COMPASS Wednesday - Archive

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COMPASS Wednesday

Wednesdays at 3:00 pm, SLAB 103 (unless stated otherwise)

Jan 09 (Tuesday, 11:00): Dr. Joshua Willis
NASA Jet Propulsion Laboratory, Pasadena, California

OMG, It's Melting.
Early Results from Oceans Melting Greenland (OMG),
and the Use of Comedy to Communicate About Climate Change

Not Funny: Oceans Melting Greenland (OMG) is an airborne NASA Mission to investigate the role of the oceans in ice loss around the margins of the Greenland Ice Sheet. A five-year campaign, OMG will directly measure ocean warming and glacier retreat around all of Greenland. By relating these two, we will explore one of the most pressing open questions about how climate change drives sea level rise: How quickly are the warming oceans melting the Greenland from the edges?

This year, OMG collected its second set of both elevation maps of marine terminating glaciers and ocean temperature and salinity profiles around all of Greenland. This give us our first look at year-to-year changes in both ice volume at the margins, as well as the volume and extent of warm, salty Atlantic water present on the continental shelf. In addition, we will compare recent data in east Greenland waters with historical ocean observations that suggest a long-term warming trend there. Finally, we will briefly review the multi-beam sonar and airborne gravity campaigns – both of which were completed last year – and their impact on bathymetry maps in the coastal waters around Greenland.

Funny: The first time I showed a funny slide at AGU, it bombed. Badly. "What causes global warming?" I asked an audience of 100 learned colleagues. I pushed the space bar. Up popped a photo-shopped picture of a gigantic Al Gore breathing fire on the Earth...

Silence. Complete silence. Even the crickets were judging me.

Since then, I've completed an entire curriculum at a world-renowned school of funny (The Conservatory Program at Second City, Hollywood), written sketch shows, told funny stories, acted in short and full-length feature films, and practiced. Mostly practiced. A lot. So, did I get better at making global warming funny? Come find out.




Feb 07: Dr. Honghai Zhang
Princeton University

Robustness of
Anthropogenically Forced Decadal Precipitation Changes
Projected for the 21st Century

Precipitation is characterized by substantial natural variability, including on regional and decadal scales. This relatively large variability poses a grand challenge in detecting anthropogenically caused precipitation changes. Here we use large ensembles of climate change experiments with multiple climate models to demonstrate that, on regional scales, anthropogenic decadal changes in ensemble-mean precipitation (i.e., mean state) are detectable, where "detectable" means the change is outside the range expected from natural variability. Relative to the 1950-1999 period, simulated anthropogenic shifts in precipitation mean state for the 2000-2009 period are already detectable over 36-41% of the globe – primarily in high latitudes, eastern subtropical oceans and the tropics. Anthropogenic forcing in future medium-to-high emission scenarios is projected to cause detectable shifts over 68-75% of the globe by 2050 and 86-88% by 2100. Our findings imply detectable anthropogenic shifts in precipitation mean state over the majority of the planet within the next few decades.

Feb 14: Dr. Brian Mapes
Department of Atmospheric Sciences, RSMAS

Professor Grumpy Fiiiinally Swallows the Open-Source Nexus Lingo;
Teaching, Research, Comms & Collabs are Transformed!

In this seminar, I will attempt to convey my newfound enthusiasm for a fantastic nexus of free software for highly collaborative computing: {Jupyter + iPython + GitHub}. I am dizzily imagining whole curricula in this space, perhaps displacing books. My whole research workflow will now be in Jupyter. It's even a communication vehicle: In addition to being a computational code, a Jupyter notebook can also be both an eye-friendly formatted document with math and text and hyperlinks (as well as the code and its resulting figures), and furthermore a slide show! And it is all naturally collaborative – world-shared, mix-and-matchable, yet with traceable contribution histories. If you want to follow along "live", consider doing these instructions and bringing your laptop. Or, just listen and learn.

