I.Climate Change
1. Observing Life near the Ocean’s Surface with Satellites
Third International Ocean Colour Science (IOCS) Meeting; Lisbon, Portugal, 15–19 May 2017
https://eos.org/meeting-reports/observing-life-near-the-oceans-surface-with-satellites
2. Democratic Leader Blasts Trump’s Pick to Head NASA
With Rep. Jim Bridenstine’s nomination hearing just days away, Sen. Patty Murray charges that his “denial of climate science” and opposition to equal rights “should disqualify him from consideration.”
https://eos.org/articles/democratic-leader-blasts-trumps-pick-to-head-nasa
3. Tropical Teleconnections
A recent article in Reviews of Geophysics explored how regional climate and weather is interconnected across space and time.
https://eos.org/editors-vox/tropical-teleconnections
II. Hazards & Disasters
1. Pollution over Southeast Asia May Threaten Ozone Health
Emissions of short-lived chlorine-based chemicals that deplete ozone are increasing worldwide. But over some regions of Asia, these chemicals may be on a fast track to the ozone layer.
https://eos.org/articles/pollution-over-southeast-asia-may-threaten-ozone-health
III. Planetary Sciences
1. Dawn Finds Possible Ancient Ocean Remnants at Ceres
Ceres' crust as we see it today, with its mixture of ice, salts and hydrated materials, represents most of the dwarf planet's ancient ocean, scientists say
https://eos.org/scientific-press/dawn-finds-possible-ancient-ocean-remnants-at-ceres
IV.Geology & Geophysics
1. Subedi Receives 2017 Donald L. Turcotte Award
Prachanda Subedi will receive the 2017 Donald L. Turcotte Award at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. This award is given annually to a recent Ph.D. recipient for “outstanding dissertation research that contributes directly to nonlinear geophysics.”
https://eos.org/agu-news/subedi-receives-2017-donald-l-turcotte-award
2. Schaefer Receives 2017 Natural Hazards Focus Group Award for Graduate Research
Lauren N. Schaefer will be awarded the 2017 Natural Hazards Focus Group Award for Graduate Research. She will be formally presented with the award at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. This award recognizes “one or more promising young scientists engaged in studies of natural hazards and risks” and is given “in recognition of outstanding contributions achieved during their Ph.D. (or highest equivalent terminal degree) research.”
3. Lisabeth and Townsend Receive 2017 Mineral and Rock Physics Graduate Research Award
Harrison Lisabeth and Joshua Townsend will receive the 2017 Mineral and Rock Physics Graduate Research Award at the 2017 American Geophysical Union Fall Meeting, to be held 11–15 December in New Orleans, La. This award is given annually to “one or more promising young scientists for outstanding contributions achieved during their Ph.D. research.” Recipients of this award are “engaged in experimental and/or theoretical studies of Earth and planetary materials with the purpose of unraveling the physics and chemistry that govern their origin and physical properties.”
V.Biogeosciences
1. Signatures of Dinosaur Poop Found in Cretaceous Coal Seams
Coal analysis suggests that plant-eating dinosaurs, by walking kilometers between their picnic areas and their toilets, distributed important nutrients widely and boosted ecosystem health.
https://eos.org/articles/signatures-of-dinosaur-poop-found-in-cretaceous-coal-seams
2. New Online Tool Teaches Students About the Energy-Water Nexus
Students use real data sets to explore how population changes, power generation, and water-saving strategies affect surface and groundwater use.
