Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University – Suceava Volume X, Issue 2 - 2011 59 THE VARIATION OF ANNUAL RAINFALL IN THE SUCEAVA PLATEAU *Ioan GONTARIU1 , Ion TĂNASĂ2 1Faculty of Food Engineering, Stefan cel Mare University, Street. Universitatii no. 13, 720229, Suceava, Romania, e-mail ioang@fia.usv.ro *Corresponding author 2Ph.D. Candidate, Stefan cel Mare University, Street. Universitatii no. 13, 720229, Suceava, Romania, e-mail ion_tanasa.meteo@yahoo.com Received 22 February 2011, accepted 6 May 2011 Abstract: The atmospherical rainfall (resulted from the condesation and crystallization of water vapours which fall from the clouds in liquid, solid or mixed form) represents one of the most important climatic elements, with noticeable influence on the natural environment of a certain region. Rainfall has an important impact on the environment of terrestrial atmosphere (which is an important link in the water’s nature circuit) and contributes to keeping the soil humid. After all, life wouldn’t have been possible without water, a key element in the formation of terrestrial atmosphere, a real protection against ultraviolet radiations and against strong termic amplitudes. Besides influencing all the other climatic elements, water plays an important part in all earth’s covers by continously modifying the relief (so it is an external factor of modelation), the configuration of hydrographical network and being involved in the formation and development of vegetation, fauna and soils (the biosphere). Like all the other elements, atmospherical rainfall could be seen as either a resource (link in the water’s circuit in nature) or a hazard (when its extremes are beyond normality and bring serious damage to society). Besides pluviometric differences, there is also an alternation of humid sectors which are positioned over the higher areas of the relief with drier sectors, sequence well distinguished on the direction North-West – South-East. Meanwhile, the slopes experiencing the change in masses of air from West and North-West, being more humid, perceive bigger quantities of precipitations while the Southern ones are drier, this also because of the foehn phenomenon. © 2011 University Publishing House of Suceava. All rights reserved Key words: climatical hazards, termic amplitudes, water vapours, terrestrial atmosphere 1. Introduction The Plateau of Suceava is positioned in the central and Northern part of Moldova, between the Eastern Carpathians and Moldova’s Plain, being the highest part of The Moldova’s Plateau and partially overlaping hystorical Bucovina [1]. The dynamic factors of the climate are the ones which record substantial changes from year to year, contributing mostly in the unperiodical variation of rainfall. The various aspects of weather, continously changing, are determined by the position of the baric centers in relation to the studied habitat, the existing dorsals of the two anticyclones, Azoric and Euroasian; cause in the North of our country the change in cold air in North and North-Est [2]. The mountainous chain of the Eastern Carpathians is a real obstacle against the movement of air masses to Suceava’s Plateau but also against the Eastern and Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University – Suceava Volume X, Issue 2 - 2011 60 North-Eastern ones, increasing their existence above this habitat [3]. The plateau is characterized by relatively abundent precipitations (between 500mm and 700 mm) and relatively moderated temperatures (between 7.5°C and 9.5°C). The most frequent pluviometrical or baric climatic hazards of termic nature are: early frosts in autumn or late frosts in spring (harmful to agricultural crop and plants), blizzards (from 9 to 14 days each year), white frost (from 10 to 12 days a year), glazed frost (9 to 12 days a year) and fog (30-50 days annually), each representing a specific phenomenon for the cold seasons of the year [4]. During the warm season, there are storms and showers, sometimes rich in precipitations, other times accompanied by hail (once or twice a year). The extraordinary variability of this climatic aspect from the habitat of Suceava’s Plateau points out remarkable pluviometrical differences during different temporal entities (annually, biannually, monthly and daily speaking), strongly related to the general or local circulation of the atmosphere (the physical, geographical factors, regional and local factors) and of the solar radiation [5]. 