Shilin： The Formation of Stone Forests in Various Rock Types （Lunan, Yunnan, China）

Shilin is among the most interesting form of stone forest to occur in karst landscapes. They develop from karren subsoil, and their shapes, entire forests or just individual pillars and their rock relief, depend on the conditions under which they were formed, their location in the karst landscape, and above all on the characteristics of the rock： its composition, stratification, and fissuring. Because of the exceptional characteristics of this karst phenomenon in China, we propose that the term ＂shilin＂ be used in the professional literature for this type of stone forest.     

Combination of long time-series of troposphere zenith delays observed by VLBI

Within the International Very Long Baseline Interferometry (VLBI) Service for Geodesy and Astrometry (IVS), long time-series of zenith wet and total troposphere delays have been combined at the level of parameter estimates. The data sets were submitted by eight IVS Analysis Centers (ACs) and cover January 1984 to December 2004. In this paper, the combination method is presented and the time-series submitted by the eight IVS ACs are compared with each other. The combined zenith delays are compared with time-series provided by the International Global Navigation Satellite System (GNSS) Service (IGS), and with zenith delays derived from the European Centre for Medium-Range Weather Forecasts (ECMWF). Before the combination, outliers are eliminated from the individual time-series using the robust BIBER (bounded influence by standardized residuals) estimator. For each station and AC, relative weight factors are obtained by variance component estimation. The mean bias of the IVS ACs’ time-series with respect to the IVS combined time-series is 0.89 mm and the mean root mean square is 7.67 mm. Small differences between stations and ACs can be found, which are due to the inhomogeneous analysis options, different parameterizations, and different treatment of missing in-situ pressure records. Compared to the IGS zenith total delays, the combined IVS series show small positive mean biases and different long-term trends. Zenith wet delays from the ECMWF are used to validate the IVS combined series. Inconsistencies, e.g., long-term inhomogeneity of the in-situ pressure data used for the determination of VLBI zenith delays, are identified.     

Estimation of volumes of aerobic and anaerobic waters in the Black Sea and of oxygen and hydrogen sulfide contained in them

The mean depth of the upper boundary of the hydrogen sulfide zone (HSZ) in winter and summer is determined from the experimental data for the last 50 years. The estimates of aerobic and anaerobic water volumes and total oxygen and hydrogen sulfide in these seasons are derived from the data on the depth of the upper boundary of the HSZ position and more precise morphological parameters of the Black Sea. The aerobic and anaerobic water ratio is approximately 1: 10 in winter and 1: 9 in summer.     

Progress in NTHMP Hazard Assessment

The Hazard Assessment component of the U.S. National Tsunami Hazard Mitigation Program has completed 22 modeling efforts covering 113 coastal communities with an estimated population of 1.2 million residents that are at risk. Twenty-three evacuation maps have also been completed. Important improvements in organizational structure have been made with the addition of two State geotechnical agency representatives to Steering Group membership, and progress has been made on other improvements suggested by program reviewers.     

Three-dimensional assimilation model of the ionosphere for the European region

We consider a three-dimensional assimilation model of the ionosphere. We discuss the governing equations of the physical model and the data assimilation technique. We provide examples of the model results: plots of the calculated ionospheric parameters, such as the density and temperature of electrons and ions. We compare the model results with independent sources of data on the state of the ionosphere. We make some conclusions regarding the model accuracy and possible areas of its practical application.     

