Climate Reconstruction for Long Island Sound Fisheries

Analyzing History to Project and Manage the Future: Simulating the Effects of Climate on Long Island Sound’s Physical Environment and Living Marine Resources

Lead PI:  Nickitas Georgas, Stevens Institute of Technology

Co-PIs:  Philip Orton, Alan Blumberg, Stevens Institute of Technology

Co-PI:  Penelope Howell, Connecticut Department of Energy and Environmental Protection

Associate Investigator:  Vincent Saba, Geophysical Fluid Dynamics Laboratory and NOAA National Marine Fisheries Service

Funding:  EPA Long Island Sound office, New York and Connecticut Sea Grant programs

In this project, we will a) conduct a multi-decadal three-dimensional hindcast of Long Island Sound (LIS) to study hypothesized linkages between the Sound’s physical climate and its recent ecological response and b) project future impacts of climate change and variability on the LIS ecosystem and its living marine resources over the span of the 21st century through model development and synthesis.

NYHOPS 3D model domain showing simulated SST, surface currents, and wind barbs. From the Google Earth viewer of the NYHOPS operational forecasts www.stevens.edu/NYHOPS

Figure 1: NYHOPS 3D model domain showing simulated SST, surface currents, and wind barbs. From the Google Earth viewer of the NYHOPS operational forecasts.

Specifically, our objectives are to:

  1. Address the paucity of physical environmental data during Long Island Sound’s (LIS) observed warming trend and accompanying fisheries shift since the 1970s by running a hindcast of the LIS circulation using the New York Harbor Observing and Prediction System (NYHOPS), an operational, comprehensive, high-resolution, three-dimensional, numerical model (Figures 1-2).
  2. Explore climate-forced links between the physical and ecological environment of the Sound by studying the statistical correlations of historic ecological data (such as the fish trawl survey data) to the physical environmental data from the NYHOPS model with a goal to explain the recent ecological regime changes and,
  3. Project the impacts of climate change and variability on the Sound’s ecosystem and its living marine resources until the year 2100, by forcing NYHOPS with Intergovernmental Panel for Climate Change (IPCC)-class global climate models, creating NYHOPS-based predictions for LIS to the end of this century, and deducing future changes to the LIS ecological regimes.
Figure 2. A zoom of the NYHOPS domain that covers the Long Island Sound. Shown is simulated SST (colored background and legend on the upper left), a popup with data from a UCONN buoy used in the NYHOPS model, and instantaneous surface current vectors also from the NYHOPS model. Screenshot taken from the NYHOPS google earth viewer 9/26/2012 1900Z.

Figure 2. A zoom of the NYHOPS domain that covers the Long Island Sound. Shown is simulated SST (colored background and legend on the upper left), a popup with data from a UCONN buoy used in the NYHOPS model, and instantaneous surface current vectors also from the NYHOPS model. Screenshot taken from the NYHOPS google earth viewer 9/26/2012 1900Z.

Justification

Over the last few decades, the LIS ecosystem has undergone profound changes. Water temperature measurements at a LIS long-term station frequently used in ecosystem assessments (LISS 2010, Howell and Auster 2012, among others) have recorded a significant warming trend (1.46ºC increase from 1976 to 2010; Dominion Resources Services 2011). Concurrently, substantial changes have occurred in the community structure and abundance of living marine resources in LIS (Howell et al 2005; Howell and Auster 2012). A dramatic example is the American lobster (Homarus Americanus) collapse, initiated by the major die-off in 1999.  Although multiple factors may have been synergistically responsible for this collapse, the increase in bottom temperature was likely the major factor that caused an increase in the mortality rate of lobsters, especially egg-bearing females (Howell et al 2005). Interestingly, the lobster collapse was exclusive to southern New England waters south of Cape Cod. The lobster stocks and fisheries further north, particularly the Gulf of Maine, are thriving. Reported landings have been at record highs over the past decade (Thunberg 2007). Based on the CT DEEP trawl survey, there seems to have been a shift in adult lobster population (ALTC 2010), that has altered the area where young lobsters recruit (Kim McKown, pers. comm.).