2. Experimental The database used in this material looks into the annual sums of precipitation from 1992-2010 (Suceava and Roman) and 1961-2010 (Radauti, Falticeni and Cotnari). Meaningful reasonings were based on documentation of specialty (see bibliography) and the main used processes were observation, statistical and mathematical analysis, comparation and also several graphical methods [6]. 3. Results and Discussion The annual average sum of atmospheric precipitations from Suceava’s Plateau is approximately 580 mm (the average of annual sums from 1961 to 2009, information provided by the 5 main meteorological centers). As we have analyzed the pluviometric repartition from the area to be studied (figure 1), we can observe meaningful differences, of over 100mm between the Southern habitat and the Northern one; in Roman an annual average quantity of 523,9mm while in Radauti 634,8mm (figure 2a) is registered. Taking into account the pluviometric stations, these differences increase even more, from 500mm in South (498.6 mm in Upper Muncel) to over 700mm in the North- Western part (737.5mm in Solca). The atmospheric precipitations gradually decrease from North-West to South–East, once the relief looses altitude (figure 2b) and once the masses of humid air, of oceanic and atlantic origin, are less frequent (including a slight foehnization). Also, the relief is largely open to East which facilitates the entrance of continental drier and warmer masses of air (of lower humidity). Figure 1. The territorial repartition of the annual quantities of precipitations in Suceava’s Plateau Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University – Suceava Volume X, Issue 2 - 2011 61 634.8 620.1 608.0 587.3 531.2 544.3 523.9 389 352 348 289 248 230 216 0 100 200 300 400 500 600 700 Rădăuţi Suceava Fălticeni Dolhas ca Cotnari Paş cani Roman mm 0 100 200 300 400 500 600 mPma Altitudinea a. b. Figure 2. The variation of the annual average quantities of atmospheric precipitations, reported to the altitude from the meteorological centers (a) and pluviometric stations (b) from Suceava (1961- 2010) Besides pluviometric differences, there is also an alternation of humid sectors which are positioned over the higher areas of the relief with drier sectors, sequence well distinguished on the direction North-West – South-East. Meanwhile, the slopes experiencing the change in masses of air from West and North-West, being more humid, perceive bigger quantities of precipitations while the Southern ones are drier, this also because of the foehn phenomenon. Analyzing the annual quantities of precipitations from 1961 to 2010, recorded at the meteorological centers from Suceava’s Plateau, we can observe a special variation in time of this climatic element, sometimes with opposite aspects. The data covering a longer period of time (before 1961), indicate an even higher variation than in the period studied, due to some years in which extremely different quantities were recorded (higher or lower, like in Suceava where the annual extremes were 330mm in 1946 and 1021.3mm in 1933, or 346.7mm in 1986 and 883.2mm in 2008). The annual sums of precipitations from Suceava’s plateau have had bigger or smaller variations, situated between the extreme values reported by the 5 meteorological centers (table 1): Radauti – 352.8mm in 1986 (56% from normality); Suceava – 330.0mm in 1946 (57%) and 1021,3mm in 1933 (173%); Falticeni – 369.2mm in 1986 (61%) and 819,1mm in 1991 (137%); Cotnari – 313.5mm in 1986 (60 %) and 825,1mm in 1991 (158%); Roman – 299.0mm in 1973 (58%) and 945.6mm in 1991 (183%). Table 1. The biggest and smallest annual sums of precipitations, exceptions and differences between them in the Suceava’s Plateau (1961-2010). Precipitations Radauti Suceava Falticeni Cotnari Roman Medium 634.8 620.1 608.0 531.2 523.9 Minimum 352.8 346.7 365.3 313.5 299.0 Year 1986 1986 1986 1986 1973 Maximum 914.5 883.2 819.1 825.1 945.6 Year (ii) 2005, 2010 2008 1991 1991 1991 Deviation- -282.0 -273.4 -242.7 -217.7 -224.9 % 56 56 60 59 57 Deviation + 279.7 263.1 211.1 293.9 421.7 % 144 142 135 155 180 Amplitude 561.7 -536.5 -453.8 -511.6 -646.6 The graphical representations of the evolution in time of the quantity of precipitations show us some very anfractuous lines, oscillating from one side of the mean to the other. Apparently, they do not obey any rule, registering general tendencies of soft increase in the analyzed time (figure 3). Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University – Suceava Volume X, Issue 2 - 2011 62 y = 0,6326x + 613,3 R2 = 0,0056 y = 1,3905x + 580,86 R2 = 0,0255 y = 1,2619x + 572,07 R2 = 0,0254 y = 1,5111x + 491,96 R2 = 0,0359 y = 1,523x + 481,35 R2 = 0,0353 200 300 400 500 600 700 800 900 1000 1961 1965 1969 1973 1977 1981 1985 1989 1993 1997 2001 2005 2009 mm Rădăuţi S uceava Fălticeni Cotnari Roman Trend Rădăuţi Trend S uceava Trend Fălticeni Trend Cotnari Trend Roman Figure 3.The evolution, variation and tendencies of annual atmospheric precipitations in Suceava. In comparison with other climatic elements (temperature, pressure, humidity, nebulosity), the variation in the annul sums of precipitation is much more highlighted. In the same time, the parallelism of the evolution of these sums is not that much noticeable, sometimes the sums intersect and other times they slowly move away one from another. The general tendency of annual precipitations from 1961 to 2010 was to easily increase, the coefficients of the regression equation (y) being positive (between 0.8741 in Radauti and 1.9067 in Roman). A more detailed analysis could determine smaller intervals of time with tendencies of a more accentuated increase between 1961-1972 and 1998-2008, but also of stagnation, between 1972-1979 and 1981-1998. On each station these periods are much more accurately registered. The spreading of the annual values of precipitations is at minimum in Roman (0.053) and at maximum in Falticeni (0.0369), from 1961 to 2009, becoming even larger for a longer period of time we analyzed (between 0.067 in Roman and 0.0748 in Suceava). The calculus and the evolution of the precipitations’ deviation from normality (the multiannual average) from all the meteorological centers in the period 1961- 2010 or beyond it (figure 4) in Suceava and Roman, point out some interesting aspects. In Radauti, some atmospherical precipitations have had the biggest variation from all Suceava’s Plateau; the minimum was of -282.0mm(1986) and the maximum 279.7 mm (2005, 2010); for a larger period of observation (1955-2008), minimum negative exception becomes - 286.9mm (1986) and the positive maximum exception changed to 577.9mm (in 1955 (when there was a maximum of 1217.6 mm per year). In Suceava, the negative minimum was of –263.1mm (1986) and the positive maximum was of 263.1mm (in 2008, year known for the biggest floods ever experienced in this area); between 1922 and 2008, the variation increased, being comprised in the total precipitations of 330mm (1946 - the drought of the century), from a negative of -249.1mm to 1021mm in 1933 and a positive maximum change of 442.1mm. Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University – Suceava Volume X, Issue 2 - 2011 63 mm y = 1.6063x - 96.929 R 2 = 0.0921 -300 -150 0 150 300 450 19 22 19 26 19 30 19 34 19 38 19 42 19 46 19 50 19 54 19 58 19 62 19 66 19 70 19 74 19 78 19 82 19 86 19 90 19 94 19 98 20 02 20 06 20 10 Abate ri plu vi om e tri ce an u a le la S u ce ava Tre n d mo bil (5 an i ) Tre n d lin ia r a. mm y = 0.53 06 x - 26 .4 72 R2 = 0.014 -250 -100 50 200 350 19 22 19 26 19 30 19 34 19 38 19 42 19 46 19 50 19 54 19 58 19 62 19 66 19 70 19 74 19 78 19 82 19 86 19 90 19 94 19 98 20 02 20 06 20 10 Abate ri plu vio me trice a n u ale la Rom an Lin ia ră (Abate ri plu vi om e tri ce an u al e la Rom an ) Tre n d m obi (5 an i) b. Figure 4.The long run evolution of annual sums of precipitations from 1922 to 2009 in Suceava (a) and Roman (b) In Roman, the variations of precipitations were registered between 299.0mm (1973) and 945.6mm (1991), with departures between -219.5 and 427mm (calculated for the period 1961- 2009) or between 212.8 and 433.8mm (1986-2009). Analyzing the frequency of the annual precipitations’ sums (figure 5), we can see that the annual sums of precipitations between 500mm and 600mm are the most numerous as percentage in Suceava’s Plateau, of 29%, with an assurance higher than 73%. On stations, the situations do not always obey this rule. In Suceava and Falticeni, years with precipitations between 600mm and 700mm are the most frequent (38%), while annual sums between 500mm and 600mm are in proportions of only 23-25%. So, the most frequent annual quantities of precipitations are between 500mm-700mm in Radauti (61%), Suceava (61%), in Falticeni (63%) and 400-600mm in Cotnari (56%) and Roman (62%). Lower frequencies were registered by the sums of precipitations between 700- 800mm (4-17%) and the minimum, the very large, ranging from 800-900mm and over 900mm (0-2%). Between 1961 and 2009, there was just one case of precipitations which registered less than 300mm (Roman) and there were not more precipitations than 1000mm. In Radauti (where the maximum annual quantity of precipitations occured), in 40% of the years were registered precipitations of 500mm-600mm and in the others below 400mm and above 900mm (2%). 