Winter Storm Extremes and Vulnerability Along the Atlantic Coast
Project Acronym: StormEVAAC
Coastal flooding associated with powerful storms is a well-recognized natural hazard along the U.S. Atlantic coast. Given the significant regional intersection of high population density and critical infrastructure and the compounding impact of rising sea levels, it is important that we continue to improve our understanding and ability to quantify the region’s exposure to weather and climate hazards as well as the areas’ societal and ecosystem vulnerabilities, and how they interact to create the overall vulnerability to climate variability and change. We proposed a study of the region’s present vulnerabilities to cold season storms in order to understand the underlying societal and physical processes and quantify them in a systematic manner both in present and in the future under climate change and projected population growth.
The backbone for the project is an analysis of the variability of extratropical cyclones that impact the coast. The analysis began with an automated identification of historical storms. Once identified, we will categorize the storms’ variability in terms of their path, frequency and strength. As extratropical cyclone strength is ambiguous, we seek to define metrics based on storm-local surface wind speed and precipitation that directly relate to hazards affecting people and ecosystems. Our preliminary analysis of TRMM-3B42 precipitation data links extreme precipitation events along the coast to the extratropical cyclones. Therefore, our work will (a) develop more robust descriptors of the different type of extremes, (b) link the precipitation extremes to social and place-based vulnerability, and (c) determine what, if any, connection exists between cyclone variability and high intensity precipitation events. Furthermore, given the large natural variability inherent in extratropical cyclone behavior, we will generate a stochastic model of the storms, which will allow a probabilistic analysis of the storm hazards.
For coastal areas, both humans and ecosystems are particularly vulnerable to storm surges. Therefore, we are characterizing the physical processes that determine the link between extratropical cyclones and storm surges, and determining the relative importance of different characteristics of the cyclones towards the generation of hazards. To accomplish this, we are running a numerical storm surge model, which will be forced by the stochastic storm model. In addition to our focus on surge dynamics, the numerical storm surge model will be adapted to study coastal erosion, a process that creates some of the worst hazards for humans living on the coast. To quantitatively assess risk and vulnerability of the coastal populations, we are carrying out systematic mapping of data from the US Census Grids, developed by NASA’s Socioeconomic Data and Applications Center (SEDAC). The drastic precipitation and temperature changes associated with winter extratropical cyclones also make them hazardous to coastal ecosystems. To assess these hazards, we are analyzing all clear MODIS-Aqua data that was collected by NASA before and after various selected extreme winter storms that impacted the U.S. East Coast over the last decade and demonstrate the value of remote sensing by assessing how the ecosystem (Chlorophyll and optical properties) respond to flood-induced erosion and sediment transport along the Northern U.S. East Coast in relation to these powerful storms.
Metrics of storm varialbility and strength and storm surge and erosion risk will utilize statistics of extreme value theory to determine return periods for different levels of events and link to our analysis of human and ecosystem vulnerability. Thus providing an improved understanding of the coupled human-natural systems along the coast in extreme winter storm situations and delivering probabilistic information in support of decisions for adaptation and response.
Focus Region for this study, The central Northeast Atlantic Coast of the United States
Categorizing Extratropical Cyclones Tracks
Major contributors: Principal Investigator Yochanan Kushnir and Scientist Donna E. Lee, Lamont-Doherty Earth Observatory, Columbia University and Co-Investigator Jimmy Booth, City College of New York
Figure 1: Five clusters of 48-hour long sea level pressure transitions leading the top 200 surge peaks at the Battery. Hierarchical cluster analysis using correlation distance with Ward linking method was carried out. The contours are cluster means, and shadings indicate the standard deviation within each cluster
Stochastic simulation of Extratropical Cyclones
Major contributors: Co-Investigator Tim Hall, NASA GISS and Co-Investigator Jimmy Booth, City College of New York
Considerably less work has been done on quantifying extratropical cyclone (ETC) hazard than tropical cyclone (TC) hazard. The development of a statistical-stochastic model for Nor’easters, one of the most damaging types of ETCs for the U.S. Northeast is a key part of our work. The model includes simulation of the genesis, track, intensity, lysis, and geometry of the storms. Use of a complete life-cycle statistical model (compared to statistical incidence models separately at each site of interest) will allow us to better understand sensitivities of hazards to large-scale climate indices, such as SST and NAO and arrive at a better probabilistic definition of the hazard.