Fisheries-independent trawl surveys in LIS have reported substantial changes in finfish community structure and abundance (Howell and Auster 2012). Correlated with the increase in the bottom temperature of LIS from 1984 to 2008, the seasonal mean catch of cold-adapted finfish [i.e. windowpane flounder (Scophthalmus aquosus), spotted hake (Urophycis regia)] has significantly decreased, while warm-adapted species [i.e. butterfish (Peprilus triacanthus), striped sea robin (Prionotus evolans)] have increased (Howell and Auster 2012). There appears to have been a cold to warm species regime shift in the 95 finfish species examined statistically separating the community seen in 1984-1998 compared to 1999-2008 (Howell and Auster 2012). Although this time-period may be too short to attribute to climate change, it is apparent that the ecosystem of LIS may have responded to a climate perturbation.

The aforementioned reports suggest a regime shift in both the climate and ecosystem of LIS occurring around 1998. Remarkably, there have been increasingly more studies reporting a 1998 regime shift in the climate and living marine resources of coastal and pelagic marine ecosystems in vastly different parts of the world. To name a few, these include the Bering Sea (Rodionov and Overland 2005), the North Pacific (Overland et al 2008), and the North Sea (Weijerman et al 2005). Therefore, there may be a large-scale climate teleconnection between the local LIS climate and the global climate, whether due to natural or anthropogenic climate perturbations.

The apparent sensitivity of LIS to climate warrants research that elucidates the specific processes that are associated with the ecosystem’s response to climate perturbations. This is especially critical for projecting the impacts of global climate change on the LIS ecosystem given the 2-3ºC increase in surface air temperature projected by climate models included in the IPCC fourth assessment report (Christensen et al 2007). In order to assess, understand, and project the biophysical and mechanistic underpinnings between climate and living marine resources of  LIS, a detailed, historical analysis of climate and living marine resources is first required. However, the historical three-dimensional physical data of LIS is very sparse and only provides a general warming trend based on a few stations (one of which is near a power plant) without details on the relationships between circulation, hydrology, high-resolution depth-profile data covering the entire area of LIS, and interaction with the shelf-waters outside of LIS. Our proposed research will attempt to fill in these gaps.

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Building resilience to storm surges and sea level rise

Building resilience to storm surges and sea level rise:
A comparative study of coastal zones in New York City and Boston

Lead-PI:  Malgosia Madajewicz, Columbia University Center for Climate Systems Research

Co-PI: Alan Blumberg, Stevens Institute of Technology

Co-Investigators:  Philip Orton, Stevens; Mark Becker, Columbia CIESIN

Statement of the problem
Large proportions of the United States’ population, infrastructure, and economic wealth are vulnerable to flooding caused by storm surges along the coastal north-eastern urban corridor (NEUC)1 (Frumhoff et al. 2007). In 2003, 53% of the population of the United States lived in coastal counties, with 34% of that 153 million residing along the northeastern Atlantic coast, which has 4 out of 10 of the nation’s largest cities (NOAA 2004). The population pressure along the coastal NEUC has eroded coastal ecosystems and their role as protective buffers against storm surges, compounding the vulnerability of society and nature (Frumhoff et al. 2007).

Storm surges are among the deadliest and most costly natural disasters (Parker 2010). In New York City (NYC) and Boston, billions of dollars of urban infrastructure lie less than 4 meters above mean sea level. Hurricane Irene was only a tropical storm when it made landfall in NYC, and it only caused a modest storm surge of 1.4 meters. However, this storm caused estimated damages totaling at least $55 million in NYC (The Associated Press 2011), flooded waterfront highways, and came close to damaging major electrical and transportation infrastructure. Hurricane Irene was preceded by a mandatory evacuation order affecting 370,000 people in NYC (Bloomberg 2011). Three hurricanes in or near NYC in 1788, 1821 and 1893 had storm surges of 3 – 4 meters and flooded about half of Manhattan below 34th Street and large swaths of East Harlem, Queens, Brooklyn and Staten Island (Scileppi and Donnelly 2007).

