AGU期刊一周Research Spotlight (Feb 24~ Apr 2, 2017)

发布时间:2017-3-3 8:43:00 点击次数:398

I. Atmospheric Sciences

1. When Lower-Atmosphere Waves Invade the Upper Atmosphere

A review of the literature shows that weather nearer Earth's surface could produce up to 35% of the ionosphere's variability.

II. Science Policy

1. Policy Experts Debate Trump Energy Plan

Lauded by free-market proponents at a policy forum, the White House plan sparked disagreements among panelists about climate implications, the potential for a coal comeback, and carbon taxes.

2. Apollo 11 Command Module Goes on Tour

The exhibit includes Buzz Aldrin's gloves and an injector plate from the rocket's first-stage engine, which was recovered from the bottom of the Atlantic Ocean.

3. AGU Endorses the March for Science in Washington, D. C.

Between now and the 22 April event, AGU will share further information about march-related resources and communications.

4. Focus NASA on Mars and Moon, Not Earth, Witnesses Tell Hearing

One speaker, the former chief scientist of NASA, spoke up for NASA's Earth science program as broadly beneficial and affordable within the agency's existing budget.

III. Hydrology, Cryosphere & Earth Surface

1. Defining Snow Drought and Why It Matters

Swings from snow drought to extreme winter rainfall make managing reservoirs, like the Oroville Dam, incredibly difficult. But what exactly is "snow drought"?

2. Air Pollution May Have Masked Mid-20th Century Sea Ice Loss

The new results challenge the perception that Arctic sea ice extent was unperturbed by human-caused climate change until the 1970s.

IV. Education

1. Women in Science: A Q&A with an Editor

A personal perspective on women in science and how we can increase representation in the the geosciences

V. Ocean Sciences

1. Saving Our Marine Archives

A concerted effort has begun to gather and preserve archives of marine samples and descriptive data, giving scientists ready access to insights on ancient environments.

VI. Geophysical Research Letters

1. Contrasting hydrogeologic responses to warming in permafrost and seasonally frozen ground hillslopes

Seasonally frozen ground (SFG) and permafrost underlay approximately half of the land surface in the Northern Hemisphere. It is anticipated that climate warming will degrade both types of frozen ground, altering groundwater discharge to streams. While the effects of permafrost degradation on groundwater discharge have been analyzed, quantification of how groundwater discharge in degrading permafrost differs from that in SFG is lacking. This study simulates coupled groundwater and heat transport under freeze-thaw conditions for four representative hillslopes underlain by either continuous permafrost or SFG and compares groundwater discharge outputs under projected warming scenarios over decadal scales. Model results show that without warming there is more groundwater discharge in hillslopes with SFG than permafrost. After a century of warming, groundwater discharge increases for both kinds of frozen ground, but permafrost experiences a larger increase than SFG. These findings have implications for aquatic ecosystems and prioritizing water resource planning.

2. Elevated atmospheric CO2 negatively impacts photosynthesis through radiative forcing and physiology-mediated climate feedback

Increasing atmospheric CO2 affects photosynthesis involving directly increasing leaf carboxylation rates, stomatal closure, and climatic effects. The direct effects are generally thought to be positive leading to increased photosynthesis, while its climatic effects can be regionally positive or negative. These effects are usually considered to be independent from each other, but they are in fact coupled through interactions between land surface exchanges of gases and heat and the physical climate system. In particular, stomatal closure reduces evapotranspiration and increases sensible heat emissions from ecosystems, leading to decreased atmospheric moisture and precipitation and local warming.

3. An increased abundance of micrometeorites on Earth owing to vesicular parachutes

Micrometeorites (MMs) are extraterrestrial dust particles that survive atmospheric entry and can be recovered from sedimentary rocks. Fossil MMs allow events beyond the Earth, such as the collisional breakup of asteroids, to be identified. Here the effects of vesicle formation during melting of dust are investigated through numerical modeling and observations of Antarctic MMs. Vesicle formation is shown to cause a parachute effect that causes rapid deceleration, decreasing peak temperature. Vesicular parachuting enhances the abundance of melted MMs formed from phyllosilicate-bearing C-type asteroid dust on the Earth surface by a factor of 2. Micrometeorites recovered from the geological record, therefore, are biased toward breakup events involving hydrated C-type asteroids, whilst those involving phyllosilicate-poor particles are diluted by the enhanced background flux of hydrous dust. The parachute effect is also likely to increase the delivery of 3He to ocean sediments by C-type asteroid dust.

