An upgraded version of the Eta model

Upgrades implemented over a number of years in an open source version of the Eta model, posted at the CPTEC web site http://etamodel.cptec.inpe.br/, are summarized and examples of benefits are shown. The version originates from the NCEP’s Workstation Eta code posted on the NCEP web site http://www.emc.ncep.noaa.gov/mmb/wrkstn_eta, which differs from the NCEP’s latest operational Eta by having the WRF-NMM nonhydrostatic option included. Most of the upgrades made resulted from attention paid to less than satisfactory performance noted in several Eta results, and identification of the reasons for the problem. Others came from simple expectation that including a feature that is physically justified but is missing in the code should help. The most notable of the upgrades are the introduction of the so-called sloping steps, or discretized shaved cells topography; piecewise-linear finite-volume vertical advection of dynamic variables; vapor and hydrometeor loading in the hydrostatic equation, and changes aimed at refining the convection schemes available in the Eta. Several other modifications have to do with the calculation of exchange coefficients, conservation in the vertical diffusion, and diagnostic calculation of 10-m winds. Several examples showing improved performance resulting from the dynamics changes are given. One includes a case of unrealistically low temperatures in several mountain basins generated by a centered vertical advection difference scheme’s unphysical advection from below ground, removed by its replacement with a finite-volume scheme. Another is that of increased katabatic winds in the Terra Nova Bay Antarctica region. Successful forecast of the severe downslope zonda wind case in the lee of the highest peaks of the Andes is also shown, and some of the recent successful verification results of the use of the upgraded model are pointed out. The code is used at numerous places, and along with setup information it is available for outside users at the CPTEC Eta web site given above.     

Paleomagnetism of the Istria peninsula, Yugoslavia

280 core samples were collected from Upper Jurassic, Cretaceous and Eocene sediments outcropping in the Istria peninsula (Yugoslavia). Due to the very low intensities of the initial natural remanent magnetizations, more than 50% of the collection, consisting mainly of rock samples of Jurassic and Eocene sediments, was not suitable for paleomagnetic studies.The Cretaceous samples yield a mean paleomagnetic pole (lat. 53°, long. 275° and α₉₅ = 4.8°), which is significantly different from the African and European paleomagnetic poles of the same age. The position of the Istria peninsula on the autochthonous Adriatic platform allows the result to be interpreted as applicable to all the autochthonous Periadriatic region. This new paleomagnetic result indicates that the autochthonous Adriatic platform rotated counterclockwise over an angle of about 30° with respect to Africa in post-Mesozoic times.     

History of Boulder 1 at Station 2, Apollo 17 based on trace element interrelationships

Correlations among the trace and minor element pairs Cl and Br, Cl and P₂O₅, and Ru and Os, present in parent igneous rocks, generally survived the processes of boulder breccia formation. Fractions of the Cl, Br, and Hg that are mobilized by water leaching and/or volatilization at moderate temperatures (?450°C) place constraints on the thermal history of Boulder 1 and its component breccias. Since, and possibly during, consolidation, the boulder has probably not been subjected to temperatures of ?450°C. The parent rocks of the Apollo 17 boulder and breccia samples studied could have been derived from two initial magmas. Boulder 1, Station 2 gray competent breccias 72255 and 72275 Clast #2 appear to be genetically unrelated to gray competent breccia and anorthositic material 72215, or to light friable breccia 72275; they do appear to be related to samples 72395 (Boulder 2) and 76315 (Station 6 boulder). Vapor clouds from apparently external sources permeated the source regions of the boulders.     

The space environment of Mercury at the times of the second and third MESSENGER flybys

The second and third flybys of Mercury by the MESSENGER spacecraft occurred, respectively, on 6 October 2008 and on 29 September 2009. In order to provide contextual information about the solar wind properties and the interplanetary magnetic field (IMF) near the planet at those times, we have used an empirical modeling technique combined with a numerical physics-based solar wind model. The Wang–Sheeley–Arge (WSA) method uses solar photospheric magnetic field observations (from Earth-based instruments) in order to estimate the inner heliospheric radial flow speed and radial magnetic field out to 21.5 solar radii from the Sun. This information is then used as input to the global numerical magnetohydrodynamic model, ENLIL, which calculates solar wind velocity, density, temperature, and magnetic field strength and polarity throughout the inner heliosphere. WSA-ENLIL calculations are presented for the several-week period encompassing the second and third flybys. This information, in conjunction with available MESSENGER data, aid in understanding the Mercury flyby observations and provide a basis for global magnetospheric modeling. We find that during both flybys, the solar wind conditions were very quiescent and would have provided only modest dynamic driving forces for Mercury's magnetospheric system.     

