AGU期刊一周Research Spotlight (March 10~ March 16, 2017)

发布时间:2017-3-17 9:19:47 点击次数:378

I. Atmospheric Sciences

1. GOES-16 Satellite Lights Up Lightning Flashes in New Video

The satellite's lightning mapper instrument will help scientists forecast extreme weather.

https://eos.org/articles/goes-16-satellite-lights-up-lightning-flashes-in-new-video

II. Science Policy

1. Water Infrastructure Needs Get Bipartisan Nod at House Hearing

A letter released at the event calls on President Donald Trump to ensure that money from a national harbor maintenance fund is used solely to improve ports and harbors.

https://eos.org/articles/water-infrastructure-needs-get-bipartisan-nod-at-house-hearing

2. Key House Member Makes a Conservative's Case for Water Projects

The White House and Democrats want to see an infrastructure package move through Congress. One House subcommittee chairman intends to make sure that water resource projects are part of the plan.

https://eos.org/articles/key-house-member-makes-a-conservatives-case-for-water-projects

III. Hydrology, Cryosphere & Earth Surface

1. Glacial Outburst Flood near Mount Everest Caught on Video

More than 2 million cubic meters of water, hidden deep within Lhotse Glacier, spilled down toward the village of Chukhung, Nepal, in 2016

https://eos.org/articles/glacial-outburst-flood-near-mount-everest-caught-on-video

IV. Hazards & Disasters

1. Future Extreme Sea Levels Could Endanger Europe's Coasts

The increase in frequency of extreme sea level events that are today considered exceptional will likely push existing coastal protection structures beyond their design limits.

https://eos.org/scientific-press/future-extreme-sea-levels-could-endanger-europes-coasts

2. Using Strain Rates to Forecast Seismic Hazards

Workshop on Geodetic Modeling for Seismic Hazard; Menlo Park, California, 19 September 2016

https://eos.org/meeting-reports/using-strain-rates-to-forecast-seismic-hazards

3. Tracking Volcanic Bombs in Three Dimensions

A new method allows researchers to precisely track in three dimensions bits of fragmented magma as they are expelled in explosive volcanic eruptions.

https://eos.org/research-spotlights/tracking-volcanic-bombs-in-three-dimensions

V. Ocean Sciences

1. Expanding a 300-Year Record of Marine Climate

Fourth International Workshop on the Advances in the Use of Historical Marine Climate Data; Southampton, UK, 18–22 July 2016

https://eos.org/meeting-reports/expanding-a-300-year-record-of-marine-climate

2. Early-Career Scientists Explore Newly Discovered Methane Seeps

UNOLS Deep Submergence Training Cruise 2016; Woods Hole, Massachusetts, 28 July to 7 August 2016

https://eos.org/meeting-reports/early-career-scientists-explore-newly-discovered-methane-seeps

VI. Geophysical Research Letters

1. Revisiting ENSO/Indian Ocean Dipole phase relationships

Here we show that the characteristics of the Indian Ocean Dipole (IOD), such as its power spectrum and phase relationship with the El Niño–Southern Oscillation (ENSO), can be succinctly explained by ENSO combination mode (C-mode) wind and heat flux forcing together with a seasonal modulation of the air/sea coupled Indian Ocean (IO) Bjerknes feedback. This model explains the observed high-frequency near-annual IOD variability in terms of deterministic ENSO/annual cycle interactions. ENSO-independent IOD events can be understood as a seasonally modulated ocean response to white noise atmospheric forcing. Under this new physical null hypothesis framework, IOD predictability is determined by both ENSO predictability and the ENSO signal-to-noise ratio. We further emphasize that lead/lag correlations between different climate variables are easily misinterpreted when not accounting properly for the seasonal modulation of the underlying climate phenomena.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL072308/full

