Walter Robinson

Overview Warm season weather and climate extremes������������������flooding rains, heat waves, and droughts������������������ have devastating impacts on people and nature. These extremes and their impacts are expected to become more severe as Earth warms, a trend that is increasingly being observed. These phenomena challenge our scientific understanding and our modeling systems, because they involve disparate processes operating across wide ranges of scales, both spatially (regional to global) and temporally (convective to seasonal). Moreover, there is growing evidence of interactions among these scales. For example, the large-scale flow that results in a heat wave, which is then amplified by local interactions with the land surface, may, in turn, be modified by the presence of that regional heat. Likewise, the latent heating of the atmosphere associated with heavy rains may influence the circulation on much larger scales. Simulating such phenomena with sufficient veracity to address associated scientific questions and to project their responses to climate change, therefore, demands modeling approaches that span as wide a range of scales as is feasible, allowing model outputs to be interrogated at meso- or even cloud-scales. Here we propose a program of research, focused on how climate change will affect warm-season weather and climate extremes in North America. The research will comprise analyses of existing output of climate models contributed to the 6th Coupled Model Intercomparison Project (CMIP6) in addition to our own high-resolution (15-km grid) numerical experiments using the Model for Prediction Across Scales-Atmosphere (MPAS-A). These simulations will start from a 30-year baseline run simulating the current climate. Future simulations will include resimulations of extreme events native to the control run under future climate conditions and 30 free running warm season time-slices. Extreme events from the time-slice simulations will be re-simulated to enable hour-by-hour analyses of physical processes within the model to determine how they are modified by climate change. Event re-simulations at convection permitting resolution will also be explored. Intellectual Merit The intellectual merit of this research is in building a predictive understanding of future changes in warm-season climate extremes, by building on existing (CMIP) climate simulations and using modeling strategies that include the multiple relevant scales of the physical climate system that participate in these extremes and the interactions among them. The PI team������������������s expertise spans weather and climate dynamics, and the influence of climate change on extreme events. Broader Impacts Broader impacts of this work will include better informing the public about future climate extremes and developing future climate scientists. The latter will be accomplished via graduate student training, undergraduate research participation, and collaboration with the North Carolina Museum of Natural Sciences in activities for high school students that will introduce them, through hands-on activities, to climate science and will inform them about pathways to future careers in climate science, and STEM generally. An open data-access strategy that facilitates classroom and project use of weather and climate datasets, including those produced by this project, will help to build data science, programming, and analysis skills for undergraduate and graduate students at NC State and Northern Illinois Universities.

Persistent anomalies in the atmospheric circulation are unusual states of the atmospheric flow and conditions that remain approximately fixed over periods longer than a few days. Such states disrupt the daily march of weather in the extratropics. Many impacts of weather on human and natural systems are cumulative: the desiccation of soils and vegetation in a drought, the saturation of the ground during an extended period of rain, and the toll taken on people and societal infrastructure by prolonged heat or cold. Thus, persistent anomalies produce significant human impacts. Understanding and ultimately projecting how the frequency, distribution, and intensity of persistent anomalies will change with changes in global climate is necessary for projecting the impacts of climate change on nature and society. Interactions with extratropical cyclones are critical for initiating and sustaining persistent anomalies. The work proposed here focuses on these interactions and builds on the PIs������������������ prior research exploring the changes in cyclones with climate. It was found that the increases with global warming in specific humidity leads to increased release of latent heat in storms, with consequent effects on storm structure and intensity. The representation of these effects was shown to exhibit strong sensitivity to model resolution. The studies proposed here are motivated by hypotheses that address the importance of cyclones, especially strong cyclones, for persistent anomalies, through their initiation and maintenance and through their conditioning of the large scale circulation on which persistent anomalies occur. Simulations will include ensemble studies of individual persistent anomaly events and the climatology of persistent anomalies in multi-year experiments, under present-day and future climate conditions. It is anticipated that model configurations (resolutions and choices of parameterizations) that produce better hindcasts of individual events will yield better climatologies of persistent anomalies under present-day conditions. These configurations can then be applied to future events and climatologies, by imposing global warming conditions. Results will be analyzed using potential vorticity and Rossby wave-breaking diagnostics and cyclone tracking. Key precursors to persistent anomalies in the case studies will be determined using model ����������������surgery���������������, in which dynamical features can be deleted from the initial conditions. A single-layer model will be used to obtain dynamical understanding of the importance of changes in cyclones and the background flow in producing changes in persistent anomalies.