https://eos.org/project-updates/new-online-tool-teaches-students-about-the-energy-water-nexus
VI.Geophysical Research Letters
1. The Transient Response of Ice Volume to Orbital Forcing During the Warm Late Pliocene
Examining the nature of ice sheet and sea level response to past episodes of enhanced greenhouse gas forcing may help constrain future sea level change. Here, for the first time, we present the transient nature of ice sheets and sea level during the late Pliocene. The transient ice sheet predictions are forced by multiple climate snapshots derived from a climate model set up with late Pliocene boundary conditions, forced with different orbital forcing scenarios appropriate to two Marine Isotope Stages (MISs), MIS KM5c, and K1. Our results indicate that during MIS KM5c both the Antarctic and Greenland ice sheets contributed to sea level rise relative to present and were relatively stable. Insolation forcing between the hemispheres was out of phase during MIS K1 and led to an asynchronous response of ice volume globally. Therefore, when variations of precession were high, inferring the behavior of ice sheets from benthic isotope or sea level records is complex.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL073535/full
2. On the Dependence of Cloud Feedbacks on Physical Parameterizations in WRF Aquaplanet Simulations
We investigate the effects of physical parameterizations on cloud feedback uncertainty in response to climate change. For this purpose, we construct an ensemble of eight aquaplanet simulations using the Weather Research and Forecasting (WRF) model. In each WRF-derived simulation, we replace only one parameterization at a time while all other parameters remain identical. By doing so, we aim to (i) reproduce cloud feedback uncertainty from state-of-the-art climate models and (ii) understand how parametrizations impact cloud feedbacks. Our results demonstrate that this ensemble of WRF simulations, which differ only in physical parameterizations, replicates the range of cloud feedback uncertainty found in state-of-the-art climate models. We show that microphysics and convective parameterizations govern the magnitude and sign of cloud feedbacks, mostly due to tropical low-level clouds in subsidence regimes. Finally, this study highlights the advantages of using WRF to analyze cloud feedback mechanisms owing to its plug-and-play parameterization capability.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL074820/full
3. Joint Modulation of Intraseasonal Rainfall in Tropical Australia by the Madden-Julian Oscillation and El Niño-Southern Oscillation
Rainfall in tropical Australia is a critical resource for the agricultural sector. However, its high variability implores improvements in our understanding of its variability. Australian tropical rainfall is influenced by both the Madden-Julian Oscillation (MJO) on intraseasonal time scales and El Niño-Southern Oscillation (ENSO) on interannual time scales. This study examines the joint relationship between the MJO, ENSO, and tropical Australian rainfall variability. We analyze daily precipitation data from stations across tropical Australia during the wet season (November to April). The wet season rainfall response to the MJO is found to be greater during El Niño than La Niña. We demonstrate that this relationship is not due to the statistical relationship between the MJO and ENSO indices but instead due to differences in how the MJO modulates the large-scale circulation during El Niño versus during La Niña.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075452/full
4. A Hydrometeorological Perspective on the Karakoram Anomaly Using Unique Valley-Based Synoptic Weather Observations
Glaciers in the eastern Hindukush, western Karakoram, and northwestern Himalayan mountain ranges of Northern Pakistan are not responding to global warming in the same manner as their counterparts elsewhere. Their retreat rates are less than the global average, and some are either stable or growing. Various investigations have questioned the role of climatic factors in regard to this anomalous behavior, widely referred to as “The Karakoram Anomaly.” Here, for the first time, we present a hydrometeorological perspective based on five decades of synoptic weather observations collected by the meteorological network of Pakistan. Analysis of this unique data set indicates that increased regional scale humidity, cloud cover, and precipitation, along with decreased net radiation, near-surface wind speed, potential evapotranspiration, and river flow, especially during the summer season, represent a substantial change in the energy, mass, and momentum fluxes that are facilitating the establishment of the Karakoram anomaly.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075284/full
5. Critical Role of Snow on Sea Ice Growth in the Atlantic Sector of the Arctic Ocean
During the Norwegian young sea ICE (N-ICE2015) campaign in early 2015, a deep snowpack was observed, almost double the climatology for the region north of Svalbard. There were significant amounts of snow-ice in second-year ice (SYI), while much less in first-year ice (FYI). Here we use a 1-D snow/ice thermodynamic model, forced with reanalyses, to show that snow-ice contributes to thickness growth of SYI in absence of any bottom growth, due to the thick snow. Growth of FYI is tightly controlled by the timing of growth onset relative to precipitation events. A later growth onset can be favorable for FYI growth due to less snow accumulation, which limits snow-ice formation. We surmise these findings are related to a phenomenon in the Atlantic sector of the Arctic, where frequent storm events bring heavy precipitation during autumn and winter, in a region with a thinning ice cover.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075494/full
