Cloud computing and virtualization within the regional climate model and evaluation system

The Regional Climate Model Evaluation System (RCMES) facilitates the rapid, flexible inclusion of NASA observations into climate model evaluations. RCMES provides two fundamental components. A database (RCMED) is a scalable point-oriented cloud database used to elastically store remote sensing observations and to make them available using a space time query interface. The analysis toolkit (RCMET) is a Python-based toolkit that can be delivered as a cloud virtual machine, or as an installer package deployed using Python Buildout to users in order to allow for temporal and spatial regridding, metrics calculation (RMSE, bias, PDFs, etc.) and end-user visualization. RCMET is available to users in an “offline”, lone scientist mode based on a virtual machine dynamically constructed with model outputs and observations to evaluate; or on an institution’s computational cluster seated close to the observations and model outputs. We have leveraged RCMES within the content of the Coordinated Regional Downscaling Experiment (CORDEX) project, working with the University of Cape Town and other institutions to compare the model output to NASA remote sensing data; in addition we are also working with the North American Regional Climate Change Assessment Program (NARCCAP). In this paper we explain the contribution of cloud computing to RCMES’s specifically describing studies of various cloud databases we evaluated for RCMED, and virtualization toolkits for RCMET, and their potential strengths in delivering user-created dynamic regional climate model evaluation virtual machines for our users.     

The age of the Roter Kamm impact crater,Namibia: Constraints from 40Ar-39Ar,K-Ar,Rb-Sr,fission track,and 10Be-26Al studies

Abstract The well-preserved 2.5 km diameter Roter Kamm impact crater is located in the Namib desert in Namibia. The impact has occurred in Precambrian granitic and granodioritic orthogneisses of the 1200–900 Ma old Namaqualand Metamorphic Complex which were partly covered by Gariep metasediments; the granites are invaded by quartz veins and quartz-feldspar-pegmatites. Previous geological field evidence suggested a crater age of about 5–10 Ma. In order to constrain this age, we selected a set of basement rocks (granites, granodiorites) exposed at the crater rim and studied the Rb-Sr, K-Ar, ⁴⁰Ar-³⁹Ar, and ¹⁰Be-²⁶Al isotopic systems as well as apatite fission track ages of these samples. The Rb-Sr isotopic systematics confirm the derivation of these samples from the Namaqualand basement (age about 1.29 Ga), which underwent Damaran orogenesis at about 650 Ma. No basement rocks with Rb-Sr ages younger than about 410 Ma were identified. The K-Ar ages of pseudotachylite and melt breccia samples show that these samples are dominated by incompletely degassed fragments of basement rocks, with some retaining their original metamorphic ages of about 470 Ma. The apatite fission track ages range from 20–28 Ma, which may be interpreted as an extension of the 25 Ma Burdigalian peneplanation event, or as incomplete resetting of the apatite fission tracks during the impact event. The ¹⁰Be and ²⁶Al exposure age of a quartz sample isolated from a quartz-pegmatite was found to be 150 ka; it is likely that the exposure of the sample began after material covering it had been removed by erosion 150 ka ago. Two glassy fractions extracted from a rim granite were dated by ⁴⁰Ar-³⁹Ar analysis. One sample gives practically a plateau age of 3.7 ± 0.3 Ma, while the other gives a minimum age of 3.6 Ma. The best available age estimate for the Roter Kamm crater is therefore 3.7 ± 0.3 Ma.     

New 1982 — 1990 photometry of λ Andromedae and its 11-year cycle

We present photoelectric photometry of λ And never before published, obtained between February 1982 and December 1990 at 29 different observatories. Then we combine it with all other photometry available to us (previously published, contained in the I.A.U. Commission 27 Archives, and obtained with the Vanderbilt 16-inch automatic telescope but not yet published), to yield a 14.8-year data base. Analysis reveals a long-term cycle in mean brightness, with a full range of 0^m.15 and a period of 11.4 ± 0.4 years. Because most of our new photometry was concentrated in the 1983-84 observing season, we analyze that one well-defined light curve with a two-spot model. Spot A keeps a 0^m.04 amplitude throughout four rotation cycles whereas the amplitude of spot B diminishes from 0^m.09 down almost to 0^m.03. The spot rotation periods were 55^d.9 ± 0^d.6 and 520^d.8 ± 1^d.0, respectively.     