Modeling of the 2011 Japan Tsunami: Lessons for Near-Field Forecast

During the devastating 11 March 2011 Japanese tsunami, data from two tsunami detectors were used to determine the tsunami source within 1.5 h of earthquake origin time. For the first time, multiple near-field tsunami measurements of the 2011 Japanese tsunami were used to demonstrate the accuracy of the National Oceanic and Atmospheric Administration (NOAA) real-time flooding forecast system in the far field. To test the accuracy of the same forecast system in the near field, a total of 11 numerical models with grids telescoped to 2 arcsec (~60 m) were developed to hindcast the propagation and coastal inundation of the 2011 Japanese tsunami along the entire east coastline of Japan. Using the NOAA tsunami source computed in near real-time, the model results of tsunami propagation are validated with tsunami time series measured at different water depths offshore and near shore along Japan’s coastline. The computed tsunami runup height and spatial distribution are highly consistent with post-tsunami survey data collected along the Japanese coastline. The computed inundation penetration also agrees well with survey data, giving a modeling accuracy of 85.5 % for the inundation areas along 800 km of coastline between Ibaraki Prefecture (north of Kashima) and Aomori Prefecture (south of Rokkasho). The inundation model results highlighted the variability of tsunami impact in response to different offshore bathymetry and flooded terrain. Comparison of tsunami sources inferred from different indirect methods shows the crucial importance of deep-ocean tsunami measurements for real-time tsunami forecasts. The agreement between model results and observations along Japan’s coastline demonstrate the ability and potential of NOAA’s methodology for real-time near-field tsunami flooding forecasts. An accurate tsunami flooding forecast within 30 min may now be possible using the NOAA forecast methodology with carefully placed tsunameters and large-scale high-resolution inundation models with powerful computing capabilities.     

The accuracy with which coordinates of radio telescopes can be estimated using VLBI observations

Methods for external estimation of the accuracy of geodetic parameters (the coordinates of radio telescopes) based on VLBI observations are discussed. Time series of the distances between radio telescopes (baselines) provide the observational material for the analysis. It is shown that the generally accepted model for estimating the accuracy of geodetic results is based on unjustified assumptions, and does not adequately describe the results of geodetic observations. A more flexible parametrical model is proposed, which takes into account the non-uniformity in the accuracies with which geodetic parameters for different stations can be estimated, and more adequately describes the observational data. The evolution of the Svetloe-Badary and Zelenchuk-Badary baselines in 2007–2012 is analyzed in detail. The Badary VLBI station located near Irkutsk is moving away from the other two stations, located in the European part of Russia, at a rate of 3–4 mm/year.     

Geologic interpretation of the near-infrared images of the surface taken by the Venus Monitoring Camera,Venus Express

We analyze night-time near-infrared (NIR) thermal emission images of the Venus surface obtained with the 1-μm channel of the Venus Monitoring Camera onboard Venus Express. Comparison with the results of the Magellan radar survey and the model NIR images of the Beta-Phoebe region show that the night-time VMC images provide reliable information on spatial variations of the NIR surface emission. In this paper we consider if tessera terrain has the different NIR emissivity (and thus mineralogic composition) in comparison to the surrounding basaltic plains. This is done through the study of an area SW of Beta Regio where there is a massif of tessera terrain, Chimon-mana Tessera, surrounded by supposedly basaltic plains. Our analysis showed that 1-μm emissivity of tessera surface material is by 15–35% lower than that of relatively fresh supposedly basaltic lavas of plains and volcanic edifices. This is consistent with hypothesis that the tessera material is not basaltic, maybe felsic, that is in agreement with the results of analyses of VEX VIRTIS and Galileo NIMS data. If the felsic nature of venusian tesserae will be confirmed in further studies this may have important implications on geochemical environments in early history of Venus. We have found that the surface materials of plains in the study area are very variegated in their 1-μm emissivity, which probably reflects variability of degree of their chemical weathering. We have also found a possible decrease of the calculated emissivity at the top of Tuulikki Mons volcano which, if real, may be due to different (more felsic?) composition of volcanic products on the volcano summit.     