Feb 21: Dr. Yoshiaki Miyamoto
Visiting Scientist, Department of Atmospheric Sciences, RSMAS

A Dynamical Mechanism for Secondary Eyewall Formation

This study proposes that secondary eyewall formation (SEF) of tropical cyclones (TCs) can be attributed to an instability of flow in the free atmosphere coupled with Ekman pumping. Unstable solutions of a 1.5-layer shallow water system are obtained under fast wind speed conditions in the free atmosphere. The instability condition derived in the linear model indicates the importance of the ratio of vorticity to angular velocity, and the condition is more likely to be satisfied when the ratio is large and its radial gradient is positive. In other words, fast angular velocity, low absolute vertical vorticity, small negative radial gradient of angular velocity, and large gradient of vertical vorticity are favorable. Eigenvalue analyses are performed by using a vorticity profile with a secondary maximum with a very small magnitude and a wide range of other parameters.

The growth rate increases with vorticity outside the radius of maximum wind (RMW), the radius of the secondary vorticity maximum, its magnitude, and the Rossby number defined as the ratio of maximum tangential velocity to the RMW multiplied by the Coriolis parameter. Furthermore, the growth rate is positive only between 2 and 7 times the RMW, and it is negative close to or far outside the RMW. These features are consistent with previous observational and modelling studies on SEF. A dimensionless quantity obtained from the unstable condition in the linear theory is applied to SEF events simulated by two different full-physics numerical models. It is observed that the dimensionless parameter increases several hours before a secondary peak of tangential velocity forms, suggesting that the initial process of SEF can be attributed to the proposed theory.

Feb 28: Dr. Matthew Igel
University of California Davis

The Cloudy Links Between Tropical Bulk-Moisture and Precipitation

The focus of this talk will be on the two-way relationships between moisture, clouds, and precipitation in the tropics. I will begin by discussing the properties of the tropical moisture distribution and the simple, but highly non-linear, way in which precipitation depends on column moisture. This latter relationship is reproduced in a high fidelity, large domain cloud resolving model run in a state of radiative convective equilibrium. Model output will be used to describe the physical pathways that transform atmospheric bulk moisture into surface precipitation. Then, the vertically-integrated column moisture will be broken down into two contributions separated by the base of the melting layer. These new layer moisture quantities will be shown to relate much more intimately with cloud processes and the distribution of cloud types than column moisture. These layers act independently to result in the non-linear coupling between column moisture and precipitation. This result will be confirmed with a combination of AIRS, CloudSat, and GPM satellite observations. Next, I will introduce a new way to use our understanding of precipitation and bulk moisture to construct a simple data-driven global hydrological model. The model is asymptotically integrable and can be used to examine the possible responses of tropical moisture and precipitation to climate warming. This simple analytic model suggests the ensemble of climate models may not simulate a wide enough distribution of possible hydrological responses. Predictions can be related back to process understanding.

Mar 02 (5:00 pm, Wetlab): POSTER SESSION

Mar 07 (Auditorium): Dr. Kerry Emanuel
Lorenz Center, Massachusetts Institute of Technology

Severe Thunderstorms and Climate

Severe thunderstorms, which are often associated with strong winds, hail, and tornadoes, pose substantial threats to people, livestock, and agriculture. While their dynamics are well understood, relatively little is known about how climate change (man?made or natural) might affect such storms. In this talk I will focus on one of the main environmental prerequisites for severe storms: Convective Available Potential Energy (CAPE), which is a measure of the potential energy stored in moist atmospheres that can be released explosively when the potential energy barrier that permits its accumulation breaks. I will discuss the work of my former PhD student that shows, rather unexpectedly, that CAPE usually accumulates over only the 6?8 hours leading up to the storm and that its build?up is strongly controlled by soil moisture. I will present observational evidence for this as well as a very simple theoretical model, and discuss how climate change should affect CAPE and how the new understanding of CAPE may someday allow for seasonal prediction of severe storm activity.

