Singularity free formulations of the geodetic boundary value problem in gravity-space

The idea of transforming the geodetic boundary value problem into a boundary value problem with a fixed boundary dates back to the 1970s of the last century. This transformation was found by F. Sanso and was named as gravity-space transformation. Unfortunately, the advantage of having a fixed boundary for the transformed problem was counterbalanced by the theoretical as well as practical disadvantage of a singularity at the origin. In the present paper two more versions of a gravity-space transformation are investigated, where none of them has a singularity. In both cases the transformed differential equations are nonlinear. Therefore, a special emphasis is laid on the linearized problems and their relationships to the simple Hotine-problem and to the symmetries between both formulations. Finally, in numerical simulation study the accuracy of the solutions of both linearized problems is studied and factors limiting this accuracy are identified.     

Role of land surface parameterizations on modeling cold-pooling events and low-level jets

Land surface parameterization schemes play a significant role in the accuracy of meso-local scale numerical models by accounting for the exchange of energy and water between the soil and the atmosphere. The role of land surface processes during large-scale cold-pooling events was studied with two land surface schemes (LSMs) in the Advanced Research Weather Forecasting model (ARW). Model evaluation was complex due to the surface and boundary layer interactions at different temporal and spatial scales as revealed by a scale dependent variance analysis. Wavelet analysis was used for the first time to analyze the model errors with specific focus on land surface processes. The ARW model was also evaluated for the formation of a low-level jet (LLJ). It is shown that vertical resolution in the model boundary layer played a significant role in determining the characteristics of LLJ, which influenced the lower boundary layer structure and moisture distribution. The results showed that the simulated low-level jet over southern Georgia was sensitive to the land surface parameterization and led to a significant difference in the boundary layer exchange. The jet shear played a crucial role in the maintenance of turbulence and weak shear caused excessive radiative cooling leading to unrealistic cold pools in the model. The results are important for regional downscaling as the excessive cold pools that are simulated in the model can go unnoticed.     

Changing climate states and stability: from Pliocene to present

We present a recently developed method of potential analysis of time series data, which comprises (1) derivation of the number of distinct global states of a system from time series data, and (2) derivation of the potential coefficients describing the location and stability of these states, using the unscented Kalman filter (UKF). We test the method on artificial data and then apply it to climate records spanning progressively shorter time periods from 5.3?Myr ago to the recent observational record. We detect various changes in the number and stability of states in the climate system. The onset of Northern Hemisphere glaciation roughly 3?Myr BP is detected as the appearance of a second climate state. During the last ice age in Greenland, there is a bifurcation representing the loss of stability of the warm interstadial state, followed by the total loss of this state around 25?kyr BP. The Holocene is generally characterized by a single stable climate state, especially at large scales. However, in the historical record, at the regional scale, the European monthly temperature anomaly temporarily exhibits a second, highly degenerate (unstable) state during the latter half of the eighteenth century. At the global scale, temperature is currently undergoing a forced movement of a single stable state rather than a bifurcation. The method can be applied to a wide range of geophysical systems with time series of sufficient length and temporal resolution, to look for bifurcations and their precursors.     

Migration of Injected Wastewater with High Levels of Ammonia in a Saline Aquifer in South Florida

Treated wastewater with high levels of ammonia has been injected, since March 1983 into the deep saline units of the Lower Floridan aquifer (LFA) from a treatment plant near the east coast of Miami-Dade County in southeastern Florida. Monitoring wells in the plant recorded ammonia concentrations above ambient levels at hydrogeologic units located about 1000 ft (304.8 m) above injection depths between 2500 and 2800 ft (762 and 853 m) below sea level. A solute-transport model was developed to assess the horizontal and vertical extent of the injected ammonia, with ammonia moving from the injected zone into the overlying units: the upper semiconfining unit, the uppermost permeable zone of the LFA, and the middle semiconfining units of the Avon Park Formation. Ammonia is assumed to be transported under the effects of local heterogeneity in a porous limestone aquifer with high-salinity ambient groundwater and via upward migration through quasi-vertical pathways. A flow model of the migration of the injected ammonia was calibrated with PEST using head, salinity, and ammonia concentration data measured from 1983 to 2013. Borehole geophysical data support the high permeability of the uppermost permeable zone in the LFA. Average simulated head, normalized salinity, and ammonia concentration residuals over all monitoring wells were −1.37 ft, 0.01, and −0.67 mg/L, respectively. Model results are consistent with undetectable ammonia concentrations in the Upper Floridan aquifer.     