Newly available out from a suite of medium- and high-resolution global atmospheric modeling experiments, conducted by the United Kingdom Meteorological Office, will be used to test the joint sensitivities of the mid-latitude storm tracks to global warming and to model resolution.

Eastern NC has a history of large and intense wildfire on both privately owned timberland and protected areas such as national wildlife refuges. A layer of soil rich with organic content plays an important factor in the wildfire susceptibility and intensity across this region. The SCONC is monitoring organic soil moisture to assess potential fire and smoldering risk and integrating this data into resources to better address coastal fire conditions and risk. As part of the proposed project, SCONC will be maintaining a network of organic soil moisture monitoring stations in eastern NC and implementing quality control routines. SCONC will also develop usable guidance using the collected data through stakeholder engagement.

The State Climate Office of NC (SCO) and NCDOT have previously partnered on the development of a comprehensive precipitation alert system, which includes a detailed mapping system and rainfall monitoring alert services. This collaborative project has been estimated to save over 110,000 work hours per year, and has won several state and national awards. This work will enhance and leverage that partnership by identifying high-risk areas during or shortly after the occurrence of heavy precipitation events as specified by NCDOT engineers. These high-risk zones will be highlighted on a map interface and/or via an alert, and will be defined by the historical likelihood of obtaining that same precipitation amount within a specified time period at a particular location. In addition, the year-to-date accumulation of rainfall for the current year will be displayed and compared to the normal (30-year average) year-to-date rainfall accumulation. These additional features will help NCDOT better prioritize and deploy resources for flood and runoff mitigation.

Objectives of this project are to develop an on-line tool to provide cotton growers with: 1) Monthly crop and irrigation water requirements. These would take the form of a table and/or graph of probability of exceedence, so that not only mean or median values would be presented, but a range of monthly water requirements to cover both times of drought and rainfall surplus. 2) Required agricultural pond storage, with tables/plots to show the expected reliability of a farm pond based on size and water supply (runoff).

The campus of North Carolina State University (NCSU) in Raleigh, NC is emerging as an epicenter for regional efforts on climate change impacts and response. The State Climate Office (SCO) has been on NCSU������������������s campus since the 1981 and has collaborated in research and public service with multiple colleges and state and federal agencies. In 2009, the US Department of the Interior (DOI) selected NCSU as the host institution for the Southeastern Climate Science Center (SE CSC). In the same year, the DOI also located the South Atlantic Landscape Conservation Cooperative (SALCC), one of six LCCs in the southeast, on NCSU's Centennial Campus. This year, the US Department of Agriculture (USDA) established the Southeast Regional Climate Hub (SERCH), also located on NCSU's Centennial Campus. NCSU is itself a regional leader in climate change research, and as Land Grand University, has a significant extension capacity. Due to both physical proximity and synergistic missions among all of these entities, there is tremendous opportunity to develop strong collaborative working relationships with regional implications. This proposal seeks to develop information and capacity that enable SERCH to meaningfully engage with NCSU, DOI SE CSC, SALCC, and the dispersed network of federal, state, and private partners throughout and beyond the Southeast.