Mar 14: Dr. Igor Kamenkovich
Department of Ocean Sciences, RSMAS

Observing System Simulation Experiments (OSSEs)
for an Array of Profiling Floats

The Argo array currently consists of more than 3000 instruments that make vertical profiles of temperature and salinity every 10 days over the upper 1500-2000 meters. Biogeochemical Argo floats, profiling to 2000 m depth, are being deployed throughout the Southern Ocean by the Southern Ocean Carbon and Climate Observations and Modeling program (SOCCOM), with the goal of reaching 200 floats by 2020. Both arrays provide a wealth of data with the goal of quantifying the role of the oceans in the global carbon and heat cycle. The spatial and temporal sampling coverage of the data is unprecedented, but still remains too sparse for accurate resolution of fields in the vicinity of sharp fronts and powerful mesoscale variability. Comprehensive analysis is needed to optimize the deployment strategy and to assess the accuracy with which large-scale properties can be derived from these local observations.

This study uses Observing System Simulation Experiments (OSSEs) designed to be relevant to the Argo and SOCCOM projects. The annual mean and seasonal cycle of temperature, salinity, dissolved oxygen and dissolved inorganic carbon are sampled, reconstructed and compared to the original model fields. The reconstruction skill is quantified with the reconstruction error (RErr), defined as the difference between the reconstructed and actual model fields, weighted by a local measure of the spatio-temporal variability. Both the comprehensive and idealized OSSEs demonstrate that the RErr depends on the magnitude of the seasonal cycle, spatial gradients, speed of float movement, amplitude of mesoscale variability and number of floats. These factors explain a large part of the spatial variability in the RErr and can be used to predict the reconstruction skill of the array. Furthermore, our results demonstrate that the SOCCOM array size of 150 floats is a reasonable choice for reconstruction of surface properties and annual-mean 2000 m inventories.

Mar 21 (1:30 pm, Auditorium): Dr. Albert Slap
Coastal Risk Consulting, LLC

Developing a Climate Technology Start-Up: A Report from the Trenches

The need for resiliency in US coastal cities and around the world has never been greater. The number of flooding events in coastal cities is growing exponentially, along with loss of life and property. The role of climate change in this escalation is becoming more and more evident. Local, state and federal governments are unable to fully respond to this challenge alone. What is the role of non-governmental organizations, academic institutions, and the private sector in supplementing governmental efforts to improve climate resiliency? How do private sector companies develop in response to this need and what opportunities are there for partnerships with academic organizations? How can Public Private Partnerships involving academics and startups be fostered in a way that enhances climate resiliency? This seminar will address these questions and provide an overview of the experience in developing a climate technology business. The seminar is intended to both inform academics of the process, challenges and opportunities involved in developing a start up business, and stimulate conversations on potential partnerships between the public and private sector.

Mar 21 (Auditorium): Dr. Johnna Infanti
Department of Atmospheric Sciences, RSMAS

Projections of South Florida Precipitation:
On Uncertainty and Working with Climate Data Users

Mar 27 (Tuesday, 11:00 am): Dr. Ronald Oremland
United States Geological Survey

Acetylene Fermentation:
Primordial Biogeochemistry,
the Search for Evidence of Life in the Outer Solar System,
and Maybe some Earthly Bioremediation too

Mar 28: Dr. Emmanuel Hanert
Catholic University of Louvain, Belgium

High-Resolution Marine Connectivity Modelling
in the Florida Coral Reef Tract

High-resolution ocean circulation models are required to simulate the complex and multi-scale currents that drive physical connectivity between marine ecosystems. However, standard coastal ocean models rarely achieve a spatial resolution of less than 1km over the >100km spatial scale of dispersion processes. Here we use the high-resolution unstructured-mesh coastal ocean model SLIM that locally achieves a spatial resolution of ~100m over the scale of the entire Florida Coral Reef Tract (FCRT). By coupling SLIM with a biophysical model of larval dispersal we can track the position of virtual larvae released into the simulated domain. Connectivity matrices are then generated from the positions of the particles at the start and at the end of the simulations. By using different connectivity measures and clustering methods, we can highlight the fine details of the connectivity patterns linking the different reefs of the FCRT. These indicators are then used to pinpoint the reefs that would need to be protected in priority and those that would be best suited to coral restoration projects. Our model is currently the first to simulate larval dispersal with such a high resolution between the thousand reefs composing the FCRT. By individually measuring each site's potential as a larval source or sink, we can provide new insights to reef restoration and protection strategies.

