AGU 期刊一周Research Spotlights (July 01~July 06, 2016)

发布时间:2016-7-7 21:50:38 点击次数:765

I. Atmospheric Sciences

1. Antarctica's Ozone Hole Is Healing, Scientists Say

First discovered in the 1980s, the hole in the Earth’s ozone layer that stretches above Antarctica every October is an iconic example of how human activity and atmospheric chemistry are inextricably linked. This hole covered an average of about 18 million square kilometers in September 1987 and widened to nearly 25 million square kilometers in September 2000, thanks to industrial pollutants that destroy ozone in the stratosphere.

II. Geology & Geophysics

1. Telica Volcano Rested Quietly Right Before Spewing Ash

The length of quiet periods predicts the severity of eruption events, according to a new model that might soon help forecast explosions worldwide.

2. How Do Tropical Forests Slow Knickpoints in Rivers?

Using Puerto Rico's Luquillo Mountains as a case study, scientists use the region's geological history to study how knickpoints—areas where there's a sharp change in the river's slope—move over time.

 

III. Ocean Sciences

1. Model Predicts Heights of Rogue Waves

Rogue waves form without warning and can tower more than 25 meters high. A new mathematical approach shows promise at simulating how high these waves can be.

IV.Earth and Space Science

1. A massive secondary landslide in Devdoraki Gorge, Georgia

In 2014 I posted about a very large landslide that caused extensive damage in the Devdoraki Gorge (which is often described as the Dariali Gorge) in Georgia.  That landslide left a very large volume of debris in the river bed. On 23rd June this debris mobilised into a new, secondary, landslide that caused extensive damage along the key highway that links with Georgia and Russia via the Kazbegi Customs checkpoint.  Thanks to a warning system installed after the 2014 events, no-one was injured, but the damage appears to be significant.  The road remains closed.

2. Conducting Long Term Annual Glacier Monitoring

This is the story of how you develop and conduct a long term glacier monitoring program.  We have been monitoring the annual mass balance of Easton Glacier on Mount Baker, a stratovolcano in the North Cascade Range, Washington since 1990.  This is one of nine glaciers we are continuing to monitor, seven of which have a 32 year long record. The initial exploration done in the pre-internet days required visiting libraries to look at topographic maps and buying a guide book to trails for the area.  This was followed by actual letters, not much email then, to climbers who had explored the glacier in the past, for old photographs.  Armed with photographs and maps we then determined where to locate base camp and how to access the glacier.  The first year is always a test to make sure logistically you can reach enough of the glacier to actually complete the mass balance work with a sufficiently representative network of measurement sites.  The second test is if you can stand the access hike, campsite, and glacier navigation, to do this every year for decades; if the answer is no, move on.  That was the case on Boulder Glacier, also on Mount Baker:  poor trail conditions and savage bugs, were the primary issue. Next we return to the glacier at the same time each year, completing the same measurements each year averaging 210 measurements of snow depth or snow melt annually.  This occurs whether it is gorgeous and sunny, hot, cold, snowy, rainy, or recently on this glacier dealing with thunderstorms.  You wake up, have your oatmeal and coffee/cider/tea, and get to work.  Lunch on the snow features bagels, dried fruit, and trail mix. Happy hour features tang or hot chocolate depending on the weather.  It is then couscous, rice, pasta or quinoa for dinner, with some added dried vegetable or avocado.  The sun goes behind a mountain ridge and temperatures fall, and the tent is the haven until the sun returns.  Repeat this 130 times on this glacier and you have a 25 year record. During this period the glacier has lost 16.1 m of water equivalent thickness, almost 18 m of thickness.  For a glacier that averaged 70 m in thickness this is nearly 25% of the volume of the glacier gone.  The glacier has not maintained sufficient snow cover at the end of the summer to have a positive balance, this is the accumulation area ratio, note below.  The glacier has retreated 315 m from 1990-2015.  This data is reported annually to the World Glacier Monitoring Service.  The glacier has also slowed its movement as it has thinned, evidenced by a reduction in number of crevasses. During this time we have collaborated with researchers examining the ice worms, soil microbes/chemistry, and weather conditions on the ice. This glacier supplies runoff to Baker Lake and its associated hydropower projects.  Our annual measurements here and on Rainbow Glacier and Lower Curtis Glacier in the same watershed provide a direct assessment of the contribution of glaciers to Baker Lake.  The glacier is adjacent to Deming Glacier, which supplies water to Bellingham, WA. The Deming is too difficult to access, and we use the Easton Glacier to understand timing and magnitude of glacier runoff from Deming Glacier.