Estimating trends of Atlantic meridional overturning circulation from long-term hydrographic data and model simulations

The ocean meridional overturning circulation (MOC) plays a central role for the climate in the Atlantic realm. Since scenarios for future climate change indicate a significant reduction of the MOC under global warming, an assessment of variations and trends of the real MOC is important. Using observations at ocean weather ship (OWS) stations and along oceanic sections, we examine the hydrographic information that can be used to determine MOC trends via its signature in water mass properties obtained from model simulations with the climate model ECHAM5/MPI-OM. We show that temperature trends at mid-latitudes provide useful indirect measure of large-scale changes of deep circulation: A mid-depth warming is related to MOC weakening and a cooling to MOC strengthening. Based on our model experiments, we argue that a continuation of measurements at key OWS sites may contribute to a timely detection of a possible future MOC slowdown and to separate the signal from interannual-to-multidecadal MOC variability. The simulations suggest that the subsurface hydrographic information related to MOC has a lower variability than the MOC trend measured directly. Based on our model and the available long-term hydrographic data, we estimate non-significant MOC trends for the last 80 years. For the twenty-first century, however, the model simulations predict a significant MOC decline and accompanied mid-depth warming trend.     

Application of calcite Mg partitioning functions to the reconstruction of paleocean Mg/Ca

Calcite Mg/Ca is usually assumed to vary linearly with solution Mg/Ca, that a constant partition coefficient describes the relationship between these two ratios. Numerous published empirical datasets suggests that this relationship is better described by a power function. We provide a compilation of these literature data for biotic and abiotic calcite in the form of Calcite Mg/Ca = F(Solution Mg/Ca)^H, where F and H are empirically determined fitting parameters describing the slope and deviation from linearity, respectively, of the function. This is equivalent to Freundlich sorption behavior controlling Mg incorporation in calcite. Using a power function, instead of a partition coefficient, lowers Phanerozoic seawater Mg/Ca estimates based on echinoderm skeletal material by, on average, 0.5 mol/mol from previous estimates.These functions can also be used to model the primary skeletal calcite Mg/Ca of numerous calcite phases through geologic time. Such modeling suggests that the Mg/Ca of all calcite precipitated from seawater has varied through the Phanerozoic in response to changing seawater Mg/Ca and that the overall range in Mg/Ca measured among various calcite phases would be greatest when seawater Mg/Ca was also high (e.g., “aragonite seas”) and lowest when seawater Mg/Ca was low (e.g., “calcite seas”). It follows that, during times of “calcite seas” when the seawater Mg/Ca is presumed to have been lower, deposition of calcite with low Mg contents would have resulted in a depressed drive for diagenetic stabilization of shelfal carbonate and, in turn, lead to greater preservation of crystal and skeletal microfabrics and primary chemistries in biotic and abiotic calcites.     

Manganiferous smectite from tirebolu (NE-Turkey)

A pink-colored (HUE 5R-7/4), predominantly calcium saturated, clay mineral from Tirebolu, NE-Turkey, is shown to be a dioctahedral, high-charge manganiferous smectite. It is probably an alteration product of volcanic tuffs of rhyodactitic composition. Ionic formula: (Si_7.71Al_0.29)^IV(Al_3.04Fe _0.12 ³⁺ Fe _0.02 ²⁺ Mg_0.92Mn _0.07 ²⁺ )^VI O₂₀ (OH)₄ 0.79 M⁺ Cation exchange capacity: 92 me/100 g (air dry sample). Unit cell parameters (ca. 20 ° C; ca. 40% RH): a₀9.02 Å b₀5.21 Å Mg⁺⁺... Mn-smectite: c₀14.65 Å Ca⁺⁺... Mn-smectite: c₀14.83 Å K⁺... Mn-smectite: c₀12.10 Å