Apr 04: Conor Smith
Department of Ocean Sciences, RSMAS
(one-hour AMP student seminar)

Advanced Correction of Near-Shore Surface Currents
from TerraSAR-X Along-Track InSAR

for Wave Contributions

Spaceborne along-track interferometric synthetic aperture radar (along-track InSAR) has been used suc-cessfully to produce estimates of the surface current velocity field on a number of occasions. Along-track InSAR data are comprised of two complex images with a very short time lag, with each pixel containing an amplitude and phase. The phase difference allows a direct measurement of the line-of-sight velocity of the Bragg scattering ripples, which includes contributions of the horizontal surface current as well as the phase velocity of the Bragg ripples and orbital motions of longer waves. To calculate the surface current field, the complicated wave-related contributions to the measured radar velocity need to be estimated and subtracted. Previously, either a single mean velocity correction was used or a spatially varying correction was computed using a relatively simple numerical current-wave interaction model. In areas with large current gradients and spatial depth changes, the resulting complicated surface wave field, such as at our test location at the Co-lumbia River, requires a sophisticated method to estimate the complex corresponding velocity corrections. In this location, a near-shore hindcast model, Delft3D/SWAN, is used to produce 2-D theoretical current fields from which the Doppler velocity correction is calculated. Presented here is new work comparing the Doppler velocity correction to various wave height, breaking and steepness predictions from Delft3D/SWAN as well as to certain artifacts in the SAR data that are related to the wave motions and hold promise to be used as an efficient indicator of the necessary Doppler velocity correction.

Apr 11 (Auditorium): Dr. Rita Colwell
SEEDS and RSMAS / DEIC 2018 Distinguished Lecturer

University of Maryland College Park and Johns Hopkins University

Global Infectious Diseases: Climate, Oceans, and Human Health

The history of marine biology is closely intertwined with human health, beginning with the oceans serving as a source of food and nutrition and providing an extraordinary diversity of life. More recently, significant advances in technology have brought new discoveries – from the outer reaches of space, where remote sensing monitors on satellites circle the earth, to the ultramicroscopic through application of next generation sequencing and informatics. Although primitive by the standards of today's technology, the early successes of the last century in culturing bacteria, viruses, fungi, and protists from the world oceans comprised the first wave of advancement in marine microbiology and provided a groundwork for studying the microscopic life of estuaries, coastal waters, and the deepest parts of the world oceans. The next wave in understanding microbial life in marine systems was essentially functional, namely determining interactive processes, including interaction of climate and ecosystems with the oceans. It is proposed that we are now in a third wave, focused on the genomics of life systems. In this lecture, examples provided from this sweep of history will be presented, employing the genus Vibrio and a prototype species, Vibrio cholerae, as a useful example of the fundamental linkage of human health to the oceans. This microorganism, the causative agent of cholera and associated with major epidemics, is a marine bacterium with a versatile genetics and recently elucidated genomics based on next generation sequencing and bioinformatics. It is distributed globally in estuaries throughout the world. Vibrio species, both nonpathogenic and those pathogenic for humans, marine animals, or marine vegetation, play a fundamental role in nutrient cycling. They have also been shown to respond to warming of surface waters of the North Atlantic, with the increase in their numbers correlated with increased incident of infections in humans. In summary, marine microorganisms provide a critical indicator of human health and wellness and the ubiquitous vibrios in the world oceans offer a model system.

