Shortwave cloud radiative forcing on major stratus cloud regions in AMIP-type simulations of CMIP3 and CMIP5 models

Cloud and its radiative effects are major sources of uncertainty that lead to simulation discrepancies in climate models. In this study, shortwave cloud radiative forcing (SWCF) over major stratus regions is evaluated for Atmospheric Models Intercomparison Project (AMIP)-type simulations of models involved in the third and fifth phases of the Coupled Models Intercomparison Project (CMIP3 and CMIP5). Over stratus regions, large deviations in both climatological mean and seasonal cycle of SWCF are found among the models. An ambient field sorted by dynamic (vertical motion) and thermodynamic (inversion strength or stability) regimes is constructed and used to measure the response of SWCF to large-scale controls. In marine boundary layer regions, despite both CMIP3 and CMIP5 models being able to capture well the center and range of occurrence frequency for the ambient field, most of the models fail to simulate the dependence of SWCF on boundary layer inversion and the insensitivity of SWCF to vertical motion. For eastern China, there are large differences even in the simulated ambient fields. Moreover, almost no model can reproduce intense SWCF in rising motion and high stability regimes. It is also found that models with a finer grid resolution have no evident superiority than their lower resolution versions. The uncertainties relating to SWCF in state-of-the-art models may limit their performance in IPCC experiments.     

Ra’s Abdah of the north Eastern Desert of Egypt: the role of granitic dykes in the formation of radioactive mineralization,evidenced by zircon morphology and chemistry

Syenogranitic dykes in the north of Egypt’s Eastern Desert are of geological and economic interest because of the presence of magmatic and supergene enrichment of radioactive mineralization. Zircon crystal morphology within the syenogranitic dykes allows precise definition of sub-alkaline series granites and crystallized at mean temperature of about 637 °C. The growth pattern of the zircons suggest magmatic and hydrothermal origins of radioactive mineralization. Hydrothermal processes are responsible for the formation of significant zircon overgrowth; high U-zircon margins might have occurred contemporaneously with the emplacement of syenogranitic dykes which show anomalous uranium (eU) and thorium (eTh) contents of up to 1386 and 7330 ppm, respectively. Zircon chemistry revealed a relative increase of Hf consistent with decreasing Zr content, suggesting the replacement of Zr by Hf during hydrothermal activity. Visible uranium mineralization is present and recognized by the presence of uranophane and autunite.     

Diurnal variability of upper ocean temperature and heat budget in the southern Bay of Bengal during October–November, 1998 (BOBMEX-Pilot)

Time-series data on upper-ocean temperature, Vessel-Mounted Acoustic Doppler Current Profiler (VM-ADCP) measured currents and surface meteorological parameters have been obtained for the first time in the southern Bay of Bengal at 7‡N, 10‡N, and 13‡N locations along 87‡E during October–November, 1998 under BOBMEX-Pilot programme. These data have been analysed to examine the diurnal variability of upper oceanic heat budget and to estimate the eddy diffusivity coefficient of heat in the upper layer. Diurnal variation of near-surface temperature is typical at northern location (13‡N) with a range of 0.5‡C while the diurnal range of temperature is enhanced to 0.8‡C at the central location (10‡N) due to intense solar radiation (1050 W/m²), clear skies and low wind speeds. At the southern location (7‡N), the diurnal variation of temperature is atypical with the minimum temperature occurring at 2000 hrs instead of at early morning hours. In general, the diurnal curve of temperature penetrated up to 15 to 20 m with decreasing diurnal range with depth. The VM-ADCP measured horizontal currents in the upper ocean were predominantly easterly/northeasterly at southern location, north/northerly at central location and northwesterly at northern location, thus describing a large-scale cyclonic gyre with the northward meridional flow along 87‡E. The magnitudes of heat loss at the surface due to air-sea heat exchanges and in the upper 50 m layer due to vertical diffusion of heat are highest at the southern location where intense convective activity followed by overcast skies and synoptic disturbance prevailed in the lower atmosphere. This and the estimated higher value (0.0235 m²/s) of eddy diffusivity coefficient of heat in the upper ocean (0–50 m depth) suggest that 1-D processes controlled the upper layer heat budget at the southern location. On the other hand, during the fair weather conditions, at the central and northern locations, the upper layer gained heat energy, while the sea surface lost (gained) heat energy at northern (central) location. This and lower values of eddy diffusivity coefficient of heat (0.0045 and 0.0150 m²/s) and the northward intensification of horizontal currents at these locations suggest the greater role of horizontal heat advection over the 1-D processes in the upper ocean heat budget at these two locations.     

