ULOGA TURBULENTNIH TOKOVA TOPLINE U PROCESIRANJU VERTIKALNE PROMJENE TEMPERATURE PRIZEMNOG SLOJA ZRAKA

U ovom radu razmatra se mogućnost procjene temperature zraka na visini hrapavosti, z0, pomoću mjerenih vrijednosti temperature zraka na 2 m visine, tijekom dana, uz pretpostavku da je osnovni mehanizam prijenosa topline od tla prema gore turbulentni tok osjetne topline. Teorijska simulacija vrjedi danju u neporemećenim uvjetima (anticiklonalna situacija). Zanemaren je utjecaj latentne topline isparavanja, advekcije i divergencije toka dugovalnog zračenja tla. Osnovna veličina u ovom modelu jest turbulentni tok osjetne topline, H = ρcp w\u27Θ\u27 koji je određen indirektno kao funkcija primljene solarne radijacije

ULOGA TURBULENTNIH TOKOVA TOPLINE U PROCESIRANJU VERTIKALNE PROMJENE TEMPERATURE PRIZEMNOG SLOJA ZRAKA

U ovom radu razmatra se mogućnost procjene temperature zraka na visini hrapavosti, z0, pomoću mjerenih vrijednosti temperature zraka na 2 m visine, tijekom dana, uz pretpostavku da je osnovni mehanizam prijenosa topline od tla prema gore turbulentni tok osjetne topline. Teorijska simulacija vrjedi danju u neporemećenim uvjetima (anticiklonalna situacija). Zanemaren je utjecaj latentne topline isparavanja, advekcije i divergencije toka dugovalnog zračenja tla. Osnovna veličina u ovom modelu jest turbulentni tok osjetne topline, H = ρcp w\u27Θ\u27 koji je određen indirektno kao funkcija primljene solarne radijacije

WIND ROSES FOR SEVERAL ONSHORE-OFFSHORE PROFILES AT THE EASTERN ADRIATIC COAST

Wind roses for three onshore-offshore profiles at the Eastern Adriatic coast (Croatia) are considered. The profiles are following: 1) the Northeast Senj – Rab – Mali Lošinj, 2) middle Adriatic profile Split Marjan – Hvar – Komiža and 3) the Southern Adriatic profile Dubrovnik – Lastovo – Palagruža. Time series of instantaneous (at 07 h, 14 h and 21 h of local time) wind data for period 1981– 1998 have been used. Wind roses strongly depends on spatial wind pattern i.e. wind type. Thus for the sea breeze conditions the winds form SW quadrant prevails for most considered weather stations, while Ethesians (from NW quadrant) wind prevails at Palagruža and Lastovo islands. During jugo (or sirocco), wind directions are concentrated on SE quadrant. An exception is Senj station where canalising jugo wind is not stressed. During bura (or bora) conditions, concentration of the wind directions is located into NE quadrant. Only one direction is very dominant at coastal locations

WIND ROSES FOR SEVERAL ONSHORE-OFFSHORE PROFILES AT THE EASTERN ADRIATIC COAST

Wind roses for three onshore-offshore profiles at the Eastern Adriatic coast (Croatia) are considered. The profiles are following: 1) the Northeast Senj – Rab – Mali Lošinj, 2) middle Adriatic profile Split Marjan – Hvar – Komiža and 3) the Southern Adriatic profile Dubrovnik – Lastovo – Palagruža. Time series of instantaneous (at 07 h, 14 h and 21 h of local time) wind data for period 1981– 1998 have been used. Wind roses strongly depends on spatial wind pattern i.e. wind type. Thus for the sea breeze conditions the winds form SW quadrant prevails for most considered weather stations, while Ethesians (from NW quadrant) wind prevails at Palagruža and Lastovo islands. During jugo (or sirocco), wind directions are concentrated on SE quadrant. An exception is Senj station where canalising jugo wind is not stressed. During bura (or bora) conditions, concentration of the wind directions is located into NE quadrant. Only one direction is very dominant at coastal locations

