The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

TRY plant trait database – enhanced coverage and open access

Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait‐based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for ‘plant growth form’. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait–environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

A Climatology of 500 hPa Closed Lows in the Northeast Pacific, 1948-2011

The Northeast Pacific is a preferential location for the formation of closed low pressure systems. These slow moving, quasi-­‐barotropic systems have the potential to produce or affect sustained precipitation episodes along the West Coast of the United States. They do so because they affect vertical stability and sustain a moist environment favoring cloudiness. In concert with other circulation features they can lead to uncommon airflow trajectories that may impact fire and wind events. As a class, these features have not been addressed as attentively in research as have been open wave disturbances and cyclones. This study uses the NCEP/NCAR Reanalysis dataset at 6-­‐hour and 2.5°x2.5° resolution for 1948-­‐2011 to develop an objective climatological description of 500 hPa closed lows in the Northeast Pacific. Time series for seasonal and annual event counts were found to exhibit strong inter-­‐ annual variability. Composites of landfalling closed low tracks revealed a preferential track as they move inland over the western United States. The features travel southeast as they travel onshore, and then make a pronounced cyclonic turn as they move over southern California. Precipitation at 30 U.S. Cooperative Observer stations was associated with closed low events, suggesting 20-­‐60% of 1948-­‐2011 precipitation along the U.S. West Coast may be driven by closed lows. A latitudinal dependence on closed low precipitation was also expressed, with stations south of 40°N receiving a greater percentage of their October-­‐March precipitation from closed lows. Values of metrics of various modes of atmospheric variability (ENSO, PDO, AO, PNA, etc.) were assessed for relationships with closed low events.iCorrelations with ENSO indices, PDO, and PNA were found to be of significance, favoring more events in the warm ENSO phase and positive PDO and PNA phases. In the period between water years 1998 and 2008, 43% of Atmospheric Rivers were found to be concurrent with identified closed lows

Characteristics of extreme precipitation in southern California and applications to post-fire debris flows, shallow landslides, and water resources

Shallow landslides and post-fire debris flows in southern California can result in loss of life and millions of dollars in damage to property and infrastructure. Persistent drought conditions reduce southern California’s local water resources and have severe socioeconomic impacts. Shallow landslides, post-fire debris flows, and water resources operate on distinct timescales, but in this region share the common theme of extreme precipitation as a driver. I use in-situ observations and atmospheric reanalysis datasets to address the question: What are the characteristics of extreme precipitation associated with mass movements and impacts to water resources in southern California? I explore the spatial and temporal variability of precipitation extremes as well as characterize atmospheric conditions associated with these events. I find that approximately 70% of post-fire debris flow events assessed in the Transverse Ranges of Southern California are associated with atmospheric rivers. Narrow cold frontal rain bands (and other squall lines) are also commonly associated with post-fire debris flow events. I examine 147 hourly precipitation gauges throughout California and find precipitation intensities that have historically triggered shallow landslides (OTPE; over threshold precipitation events) are most frequently observed in south-facing terrain in the Coast Ranges and Transverse Ranges, as well as in the northern Sierra Nevada. Depending on location, 60-90% of OTPE are associated with atmospheric rivers and multiple OTPE may occur within a storm event. Last, I show that the difference between a wet and dry year in the Santa Ynez River Basin is typically two to three >90th percentile precipitation events. While there are often more >90th percentile events in El Niño years, there is considerable variability in the record analyzed. Synoptic to mesoscale conditions producing precipitation extremes are also described in this work. These results provide quantitative documentation of previously qualitative observations such that they can serve as a building block for future research, e.g., how these processes might be influenced by a changing climate. Additionally, my results improve situational awareness of the hazards addressed for weather forecasters, emergency managers, and water resource managers, as well as inform natural hazards-related communication and outreach efforts

Hourly Analyses of the Large Storms and Atmospheric Rivers that Provide Most of California’s Precipitation in Only 10 to 100 Hours per Year

https://doi.org/10.15447/sfews.2018v16iss4art1 California is regularly affected by floods and droughts, primarily as a result of too many or too few atmospheric rivers (ARs). This study analyzes a 2-decade-long hourly precipitation data set from 176 California weather stations and a 3-hourly AR chronology to report variations in rainfall events across California and their association with ARs. On average, 10–40 and 60–120 hours of rainfall in southern and northern California, respectively, are responsible for more than half of annual rainfall accumulations. Approximately 10% to 30% of annual precipitation at locations across the state is from only one large storm. On average, northern California receives 25 to 45 rainfall events annually (40% to 50% of which are AR-related). These events typically last longer and have higher event-precipitation totals than those in southern California. Northern California also receives more AR landfalls with longer durations and stronger Integrated Vapor Transport (IVT). On average, ARs contribute 79%, 76%, and 68% of extreme-rainfall accumulations (i.e., top 5% events annually) in the north coast, northern Sierra, and Transverse Ranges of southern California, respectively.The San Francisco Bay Area terrain gap in the California Coast Range allows more AR water vapor to reach inland over the Delta and Sacramento Valley, and thus influences precipitation in the Delta’s catchment. This is particularly important for extreme precipitation in the northern Sierra Nevada, including river basins above Oroville Dam and Shasta Dam. This study highlights differences between rainfall and AR characteristics in coastal versus inland northern California — differences that largely determine the regional geography of flood risks and water reliability. These analyses support water resource, flood, levee, wetland, and ecosystem management within the catchment of the San Francisco Estuary system by describing regional characteristics of ARs and their influence on rainfall on an hourly time-scale.

Winter Snow Level Rise in the Northern Sierra Nevada from 2008 to 2017

The partitioning of precipitation into frozen and liquid components influences snow-derived water resources and flood hazards in mountain environments. We used a 915-MHz Doppler radar wind profiler upstream of the northern Sierra Nevada to estimate the hourly elevation where snow melts to rain, or the snow level, during winter (December–February) precipitation events spanning water years (WY) 2008–2017. During this ten-year period, a Mann-Kendall test indicated a significant (p < 0.001) positive trend in snow level with a Thiel-Sen slope of 72 m year−1. We estimated total precipitation falling as snow (snow fraction) between WY1951 and 2017 using nine daily mid-elevation (1200–2000 m) climate stations and two hourly stations spanning WY2008–2017. The climate-station-based snow fraction estimates agreed well with snow-level radar values (R2 = 0.95, p < 0.01), indicating that snow fractions represent a reasonable method to estimate changes in frozen precipitation. Snow fraction significantly (p < 0.001) declined during WY2008–2017 at a rate of 0.035 (3.5%) year−1. Single-point correlations between detrended snow fraction and sea-surface temperatures (SST) suggested that positive SST anomalies along the California coast favor liquid phase precipitation during winter. Reanalysis-derived integrated moisture transported upstream of the northern Sierra Nevada was negatively correlated with snow fraction (R2 = 0.90, p < 0.01), with atmospheric rivers representing the likely circulation mechanism producing low-snow-fraction storms

Atmospheric rivers emerge as a global science and applications focus

ISSN:0003-0007ISSN:1520-047