Morphology of the cloud tops as observed by the Venus Express Monitoring Camera

Since the discovery of ultraviolet markings on Venus, their observations have been a powerful tool to study the morphology, motions and dynamical state at the cloud top level. Here we present the results of investigation of the cloud top morphology performed by the Venus Monitoring Camera (VMC) during more than 3 years of the Venus Express mission. The camera acquires images in four narrow-band filters centered at 365, 513, 965 and 1010 nm with spatial resolution from 50 km at apocentre to a few hundred of meters at pericentre. The VMC experiment provides a significant improvement in the Venus imaging as compared to the capabilities of the earlier missions. The camera discovered new cloud features like bright “lace clouds” and cloud columns at the low latitudes, dark polar oval and narrow circular and spiral “grooves” in the polar regions, different types of waves at the high latitudes. The VMC observations revealed detailed structure of the sub-solar region and the afternoon convective wake, the bow-shape features and convective cells, the mid-latitude transition region and the “polar cap”. The polar orbit of the satellite enables for the first time nadir viewing of the Southern polar regions and an opportunity to zoom in on the planet. The experiment returned numerous images of the Venus limb and documented global and local brightening events. VMC provided almost continuous monitoring of the planet with high temporal resolution that allowed one to follow changes in the cloud morphology at various scales.We present the in-flight performance of the instrument and focus in particular on the data from the ultraviolet channel, centered at the characteristic wavelength of the unknown UV absorber that yields the highest contrasts on the cloud top. Low latitudes are dominated by relatively dark clouds that have mottled and fragmented appearance clearly indicating convective activity in the sub-solar region. At ～50° latitude this pattern gives way to streaky clouds suggesting that horizontal, almost laminar, flow prevails here. Poleward from about 60°S the planet is covered by almost featureless bright polar hood sometimes crossed by dark narrow (～300 km) spiral or circular structures. This global cloud pattern can change on time scales of a few days resulting in global and local “brightening events” when the bright haze can extend far into low latitudes and/or increase its brightness by 30%. Close-up snapshots reveal plenty of morphological details like convective cells, cloud streaks, cumulus-like columns, wave trains. Different kinds of small scale waves are frequently observed at the cloud top. The wave activity is mainly observed in the 65–80° latitude band and is in particular concentrated in the region of Ishtar Terra that suggests their possible orographic origin. The VMC observations have important implications for the problems of the unknown UV absorber, microphysical processes, dynamics and radiative energy balance at the cloud tops. They are only briefly discussed in the paper, but each of them will be the subject of a dedicated study.     

Observations of atmospheric water vapor above the Tharsis volcanoes on Mars with the OMEGA/MEx imaging spectrometer

The OMEGA imaging spectrometer onboard the Mars Express spacecraft is particularly well suited to study in detail specific regions of Mars, thanks to its high spatial resolution and its high signal-to-noise ratio. We investigate the behavior of atmospheric water vapor over the four big volcanoes located on the Tharsis plateau (Olympus, Ascraeus, Pavonis and Arsia Mons) using the 2.6 μm band, which is the strongest and most sensitive H₂O band in the OMEGA spectral range. Our data sample covers the end of MY26 and the whole MY27, with gaps only in the late northern spring and in northern autumn. The most striking result of our retrievals is the increase of water vapor mixing ratio from the valley to the summit of volcanoes. Corresponding column density is often almost constant, despite a factor of ∼5 decrease in air mass from the bottom to the top. This peculiar water enrichment on the volcanoes is present in 75% of the orbits in our sample. The seasonal distribution of such enrichment hints at a seasonal dependence, with a minimum during the northern summer and a maximum around the northern spring equinox. The enrichment possibly also has a diurnal trend, being the orbits with a high degree of enrichment concentrated in the early morning. However, the season and the solar time of the observations, due to the motion of the spacecraft, are correlated, then the two dependences cannot be clearly disentangled. Several orbits exhibit also spatially localized enrichment structures, usually ring- or crescent-shaped. We retrieve also the height of the saturation level over the volcanoes. The results show a strong minimum around the aphelion season, due to the low temperatures, while it raises quickly before and after this period. The enrichment is possibly generated by the local circulation characteristic of the volcano region, which can transport upslope significant quantities of water vapor. The low altitude of the saturation level during the early summer can then hinder the transport of water during this season. The influence of the coupling between atmosphere and surface, due mainly to the action of the regoliths, can also contribute partially to the observed phenomenon.