AGU期刊一周Research Spotlight (June 23~ June 28, 2017)

发布时间:2017-6-30 10:09:55 点击次数:150

I.Ocean Sciences

1. New Volcanic Island Unveils Explosive Past

A recent volcanic eruption near Tonga in the southwest Pacific created a new island, giving scientists a rare opportunity to explore the volcanic record of this remote region.

https://eos.org/project-updates/new-volcanic-island-unveils-explosive-past

2. Accounting for Accelerated East Coast Sea Level Rise

An analysis of tide gauge records and physical models shows acceleration of sea level rise on the East Coast due to melting of the Greenland Ice Sheet is especially pronounced south of 40°N latitude.

https://eos.org/research-spotlights/accounting-for-accelerated-east-coast-sea-level-rise

3. How Does Wind Push Water?

A new 3-D model shows how wind affects hydrodynamic mixing in a northern Italian lake.

https://eos.org/research-spotlights/how-does-wind-push-water

II. Hazards & Disasters

1. How Shifting Winds Turn Tropical Storms into Hurricanes

Researchers present a novel method for analyzing how wind shear affects tropical cyclone strength and structure.

https://eos.org/research-spotlights/how-shifting-winds-turn-tropical-storms-into-hurricanes

III. Hydrology, Cryosphere & Earth Surface

1. Bringing Together Observers and Modelers of Sea Ice

Sea Ice Thickness: Innovative Strategies to Integrate Measurements and Modeling; Boulder, Colorado, 16–17 November 2016

https://eos.org/meeting-reports/bringing-together-observers-and-modelers-of-sea-ice

2. Timothy A. Cohn (1957–2017)

Cohn emphasized the use of hydrologic science for the public good, to protect ordinary citizens from flood and pollution hazards and to reduce losses from natural disasters.

https://eos.org/articles/timothy-a-cohn-1957-2017

3. The Uncertain Future of the West Antarctic Ice Sheet

A recent paper in Reviews of Geophysics discusses how climate change could affect ice streams, ice sheets, ice shelves, and sea ice in Antarctica.

https://eos.org/editors-vox/the-uncertain-future-of-the-west-antarctic-ice-sheet

4. Growing More with Less Using Cell Phones and Satellite Data

Researchers from the University of Washington and Pakistan are using 21st century technology to revive farming as a profitable profession in the Indus Valley.

https://eos.org/project-updates/growing-more-with-less-using-cell-phones-and-satellite-data

IV.Planetary Sciences

1. How Quickly Is Mercury’s Surface Evolving?

New measurements of impact craters on Mercury’s smooth plains suggest that the topography of the solar system’s innermost planet is changing at twice the rate of landforms on the Moon.

https://eos.org/research-spotlights/how-quickly-is-mercurys-surface-evolving

2. Ten Earth-Sized Planets Found by Exoplanet-Hunting Telescope

A new analysis of exoplanet candidates also reveals a previously unrecognized tendency for smaller exoplanets to grow into two distinct sizes.

https://eos.org/articles/ten-earth-sized-planets-found-by-exoplanet-hunting-telescope

V.Biogeosciences

1. Studying Yellowstone by Integrating Deep Carbon Science

Second Deep Carbon Observatory Summer School; Yellowstone National Park, Montana and Wyoming, 23–28 July 2016

https://eos.org/meeting-reports/studying-yellowstone-by-integrating-deep-carbon-science

2. Climate and Other Models May Be More Accurate Than Reported

Replacing a commonly used statistical measure of average error with an alternative measure would give a more meaningful assessment of model performance.

https://eos.org/opinions/climate-and-other-models-may-be-more-accurate-than-reported

