Description: Space-based remote sensing of the column-averaged methane dry air mole fraction (XCH 4 ) has greatly increased our understanding of the spatiotemporal patterns in the global methane cycle. The potential to retrieve multiple pieces of vertical profile information would further improve the quantification of CH 4 across space-time scales. We conduct information analysis for channel selection and evaluate the prospects of retrieving multiple pieces of information as well as total column CH 4 from both ground-based and space-based near-infrared remote sensing spectra. We analyze the Degrees of Freedom of signal ( DOF ) in the CH 4 absorption bands near 2.3 μ m and 1.6 μ m and select ∼1% of the channels that contain 〉95% of the information about the CH 4 profile. The DOF is around 4 for fine ground-based spectra (resolution = 0.01 cm −1 ) and 3 for coarse space-based spectra (resolution = 0.20 cm −1 ) based on channel selection and a signal-to-noise ratio (SNR) of 300. The DOF varies from 2.2 to 3.2 when SNR is between 100 and 300 and spectral resolution is 0.20 cm −1 . Simulated retrieval tests in clear-sky conditions using the selected channels reveal that the retrieved partial column-averaged CH 4 values are not sensitive to the a priori profiles and can reflect local enhancements of CH 4 in different partial air columns. Both the total and partial column-averaged retrieval errors in all tests are within 1% of the true state. These simulated tests highlight the possibility to retrieve up to 3 to 4 pieces of information about the vertical distribution of CH 4 in reality.

Description: No abstract is available for this article.

Description: Fog and low cloud cover (FLCC) strongly influences the water, energy, and nutrient flux of coastal ecosystems. Easy-to-use FLCC data are needed to quantify the impacts of FLCC on ecosystem dynamics especially during hot and dry Mediterranean climate summers. Monthly, annual, and decadal FLCC digital maps (indices) were derived for June, July, August, and September, 1999–2009 for coastal California, latitude 34.50°N (south of Monterey Bay) to latitude 41.95°N (north of Crescent City) from 26,000 hourly night and day Geostationary Environmental Operational Satellite (GOES) images. Monthly average FLCC ranges from 〈 2 to 18 hours per day (h/d). Average FLCC over the ocean increases from north (9 h/d) to south (14 h/d) whereas on land, FLCC is highest where land juts into the prevailing NW winds and is lowest in the lee of major capes. FLCC advects furthest inland through low-lying NW ocean-facing valleys. At night, average total hours of FLCC is higher more frequently on land than over the ocean. The interannual FLCC coefficient-of-variation shows long term geographic stability that is strongly associated with landform position. FLCC hours per day mapped contours, derived from decadal average FLCC, delineate the commonly used term ‘fog belt’ into FLCC zones with increased locational precision. FLCC indices are available for download from the California Landscape Conservation Cooperative Climate Commons website ( http://climate.calcommons.org/datasets/summertime-fog ). FLCC indices can improve analyses of biogeographic and bioclimatic species distribution models; understanding meteorological mechanisms driving FLCC patterns; solar energy feasibility studies; investigations of ecohydrology, evapotranspiration, and agricultural-irrigation-demand; and viticulture ripening models. This article is protected by copyright. All rights reserved.

Description: This study presents a geophysicochemical model of an ionospheric auroral gyroscope. The gyroscopic effect occurs due to the electromagnetic interaction in Earth's polar regions between two types of vertical cavity auroras: the herpolhodic cone (proton cavity aurora), operating in the cusp polar region, and two polhodic cones (an electronic cone and a protonic cone), operating in the aurora region. The ratio between the angular speeds of the herpolhodic and polhodic cones is established by the angle between Earth's rotational axis and the geomagnetic dipole axis. We have developed a theory of the ionospheric auroral gyroscope as a kinematic part of the terrestrial magnetosphere and ionosphere that enables a unified explanation of important macroscopic phenomena that occur at this level. Accordingly, we have explained the oval shape of the polar auroras, Schumann resonances, geomagnetic micro-pulsation excitation, and the structuring of Earth's areas of radiation. The terrestrial gravitomagnetic field and dark matter are implicated in the initiation and behavior of the auroral ionospheric gyroscope, both of which provide stability and accuracy. Viewed in a wider context, the ionospheric auroral gyroscope theory could offer a way to experimentally investigate dark matter on Earth. Furthermore it may have a potential value as a predictive tool, providing information about the large earthquakes and Earth's phenomena. This article is protected by copyright. All rights reserved.

Description: We use a 1D cloud model run using a prescribed temperature field to investigate the role of gravity waves in dehydration in the Tropical Tropopause Layer (TTL). We find that gravity waves play an important role in the TTL dehydration process beyond just lowering the minimum temperature experienced by the air parcels. We show that the more rapid cooling in the presence of gravity waves significantly increases the abundance ice crystals. This increase in ice crystal concentration causes a more rapid depletion of vapor in excess of saturation, and the resultant cloud dehydration efficiency is increased. Using a spectrum of gravity waves, we generate ice particle statistics that are in good agreement with observations. We also find that the gravity waves increase cloudiness. Our results show that cloud physics and gravity wave temperature fluctuations cannot be neglected in simulating the TTL physics. In fact, it appears short period waves may be an essential component of the TTL cloud dehydration process.

