Mechanisms for the Seasonal Transition of Precipitation Organization in the Southeastern United States: Current and Future Climate

GSTDTAP

项目编号	1660049
	Mechanisms for the Seasonal Transition of Precipitation Organization in the Southeastern United States: Current and Future Climate
	Rosana Nieto-Ferreira
主持机构	East Carolina University
项目开始年	2017
	2017-04-01
项目结束日期	2020-03-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	146982(USD)
国家	美国
语种	英语
英文摘要	Seasonal transition The Southeastern United States (SE US) owes its ample water resources to many forms of precipitation, from the large-scale precipitation associated with frontal weather systems to sea-breeze convection associated with the adjacent Atlantic, to tropical cyclones, mesoscale convective systems and afternoon thunderstorms. These precipitation types differ in important ways including their predictability and their sensitivity to changes in regional climate, thus an understanding of their behavior and relative contributions to mean precipitation and precipitation change over the SE US is desirable. The PIs have developed a simple characterization of precipitating cloud systems into mesoscale precipitation features (MPFs), which consist of a contiguous region of precipitation of at least 100 km length, and smaller and shorter-lived isolated precipitation features (IPFs). Despite the simplicity of the classification scheme, it has proven effective for understanding the geographical and temporal behavior of SE US precipitation. A key result of the PIs' previous research is that while MPFs (which include frontal precipitation and mesoscale convective systems) do not exhibit a strong seasonal cycle, the seasonal cycle of IPFs is characterized by a relatively abrupt spring onset occurring between May and June and concentrated over Florida, the adjacent coastline of the Gulf of Mexico, and the Atlantic coast as far north as Cape Hatteras. The onset of IPF rainfall over the SE US is somewhat reminiscent of the abrupt transition to the rainy season in monsoon regions such as West Africa and East Asia, which have been more extensively studied than the SE US. Work conducted here explores the springtime IPF onset using a combination of observational data and numerical model simulations. Observational data come from the National Mosaic and Multi-sensor Quantitative Precipitation Estimation (NMQ) dataset, NEXRAD-based and gauge-adjusted precipitation dataset, a precipitation dataset constructed from the NEXRAD network of radar stations that covers nearly all of the continental US. The PIs have developed an automated precipitation organization classification algorithm to identify MPFs and IPFs, and they apply the algorithm to to 11 years (2002-2012) of NMQ data on a one hourly basis to capture statistics of the spring IPF onset. These data will be used in conjunction with the North American Regional Reanalysis to assess contributions to the onset from thermodynamic factors such as convective available potential energy and convective inhibition, or circulation changes such as the seasonal movement of the North American subtropical high (NASH) and low-level jets in the region. A further goal is to understand how IPF seasonality may change in a changing climate. The PIs hypothesize that the IPF onset would occur earlier in a warmer climate, as the relevant thermodynamic factors would likely occur earlier in the year given a warmer base state. Research on IPF sensitivity to background warming is conducted using the Weather Research and Forecasting (WRF) model, which is used to simulate weather and climate over a regional domain given meteorological conditions at the boundaries. The simulations use the pseudo global warming (PGW) method, in which meteorological conditions are taken from operational meteorological analysis to simulate the seasonal transition in recent years of record, and simulations are then repeated using boundary conditions to which differences between future and present-day climate simulations are added to represent anticipated climate change. The seasonal transition of precipitation types over the SE US is of interest for practical as well as scientific reasons, as decision makers rely on weather and climate forecasts for agricultural planning as well as guidance on precipitation-related hazards and urban development. The PIs engage with local communities from Raleigh to the Outer Banks through the general public. Results of the project are used in courses taught by the PIs, in part though a WRF-based teaching laboratory for weather forecasting, which serves an educational purpose and also enhances the success of students pursuing careers in weather prediction.
来源学科分类	Geosciences - Atmospheric and Geospace Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/70953
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Rosana Nieto-Ferreira.Mechanisms for the Seasonal Transition of Precipitation Organization in the Southeastern United States: Current and Future Climate.2017.