Diurnal Variation of Air Temperature in the Atmospheric Surface Layer

In order to illustrate the nature of the diurnal temperature variations in the atmospheric surface layer in all seasons a set of hourly observations at the Zagreb-Maksimir Observatory (Croatia), measured at three different levels (5 cm, 50 cm and 2 m above ground) during the year 2005, was used. An approximate method for calculating air temperature at 5 cm, using the air temperature at 2 m, is presented. For this purpose, hourly data (screen height temperature, cloudiness, air pressure at barometer level and wind speed at 2 m) collected at the Zagreb-Maksimir Observatory during the summer season of 2005 have been used. Th is method is based on the Monin-Obukhov similarity theory. Estimated values have been compared with observations. The results obtained are the most accurate for cloudy weather, and the least accurate in the case of clear sky. A systematic error of this approach was discovered using a clustering procedure and is briefly discussed

Analysis of Climate Elements in Central and Western Istria for the Purpose of Determining Irrigation Requirements of Agricultural Crops

A consequence of climate changes is an increasing frequency of drought, which on average occurs in Croatia every third to fifth year and during the vegetation period it can reduce crop yield significantly. The aim of the research is both to determine crop water requirements in an average and in a dry year and to determine the decline in crop yields in an average and in a dry year. The multi-annual climate data series for a 30-year period, 1981-2010 from station Pazin in central Istria and 1981-2010 from Poreč in western Istria was used. Based on these data, a reference evapotranspiration was calculated for an average and a dry year using the Penman-Monteith method through "Cropwat" software. The crop water requirement for five different crops is determined by soil water balance using the Palmer method (Palmer, 1965), corrected according to Širić and Vidaček (1988), using "Hidrokalk" software. Crop response to the lack of soil water and yield decline were determined according to the method published by Doorenbos and Kassam (1979). Correlation test was used to determine correlation between precipitation and crop yields. In central Istria, water shortage in an average year ranged from 3.4 mm (olives) to 110.7 mm (alfalfa) and yield decline ranged from 1.1% (olives) to 18.6% (alfalfa), while in a dry year water shortage ranged from 43.2 mm (olives) to 229.5 mm (alfalfa) and ranged from 10.3% (olives) to 37.7% (alfalfa). In western Istria, in an average year water shortage ranged from 35.5 mm (olives) to 239.7 mm (alfalfa) and yield decline ranged from 7% (olives) to 40.2% (tomatoes), and in a dry year water shortage ranged from 74.4 mm (olives) to 288.9 mm (alfalfa) and yield decline ranged from 14.4% (olives) to 40.7% (alfalfa). The determined water shortage and reduced yields are sufficient indicators of irrigation requirements in Istria

Analysis of Climate Elements in Central and Western Istria for the Purpose of Determining Irrigation Requirements of Agricultural Crops

A consequence of climate changes is an increasing frequency of drought, which on average occurs in Croatia every third to fifth year and during the vegetation period it can reduce crop yield significantly. The aim of the research is both to determine crop water requirements in an average and in a dry year and to determine the decline in crop yields in an average and in a dry year. The multi-annual climate data series for a 30-year period, 1981-2010 from station Pazin in central Istria and 1981-2010 from Poreč in western Istria was used. Based on these data, a reference evapotranspiration was calculated for an average and a dry year using the Penman-Monteith method through "Cropwat" software. The crop water requirement for five different crops is determined by soil water balance using the Palmer method (Palmer, 1965), corrected according to Širić and Vidaček (1988), using "Hidrokalk" software. Crop response to the lack of soil water and yield decline were determined according to the method published by Doorenbos and Kassam (1979). Correlation test was used to determine correlation between precipitation and crop yields. In central Istria, water shortage in an average year ranged from 3.4 mm (olives) to 110.7 mm (alfalfa) and yield decline ranged from 1.1% (olives) to 18.6% (alfalfa), while in a dry year water shortage ranged from 43.2 mm (olives) to 229.5 mm (alfalfa) and ranged from 10.3% (olives) to 37.7% (alfalfa). In western Istria, in an average year water shortage ranged from 35.5 mm (olives) to 239.7 mm (alfalfa) and yield decline ranged from 7% (olives) to 40.2% (tomatoes), and in a dry year water shortage ranged from 74.4 mm (olives) to 288.9 mm (alfalfa) and yield decline ranged from 14.4% (olives) to 40.7% (alfalfa). The determined water shortage and reduced yields are sufficient indicators of irrigation requirements in Istria

