Determination of the geopotential scale factor from satellite altimetry

Summary The geopotential scale factor R ₀ =GM/W ₀ has been determined on the basis of satellite altimetry as R _{0=(6 363 672·5±0·3) m} and/or the geopotential value on the geoid W ₀ =(62 636 256·5±3) m ² s ^–2 . It has been stated that R ₀ and/or W ₀ is independent of the tidal distortion of surface W=W ₀ due to the zero frequency tide.

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¶rt;a nmu amumuu u ama amnmuaa R ₀ =GM/W ₀ =(6 363 672,5±0,3) m u/uu aunmuaa a nmuu¶rt;a W ₀ =(62 636 256,5±3) m² s^–2. m, m R ₀ u/uu W ₀ auum m nm amu a a nuu ¶rt;au nmu W=W ₀ .

     

On the origin of the fourth zonal geopotential harmonic

Summary It has been proved that the fourth geopotential (Stokes) parameter J₄ of the actual Earth can be explained by its long-term rotational distortions. However, this is not the case of the sixth zonal prameter J₆; its origin should be explained geophysically in another way.Dedicated to the Memory of Professor Karel P     

Gravitational potential energy of terrestrial planets

Summary The gravitational potential energies of Mercury, Venus and Mars have been computed on the basis of density models and compared to that of the Earth. It has been stated that the specific potential energy per unit mass is very close as regards the pair Earth and Venus, as well as the pair Mercury and Mars.Dedicated to the Memory of K. P     

Climate induced changes of Lithuanian rivers runoff in 1960–2009

The primary objective of this study was the evaluation of runoff regime changes over the last 50 years in Lithuanian rivers. These changes were compared with the Neman river runoff regime changes in 1812–2009. On the basis of daily water discharge data, trends in the annual, maximum and minimum runoff characteristics as well as changes in the seasonal pattern of runoff were estimated. Regression analysis and the Mann-Kendall test were used to determine changes in the long-term hydrological regime. The magnitude of changes was estimated using Theil-Sen estimator. 1960–2009 runoff changes in Lithuanian rivers can be related to climatic changes. Sharp increases of January and February runoff during 1960–2009 were the largest changes throughout the observation period 1812–2009. The rate off runoff decrease in April was also among the largest decreases recorded. Spring flood and cold season minimum flow dates have become earlier than used to be.     

Gravitational potential energy of the Sun

Summary The gravitational potential energy of the Sun and its corresponding internal energy have been estimated on the basis of the standard model of the Sun's internal structure. It is demonstrated that the principal moment of inertia of the Sun, computed from the model, does not fit the hydrostatic equilibrium limit.     

Weather categorization — a useful tool for assessing climatic trends

Summary A computer-assisted weather categorization was applied to meteorological time series measured at the Mileovka Observatory (a mountain station) and Prague-Klementinum (an inner city site). Groups of winter days (December, January and February) with extreme mean temperatures were examined with respect to their frequency of occurrence and presence of any trends in the period 1941–1988. In general, frequencies of cold categories exhibited a decreasing trend, and frequencies of warm categories tended to increase. In both series a prominent negative trend in temperature amplitude was detected within warm clusters, related to a statistically insignificant decline in the maximum temperature and an increase in the minimum temperature. Additional analysis indicates that changes in circulation patterns occurred over the region during the period investigated, namely strengthening of zonal circulation in winter.With 6 Figures     

A method of reducing the disturbing effects in gamma — Spectrometric measurements of rock radioactivity

Summary The long-termed stability of the NTA 1024 Gamma spectrometer was investigated. In order to reduce the influence of the instability of the linear amplifier, a method of mathematical transformation of the spectrum was introduced.     

Modelled sulphur depositions over Croatia

Summary A Lagrangian receptor-oriented long-range transport model has been applied in order to estimate the relative contribution of domestic, Austrian, Hungarian, Italian and Slovenian emissions to the long-term deposition of airborne sulphur in Croatia. During the November 1, 1991 to April 30, 1992 period 163.31 thousands of tonnes of sulphur were deposited over Croatia., where 90.9% originated from transboundary emission sources. Relative contribution of domestic sources was the biggest (9.1%), while Austrian contribution was the smallest (0.4%).With 1 Figure     

Climate change scenarios of heat waves in Central Europe and their uncertainties

The study examines climate change scenarios of Central European heat waves with a focus on related uncertainties in a large ensemble of regional climate model (RCM) simulations from the EURO-CORDEX and ENSEMBLES projects. Historical runs (1970–1999) driven by global climate models (GCMs) are evaluated against the E-OBS gridded data set in the first step. Although the RCMs are found to reproduce the frequency of heat waves quite well, those RCMs with the coarser grid (25 and 50 km) considerably overestimate the frequency of severe heat waves. This deficiency is improved in higher-resolution (12.5 km) EURO-CORDEX RCMs. In the near future (2020–2049), heat waves are projected to be nearly twice as frequent in comparison to the modelled historical period, and the increase is even larger for severe heat waves. Uncertainty originates mainly from the selection of RCMs and GCMs because the increase is similar for all concentration scenarios. For the late twenty-first century (2070–2099), a substantial increase in heat wave frequencies is projected, the magnitude of which depends mainly upon concentration scenario. Three to four heat waves per summer are projected in this period (compared to less than one in the recent climate), and severe heat waves are likely to become a regular phenomenon. This increment is primarily driven by a positive shift of temperature distribution, but changes in its scale and enhanced temporal autocorrelation of temperature also contribute to the projected increase in heat wave frequencies.