1.
Vujnović, V., G. Verbanac, J.
Orešković, A. Marki, K. Marić, I. Lisac and M. Ivandić (2004): Results of the preliminary
geomagnetic field strength measurements in the northern part of middle Croatia. Geofizika,
21, 1-14.
ABSTRACT:
In autumn 2003 we made a survey of
total magnetic field strength in a part of Croatia from river Drava north to
river Sava and Pokuplje, between the lines Zagreb – Koprivnica on west,
and Hrvatska Kostajnica – Virovitica on east. Thirty positions were surveyed
in the net with spacing of 15 –20 km. For data reduction, the field
variations were recorded at the base station in Pokupsko, acting as provisional
geomagnetic observatory. A geomagnetic map was constructed and discussed. The
gradient of the field generally points to the north-east, having at minimum 18
nT/10 km, and at maximum 38 nT/10 km. Accounting for the all inaccuracies, we
find the positional error of the isodynames to be 1.3 to 3.0 km, depending on
the field gradient found in the area.
Using scarce data published for the
epoch 1927.5, we found an average change of 2900 nT and obtained an estimate of
the secular variation equal to +40 nT/year. By exploiting the data of
geomagnetic survey in Hungary for the epoch 1995.0, we have improved a part of
the geomagnetic map close to the Hungarian border. Further, we have compared
hourly means for the observational periods September 22–29, 2003 and
October 14–20, 2003 with the data obtained at the Niemegk Observatory
(Germany). As a numerical parameter describing the differences we introduced
the average standard deviation of differences between signals Niemegk-Pokupsko;
this changed from the first to the second observational period from 5.2 nT to
8.7 nT. We also compared our 1-minute means with the similar recordings of
observatories in Tihany and l’Aquila for the most disturbed day.
Keywords: Geomagnetic
field, total field strength, secular variation, northern middle Croatia
[PDF]
2.
Radić,
V., Z. Pasarić and N. Šinik
(2004): Analysis of Zagreb climatological data
series using empirically decomposed intrinsic mode functions. Geofizika,
21, 15-36.
ABSTRACT:
The empirical mode decomposition method
(EMD) (Huang, 1998) is applied to the series of annual and seasonal averages of
temperature, cloudiness, air pressure and annual and seasonal sums of global
radiation and precipitation, all observed in Zagreb-Grič in the period
1862–2002. The method itself decomposes the original series into so
called intrinsic mode functions (IMF), each being characterized by its own,
intrinsic time scale.
Sums of the low-frequency IMFs for the
single element revealed present climatic fluctuations on the decade-to-century scale.
It is confirmed that climatic fluctuations of every single element,
particularly temperature and cloudiness, are the results of variations in the
global atmospheric circulation above the whole Europe. Trend and long-term
variations of Zagreb temperature fits to globally observed increase of
temperature but also to variations of zonal circulation index. Exchange of
Hadley’s zonal and Rossby’s wave regime of the general atmospheric
circulation at the beginning of the 20th century is observed in the long-term
variations of almost every element. Linear correlation coefficients between
annual and seasonal long-term variations are calculated. It is shown that
spring and winter variations mostly influenced annual fluctuations that are due
to internal feed-back processes. Also, correlation coefficients for every pair
of climatic element are calculated, enabling conclusions about interaction
between elements on long-term scales.
Keywords: Empirical mode decomposition, intrinsic mode functions,
climatological series, climatic fluctuations, Zagreb
[PDF]
3.
Ferreira
de Pinho, U., P. C. Liu and C. E. Parente Ribeiro (2004): Freak Waves at Campos
Basin, Brazil.
Geofizika, 21, 53-67.
ABSTRACT:
Freak waves occur abundantly in Campos
Basin, located on the northeast coast of Rio de Janeiro, Brazil in the South
Atlantic Ocean. This surprising and unexpected discovery was made from a search
of the time-series data of wave measurements recorded in the Campos Basin from
1991 to 1995. In a study on the occurrence of freak waves and their relevant
properties, we have also found that freak waves are not of rare occurrence as
conventionally presumed, and they occur not only during storm conditions but
also during fair weather states as well. While the conventional approach of
spectrum analysis provides some weak inference of freak wave effects, the
basically stationary random process approach is clearly incapable of contending
with the localized non-stationary process of freak wave occurrences.
Keywords: Freak waves, ocean waves, wave data analysis
[PDF]
4.
Pasarić,
M. and M. Orlić (2004): Meteorological forcing of the Adriatic:
present vs. projected climate conditions. Geofizika,
21, 69-87.
ABSTRACT:
Meteorological forcing of the Adriatic
is examined under the present and predicted climate conditions. Fields from the
time slice-experiment performed with ECHAM4 model (W. May and E. Roeckner: A
time-slice experiment with the ECHAM4 AGCM at high resolution – the
impact of horizontal resolution on annual mean climate change, Climate
Dynamics, 17, 2001, 407–420) are closely analysed for the Adriatic
region. Results obtained for the control period, when compared to a number of
data, are found to reproduce the main features of the present-day surface heat
flux, water flux and wind field above the Adriatic. In the future, the Adriatic
should experience a reduction of heat loss to the atmosphere as well as an
enhanced evaporation accompanied with a reduced precipitation leading to an
overall increase of fresh-water loss to the atmosphere. The changes in synoptic
activity should lead to an abatement of bora winds and to a reduced frequency
of sirocco events which, however, are expected to be much more persistent.
Finally, changes in the dynamics of the Adriatic, induced by altered
meteorological forcing, are briefly discussed.
Keywords: Climate change, meteorological
forcing, Adriatic
[PDF]
5.
Kos,
I., D. Belušić, A. Jeričević, K.Horvath, D. Koračin and M. Telišman Prtenjak
(2004): Education and research:
Initial development of the Atmospheric Lagrangian Particle Stochastic (ALPS)
Dispersion Model. Geofizika, 21, 37-52.
ABSTRACT:
The Atmospheric Lagrangian Particle
Stochastic (ALPS) dispersion model was created as an experimental student
project and tested under idealized and complex atmospheric and topographic
conditions. The challenge of the project was to bring current scientific
technology to the direct involvement of students in the framework of problem
based learning educational theory. The model simulates dispersion of a passive
scalar in the atmosphere by calculating a large number of Lagrangian particle
trajectories. It uses meteorological model output to obtain mean meteorological
fields. The predicted turbulence kinetic energy (TKE) from a higher order turbulence
closure nonhydrostatic meteorological model is used for the simulations.
Idealized tests showed that ALPS is correctly responding to different static
stability conditions and associating dispersion of particles according to the
magnitude of turbulence, satisfying the well-mixed criterion.
Keywords: Student project, air quality
modelling, idealized simulations
[PDF]