VI.Geophysical Research Letters

1. High-frequency internal waves and thick bottom mixed layers observed by gliders in the Gulf Stream

Autonomous underwater gliders are conducting high-resolution surveys within the Gulf Stream along the U.S. East Coast. Glider surveys reveal two mechanisms by which energy is extracted from the Gulf Stream as it flows over the Blake Plateau, a portion of the outer continental shelf between Florida and North Carolina where bottom depths are less than 1000 m. Internal waves with vertical velocities exceeding 0.1 m s−1 and frequencies just below the local buoyancy frequency are routinely found over the Blake Plateau, particularly near the Charleston Bump, a prominent topographic feature. These waves are likely internal lee waves generated by the subinertial Gulf Stream flow over the irregular bathymetry of the outer continental shelf. Bottom mixed layers with O(100) m thickness are also frequently encountered; these thick bottom mixed layers likely form in the lee of topography due to enhanced turbulence generated by O(1) m s−1 near-bottom flows.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL072580/full

2. Preconditioning of Antarctic maximum sea ice extent by upper ocean stratification on a seasonal timescale

This study uses an observationally constrained and dynamically consistent ocean and sea ice state estimate. The author presents a remarkable agreement between the location of the edge of Antarctic maximum sea ice extent, reached in September, and the narrow transition band for the upper ocean (0–100 m depths) stratification, as early as April to June. To the south of this edge, the upper ocean has high stratification, which forbids convective fluxes to cross through; consequently, the ocean heat loss to the atmosphere is an efficient way to cool the surface ocean to the freezing point during April to September. To the north, the upper ocean has low stratification such that the ocean heat loss to the atmosphere is not efficient to cool the upper ocean. The upper ocean is instead cooled mainly through mixing with the colder inflow carried by northward Ekman transport but cannot reach the freezing point due to the nature of mixing. Therefore, upper ocean stratification, dominated by salinity here, provides an important constraint on the northward expansion of Antarctic sea ice to its maximum.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL073236/full

3. Efficiency of turbulent mixing in the abyssal ocean circulation

Turbulent mixing produced by breaking of internal waves plays an important role in setting the patterns of downwelling and upwelling of deep dense waters and thereby helps sustain the global deep ocean overturning circulation. A key parameter used to characterize turbulent mixing is its efficiency, defined here as the fraction of the energy available to turbulence that is invested in mixing. Efficiency is conventionally approximated by a constant value near one sixth. Here we show that efficiency varies significantly in the abyssal ocean and can be as large as approximately one third in density stratified regions near topographic features. Our results indicate that variations in efficiency exert a first-order control over the rate of overturning of the lower branch of the meridional overturning circulation.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL072452/full

 

VII. AGU Blogs

1. Extraordinary storms caused massive Antarctic sea ice loss in 2016

Antarctic sea ice – frozen ocean water that rings the southernmost continent – has grown over the past few decades but declined sharply in late 2016. By March of 2017 – the end of the Southern Hemisphere’s summer – Antarctic sea ice had reached its lowest area since records began in 1978. Puzzled scientists wanted to know why.

http://blogs.agu.org/geospace/2017/06/21/extraordinary-storms-caused-massive-antarctic-sea-ice-loss-2016/

2. Tom Nichols is Spot On

The Death of Expertise “Tom Nichols, a professor of national security affairs at the US Naval War College, says America has become a country “obsessed with the worship of its own ignorance.” Americans have always been skeptical of intellectuals and experts. Today, says Nichols, that attitude has mutated into outright hostility. In general, Americans have never been so willing to reject the knowledge of those who actually know something. 

http://blogs.agu.org/wildwildscience/2017/06/25/tom-nichols-spot/

3. Head of the American Meteorological Society To Secretary of Energy: You’re Dead Wrong on Climate.

There is just no doubt anymore that the warming of the last century is due to rising greenhouse gases in the atmosphere. Yes, there are a ton of myths out there but no one who understands the basic science has any doubt. Even the latest surveys show that among those in the field the agreement is over 99%. 

http://blogs.agu.org/wildwildscience/2017/06/21/head-american-meteorological-society-secretary-energy-youre-dead-wrong-climate/