2. Global changes of extreme coastal wave energy fluxes triggered by intensified teleconnection patterns

In this study we conducted a comprehensive modeling analysis to identify global trends in extreme wave energy flux (WEF) along coastlines in the 21st century under a high emission pathway (Representative Concentration Pathways 8.5). For the end of the century, results show a significant increase up to 30% in 100 year return level WEF for the majority of the coastal areas of the southern temperate zone, while in the Northern Hemisphere large coastal areas are characterized by a significant negative trend. We show that the most significant long-term trends of extreme WEF can be explained by intensification of teleconnection patterns such as the Antarctic Oscillation, El Niño–Southern Oscillation, and North Atlantic Oscillation. The projected changes will have broad implications for ocean engineering applications and disaster risk management. Especially low-lying coastal countries in the Southern Hemisphere will be particularly vulnerable due to the combined effects of projected relative sea level rise and more extreme wave activities.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL072488/full

3. The sensitivity of West Antarctica to the submarine melting feedback

We use an ice sheet model with realistic initial conditions to forecast how the Amundsen Sea sector of West Antarctica responds to recently observed rates of submarine melting. In these simulations, we isolate the effects of a positive feedback, driven by submarine melt in new ocean cavities flooded during retreat, by allowing the present climate, calving front and melting beneath existing ice shelves to persist over the 21st century. Even without additional forcing from changes in climate, ice shelf collapse, or ice cliff collapse, the model predicts slow, sustained retreat of West Antarctica, driven by the marine ice sheet instability and current levels of ocean-driven melting. When observed rates of melting are included in new subglacial ocean cavities, the simulated sea level contribution increases, and for sufficiently intense melting it accelerates over time. Conditional Bayesian probabilities for sea level contributions can be derived but will require improved predictions of ocean heat delivery.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL072514/full

4. Active microwave observations of diurnal and seasonal variations of canopy water content across the humid African tropical forests

A higher frequency of severe droughts under warmer temperatures is expected to lead to large impacts on global water and carbon fluxes and on vegetation cover—including possible widespread mortality. Monitoring the hydraulic state of vegetation as represented by the canopy water content will allow rapid assessment of vegetation water stress. Here we show the potential of active microwave backscatter observations at Ku band for monitoring the diurnal and seasonal variations of top-of-canopy water content. We focus on the humid tropical forests of Central Africa and examine spatiotemporal variations of radar backscatter from QuikSCAT (2001–2009) and RapidScat (2014–2016). Diurnal variations in RapidScat backscatter demonstrate the occurrence of widespread midday stomatal closure in this region. Increases in backscatter during the dry seasons in humid forests could be explained by both dry season leaf flushing (as supported by canopy structure) and vapor pressure deficit-driven increases in evapotranspiration rates.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL072388/full

5. The role of historical forcings in simulating the observed Atlantic multidecadal oscillation

We analyze the Atlantic multidecadal oscillation (AMO) in the preindustrial (PI) and historical (HIST) simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to assess the drivers of the observed AMO from 1865 to 2005. We draw 141 year samples from the 41 CMIP5 model's PI runs and compare the correlation and variance between the observed AMO and the simulated PI and HIST AMO. The correlation coefficients in 38 forced (HIST) models are above the 90% confidence level and explain up to 56% of the observed variance. The probability that any of the unforced (PI) models do as well is less than 3% in 31 models. Multidecadal variability is larger in 39 CMIP5 HIST simulations and in all HIST members of the Community Earth System Model Large Ensemble than their corresponding PI. We conclude that there is an essential role for external forcing in driving the observed AMO.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL071337/full