A systematic regional approach for climate change adaptation to protect biodiversity

Developing appropriate climate change adaptations to protect biodiversity requires taking into account the dynamics of agro-ecological and socio-economic change. A framework for approaching this problem was proposed, but not applied in detail, as part of a major biodiversity and climate change report prepared in Australia. This paper describes the first trial application of the method. It was applied across Vietnam as the Government is interested in identifying adaptation options and detailed data are readily available for its 65 provinces. The process involves identifying ecoregions and collating information for each region based on the current conditions and trends in biodiversity, population, income and agricultural production. Climate change scenarios are identified for each region, together with governance options. Educational needs and key adaptation actions are then identified for each region taking into account the agro-ecological and socio-economic input data. It is concluded that the framework could easily be applied in other countries and should assist the development of strategic adaptation options.     

Potential for forest carbon plantings to offset greenhouse emissions in Australia: economics and constraints to implementation

The theoretical potential for carbon forests to off-set greenhouse gas emissions may be high but the achievable rate is influenced by a range of economic and social factors. Economic returns (net present value, NPV) were calculated spatially across the cleared land area in Australia for ‘environmental carbon plantings’. A total of 105 scenarios were run by varying discount rate, carbon price, rate of carbon sequestration and costs for plantation establishment licenses for water interception. The area for which NPV was positive ranged from zero ha for tightly constrained scenarios to almost the whole of the cleared land (104 M ha) for lower discount rate and highest carbon price. For the most plausible assumptions for cost of establishment and commercial discount rate, no areas were identified as profitable until a carbon price of AUD$40 t CO₂ ^?1 was reached. The many practical constraints to plantation establishment mean that it will likely take decades to have significant impact on emission reductions. Every 1 M ha of carbon forests established would offset about 1.4 % of Australia’s year 2000 emissions (or 7.4 Mt CO₂ year^?1) when an average rate of sequestration per ha was reached. All studies that predict large areas of potentially profitable land for carbon forestry need to be tempered by the realities that constrain land use change. In Australia and globally, carbon plantings can be a useful activity to help mitigate emissions and restore landscapes but it should be viewed as a long-term project in which co-benefits such as biodiversity enhancement can be realised.     

Analysis of Galileo E5 and E5ab code tracking

The world of global navigation satellite systems has been enhanced with several new or improved signals in space aiming to optimize accuracy, reliability, navigation solution, and interoperability between different constellations. However, such developments bring various challenges to the receivers’ designers. For example, acquisition and tracking stages turn into more complex processes while handling the increasing bandwidth requires additional processing power. In this context, we study the code tracking of Galileo E5ab in a full band or of only one of its components, i.e., either E5a or E5b. More specifically, an architecture for tracking the E5 pilot channel as an AltBOC(15,10) or BPSK(10) modulation is introduced, and the performance of well-known discriminator types is analyzed using analytical derivations and simulations of linearity and stability regions, thermal noise tracking errors, multipath error envelopes and tracking thresholds. Different parameters, such as the front-end filter bandwidth, the early/late chip spacing, un-normalized and normalized discriminators, are taken into consideration. The results obtained are used to illustrate the main advantages and drawbacks of tracking the E5 signal as well as to help defining the main tracking loop parameters for an enhanced performance.     

Lunar bulk sample trace element contents and kreep

The geochemical coherence between the labile element Cl and more refractory F, K, REE and P in lunar soils is utilized to gain insight into the evolution of the lunar samples studied.Paper dedicated to Prof. Harold C. Urey on the occasion of his 80th birthday on 29 April 1973.Work sponsored by USAEC and NASA.     

196Hg and202Hg isotopic ratios in chondrites: revisited

Additional evidence for an isotopically anomalous Hg fraction in unequilibrated meteorites has been obtained using neutron activation to produce¹⁹⁶Hg and²⁰²Hg followed by stepwise heating to extract the Hg. In the latest experiments Allende matrix samples released the anomalous Hg but various high-temperature inclusions did not. Nucleogenetic processes are suggested as the probable cause of the anomaly.