ALBERT

Description: We present a study of the potential radiation hazard of the powerful, superfast interplanetary coronal mass ejection (ICME) observed by STEREO A on 23 July 2012. Using energetic proton flux data from the HET and LET instruments aboard STEREO A together with the EMMREM radiation model, we compute dose rates and accumulated doses during the event for both skin/eye and blood forming organs using four physically relevant levels of shielding. For spacesuit equivalent shielding, we compute a peak skin/eye dose rate of 1970 cGy-Eq/day, a value far greater than those of the 2003 Halloween storms or the January and March SEP events of 2012. However, due to the relative brevity of the event, the resulting accumulated dose was just 383 cGy-Eq, which is more aligned with the total doses of the 2003 Halloween and 2012 January/March events. Additionally, we use dose rates at STEREO B and LRO/CRaTER during the event to show how the radiation impact is affected by the position of the ICME relative to the observer. Specifically, we find that the energetic particle event associated with the local shock and ICME passage at STEREO A caused greatly enhanced dose rates when compared to STEREO B and LRO/CRaTER, which were longitudinally distant from the ICME. The STEREO A/B dose rates used here will soon be made available to the community as a tool for studying the energetic particle radiation of solar events from different longitudes as a part of NASA's Heliophysics Virtual Observatories and on the PREDICCS and CRaTER websites.

Description: Abstract In this study, we estimate atmospheric turbulence in the free atmosphere in terms of the Thorpe scale (LT) and eddy dissipation rate (ε) using U.S. high vertical‐resolution radiosonde data over 4 years (September 2012 to August 2016) at 68 operational stations. In addition, same calculations are conducted for 12 years (October 2005 to September 2017) at four stations among the 68 stations. These high vertical‐resolution radiosonde data have a vertical resolution of approximately 5 m and extend to an altitude of approximately 33 km, and thus, turbulence can be retrieved in the entire troposphere and lower stratosphere. There are thicker and stronger turbulent layers in the troposphere than in the stratosphere, with mean ε values of 1.84 × 10−4 and 1.37 × 10−4 m2/s3 in the troposphere and stratosphere, respectively. The vertical structure of ε exhibits strong seasonal variations, especially in the upper troposphere and lower stratosphere, with the largest ε values in summer and the smallest in winter. In the horizontal distribution of ε, large ε is seen mainly above the mountainous region in the troposphere, but this pattern is not seen in the stratosphere. Although ε is estimated by the square of LT multiplied by the cube of the Brunt‐Väisälä frequency (N), the regions of large ε are matched with large LT regions where N is relatively small. For the time series of ε near the tropopause for 12 years at four stations, an annual variation is prominent at all stations without significant interannual variations. There is, however, a slightly increasing trend of ε at two stations.

Description: :  This study offers insights into the diagenetic alteration of coastal carbonates that formed coevally with nearly continuous siliciclastic influx in a humid equatorial setting. A multi-disciplinary petrographic, cathodoluminescent, stable-isotope, trace-element and major-element investigation allowed characterization of diagenetic features, paragenetic sequencing, and an interpretation of diagenetic environments from Neogene patch reefs of the Samarinda region, Mahakam Delta, Borneo, SE Asia. Marine cements are absent from the patch reefs, with grain micritization the only marine diagenetic feature recognized. The predominant diagenetic feature within the patch reefs is pervasive neomorphic stabilization and cementation of aragonite reef components to calcite that pre-dates all compaction features. Meteoric aquifer flow derived from the adjacent landmass is inferred as the main parent diagenetic fluid, since 18 O V-PDB values of calcite cements of –3.6 to –11.7 are consistent with precipitation from SE Asian freshwater, and inconsistent with a wholly marine origin. Late-stage fracturing, cementation, and chemical compaction are relatively minor features and attest to a changing paleohydrologic and diagenetic environment. Evidence for a shallow to moderate burial diagenetic regime for these later features are maximum temperature of 53 °C and burial depths 〈 1000 m inferred from stable-isotope values of calcite and late dolomite cements, dolomite crystal fabrics, the onset depth of stylolite or dissolution-seam formation, and regional geothermal gradients. The humid tropical environment and "ever-wet" conditions on the island of Borneo together with rapid Cenozoic uplift likely led to paleoaquifer flow with fluids focused through adjacent deltaic units into the reef carbonates. In these coastal carbonates from the humid Samarinda region, continental groundwater flow has resulted in pervasive stabilization and calcitization, features rare in arid or temperate counterparts.