6. Fault size and depth extent of the Ecuador earthquake (Mw 7.8) of 16 April 2016 from teleseismic and tsunami data

The April 2016 Ecuador Mw 7.8 earthquake was the first megathrust tsunamigenic earthquake along the Ecuador-Colombia subduction zone since 1979 (Mw 8.2 with 200 deaths from tsunami). While there was no tsunami damage from the 2016 earthquake, small tsunamis were recorded at Deep-ocean Assessment and Reporting of Tsunami and tide gauges. Here we designed various fault models with and without shallow-slip area and compared the computed teleseismic and tsunami waveforms with the observations. While teleseismic inversions were indifferent about inclusion or exclusion of the shallow slip, tsunami waveforms strongly favored the slip model without shallow slip. Our final slip model has a depth range of 15–44 km, and its western shallowest limit is located at the distance of ~60 km from the trench. Maximum and average slips were 2.5 and 0.7 m, respectively. The large-slip area was 80 km (along strike) × 60 km (along dip) in the depth range of 15–35 km.

http://onlinelibrary.wiley.com/doi/10.1002/2017GL072545/full

VIII. AGU Blogs

1. Volcanic eruption expanded ozone hole to record size

On April 22, 2015, the Chilean volcano Calbuco erupted, spewing volcanic ash 10 kilometers (six miles) skyward. But Calbuco didn’t just tear a hole in the Earth that day. A new study suggests it also tore a hole in the sky.

http://blogs.agu.org/geospace/2017/03/14/volcanic-eruption-expanded-ozone-hole-record-size/

2. A perfect storm of fire and ice may have led to snowball Earth

Harvard University researchers have a new hypothesis about what caused the runaway glaciation that covered the Earth pole-to-pole in ice.

http://blogs.agu.org/geospace/2017/03/13/perfect-storm-fire-ice-may-led-snowball-earth/

3.Climate change puts California’s snowpack under the weather

Skiing in July? It could happen this year, but California’s days of bountiful snow are numbered. The Sierra Nevada snowpack, which provides 60 percent of the state’s water via a vast network of dams and reservoirs, has already been diminished by human-induced climate change and if emissions levels aren’t reduced, the snowpack could largely disappear during droughts, a new study finds.

http://blogs.agu.org/geospace/2017/03/09/climate-change-puts-californias-snowpack-under-the-weather/

4.GOES-16 Data Back Online

The GOES-16 non-operational data is back online! It’s amazing too. I have been looking at one-minute data of storms over Kentucky and Tennesee tonight, and it is a real WOW. I grabbed the images below, and this data quickly told me that the storms in Kentucky were maintaining their strength. I suspect it was very valuable to the NWS offices in Tennesee and Kentucky tonight. Many warnings were issued and …

http://blogs.agu.org/wildwildscience/2017/03/10/goes-16-data-back-online/

5. Friday fold: Sheba Mine sample

When touring the geology of the Barberton Greenstone Belt last August, our group visited the Sheba Mine, a gold mine high in the hills. Their geologist kindly showed us around and allowed us to visit his history-laden office. I have no idea where this sample originated, but it was the only fold I saw in the place, nestled between sepia-toned photographs and old lanterns and rusty picks.

http://blogs.agu.org/mountainbeltway/2017/03/10/friday-fold-sheba-mine-sample/

6. Lugworm casts on the beach, Islay

Lugworms are marine worms that live as benthic infauna. You’d be lucky to catch a glimpse of one in the flesh, since they spend most their time in the sediment, but you can see their traces if you walk the beach at low tide at Ardnave, in northern Islay, along the western shore of Loch Gruinart.

http://blogs.agu.org/mountainbeltway/2017/03/09/lugworm-casts-beach-islay/

IX. AGU News

1. AMERICAN GEOPHYSICAL UNION EXPERTS AVAILABLE TO COMMENT ON IMPENDING WINTER STORM

WASHINGTON, DC — Heavy snowfall is forecast for the Upper Midwest, Northeast and mid-Atlantic as a powerful winter storm moves through the region Monday night and Tuesday morning. Widespread heavy snow and blizzard conditions are expected along most of the I-95 corridor from Washington, DC to Boston. Members of the American Geophysical Union are available to comment on the science behind the storm and its potential impacts on the affected regions.

https://news.agu.org/press-release/american-geophysical-union-experts-available-comment-impending-winter-storm/