Antun Marki - Academia.edu (original) (raw)

Papers by Antun Marki

Meteorologische Zeitschrift, Oct 29, 1993

In memoriam - Dr. sc. Josip Juras (Split, 22. lipnja 1936. – Zagreb, 7. listopada 2019.

System for Radiowave Refraction Modelling in Real Conditions - Feasibility Study, 2004

Hrvatski meteorološki časopis, Dec 16, 1999

The strong wind blowing from the southeastern quadrant over the Adriatic Sea region is known as j... more The strong wind blowing from the southeastern quadrant over the Adriatic Sea region is known as jugo, in the eastern coastal area customarily also called scirocco. The Tugo wind type has been separated from the five-year hourly wind data (197G-1980) for three stations (Pula, Split and Dubrorrrik), by introducing a criterion with conditions a wind vector should satisfu during a jugo event. The stations are situated on the northern, middle and southern part of the eastern (Croatian) Adriatic coast. All jugo events consisting of hourly mean wind velocities > 0.3 ms-', and subsets of jugo events, referred to as stronger jugo, consisting of hourly mean wind velocities. B ms-', were analysed. The results show that wind frorn the SE quadrant (6 wind directions), independent of any wind type criterion, accounts for 33Vo to 40Vo of all the five-year wind data (16 wind directions) with percentages growing from the north toward the south, along the Croatian part of the Adriatic coast. Alljago events contribute from LgVo to 27Vo, going from the north toward the south. Strongerjzgo contributes oriy 6Vo to 20Vo going in the same direction along the coast. Increased seasonal frequencies of jugo events were obtained in spring for Pula, and in both winter and spring for Split and Dubrovnik. The mathematical approximation of the Tugo wind roses by means of mixlure distribution resulted in two components in each of the seasonal wind roses. The shape and contribution ofthese components change from season to season and from station to station. Two components for thejugo wind roses approximation calls to mind the known, but yet unproved empirical statement about the existence of a cyclonic and an anticyclonic Tugo wind type.

One way of modeling the convectively coupled Kelvin waves in an equatorial non-rotating atmospher... more One way of modeling the convectively coupled Kelvin waves in an equatorial non-rotating atmosphere is presented. It implements a simple linear, analytical model using the boundary-layer quasiequilibrium approximation and wind-induced surface heat exchange. The dynamics of the model are based on the assumption that the vertical heating profile has the shape of the first baroclinic mode. The vertical velocity has two sinusoidal components of different vertical wavelengths. One component corresponds to deep convection and the imposed heating profile while the other component, with shallower vertical wavelength, defines the phase speed of the convectively coupled Kelvin wave. The results of the model show fast Kelvin waves that resemble adiabatic modes with the vertical wavelength being twice the depth of the troposphere and convectively coupled Kelvin waves that are damped and propagate with phase speed of 18 m/s. Wind-induced surface heat exchange causes the instability of the convect...

Ecological Modelling, 2001

Empirical models for seven climatic variables (monthly mean air temperature, monthly mean daily m... more Empirical models for seven climatic variables (monthly mean air temperature, monthly mean daily minimum and maximum air temperature, monthly mean relative humidity, monthly precipitation, monthly mean global solar irradiation and monthly potential evapotranspiration) were built using neural networks. Climatic data from 127 weather stations were used, comprising more than 30 000 cases for each variable. Independent estimators were elevation, latitude, longitude,

Meteorologische Zeitschrift, 1999

A method is proposed for estimating monthly mean hourly direct, diffuse, and global solar radiati... more A method is proposed for estimating monthly mean hourly direct, diffuse, and global solar radiation from annual stochastical models (correlation coefficients are higher than 0.99), using only actual and daily maximum solar elevation and respective daily radiation as input data. The annual model (based on data collected on 45.8° northern latitude) of monthly mean hourly global solar radiation relative to the monthly mean daily radiation is found to be acceptable for latitudes between 40 and 50°N, if compared to other models. The same latitudinal validity is assumed for the annual models of diffuse and direct solar radiation. Similar models for other latitudes could be derived if representative pyrranometer data are available.