Description: The present study aims to determine synoptic regimes associated with rain and no-rain days in south-eastern Queensland. A k-means cluster analysis is used on upper-air data from Brisbane Airport to identify dominant weather regimes for the region. Eight weather regimes appear to succinctly describe the main types of conditions experienced in south-eastern Queensland. Using rainfall data from 307 sites across the region, the rainfall associated with each weather regime is then characterized. Four of the regimes are associated with moist conditions; each accounts for about 15–20% of the mean total annual rainfall. These regimes preferentially occur during the summer and are characterized by high onshore moisture flux. The four dry regimes are characterized by southerly moisture flux and generally occur throughout the year. These regimes combined account for less than 25% of the mean total annual rainfall but more than 60% of the days in a year. Back trajectories at five levels were computed for each of the regimes using the HYSPLIT model. Case studies were selected for the four wet regimes and examined in detail. The wet regimes exhibit geographically shorter back trajectories, particularly at lower levels, than the dry regimes. In addition, there is usually a northerly component to the 500 m level trajectories close to Brisbane for the wet regimes. Copyright © 2012 Royal Meteorological Society

Description: The present study aims to determine synoptic regimes associated with rain and no-rain days in south-eastern Queensland. A k-means cluster analysis is used on upper-air data from Brisbane Airport to identify dominant weather regimes for the region. Eight weather regimes appear to succinctly describe the main types of conditions experienced in south-eastern Queensland. Using rainfall data from 307 sites across the region, the rainfall associated with each weather regime is then characterized. Four of the regimes are associated with moist conditions; each accounts for about 15–20% of the mean total annual rainfall. These regimes preferentially occur during the summer and are characterized by high onshore moisture flux. The four dry regimes are characterized by southerly moisture flux and generally occur throughout the year. These regimes combined account for less than 25% of the mean total annual rainfall but more than 60% of the days in a year. Back trajectories at five levels were computed for each of the regimes using the HYSPLIT model. Case studies were selected for the four wet regimes and examined in detail. The wet regimes exhibit geographically shorter back trajectories, particularly at lower levels, than the dry regimes. In addition, there is usually a northerly component to the 500 m level trajectories close to Brisbane for the wet regimes. Copyright © 2012 Royal Meteorological Society

Description: Multiple bioclaustrations identified as possible Chaetosalpinx are reported from a stromatoporoid of Rhuddanian age from Hiiumaa Island, Estonia. This is the second record of symbiotic worm endobionts from the end-Ordovician mass extinction recovery fauna of Estonia. The end-Ordovician mass extinction did not terminate complex ecological relationships between at least some worm endobionts and their hosts.

Description: Interchange injections events are commonly observed by the Cassini spacecraft in the region between about 6 and 12 Rs (1Rs = 60268 km) and even frequently beyond. In this study, thirteen examples of interchange injection events are identified in Cassini/CAPS data under special conditions such that time-of-flight (TOF) mass spectra could be obtained from entirely within the events. Using the TOF data to separate the main ion species H + , H 2 + , and W + , approximate densities of each species are calculated under the assumption that all distributions were isotropic. The light-ion density ratios, H 2 + /H + , in the injection events are not discernibly different from those ratios in control intervals from the ambient plasma. However, the water-group ratio, W + /H + , is significantly lower than ambient. Comparison of the measured density ratios with the range of values observed throughout Saturn's magnetosphere indicates that values of W + /H + that are as low as those observed within the injection events are found primarily beyond L ~ 14 (where L is the equatorial crossing distance, in Rs, of a dipole field line), indicating that the injection events are delivering plasma from the outer magnetosphere, at times traveling at least 6 Rs.