1.
Peters, H. and M. Orlić (2005):
Turbulent mixing in the
springtime central Adriatic Sea. Geofizika, 22,
1-19.
ABSTRACT:
A
small set of observations of upper ocean turbulent mixing, stratification and
currents was obtained in the central Adriatic Sea in May 2003. Owing to light
winds, the surface mixed layer was at most 10 m thick and usually much thinner.
The water column below was mostly strongly stratified with partially restratified remnant of previous mixed layers. Mesoscale currents were weak with a significant barotropic component. Weak shear and strong stratification
tended to combine to large Richardson numbers. Below a layer of enhanced mixing
in the upper 10–20 m, eddy diffusivities were mostly small, ranging from
10–6 m2 s–1 to about 5 x 10–5
m2 s–1. Much larger values occurred in a few
events, however.
Keywords: microstructure,
turbulence, Adriatic
[PDF]
2.
Koračin, D., D. F. Leipper and J.M. Lewis
(2005): Modeling sea fog on the
U.S. California coastduring a hot spell event. Geofizika, 22, 59-82.
ABSTRACT:
The
occurrence of sea fog along the U.S. Pacific Coast in summer is frequently
associated with the movement of a high pressure system from the eastern Pacific
to the land. Subsequently there is strong heating of the land over several days
or more and development of »hot spells« and offshore flows in the
coastal region preceding sea fog formation. This study focuses on modeling the
formation and evolution of sea fog in response to interaction between the warm
and dry offshore flows and the cool and moist marine atmospheric boundary
layer. Simulation results support a conceptual model of fog formation and
evolution based on physical processes initiated by offshore flows that
efficiently lower the marine inversion near the sea surface. In spite of the
warm and dry advection, fog formed in the shallow, near-surface marine layer
capped by a strong temperature inversion of 10 °C or
more and a hot-air layer above the inversion. Prior to sea fog formation,
negative surface heat flux initiates cooling and condensation, while the
surface moisture flux contributes to increased humidity and turbulence within
the surface layer. The dryness of the hot-air layer overlying the shallow and
moist marine layer triggers enhanced radiative
cooling at the marine layer top and facilitates the marine layer’s
saturation. The thin cloud forms, rapidly propagates downward, and transforms
into fog. As soon as the fog is formed, longwave radiative cooling at its top generates turbulent mixing and
the growth of the fog as a mixed layer. Due to the fog-top radiative
cooling, the fog layer is initially colder than the underlying surface. In the
later stage of the fog evolution, continuous mixing of the cool and moist
near-surface air with the dry and warm layer above the inversion during the fog
growth generally curtails turbulence. This process elevates the lifting
condensation level and can lead to sea fog dissipation or generation of
stratus.
Keywords: Air-sea interaction, longwave
radiation cooling, marine atmospheric boundary layer, numerical simulations,
offshore flows, offshore fog, U.S. West Coast
[PDF]
3.
Stiperski,
I.
(2005):
The causes of supercell development with tornadogenesis
on 30th August 2003 – A case study. Geofizika, 22, 83-105.
ABSTRACT:
A supercell
storm with tornadogenesis in the afternoon hours of
the 30th August 2003 in NW Croatia is studied. As was seen from radar and
satellite material the cell developed in Slovenia and crossed into Croatia,
where interacting with favorable wind patterns (indicated by high SREH and vertical wind shear) it evolved into a supercell. Macroscale forcing was
found to be lacking. On the other hand, the pattern, characterized by a
pronounced thermal ridge and a baroclinic boundary
associated with it, was favorable for supercell
generation as has been seen in several studies in the USA. Mesoscale
forcing was also enhanced by the existence of the jet stream and outflow
boundaries from previous convection associated with a night-time cold front
passage. Several severe storm and stability indices were tested for this case
and it has been found that they generally did not correspond to the severity of
the convection that took place.
Keywords: Supercell, baroclinic
boundary
[PDF]
4.