6. State-Dependence of the Climate Sensitivity in Earth System Models of Intermediate Complexity
Growing evidence from general circulation models (GCMs) indicates that the equilibrium climate sensitivity (ECS) depends on the magnitude of forcing, which is commonly referred to as state-dependence. We present a comprehensive assessment of ECS state-dependence in Earth system models of intermediate complexity (EMICs) by analyzing millennial simulations with sustained 2×CO2 and 4×CO2 forcings. We compare different extrapolation methods and show that ECS is smaller in the higher-forcing scenario in 12 out of 15 EMICs, in contrast to the opposite behavior reported from GCMs. In one such EMIC, the Bern3D-LPX model, this state-dependence is mainly due to the weakening sea ice-albedo feedback in the Southern Ocean, which depends on model configuration. Due to ocean-mixing adjustments, state-dependence is only detected hundreds of years after the abrupt forcing, highlighting the need for long model integrations. Adjustments to feedback parametrizations of EMICs may be necessary if GCM intercomparisons confirm an opposite state-dependence.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075457/full
7. Southern Ocean Origin of Multidecadal Variability in the North Brazil Current
Analysis of model data from a long (200 years) simulation of a high-resolution version of the Parallel Ocean Program indicates a connection between a mode of multidecadal variability in the Southern Ocean, the so-called Southern Ocean Mode, and multidecadal variability in the North Brazil Current. The multidecadal sea surface height variability in the Southern Ocean propagates northward and submerges at about 40°S. Northward propagating anomalies in ocean heat content are found between 5° and 40°S at depths down to 1 km and affect the North Brazil Current. Similar variability and connections between Southern Ocean and North Brazil Current are also found in a (200 years) simulation of a high-resolution global version of the Community Earth System Model. The results provide a new mechanism for the low-frequency variability of the North Brazil Current.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL074815/full
8. Weak Thermocline Mixing in the North Pacific Low-Latitude Western Boundary Current System
Despite its potential importance in the global climate system, mixing properties of the North Pacific low-latitude western boundary current system (LLWBC) remained unsampled until very recently. We report here on the first measurements of turbulence microstructure associated with these currents, made in the western boundary region of the tropical North Pacific east of the Philippines. The results suggest that thermocline mixing in the North Pacific LLWBC is generally weak with the diapycnal diffusivity κρ～O(10−6) m2 s−1. This is consistent with predictions from internal wave-wave interaction theory that mixing due to internal wave breaking is significantly reduced at low latitudes. Enhanced mixing is found to be associated with a permanent cyclonic eddy, the Mindanao Eddy, but mainly at its south and north flanks. There, κρ is elevated by an order of magnitude due to eddy-induced geostrophic shear. Mixing in the eddy core is at the background level with no indication of enhancement.
http://onlinelibrary.wiley.com/doi/10.1002/2017GL075210/full
VII. AGU Blogs
1. Monday Geology Picture: Pretty Pahoehoe
For this week’s picture, here’s another lovely shot of pahoehoe basalt that I took during a March 2017 vacation to Réunion Island. I previously shared a picture of some Réunion pahoehoe here.
http://blogs.agu.org/georneys/2017/10/30/monday-geology-picture-pretty-pahoehoe/
2. Planet Labs imagery of the Mishor Rotem tailings dam failure
Back in early July I blogged about yet another tailings dam failure, this time at the Mishor Rotem facility in Israel. I have seen remarkably little about the Mishor Rotem tailings dam failure since – far less than for many other tailings dam events.
http://blogs.agu.org/landslideblog/2017/10/31/mishor-rotem-tailings-dam/
3. Sol 1856-1857: Take two (almost)!
After Monday’s communications hiccup (detailed here) that prevented us from uplinking our two-sol plan, today we’re hoping to redo most of what we had in Monday’s plan. This primarily includes a remote science block, during which we’ll shoot a few ChemCam targets named ‘Hartley,’ ‘Hooggenoeg,’ and ‘Beaufort’ to study nearby pebbles and bedrock. We’ll also look behind us to take some Mastcam mosaics of Aeolis Palus, the Gale crater plains to the north of Mount Sharp. We’ll take some additional Mastcam images to document local bedrock features as well as the Vera Rubin Ridge terrain just in front of the rover.
http://blogs.agu.org/martianchronicles/2017/10/28/sol-1856-1857-take-two-almost/
VII. AGU News
1. DINOSAUR-KILLING ASTEROID IMPACT MAY HAVE COOLED EARTH’S CLIMATE MORE THAN PREVIOUSLY THOUGHT
WASHINGTON D.C. — The Chicxulub asteroid impact that wiped out the dinosaurs likely released far more climate-altering sulfur gas into the atmosphere than originally thought, according to new research. https://news.agu.org/press-release/dinosaur-killing-asteroid-impact-may-have-cooled-earths-climate-more-than-previously-thought/