Increased damage from coastal flooding related to storm surges is among the most certain impacts of climate change along the coastal NEUC (Frumhoff et al. 2007). Climate change has a two-fold impact on coastal storms. First, storms are likely to bring more intense rainfall (see for example Trenberth et al. 2003; Rosenzweig et al. 2010). Second, sea level rise will raise the height reached by storm surges (e.g. Solomon et al. 2007). Even conservative sea level rise
projections triple the frequency of current 1 in 10 year coastal floods in many areas (Horton et al. 2010; Horton et al. 2008). The increased flooding risk could greatly impact NYC’s and Boston’s coastal communities, critical infrastructure, and major urban transportation routes, as well as compound development pressures from anticipated population growth (Kirshen et al. 2004; Rosenzweig et al. 2011). In NYC, for example, Rosenzweig et al. 2011 estimate that “a direct hit from a major hurricane would cause $100s of billions in damage, with economic losses accounting for roughly two times the insured loss” (94). In metropolitan Boston, sea-level rise of about 20 inches will increase the value of assets exposed to damage by coastal storms from less than $100 billion today to about $500 billion (Climate Action Leadership Committee 2010).

Summary of proposed work

In this project, we will seek to advance the design of effective approaches to adaptation to coastal flooding associated with storm surges, based on research in two cities, NYC and Boston. We will work with decision makers in NYC and Boston to design and evaluate adaptation blueprints for different types of neighborhoods. We will inform the design with a multi-dimensional analysis of vulnerability to coastal flooding.  We will produce probabilistic predictions of coastal flooding for the 2010s, 2050s and 2080s, in the form of spatial maps of inundation probability per year. We will combine the inundation maps with dynamic maps of a vulnerability index that combines information about several dimensions of vulnerability as represented by land use, characteristics of infrastructure, and socioeconomic data. We will work with decision makers to use the vulnerability maps to develop blueprints that specify adaptive decision and implementation processes for adaptation in different types of neighborhoods. We will assess the likely impacts on vulnerability and costs of approaches proposed in each blueprint, and we will determine under what conditions each blueprint may be effective in other coastal urban areas.

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Coastal-Urban Microclimates

Weather and wind forecasting typically relies upon low-resolution computer simulations, with no more detail than a 12-kilometer grid.  Also, these model simulations virtually never incorporate urban features such as pavement and skylines.  As a result, they cannot accurately predict how temperature varies over city neighborhoods during a heat wave, nor can they always tell what direction wind will be blowing an atmospheric contaminant.  In the end, weather forecasters do an amazing job with mediocre weather models by using their long-term knowledge of what works for various situations and locations.

Air temperature measurements at 1:15 AM during a recent heat wave. The 240 weather stations demonstrate how some neighborhoods around New York City were as much as 15 degrees warmer than rural areas. Data credits given below.

Sometimes this isn’t good enough, so a goal of a research collaboration between our research group and collaborators at the Naval Research Laboratory and City College of New York is to push the boundaries of dealing with these shortcomings in atmospheric prediction.  Our research can help improve prediction capabilities for weather and atmospheric transport, as well as the scientific understanding of urban weather features such as the urban heat island, which often keeps temperatures 10-15 degrees (F) warmer than rural areas at night, as shown above.  The influence of the ocean and sea breezes on weather is also captured much better by COAMPS than by most weather models.  Previous results and publications from this research are summarized on Julie Pullen’s webpage.

We are working with the Navy’s Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) computer model, and using grids as high as 333 meters resolution.  For checking the model results with actual weather observations, we are using the usual airport and city weather stations, maintained by NOAA, but also hundreds of civilian-run weather stations — all these are conveniently merged in City College’s NYC Met Net.

 

[Temperature figure data credits:  NOAA (NOS-PORTS, NWS-ASOS, NWS-HADS, Urbanet), Rutgers NJ Weather and Climate Network, APRSWXNET, AWS Convergence Technologies, Inc. (WeatherBug), and Weatherflow, via Mark Arend (NYCMetNet).]

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The NYC Storm Surge Threat

New York City is highly vulnerable to a hurricane strike due to its location near the coast where winds and storm surges are usually at their maximum.  On one hand, we are fortunate that direct hurricane strikes are extremely rare – four hurricanes have struck NYC since 1600. On the other hand, residents have been lulled to complacency by this recent long period without a hit. Storm surges in these hurricanes were 10-13 feet, which flooded about half of Manhattan below 34th Street and large swaths of East Harlem, Queens, Brooklyn and Staten Island.