4. Experimental observation of the onset of fracture percolation in columnar ice

While the contribution of brine channels to the critical behavior of sea ice permeability is well known, fractures can also contribute to the critical behavior of ice permeability. Above a critical fracture density, cracks link together to create a continuous pathway for flow. To isolate the contribution of fractures to percolation through ice, we present novel experiments to quantify the critical strain required for the onset of fracture percolation in freshwater columnar-grained ice. We monitored the percolation of the ice as it was compressed uniaxially across the columns at −10oC to axial strains of 0.5–2% at a strain rate of 10−5 s−1, i.e., 1 order of magnitude below the ductile-to-brittle transition. We observed that the threshold for along-column permeability corresponds with peak strength. Lateral connectivity develops over limited distances postpeak strength near the onset of near-steady state flow and is facilitated by the breakage of the columns.

5. Modeling the ionospheric prereversal enhancement by using coupled thermosphere-ionosphere data assimilation

We report that assimilating total electron content (TEC) into a coupled thermosphere-ionosphere model by using the ensemble Kalman filter results in improved specification and forecast of eastward prereversal enhancement (PRE) electric field (Efield). Through data assimilation, the ionospheric plasma density, thermospheric winds, temperature, and compositions are adjusted simultaneously. The improvement of duskside PRE E field calculation over the prior state is achieved primarily by intensification of eastward neutral wind.

6. Multiple mechanisms generate a universal scaling with dissipation for the air-water gas transfer velocity

A large corpus of field and laboratory experiments support the finding that the water side transfer velocity kL of sparingly soluble gases near air-water interfaces scales as kL~(νε)1/4, where ν is the kinematic water viscosity and ε is the mean turbulent kinetic energy dissipation rate. Originally predicted from surface renewal theory, this scaling appears to hold for marine and coastal systems and across many environmental conditions. It is shown that multiple approaches to representing the effects of turbulence on kL lead to this expression when the Kolmogorov microscale is assumed to be the most efficient transporting eddy near the interface.


1. Are we living in a warm peak between ice ages?

By Ned Rozell As another major rainstorm hit California in February, downtown San Francisco surpassed its normal rain total for an entire year. Reservoirs in the high country were spilling over. So ended a five-year drought in the state that some people attributed to human-caused climate change. Those pictures of dried-up California lakes bothered Syun-Ichi Akasofu, who recently gave a talk “The Forthcoming Ice Age” at the University of Alaska …

2. Meteorological Winter Ends With Record Warmth and Storms

It has been an amazing if not astonishing February across the U.S. Very little snow and record highs falling by the thousands! So far in February, we have recorded 5857 record highs and only 97 record lows. There were 408 stations that had the warmest temperature on record for any day in February and only one station saw the coldest temp. on record for February! Look at the monthly temperature …

3. Why GOES-16 Is Such A Big Deal

I put this piece together about GOES-16 and it aired today. Hat tip to my excellent editor Kevin Reynolds here at WBOC-TV.

4. Rapid Scan Imagery from GOES-16

Here is the first rapid scan imagery from the new GOES-16 satellite. One image every 30 seconds:   Here are the Louisiana tornadoes last week in all channels:

IX. AGU News


WASHINGTON D.C. — The world’s largest organization of Earth and space scientists, the American Geophysical Union, is accepting nominations for its 2017 journalism awards through 15 March 2017. This year, AGU plans to present the three awards listed below. The authoritative statements of the rules governing these awards are available at the included links. Submissions for all three awards should be made through AGU’s online nomination system. Please see instructions for using the online nomination system at the bottom of this release or by clicking here.