Apr 18: Juan Pinales
Department of Ocean Sciences, RSMAS
(one-hour AMP student seminar)

Analyzing Oil Spill Candidates in SAR Imagery
Using Textural and Shape Information

Previous studies have demonstrated the ability to detect and classify marine hydrocarbon films with spaceborne synthetic aperture radar (SAR) imagery due to the dampening effect of hydrocarbon discharges on surface capillary-gravity waves, rendering oil-covered regions "radar dark" compared with standard wind-roughened ocean surfaces. However, classifying oil spills in these data remains a challenging task due to the inherent difficulty of processing SAR imagery, as well as the presence of false positives or lookalike shapes that have a similar appearance to oil spills despite having different oceanographic origins. A multi-step approach breaks the oil spill classification problem into three stages: dark spot detection, where shapes that might be oil spills are segmented; feature extraction, which involves the analysis of shapes as oil spill candidates; and finally classification which involves making a final decision about the label of the shape. The effectiveness of the feature extraction stage depends on the types of measures we derive from these shapes and the ways in which they are combined to help discriminate shapes from false positives. In this talk, a brief overview of the feature extraction problem for oil spill detection applications is presented. Envisat-ASAR C-band SAR data acquired during the 2010 Deepwater Horizon oil spill is used to extract two kinds of features from oil spill candidate objects: shape calculations and texture-based calculations. Texture calculations exploit spatial relationships and intensity differences of pixels in imagery, while shape-based features include calculating geometric measures characterizing the contours and extent of the shape. These computations are commonly processed using statistical methods to eliminate false positive from classification products.

Apr 25: Alexis Denton
Department of Ocean Sciences, RSMAS
(one-hour AMP student seminar)

Improving Satellite Retrieval of High-Resolution Sea Ice Dynamics
in the Arctic

Alongside thermodynamic processes, the dynamics of drifting sea ice in the Arctic Ocean govern important parameters in the state of the Arctic and act as a metric of this system; they dictate where energy exchanges occur across the atmosphere-ice-ocean interface, influence the open water fraction in any given area, and affect the distribution of sea ice thickness via the displacement of ice floes. Sea ice motion datasets are often derived using successive satellite acquisitions at resolutions typically worse than 40 m with point measurements made by drifting buoys in the ice serving as validation. As open water fractions increase due to accelerating melt of ice in the summer, the summer Arctic sees greater free drift of sea ice. Due to the uncertainty in collocating in-situ measurements to satellite acquisitions in highly dynamic areas like the summertime Marginal Ice Zone, much of the sea ice motion characterization is done on a basin-wide scale in the wintertime when the pack is more constrained and lower satellite resolutions are not a hindrance. If we are to accurately characterize summertime sea ice dynamics and the role they play in the overall dynamics of the Arctic system, we must take advantage of higher-resolution satellite sensors and improve upon motion characterization methods such as cross-correlation which depend on motion being largely translational. In the spring of 2014, the Office of Naval Research's Marginal Ice Zone Departmental Research Initiative deployed dozens of buoys within the Marginal Zone of the Beaufort Sea north of Alaska to drift through the summer. In tandem with this deployment, high-resolution synthetic aperture radar (SAR) and optical imagery was acquired. In late September, a lead opened amidst a cluster of instruments and its evolution was captured in a week of successive TerraSAR-X (3 m) and panchromatic optical (1 m) images. This weeklong dataset provided the chance to test existing motion characterization methods on the drifting ice floes surrounding the buoys. A new hybrid characterization method combining the typical cross-correlation with a feature-tracking algorithm was determined to improve the characterization of a complex motion field involving rotation in addition to translation. Still, the need for improved collocation between the in-situ instruments and satellite sensors remains if validation of high-resolution motion is to be done. Later, in 2017, an opportunity was taken to deploy small radar reflectors on the ice in the Chukchi Sea in collaboration with the European Union's Ice, Climate, Economics – Arctic Research on Change (ICE-ARC) program. The reflectors were deployed near high-precision GPS units accurate to the cm level in the horizontal. The instrument arrays were tracked and imaged with TerraSAR-X's spotlight mode (1 m), and the resulting images reveal the exact location of the arrays, allowing for precise cross-platform validation. In addition, the accuracy of three different ephemeris products offered by TerraSAR-X (Quick-Look, Rapid, and Science) of varying geolocational accuracy were assessed using the location of the GPS units as ground truth. It was found, as expected, that the Science ephemeris offered the best geolocational accuracy with a 90% circular probability error (CE90) of 2.21 m. Somewhat surprisingly, the Rapid ephemeris offered almost identical accuracy with a CE90 of 2.20 m. In the future, this work will expand to incorporate the possibility of the SAR layover effect in this error; in relation to the motion fields, high-resolution deformation fields will be characterized in the hopes of improving knowledge of the thickness distribution in the finer scale and how it affects the basin-wide distribution.