Searching for nanoflares

The evolution of hydrodynamic shocks generated by nanoflares in coronal loops is investigated in order to suggest requirements for future observations. The shocks produced by nanoflares of 10²⁴ ergs decay within a few seconds, which sets stringent requirements for Doppler or transverse velocity measurements. With feasible improvements, the Normal Incidence X-ray Telescope could observe the time-averaged emission from a nanoflare, however. We also consider collisions between shocks and show that these could also be observed.Operated by the Association of Universities for Research in Astronomy (AURA) under agreement with the Natinal Science Foundation.     

In search of the Australasian tektite source crater: The Tonle Sap hypothesis

Abstract— The source crater for Australasian tektites remains to be positively identified We suggest that Tonle Sap, a roughly oval lake in south-central Cambodia, may represent the remnant of that crater. The size of the lake (about 100 km × 35 km), location (Indochina), inferred geologic age (recent), and orientation of the lake, as well as the geographical distribution of tektites, are consistent with this suggestion. The elongated shape of the lake with its long axis pointing toward Australia may be the result of an oblique impact of a NW to SE-moving object a few km in diameter. The absence of a raised rim and a central peak may be related to a low impact angle, soft target rocks, or high post-impact erosion and sedimentation rates. The scarcity of Muong Nong-type (layered) tektites near Tonle Sap may be due to extensive post-impact alluvial deposition, which buried the tektites. The chemical composition of Upper Indosinias formation sandstones from Phnom Batheay was determined. There are significant differences between the composition of indochinite tektites and these rocks, which are thus unlikely to represent tektite source rocks.     

Flows in quiescent prominences

Earlier studies of quiescent prominences claim that there is a systematic downward directed motion of the small-scale structure. Disk observations, on the other hand, have detected mass motions both upwards and downwards. The earlier high-resolution observations of limb prominences have been re-examined using local cross-correlation techniques for measurements of motion perpendicular to the line of sight. The new measurements reveal flow speeds and directions that are in good agreement with current Doppler measurements on the disk.     

Theoretical meteor radiants of Apollo,Amor, and Aten asteroids

A compilation of theoretical meteor radiants is presented for all numbered (through 2525) asteroids which approach the Earth's orbit to within 0.20 AU. On the basis of orbital similarity, asteroids associated with current meteor streams and Prairie Network fireballs are listed; plausible associations with medieval fireball radiants are also given. The best defunct comet candidates in terms of meteoric evidence appear to be 2101 Adonis and 2201 1947XC. Asteroids which may be either extinct comets or perturbed main belt asteroids accompanied by collisional debris (represented by fireballs) are 1917 Cuyo, 2202 Pele, 2061 Anza, and 2340 Hathor. 1566 Icarus and 1981 Midas are the only asteroids whose orbits approach to less than 0.07 AU of the Earth's orbit, have a northern radiant, and still show no certain meteoric activity. The majority of Atens, Apollos, and Amors do not pass sufficiently close (<0.07 AU) to the Earth's orbit for a reasonable expectation of meteoric activity, or have radiants south of ?20° declination, requiring southern hemisphere observations.     

Cracking in clays: Solutions to problems in earth structures

Methods are presented for analysing earth structures subjected to tensile stresses that may produce cracking. The linear elastic fracture mechanics approach is emphasized. Methods of solution are proposed for cracking of a clay layer above the water table due to desiccation; cracking of layered earth structures subjected to external loads; cracking of clay caps for landfills due to differential settlement; and radial cracking in pressurized boreholes. Causes and mechanisms of cracking are discussed for each problem and models pertinent to each problem are proposed. Solutions have been developed by synthesizing analytical and numerical methods. Published experimental data have been incorporated in modelling matric suction and cracked beams on elastic foundations. Finite element analyses were employed to obtain solutions for cracking due to differential settlement and radial cracking in boreholes. The solutions presented herein can be used to assess the soundness of existing structures or to assess the risk of cracking for the design of new structures.     

Surface features on glass spherules from the Luna 16 sample

Two ellipsoidal spherules approximately 0.5 mm in diameter were studied in detail using a scanning electron microscope. A variety of surface features were observed: vesicles, mounds, dimples, streaks, ridges, grooves, accretion phenomena, and high-speed impact craters. The diameters of 27 glass-lined pits formed by impact on one spherule range from less than 1m to approximately 50m. Intermediate-sized glass-lined pits surrounded by concentric fractures demonstrate the transition between larger craters that have both a pit and a spall zone and generally smaller craters that have only a pit. Assuming all craters showing evidence of impact-related melting or flow are the result of primary impacts, the differential mass spectrum of impacting meteoroids in the range 10^–11 to 10^–10 g is in good agreement with a spectrum based on satellite-borne particle-detecting experiments.