Water Quality in Hydroameliorated Agricultural Areas

Three-year investigations (2007-2009) of water quality in hydroameliorated agricultural areas were carried out at the experimental amelioration field “Jelenščak” Kutina, on hydroameliorated Gleyic Podzoluvisol. Soil was drained in four different drainpipe spacing variants (15 m, 20 m, 25 m and 30 m), set up in four replications. The areas of spacing variants were: 1425 m2, 1900 m2, 2375 m2 and 2850 m2. The same crop was grown in each research year in all variants and the same agricultural management practices were applied. Winter wheat was grown in 2007 and in 2009 and soybean in 2008. Samples of drainage water were taken at drainpipe outlets into the canal. The following parameters were determined in the samples: nitrate concentration and concentration of chlortoluron. Based on the drainage water analysis, it was established that nitrate concentration as well as chlortoluron concentration exceeded the prescribed MAC values (10 mg.dm-3 NO3-N) in each year and in all variants. Nitrogen concentration in drainage water exceeded the MAC in five months (2006/07), in two months (2008) and in seven months (2008/09). Concentration of chlortoluron in drainage water exceeded the MAC (100 ŋg.dm-3) in five months (2006/07) and in seven months (2008/09). Maximum nitrate concentration was up to 28.42 mg.dm-3, and that of chlortoluron up to 365 ŋg.dm-3

Water Quality in Hydroameliorated Agricultural Areas

Three-year investigations (2007-2009) of water quality in hydroameliorated agricultural areas were carried out at the experimental amelioration field “Jelenščak” Kutina, on hydroameliorated Gleyic Podzoluvisol. Soil was drained in four different drainpipe spacing variants (15 m, 20 m, 25 m and 30 m), set up in four replications. The areas of spacing variants were: 1425 m2, 1900 m2, 2375 m2 and 2850 m2. The same crop was grown in each research year in all variants and the same agricultural management practices were applied. Winter wheat was grown in 2007 and in 2009 and soybean in 2008. Samples of drainage water were taken at drainpipe outlets into the canal. The following parameters were determined in the samples: nitrate concentration and concentration of chlortoluron. Based on the drainage water analysis, it was established that nitrate concentration as well as chlortoluron concentration exceeded the prescribed MAC values (10 mg.dm-3 NO3-N) in each year and in all variants. Nitrogen concentration in drainage water exceeded the MAC in five months (2006/07), in two months (2008) and in seven months (2008/09). Concentration of chlortoluron in drainage water exceeded the MAC (100 ŋg.dm-3) in five months (2006/07) and in seven months (2008/09). Maximum nitrate concentration was up to 28.42 mg.dm-3, and that of chlortoluron up to 365 ŋg.dm-3

INHOMOGENEITIES IN TEMPERATURE TIME SERIES IN CROATIA

All studies concerning climate variability reveal the necessity of the homogeneity testing of data as the first step in further research. Inhornogeneities caused by station relocation, installation of new instruments, etc. can be the cause of misleading conclusions that do not correspond to real changes. It is quite obvious that data must be tested in order to locate possible inhomogeneities/discont in uities. This paper describes the homogeneity testing of the mean monthly and annual air temperature in Croatia. Several 50-year temperature time series during the period from 1949 to 1998 were tested using the Standard Normal Homogeneity Test (SNHT). The exact cause of discontinuities was searched from the meta data