Once a nor’easter model is developed, tested, and validated it will be used to generate a large (~107) set of synthetic storms. We will then perform frequency analysis on this large set to estimate (with uncertainty) annual occurrence probabilities on Northeast US locations in various combinations of hazard variables; e.g., intensity, size, and propagation speed. We will compute these probabilities as a function of the predictor climate-state variables. A generic sample storm from each of the most hazardous variable combinations will be used to drive the hydrodynamic model to assess storm flood risk.
From Tim Hall NASA / GISS: SynthETC - A Stochastic Extra-Tropical Cyclone Model for U.S. Winter Storm Hazard
Assesment of Coastal Flooding
Major contributors: Co-Investigator Philip Orton and Scientist John Miller, Stevens Institute of Technology
Modeled storm tide, wind and pressure for the 1992 December 11 Nor'easter in the New York City region. At the top right is a time series of the water elevation at New York City's Battery Park, showing the undulation of the tides over 6 days and how the storm surge gradually raised the tides higher to form the maximum storm tide of 2.3 m. In the other two panels are different scales of maps of the region, showing wind vectors (see scale of a threshold 33 m/s hurrican strength wind speed), isobar lines and color shading of water elevations.
Analysis IV- part one:
Human and Ecosystem Vulnerabilities to Extratropical Cyclones - Winter storm impact on coastal ecoysytem
Major contributors: Co-Investigator Ray Sambrotto, Lamont-Doherty Earth Observatory, Columbia University, and subawardees Sherwin Ladner and Sean McCarthy, Naval Research Lab
The nature of winter precipitation also may be important in that rainfall distributed evenly throughout the winter appears to lead to different ecological outcomes than a large snow pack that supports an unusually large freshet.
MODIS Aqua data processed by the Naval Research Laboratory’s (NRL) Automated Processing System (APS) software at pseudo 250 m resolution. A and B are the Total Suspended Solids (TSS) product 2 days before (A) and 2 days after (B) an extratropical cyclone on 3/14/10. C and D are the Chl a product 7 days before (C) and 11 days after (D) Hurricane Sandy on 10/29/12. Sandy was followed closely by a Nor’easter and the scenes reflect the impact of both storms.
Analysis IV - part two:
Human and Ecosystem Vulnerabilities to Extratropical Cyclones - Mapping human vulnerability in areas impacted by wintertime storms and associated flooding
Major contributors: Co-Investigator Susana Adamo, Center for International Earth Science Information Network, Columbia University and assisted by center staff scientists
We are assessing and analyzing human vulnerability –i.e. the vulnerability of human populations, households, livelihoods and infrastructure—to winter storms in the NE United States in 1990, 2000 and 2010 using a mixed approach: place vulnerability and vulnerability mapping. We aim to address exposure to hazard, social vulnerability, and temporal and spatial variability and trends, to uncover the underlying structural conditions of human systems, and to estimate the impact and aftermath of specific events.
Table 1: Dimensions and indicators of hman vulnerability to be considered in the vulnerability assessment
Human and Ecosystem Vulnerabilities to Extratropical Cyclones - Collecting relevant data to determine benefits of adaptation measures and factors determining decisions
Major contributors: Co-Investigator Mingfang Ting, Lamont-Doherty Earth Observatory, Columbia University and Scientist Malgosia Madajewicz, Center for Climate Systems Research, Columbia University
Figure 1: Damage per event type for all major winter storm losses for Connecticut, New Jersey and New York combined. The chart indicates the hazards, or “events,” contributing to the overall losses total. Each event type’s percent of the damage (all hazard losses combined) and property damage dollar amount are listed. Flood losses (freshwater and coastal) account for most of the damages overall
Figure 2: Distribution of damage among storm classes for all states combined. The damage amount per type and percentage of total damage for all storms combined are listed. The number in parentheses indicates the number of storms that fell in that category. Multiple Category storms caused the most damage by far. Storm surge and storm tide storms caused more damage than precipitation and wind and with fewer storms.