3. Electric forces in desert air create mighty dust storms, study finds

Electric fields in dust storms have been discovered lifting 10 times more dust into the air than winds alone, according to new experiments conducted in the Sahara Desert. The discovery has big implications for global climate studies, as well as for understanding dust storms on Mars.

4. Lamplugh Glacier rock avalanche: A massive new landslide in Alaska on Tuesday

The media in Alaska is reporting a find by a local pilot, Paul Swanstrom of Mountain Flying Service, of a huge new landslide, the Lamplugh Glacier rock avalanche, which occurred in Alaska on Tuesday.  This is yet another enormous event in this area of North America – this is an image that he took of the landslide, which is posted on his company Facebook Page:

5. Lake Erie Watershed Soil Phosphorus Study Shows Glyphosate Link

As reported recently in the online magazine No-till Farmer, a study led by Ohio Northern University chemistry professor Christopher Spiese links the popular herbicide glyphosate to dissolved reactive phosphorus (DRP) desorption in soils. Mobilization and runoff of phosphorus to streams and lakes is associated with toxic algae blooms in Lake Erie and the Gulf of Mexico Dead Zone.

6. Odd behavior of Jovian moon dust could inform future space missions, search for life

New research into the movements of dust around Jupiter’s four largest moons could help scientists searching for life in our solar system, according to a new study.

 V. Geophysical Research Letters

1. Observing bubbles from underwater gas seeps

Natural oil and gas seeps exist on the ocean floor all over the world. Although humans have known about and exploited these natural resources for thousands of years, scientists know little about how oil and gas droplets disperse in deep water and how they affect underwater ecosystems. During a July 2014 research cruise in the Gulf of Mexico, researchers examined the fate of bubbles rising from two natural gas seeps close to the site of the 2010 Deepwater Horizon accident. They used high-speed cameras mounted on a remotely operated vehicle to observe the bubbles in real time and determine how high they rose in the water column and how fast they dissolved. Here, Binbin Wang, a postdoctoral researcher at Texas A&M University in College Station, Texas, describes what the research team learned about bubbles emanating from natural gas seeps. Wang and his colleagues detailed their findings in a recent paper published in the Journal of Geophysical Research: Oceans, a journal of the American Geophysical Union.

2. Influence of Venus topography on the zonal wind and UV albedo at cloud top level: The role of stationary gravity waves

Based on the analysis of UV images (at 365 nm) of Venus cloud top (altitude 67 ± 2 km) collected with Venus Monitoring Camera on board Venus Express (VEX), it is found that the zonal wind speed south of the equator (from 5°S to 15°S) shows a conspicuous variation (from −101 to −83 m/s) with geographic longitude of Venus, correlated with the underlying relief of Aphrodite Terra. We interpret this pattern as the result of stationary gravity waves produced at ground level by the uplift of air when the horizontal wind encounters a mountain slope. These waves can propagate up to the cloud top level, break there, and transfer their momentum to the zonal flow. Such upward propagation of gravity waves and influence on the wind speed vertical profile was shown to play an important role in the middle atmosphere of the Earth by Lindzen (1981) but is not reproduced in the current GCM of Venus atmosphere from LMD. (Laboratoire de Météorologie Dynamique)

3. Arctic Survey Hunts for Missing Nitrogen and Phosphorus

A new survey of ocean waters flowing in and out of the Arctic may shed light on how dissolved organic nitrogen and phosphorus contribute to nutrient cycling in the Arctic.

VI. AUG Newsroom

1. Citizen Scientists Train a Thousand Eyes on the North Pole

During expedition cruises, tourists participate in collecting scientific data and contribute to ongoing observations of sea ice conditions in the Arctic.