---

Zusammenfassung Ein rosa (HUE 5R-7/4), weitgehend Calcium-gesättigtes Tonmineral von Tirebolu (NO-Türkei) wurde als ein dioktaedrischer, hochgeladener manganhaltiger Smektit identifiziert. Er ist wahrscheinlich ein Umwandlungsprodukt eines rhyodazitischen Tuffs. Strukturformel: (Si_7.71Al_0.29)^IV(Al_3.04Fe _0.12 ³⁺ Fe _0.02 ²⁺ Mg_0.92Mn _0.07 ²⁺ )^VI O₂₀ (OH)₄ 0.79 M⁺ Kationaustauschkapazität: 92 me/100 g (luftgetrocknet). Gitterkonstanten (ca. 20° C; ca. 40% RF): a₀9.02 Å b₀5.21 Å Mg⁺⁺... Mn-Smektit: c₀14.65 Å Ca⁺⁺... Mn-Smektit: c₀14.83 Å K⁺... Mn-Smektit: c₀12.10 Å

     

Die Mittleren Geschwindigkeiten Der Sterne In 58 Kugelförmigen Sternhaufen

The mean velocities of the stars in 58 globular clusters are derived from the photometric measurements of Kron and Mayall (1960). The mass-visual brightness ratio is used. The velocities are falling in the interval 2.9v11.6 km s^–1, their mean value is 6.75 km s^–1.

---

---

Mitteilungen Serie A.     

The Project for Intercomparison of Land-surface Parameterization Schemes (PILPS) phase 2(c) Red-Arkansas River basin experiment:: 2. Spatial and temporal analysis of energy fluxes

The energy components of sixteen Soil-Vegetation Atmospheric Transfer (SVAT) schemes were analyzed and intercompared using 10 years of surface meteorological and radiative forcing data from the Red-Arkansas River basin in the Southern Great Plains of the United States. Comparisons of simulated surface energy fluxes among models showed that the net radiation and surface temperature generally had the best agreement among the schemes. On an average (annual and monthly) basis, the estimated latent heat fluxes agreed (to within approximate estimation errors) with the latent heat fluxes derived from a radiosonde-based atmospheric budget method for slightly more than half of the schemes. The sensible heat fluxes had larger differences among the schemes than did the latent heat fluxes, and the model-simulated ground heat fluxes had large variations among the schemes. The spatial patterns of the model-computed net radiation and surface temperature were generally similar among the schemes, and appear reasonable and consistent with observations of related variables, such as surface air temperature. The spatial mean patterns of latent and sensible heat fluxes were less similar than for net radiation, and the spatial patterns of the ground heat flux vary greatly among the 16 schemes. Generally, there is less similarity among the models in the temporal (interannual) variability of surface fluxes and temperature than there is in the mean fields, even for schemes with similar mean fields.     

Der offene Sternhaufen NGC 5617

Zusammenfassung Der offene Sternhaufen NGC 5617 wurde nach dem Streifenverfahren auf Karten von photographischen Aufnahmen verschiedener Belichtungszeiten mit dem 1m-Schmidt-Teleskop des European Southern Observatory in Chile untersucht. Der Haufen enthält etwa 460 Sterne mit einer Gesamtmasse von 700 . Der Radius beträgt 3.7 pc, die Sterndichte im Zentrum 50 Sterne pc^–3, und die mittlere Sterngeschwindigkeit 0.89 km s^–1. Auf den länger belichteten Aufnahmen taucht im Abstand von 12.3 in Richtung SSE ein unbekannter offener Sternhaufen auf, der einen Radius von etwa 4.3 hat und etwa 150 Sterne bis zur GrenzgrößeV19^m enthält.

---

The open cluster NGC 5617 was investigated by the strip method on charts of photographs with different exposure times taken with the 1-m Schmidt telescope of the European Southern Observatory. The cluster contains about 460 stars with a total mass of 700 . Its radius amounts to 3.7 pc; the star density in the center is 50 stars pc^–3; and the mean stellar velocity, 0.89 km s^–1. On longerexposed photographs at a distance of 12.3 in direction to SSE an unknown open star cluster becomes visible with a radius of 4.3, containing about 150 stars to the limiting magnitudeV19^m.

---

---

Mitteilungen Serie A.