1 4 11 28 30 21 7 1 5 16 44 74 95 102 y = -58,861Ln(x) + 119,83 R2 = 0,8945 0 20 40 60 80 100 120 <400mm 400-500 500-600 600-700 700-800 800-900 >900mm % % Po d. S uce ve i Asigu rare Tl og_Asi gura re Figure 5. Probability and assurance rate on intervals of 100mm for annual sums of precipitations in Suceava’s Plateau. In most of the cases, years with precipitations in surplus, close to normal in deficit, are grouped in shorter or longer periods. Certain years have had annual quantities much more below average (1887, 1896, 1964 and 1973); the smallest sums of precipitations occurred due to atmospheric anticyclonic circulation, with changes resulting in warm masses of air [7]. In other situations, annual sums were beyond the multiannual average, thanks to Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University – Suceava Volume X, Issue 2 - 2011 64 the predominant cyclonic activity (1933, 1943, 1974, 1981, 1985, 1988 and 1991). These large quantities of precipitations were generated by rain and abundant showers during the warm season and transition periods (They characterize a relatively humid region, rich in precipitations, which combined with the thermal regime and evaporation (both low), assure a normal development of spontaneous vegetation and agricultural crops, because of the periods of drought and dryness [8]. Also, this phenomenon occurs in autumn months, when the vegetative cycle of plants is over or almost finalized and is more frequent in the South-Eastern part of the studied area. From the pluviometric point of view, in the Plateau of Suceava rainy periods are more frequent than the droughty ones [9]. 4. Conclusion ◊ The small quantities of precipitations in the habitat of Suceava city have had a great variation in time, the pluviometric excess and deficit fallowing one another in many different intervals of time. ◊ Taking into account the frequency of the annual precipitations’ sums we can see that the annual sums of precipitations between 500 mm and 600 mm are the most numerous as percentage in Suceava’s Plateau, of 29%, with an assurance higher than 73%. ◊ This variation is increasing, as naturally, with the expanding of the periods we have analyzed and it fits numerically the extreme quantities of precipitations: annually (330mm-1946 and 1021mm-1933), seasonally (69mm-1935- 1936, 311mm-1987-1988 in the cold season, 173mm–1976 and 694mm-1974 in the warm season), monthly (0mm in november 1926, february or december 1931 and 253mm july 2003), daily (between days without precipitations and the maximum of 85.5mm registered July 8th, 1967). 5. References 1. POPP N., IOSEP I., PAULENCU D. 1973 - Judeţul Suceava, Editura Academiei R.S. România, Bucureşti. 2. CĂLINESCU Gh., CĂLINESCU Niculina, SOARE Elena, 1994 - Caracteristici şi tendinţe ale precipitaţiilor maxime căzute în diferite intervale de timp în Moldova, Lucr. Sem. Geogr. „Dimitrie Cantemir”, Iaşi. 3. APĂVĂLOAE M., APOSTOL L., PÎRVULESCU I., 1984 - Topoclimatele oraşului Suceava, Buletin ştiinţific, I.I.S. Suceava. 4. APOSTOL L., 2000 - Precipitaţiile atmosferice din Subcarpaţii Moldovei, Editura Universităţii “Ştefan cel Mare”, Suceava. 5. FILIPOV F., LUPAŞCU Angela, RĂDUCU Daniela, BELDIMAN Brânduşa Elena, 2001 - Influenţa măsurilor ameliorative asupra însuşirilor morfologice fizice şi chimice ale solurilor cu exces de umiditate din Podişul Sucevei, Iaşi. 6. ŢÎŞTEA D., NEACŞA O., SABĂU A., SÎRBU V., CĂLINESCU N., 1974 - Studiul parametrilor climatici locali pentru stabilirea condiţiilor de restaurare şi conservare a picturilor murale ale unor monumente istorice din Bucovina, Studii de climatologie, vol. 1, I.M.H., Bucureşti. 7. SLAVIC Gh., 1977 - Podişul Sucevei - studiu climatologic, Rezumatul tezei de doctorat, Iaşi. 8. ERHAN Elena, 1986 - Fenomenul de grindină în Podişul Moldovei, Analele Ştiinţifice ale Universităţii „Al. I. Cuza”, din Iaşi, secţ. II b geol.- geogr., tom XXXII. 9. TOPOR N., 1963 - Ani ploioşi şi secetoşi în R.P.R., I.M., Bucureşti. *** (1962, 1966) „Clima R.P.R.”, Institutul Meteorologic, vol. I şi II, Bucureşti. *** (1983) „Geografia României I. Geografia fizică”, vol. I, Bucureşti. *** (1989) „Geografia României IV. Geografia fizică”, vol. IV, Bucureşti. *** (1984) „Un secol de la înfiinţarea Serviciului meteorologic al României”, I.N.M. Bucureşti. *** (1972 -2001) Arhiva de date climatologice a Staţiei meteorologice Suceava, Centrul Meteorologic Regional Moldova