OIB-type basalts of the Irbistu River basin (Southeast Mountain Altai): Evidence for the HIMU component in the magmatic source

It has been found that basalts of the Irbistu River basin (southeast Altai Mountains) belong to the intraplate OIB type. The peculiarities of their material composition do not indicate interaction effects between the basic melt and continental crust, and signifies that there was a magmatic source in the moderately depleted mantle comparable to the HIMU domain. It is suggested that basalts of the Irbistu River basin, along with other manifestations of similar volcanites in the Altai Mountains, reflect the Neoproterozoic-Early Paleozoic stage of the North Asian plume’s activity during closure of the Paleoasian Ocean.     

Reflections on the history of research on large wood in rivers

Dynamics and functions of large wood have become integral considerations in the science and management of river systems. Study of large wood in rivers took place as monitoring of fish response to wooden structures placed in rivers in the central United States in the early 20th century, but did not begin in earnest until the 1970s. Research has increased in intensity and thematic scope ever since. A wide range of factors has prompted these research efforts, including basic understanding of stream systems, protection and restoration of aquatic ecosystems, and environmental hazards in mountain environments. Research and management have adopted perspectives from ecology, geomorphology, and engineering, using observational, experimental, and modelling approaches. Important advances have been made where practical information needs converge with institutional and science leadership capacities to undertake multi-pronged research programmes. Case studies include ecosystem research to inform regulations for forest management; storage and transport of large wood as a component in global carbon dynamics; and the role of wood transport in environmental hazards in mountain regions, including areas affected by severe landscape disturbances, such as volcanic eruptions. As the field of research has advanced, influences of large wood on river structures and processes have been merged with understanding of streamflow and sediment regimes, so river form and function are now viewed as involving the tripartite system of water, sediment, and wood. A growing community of researchers and river managers is extending understanding of large wood in rivers to climatic, forest, landform, and social contexts not previously investigated. © 2020 John Wiley & Sons, Ltd.     

Crustal impurities and the internal temperature of a neutron star crust

When the upper part of a neutron star crystallizes to form the crust, the constituting ions are trapped in the lattice as a result of the low diffusion rates in the solid phase. As a consequence, the local composition of the crust corresponds to the equilibrium condition at the melting point and not at the present internal temperature. The inclusion of the small entropic contribution to the free energy does not lead to marked changes in our view of the microscopic structure of a neutron star crust, because the melting temperature is much smaller than the typical energies at play in the crystal cell. However, mixing between layers characterized by different nuclear species is found to be an important effect for the production of impurities. We show that one should expect an increase of the thermal diffusion time through the crust at small temperatures, because of the decrease of thermal conductivity in relatively thin impurity-rich layers acting as isolating shields.     

A SIMPLE SOIL MOISTURE INDEX TO FORECAST CROP YIELDS

Neutron probe soil moisture measurements obtained biweekly during the growing season between 1982 and 1991 from multiple depths under grass-covered plots at 17 Illinois Climate Network sites are used to forecast crop yields. A Soil Moisture Index (SMIX) that combines the effect of intensity, duration, and timing of drought or excessively wet conditions was computed by integrating the quantity of available soil moisture throughout the rooting zone over the growing season. Relationships between the SMIX values and crop yields are evaluated at county, regional, and statewide scales. Coefficients of determination (r ²) for relationships between the SMIX values and maize, soybeans, and hay yields at the statewide level are 0.88, 0.74, and 0.81, respectively, when the period of integration is terminated at the end of the growing season. This new soil index can be employed to forecast yields as early as 12 weeks before harvest for the state of Illinois. However, predictions with RMSE ≤ 10% of the mean yield can be achieved only for SMIX integration periods ending 5, 9, and 6 weeks before harvest for maize, soybeans, and hay, respectively. Nomograms are presented for using the relationships between the SMIX values and crop yields to forecast Illinois's major crops well before harvest.     

Seismic moment tensor of Pribaikalye earthquakes from the surface-wave amplitude spectra

The method of surface-wave amplitude spectra inversion for the seismic moment tensor (SMT) is implemented and tested in the Pribaikalye region. The SMTs are calculated for 39 events with M _w = 4.4–6.3, which occurred in the region in 2000–2011. Based on the obtained data, the seismotectionic deformations of the crust are estimated in two seismically active areas-the Northern Pribaikalye and northeastern Baikal rift zone. It is found that on a level of moderate-magnitude events, the region is dominated by the regimes of subhorizontal northwestern extension and strike-slip faulting, which reflects the long-term trends in the stress field of the crust in these parts of the rift.