Geofizika, 1998

In atmospheric numerical weather prediction (NWP) models, the use of long time-steps as allowed b... more In atmospheric numerical weather prediction (NWP) models, the use of long time-steps as allowed by efficient numerical/dynamical schemes can lead to spurious oscillations due to the parameterized physical part. Typical examples of this are the oscillations associated with simplified parameterization schemes for vertical diffusion or shallow-convection, such as usually used for NWP. The oscillations generated by K-type vertical-diffusion schemes are well documented, and being called fibrillations; they are characterized by high temporal and vertical frequencies. Since they are linked to high vertical resolution, these spurious oscillations are generally found in the low-levels of model’s domain. In ARPEGE, the METEO-FRANCE NWP global model, and in ALADIN, its limited-area model (LAM) version developed in cooperation with Eastern European countries, and also used for operational NWP purpose, some oscillations still remained in the evolution of the forecast fields, despite the fact tha...

Geofizika, 2006

In Croatia is observed the increasing trend in mean annual air temperature and the large variabil... more In Croatia is observed the increasing trend in mean annual air temperature and the large variability in the measured extreme precipitation from prominent drought to severe flooding. Climatological studies based on regional climate models show the intensification of the extreme values of temperature and precipitation over Europe in the future climate. These changes in temperature and precipitation have a great impact on viticulture, considering that of all living organisms, plants react first to the change of surface temperature. Due to climate change, changes in temperature will affect: (i) differently all developmental stages of vines in certain wine-growing areas in Croatia (i.e. their phenological characteristics) and (ii) differently on different varieties. At the same time, the temperature increase changes convective activity (storms) and thus the occurrence of hail that are estimated as the second biggest cause of material damage in Croatia. The trend of increasing average dur...

Singular spectrum analysis (SSA) has been applied to the series of mean annual temperature for th... more Singular spectrum analysis (SSA) has been applied to the series of mean annual temperature for the period 1862-1999 at Zagreb, Croatia. It has been proven to be very efficient in extracting from the series those parts which can be treated as deterministic ones and which display at Zagreb about 27% of total variance. Series reconstruction by means of the first principal component indicates an increasing trend during the first half of 20th century which stops around 1940ies and which is here assumed to belong to long term natural climatic fluctuation. During the last decade of the 20th century a new increase of the tempretaure might be connected with anthropogenic influences. The second principal component might illustrate a negative feed-back mechanism which caused the abeyance of the temperature increase fifty years ago. The third and fourth principal components complete the deterministic group. Their oscilatory behaviour during second half of the last century indicates an influence...

U ovom radu analizirana je vremenska situacija za vrijeme dva sumska požara na poluotoku Peljescu... more U ovom radu analizirana je vremenska situacija za vrijeme dva sumska požara na poluotoku Peljescu. Požari su podmetnuti u noci s 20. na 21. srpanj 2015. Cilj je rada prouciti situaciju koja je uz ljudski cimbenik dovela do pocetka požara, te provjeriti kakvu su prognozu davali modeli WRF i ALADIN/HR u dane požara i koliko se ta prognoza dobro slagala s izmjerenim podacima. Analiziran je mjesec srpanj u klimatskom smislu za Ploce u razdoblju 1981.-2014. Analizirani podaci pokazali su da je srpanj 2015. bio topliji od visegodisnjeg prosjeka, a oborina je izostala. U srpnju je bilo 30 vrucih dana sto je dvostruko vise od prosjeka. Izostanak oborine i ekstremno topao srpanj pridonjeli su tome da dođe do najgoreg moguceg požara, požara krosnji. Vrijeme je bilo pretežno vedro, na sam dan izbijanja požara temperatura je dostizala vrijednosti 39 °C, a i iducih se dana maksimalna temperatura nije spustala ispod 30 °C na Peljescu. Relativna vlažnost zraka tijekom dana najcesce je iznosila oko...