While the annual march of insolation drives Earth seasonal cycles, in some regions, notably the high latitudes of the Northern Hemisphere, the advance of spring is abrupt, indicating an important role for dynamical processes. The abrupt onset of Arctic spring is associated with atmospheric ridging over Baffin Bay and the Labrador Sea with a consequent increase in the westward mountain torque from Greenland, and weakening of westerly winds southeast of Greenland. These changes are important for the Arctic climate and environment, because they effect surface hydrology and ecosystems, and establish conditions that influence sea-ice cover in the following summer and fall. The timing of these abrupt changes varies from year to year, but they are centered in mid-April. We hypothesize that the spring transition is driven by one or more of the following dynamical processes: downward influence of the springtime final stratospheric warming, an abrupt change in the topographic blocking of flow over Greenland, and an abrupt switch in the nature of Rossby wave breaking over the North Atlantic or in the frequency and tracks of extratropical cyclones entering the Arctic. These spring transition processes have strong impacts on the surface climate and may be shaped by feedbacks from surface processes. We will test this hypothesis, and explore its implications for future changes in the Arctic environment, through a coordinated program of diagnostic analyses of atmospheric and Arctic surface data, mechanism-driven experiments with a global atmospheric model, and analyses of 20th Century and future climate simulations carried out as part of the Coupled Model Intercomparison Project (CMIP5). The intellectual merits of this project are that it will develop a mechanistic dynamical understanding of the Arctic spring transition and its interactions with the Arctic environment, and that it will use this understanding to evaluate climate models and their projections of Arctic change. The broader impacts of this project are generating projections of Arctic climate change from models that have been thoroughly evaluated in their ability to simulate key features of Arctic climate. Three graduate students will be trained in an interdisciplinary context spanning diagnostic analyses of global data, Arctic system science, and atmospheric dynamics and modeling.

It is expected that the tracks and intensities of extratropical cyclones will change over the coming decades as climate warms, though the magnitudes and even the signs of these changes remain uncertain. The potentially competing effects of weaker lower-tropospheric temperature contrasts and enhanced specific humidity, further complicated by the uncertain influences of an expected deepening of the troposphere, stronger baroclinicity in the upper troposphere, and an altered global circulation, lead to great uncertainty in projecting changes in extratropical cyclones and stormtracks and, in turn, in projecting changes in their roles in Earth?s climate. Studies of the dynamics of individual storms reveal that the release of latent heat, through the diabatic production of low-level potential vorticity (PV), is critical for storm development and for contributing to damaging winds and flooding rains. These dynamics should become more vigorous in a warmer and moister atmosphere, but the scales of the relevant features?frontal rainbands and low-level jets?fall below the resolved spatial scales of current GCMs. We hypothesize that both individual storms and the stormtracks, including their climatically important poleward transports of heat and moisture, will be sensitive to model resolution at sub-GCM scales, and because this sensitivity is tied to the release of latent heat that it will be greater in a warmer climate. Similarly, we expect the modeled sensitivity of the stormtracks to global warming to be greater at higher resolutions. We propose to test this hypothesis and explore its implications through a program of high-resolution model simulations of the North Atlantic stormtrack under current day and climate-change conditions, using the Weather Research and Forecasting (WRF) model, in regional and global configurations and employing 1 and 2-way nests to enhanced resolution over the stormtrack region. The intellectual merit of this work is in systematically exploring the two-way interactions between diabatic processes in storms and the global climate system. Understanding how the storm tracks will change in a changing climate requires the examination of the scale dependence of moist processes we propose. Changes in extratropical storms and stormtracks have potentially important impacts on society, through their effects on the availability of water and on the risks of damaging winds, flooding rains, and high waves. More reliable projections of these changes and improved understanding of their associated uncertainties are a potential societal benefit from this research and a broader impact of the proposed project. Additional broader impacts include the mentoring of graduate and undergraduate researchers, education and outreach based on project results, and the value, to the broader climate research community, of testing the WRF model in climate applications. The proposed project is potentially transformative in bringing together the fields of climate and synoptic dynamics and in its potential for revealing critically important but hitherto neglected aspects of climate change.