Roy, S. S., R. K. Datta,
R. C. Bhatia and A. K. Sharma (2005): Drop size distributions of tropical rainover south India. Geofizika, 22, 105-130.
ABSTRACT:
Drop
size distributions (DSD) associated with tropical
rainfall at Cuddalore in the south-eastern part of
India have been measured by a Joss-Waldvogel
disdrometer (RD–80 model) during September to
November 2002. The rainfall data corrected for instrumental error, matches very
well with rainfall rates measured by a self recording raingauge,
at the same site. For further analysis of the DSD, the
rainfall events were separated into convective and stratiform
rainfall by an algorithm based on variation of DSD
parameters. One rain event in the form of a squall line of 15 September 2002, was analysed in greater
detail to investigate the validity of the classification scheme as well as to
study the variation of the DSD parameters during the
course of a rain event. It was observed that, the algorithm was robust and had
quite good correspondence with other independent rainfall separation
algorithms. During the rain event, at low rainrates,
the convective phase of the rainfall event was marked by DSD
spectra that have greater population of small droplets as compared to stratiform DSDs at the same rainrates. At higher rainrates,
the convective regime is characterised by narrow
spectra centred at higher diameters. At the
transition region between convective and stratiform
spectra, mixed large and small drop spectra are observed. Similar variation was
also observed in the averaged drop spectra. In addition, the averaged spectra
also reveal an equilibrium distribution of the drop population in DSDs at higher rainrates (>39
/hr) for diameter range (>1.91 mm) corresponding to nearly constant values
of the slope of the distribution, the intercept and the mean mass diameter. The
value of the shape parameter, which for small rainrates
varies the same as the slope parameter, starts to increase with increasing rainrate as the other two parameters of the gamma
distribution approach a constant value corresponding to equilibrium shape. The
value of the intercept parameter is highest for low to moderate convective
rainfall and decreases as the rainrate increases.
Keywords: Convective, stratiform
rainfall, disdrometer, deadtime
correction, squall line, gamma distribution, drop coalescence, aggregation,
riming
[PDF]
5.
Vilibić, I., M. Orlić, S. Čupić, N. Domijan, N. Leder, H. Mihanović, M. Pasarić, Z. Pasarić, M. Srdelić and G. Strinić (2005): A new approach to sea level observations
in Croatia. Geofizika, 21,
21-57.
ABSTRACT:
The
paper comprises an overview of recent international and national efforts and
activities directed towards the improvement of tide gauge network on the
eastern coast of the Adriatic Sea. A brief overview of the available measuring
techniques is given first. Then the characteristics of Adriatic sea level are outlined, followed by a note on the history of
sea level measurements and research in the Adriatic. The present sea level
related activities are introduced by the institutional structure in Croatia,
followed by a summary of recent projects and programmes
(European Sea Level Service – Research Infrastructure (ESEAS-RI), Mediterranean Global Observing Sea Level System
(MedGLOSS), Project Adriatic and Adriatic Tides and
Sea Level On-line). Concrete activities on the upgrade of Croatian tide gauges,
data acquisition and maintenance, and on-line data presentation are presented
in detail. In addition, the initiation of measurements of vertical land movements
is documented, as a Continuous GPS antenna and receiver (CGPS)
has been installed in 2004 at the roof of the Split Harbour
tide gauge. A lot of effort has been put into the rescue of historical sea
level records, both by digitising and scanning of the
charts, which will prevent data loss in case of their ruination or
disappearance. Finally, the impact of the recent activities on the scientific
exploration of high-frequency resonant coupling of air pressure disturbances
with the eastern Adriatic waters is highlighted in the paper,
as such research is not possible to carry out properly with the measuring
systems based on the analog records.
Keywords: Adriatic Sea, tide gauge, sea level,
projects, upgrade, data maintenance and archaeology, scientific outcome
[PDF]
6.
Roy Bhowmik, S.
K., D. Joardar and A. K. Das
(2005):
Radius of rainfall influence over Indianmonsoon
region. Geofizika, 22,
131-141.
ABSTRACT:
The
paper describes an analysis of rain gauge data to determine an appropriate
radius of influence to use for the objective analysis of rainfall over Indian
monsoon region. The correlation co-efficient (CC) of rainfall between rain
gauges in discrete distance intervals is computed, and the distance at which CC
falls to 0.3 is chosen as the radius of rainfall influence. The method is
applied for the monthly mean rainfall observations for June, July and August of
Indian summer monsoon 2001. The method is also tested for a few case studies in
relation to varying geographical and synoptic situations. The study shows that
the radius of influence of rainfall over Indian region, in general, is around
200 km, but it has certain day to day variations depending on the prevailing
synoptic conditions. The finding of the study is expected to be very useful for
the objective analysis of rainfall over Indian region.
Keywords: objective analysis of rainfall,
radius of rainfall influence, monsoon
[PDF]