Meteorology Commons^™

Predictability Of Sea Ice Near Bifurcations, Dawn Marie Kopacz

Theses and Dissertations

There is evidence in Earth’s history of relatively stable climate regimes abruptly transitioning to alternative states. It has been argued that the greatest potential for such abrupt transitions in Earth’s system in the near future is located in the Arctic. Here we analyze the Arctic sea ice evolution of two current generation climate models that exhibit critical transitions. We demonstrate the detectability of two early warning signals: increased variance and increased autocorrelation. We introduce another metric that forewarns of abrupt changes in sea ice; a decrease in predictability before the threshold points. Observations of Arctic sea ice extent are searched …

Seasonal Influences Upon And Long-Term Trends In The Length Of The Atlantic Hurricane Season, Juliana Marie Karloski

Theses and Dissertations

Atlantic tropical cyclone (TC) seasons vary yearly in length with some seasons significantly shorter or longer than normal. Kossin (2008) suggested that from 1980 to 2007, the Atlantic TC season increased in length; however, their study only considered a subset of the Atlantic basin south of 30°N and east of 75°W. It is uncertain whether this trend holds over the entire Atlantic basin or continues into the present. It is also unclear as to whether meaningful sub-seasonal variability in the environmental factors necessary for TC formation exists between early- and late-starting and -ending seasons.

Quantile regression is used to evaluate …

Using A Semiprognostic Test To Elucidate Key Model Errors Of Warm Rain Processes Within A Unified Parameterization Of Clouds And Turbulence, Justin Kyle Weber

Theses and Dissertations

The representation of clouds and turbulence remains one of the foremost challenges in modeling earth's climate system and continues to remain one of the greatest sources of uncertainty in future climate projections. Increased attention has been given to unifying cloud and turbulence parameterizations in order to avoid the artificial categorization of cloud and turbulence regimes. One such unified parameterization is known as the Cloud Layers Unified by Binormals (CLUBB). CLUBB is a single column model of clouds and turbulence that assumes subgrid scale variability can be represented by a joint probability density function (PDF) of temperature, moisture, momentum, and hydrometeors. …

Utilizing Four Dimensional Lightning And Dual-Polarization Radar To Develop Lightning Initiation Forecast Guidance, Andrew J. Travis

Theses and Dissertations

Lightning initiation is a major forecast challenge faced by Air Force's 45th Weather Squadron (45 WS), which provides weather support to Cape Canaveral Air Force Station and Kennedy Space Center (KSC). Prior studies by Thurmond (2014) and Woodard (2011) have shown that dual-polarization (DP) radar can be used to identify the presence of hydrometeors indicative of cloud charging, leading to improved lightning initiation forecasts. The 45 WS currently employs empirical lightning initiation forecast rules which state that in-cloud lightning is likely when radar reflectivity meets or exceeds 37.0 dBZ above the -10°C height. This study examined 249 convective cells from …