May 02: Dr. Kerri Pratt
University of Michigan

Atmospheric Aerosol Sources and Chemical Composition
in the Changing Arctic

Unprecedented summertime Arctic sea ice loss is leading to increasing open water, thinning sea ice, ship traffic, and development. Arctic aerosol emissions are expected to rise with increasing oil and gas activities and the production of sea spray aerosol. These particles have significant climate effects, including interacting with radiation, forming cloud droplets and ice crystals, and depositing onto surfaces. Development may also be changing the air quality of native villages, leading to human health impacts. Given the complexity and evolving nature of atmospheric aerosols, as well as the challenges associated with Arctic measurements, significant uncertainties remain in our understanding of aerosol sources, evolution, and impacts in the Arctic. The Pratt Lab has conducted several field campaigns in the Alaskan Arctic, identifying aerosol sources and atmospheric aging pathways over multiple seasons. We use single-particle mass spectrometry and computer-controlled scanning electron microscopy with energy-dispersive X-ray spectroscopy to measure the chemical composition of individual atmospheric particles. I will discuss results of studies conducted near Utqiagvik (Barrow) and Oliktok Point (Prudhoe Bay), Alaska.

May 17 (Thursday, 11:00 am, MSC 125): Dr. Bruce M. Howe
University of Hawaii at Manoa

SMART Subsea Cables: Sensing the Pulse of the Planet

The deep ocean is key to understanding environmental and societal threats, from climate and ocean warming to rising sea level, ocean acidification, and tsunamis. The deep ocean, however, is difficult and costly to monitor, and we lack fundamental data needed to adequately model, understand, and address these threats.

One solution is to integrate sensors into future undersea telecommunications cable systems. This is the mission of the SMART cables initiative (Science Monitoring And Reliable Telecommunications), a Joint Task Force (JTF) sponsored by three UN agencies. SMART sensors would "piggyback" on the power and communications infrastructure of more than a million kilometers of undersea fiber optic cable and tens of thousands of repeaters, creating the potential for global coverage at modest incremental cost. Initial sensors would measure temperature, pressure, and acceleration. The resulting data would address two critical scientific and societal issues: a) the long-term need for sustained climate-quality data from the under-sampled deep oceans, and b) the near term need for improvements to global tsunami warning networks.

The presentation explores the ocean observing improvements available from SMART cables. Simulations show deep ocean temperature and pressure measurements can improve estimates of ocean circulation and heat content, and cable-based pressure and acceleration sensors can improve tsunami warning times and earthquake parameters. The technology of integrating sensors into fiber optic cables is discussed. With a suitable interface, one can contemplate future additional sensors, such as hydrophones and/or a "general purpose acoustic transducer" for passive acoustic monitoring, noise interferometry, communications, inverted echosounder and unit-to-unit "tomography".

SMART cables have been endorsed by major ocean science organizations. JTF is working with cable suppliers and sponsors, development banks and end-users to incorporate SMART capabilities into future cable projects. By providing a global ocean network of long-lived sensors, SMART cables would be a first-order addition to the global ocean observing system.