Description: Water tracks are an intrinsic part of the surficial drainage network in the foothills of the Brooks Range, Alaska. They preferentially transport water off hill slopes and represent the interplay between hydrology, vegetation, geomorphology and permafrost characteristics. This research on mapping the location of water tracks builds on previous work which demonstrated that different types of water tracks exist due to difference primarily driven by geomorphology. We used a combination method where spectral classifications, texture and topography were fed into random forests to identify the water track classes. The most accurate distributions were obtained for the organic-rich and wide water track classes. The distinct linear shapes of the water tracks could also be visualized for many of the classes, especially in areas where the water tracks were particularly discrete. The biggest challenges to mapping the water tracks were due to class imbalances and high variability within and overlapping between classes. This research presents a significant step forward in understanding periglacial landscape dynamics.

Description: A better understanding of water movement on hillslopes in Arctic environments is necessary for evaluating the effects of climate variability. Drainage networks include a range of features that vary in transport capacity from rills to water tracks to rivers. This research focuses on describing and classifying water tracks, which are saturated linear-curvilinear stripes that act as first-order pathways for transporting water off of hillslopes into valley bottoms and streams. Multiple factor analysis was used to develop five water tracks classes based on their geomorphic, soil and vegetation characteristics. The water track classes were then validated using conditional inference trees, to verify that the classes were repeatable. Analysis of the classes and their characteristics indicate that water tracks cover a broad spectrum of patterns and processes primarily driven by surficial geology. This research demonstrates an improved approach to quantifying water track characteristics for specific areas, which is a major step towards understanding hydrological processes and feedbacks within a region.

Description: No abstract is available for this article.

Description: Nitrogen (N) fertilizer applications have resulted in widespread groundwater nitrate-N (NO 3 -N) contamination in the U.S. Corn Belt. Goodwater Creek Experimental Watershed (GCEW) is an agricultural watershed in the claypan soil region of northeastern Missouri with a network of 96 wells at depths of 2.7-15.7 m. The objectives of this study were to: (1) inspect the spatial and temporal variations of NO 3 -N concentrations in GCEW's groundwater, particularly with well depth at scales ranging from individual well, well nest, and field to the entire watershed during the period 1991 to 2004, (2) understand the processes controlling the variability of NO 3 -N concentrations in groundwater at various scales within GCEW, and (3) compare groundwater NO 3 -N concentrations in GCEW to other agricultural watersheds in the U.S. Nitrate-N concentrations were determined in more than 2000 samples collected from 1991 to 2004. Despite the low hydraulic conductivity of the claypan soils, considerable NO 3 -N contamination of the glacial till aquifer occurred, with 38% of the wells exceeding 10 mg l -1 . Groundwater recharge by preferential pathways through the claypan appeared to be the primary mechanism for NO 3 -N movement to the aquifer. Changes in concentration with depth steadily increased to 8.5-10 m, and then decreased with further depth. This pattern was consistent with decreased hydraulic conductivity in the Paleosol layer at 8.5-10 m, denitrification below this layer, and mixing of recent contaminated water with older uncontaminated water in the lowest strata. Only 19-23% of sampled wells exceeded 10 mg l -1 in non-claypan agricultural watersheds over the continental U.S., suggesting that groundwater in GCEW was more susceptible to NO 3 -N contamination than non-claypan watersheds. These results demonstrated that preferential flow through the soil and hydraulic conductivity of the sub-surface strata controlled NO 3 -N transport in this claypan watershed.

Description: Determining the relationship between folding and faulting in fold and thrust belts is important for understanding the growth of geological structures, the depth extent of seismic slip and consequently the potential earthquake hazard. The 2013 Mw6.2 Khaki-Shonbe earthquake occurred in the Simply Folded Belt of the Zagros Mountains, Iran. We combine seismological solutions, aftershock relocations, satellite interferometry and field observations to determine fault geometry and its relationship with the structure, stratigraphy and tectonics of the central Zagros. We image reverse slip on two along-strike, south-west dipping fault segments. The mainshock rupture initiated at the lower northern end of the larger north-west segment. Based upon the hypocentre and rupture duration, slip on the smaller southern segment is likely aseismic. Both faults verge away from the foreland, towards the high range interior, contrary to the fault geometries depicted in many structural cross-sections of the Zagros. The slip modelled occurred over two mutually exclusive depth ranges above 10km, resulting in long (∼16km), narrow rupture segments (∼7km). Aftershocks cluster in the depth range 3–14km. This indicates reverse slip and coseismic shortening occurred mostly or exclusively in the sedimentary cover, with slip distributions likely to be lithologically controlled in depth by the Hormuz salt at the base of the sedimentary cover (∼10–12km), and the Kazhdumi Formation mudrocks at upper-levels (∼4–5km). Our findings suggest lithology plays a significant role in the depth extent of slip found in reverse faults in folded belts, providing an important control on the potential size of earthquakes.