Flooding in the Hoboken PATH station during a 1992 noreaster, which shut down the entire NYC subway system (Metropolitan NY Hurricane Transportation Study 1995).

Even a powerful nor’easter can cause serious damage in NYC, and the most recent severe flooding incident occurred in December, 1992.  Seawalls around the city are mostly only a few feet above normal high tide levels, so a relatively modest peak storm surge of 4.3 ft during that storm flooded into and shut down the subway system for several days.  The funnel-shaped coastline offshore can focus and build a storm surge to a greater height, and the two water pathways through New York Bay and Western Long Island Sound can cause a merging surge that is difficult to predict.

As one part of a project called Consortium for Climate Risk in the Urban Northeast, we are quantifying storm surge risk in NYC, Philadelphia and Boston, in our current climate as well as future climate with sea level rise.  Climate change is likely to increase the storm surge threat due to sea level rise and also potentially due to ocean warming, which may (or may not) increase the number of intense coastal storms. Sea level rise has proceeded at a rate of 1.8 cm per decade over the past century, but is projected to be between 5 and 30 cm per decade in the 2080s. Even conservative sea level rise projections, when combined with historical storms, can triple the frequency of key planning metrics such as the 1 in 10 year coastal flood event (Horton et al., 2010).

Storms occur infrequently, so it is useful to use computer simulations of thousands of storms and the ocean’s response, to understand flood probabilities.  We are running storm surge simulations using the ocean model sECOM, the Stevens Institute version of the popular ECOM (Estuary and Coastal Ocean Model).  Coastal water level predictions are available for the New York and New Jersey, and Connecticut coastlines through the New York Harbor Observation and Prediction System (NYHOPS) and the Stevens Storm Surge Warning System.

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Did the Oil Spill Stop Hurricanes?

It has been known for centuries that oil reduces the ability for wind to create sea surface waves. Benjamin Franklin famously hid oil in the bottom of his cane, so he could shake it over a pond like a sorcerer, and stop the wind’s creation of ripples. More recently, scientists have demonstrated the mechanism that is at work – oil films reduce water’s surface tension, reducing the air-to-water flux of momentum, also known as wind stress.  Studies have even shown that natural oil slicks above seafloor seeps in many parts of the world are visible from space due to their effects on sea surface roughness.

credit: Washington Post

The widespread and persistent surface oil on the Gulf of Mexico caused by the 2010 oil spill provided an unprecedented opportunity last summer to explore the effect of oils on atmosphere-ocean exchanges of momentum, as well as heat and gases.  I wrote a proposal with Wade McGillis (Columbia University) that was funded by the National Science Foundation.  The plan was to quantify these effects using an anchored catamaran on the Alabama continental shelf, as well as large-scale mapping aboard a ship with air-sea flux measurements.

The research also has many applications related to understanding the Gulf oil spill and its consequences, because modified air-sea exchanges of heat, moisture and momentum could impact oil spill transport, atmospheric delivery of moisture to the Southeastern United States, and transfer of heat from the ocean to the atmosphere, an important factor during hurricane season.  The hurricane season was quiet in the Gulf, and it is possible that the oil films left over from the spill reduced the availability of the ocean’s heat and moisture for growing tropical storms.

The mooring study was conducted from July 30 through August 10, examining the water column heat budget and air-sea heat and CO2 fluxes. The study included one hydrographic profile mooring, vessel-based measurements, and a moored catamaran with measurements of oxygen, chlorophyll, turbidity, atmosphere and water pCO2, air-sea fluxes of CO2, heat, momentum, and moisture using the gradient flux (atmospheric profile) technique (McGillis et al. 2001), and net shortwave and longwave radiation.

The oil spill was capped right before we began the field work, so — fortunately for those who live in and around the Gulf — we never got the opportunity to study how oils affected the air-sea fluxes.  And there is only so much you can do with three months of post-doc funding, so deeper analysis of our field data will require additional funding.  In retrospect, it was an amazing adventure and great experience for Wade, four undergraduate students, and myself, learning how to make automated field measurements of the coastal ocean heat budget.

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