US Army Corps of Engineers (USACE) is mandated to maintain and repair aging breakwall structures in all commercial ports on the Great Lakes. In May of 2014, the construction of Milwaukee Harbor USACE “green” breakwall (GBW) reconciliation created complex rocky aquatic habitat by depositing cobble-sized stone as a veneer over standard 6-10 ton boulders, thus creating “control” (boulder) and “treatment” (cobble) habitats. The breakwall is home to a prolific population of Hemimysis anomala, the introduced Ponto-Caspian mysid, which is significantly more abundant on cobble versus boulders (p<0.05, using a novel trap for Hemimysis). Fish and forage communities were sampled in 2015 and 2016 using a combination of experimental and micromesh gill nets, night scuba diving surveys, and a novel Hemimysis trap. This nearshore lithophilic mysid appears to provide a significant new seasonal food resource in the Milwaukee Harbor for pelagic prey fishes during inshore spawning migrations and upwelling events. Alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) fed heavily on Hemimysis with some individuals consuming hundreds of mysids. Night scuba diving surveys and gill netting confirmed that rainbow smelt preferred to forage on the cobble section (p<0.05), and also consumed more Hemimysis there than they did at the control breakwall site (p<0.05). Hemimysis were also the primary food item consumed by nearshore game fishes such as YOY yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris) caught at the breakwall. This study provides the first documented evidence that where abundant in the Laurentian Great Lakes, Hemimysis do have the ability to significantly impact local food webs and drive the feeding ecology of both pelagic transient and nearshore resident fishes.

An Examination Of The Dynamics Of A Rear-Inflow Jet Associated With An Idealized Mesoscale Convective System, Caitlin Crossett

Theses and Dissertations

This study evaluates the main controls on the descent of the rear-inflow jet (RIJ), associated with a mesoscale convective system (MCS), toward the surface. This study employs the Cloud Model 1 (CM1), release 18.3, to simulate idealized MCSs. The model has a horizontal grid spacing of 1 km with 100 vertical levels, and utilizes doubly periodic lateral boundary conditions. The Morrison double-moment explicit moisture scheme is used and Coriolis accelerations are ignored. To initiate convection, a 2 K warm bubble is applied over a limited subset of the domain. Simulations in which the magnitude of vertical wind shear is perturbed, …

Adaptive Monte Carlo Sampling For Cloud And Microphysics Calculations, Thomas Franz-Peter Roessler

Theses and Dissertations

An important problem in large-scale modeling of the atmosphere is the parametrization of clouds and microphysics on subgrid scales. The framework Cloud Layers Unified By Binormals (CLUBB) was developed to improve the parametrization of subgrid variability. Monte Carlo sampling is used to couple the different physical processes, which improves the grid average of subgrid tendencies.

In this Thesis we develop an adaptive Monte Carlo sampling algorithm that re-uses sample points of the previous time step by re-weighting them according to the change of the underlying distribution. This process is called 'what-if sampling' and is an application of importance sampling. An …

Performance Test Of The Pasquill Stability Classification Scheme, Hillary Lin Chapman

Theses and Dissertations

In 1961, Frank Pasquill proposed a method for classifying atmospheric stability based on routinely available surface observations – namely wind speed, cloud cover, and the strength of incoming solar radiation. Stability is classified into six categories: extremely unstable (A); moderately unstable (B); slightly unstable (C); neutral (D); slightly stable (E); and moderately stable (F). These categories are ultimately meant to be used to determine the rate of diffusion of windblown pollutants, but since their inception, the classes have often seen use outside of their originally intended purpose. In this thesis, the performance of the Pasquill scheme is tested in order …

Downstream Predictability Of The Path Of Severe Wind Producing Mcss Using Ruc Analysis Data, Russell Danielson

Theses and Dissertations

A method for predicting the track of mesoscale convective systems (MCSs) is developed, based upon meteorological parameters in the path of the systems. Rapid Update Cycle model analysis from the years 2007 through 2011 were used to gather meteorological data for 94 MCS events. An artificial neural network model was developed to predict whether the MCS will track to the “Right”, “Left”, or stay on its current path. The most important parameters to predict the track of an MCS in this model are precipitable water, most unstable CAPE, 700hPa temperature, surface-500hPa mean wind, low-level equivalent potential temperature difference, and 700-500hPa …