Wyniki wyszukiwania - Biblioteka Nauki

1

Wpływ cyrkulacji atmosferycznej na temperaturę wody u polskiego wybrzeża Bałtyku w chłodnej porze roku

100%

Girjatowicz J.

Inżynieria Morska i Geotechnika

|

1999

|

tom nr 1

4-7

2

Rola cyrkulacji atmosferycznej w kształtowaniu stopnia czystości powietrza napływającego nad aglomeracje miejsko-przemysłowe (na przykładzie Łodzi)

80%

Skrzypski J. , Politechnika Łódzka W. I. P. i. O. Ś.

Acta Universitatis Lodziensis. Folia Geographica Physica

|

1999

|

tom 3

PL

Zanalizowano zmiany poziomu zanieczyszczenia pyłem zawieszonym i SOz mas powietrznych napływających nad zachodnie i wschodnie peryferie Łodzi. Stwierdzono wyraźne zmniejszenie tego poziomu, a także jego zaJeźność od typu cyrkulacji atmosferycznej. Wykazano, że obserwowana w miastach Polski poprawa sytuacji aerosanitarnej wynika z uwarunkowań zewnętrznych. Wykazano również wpływ zmian frekwencji poszczególnych typów cyrkulacji (wpływ okresowości procesów cyrkulacyjnych) na zanieczyszczenie powietrza w aglomeracjach miejsko-przemysłowych.

EN

Changes in dust and S02 concentration in the air masses flowing onto western and eastern suburbs of Łódź are analyzed. A significant decrease in these values was observed and dependence of the concentration on the type of air circulation was found. It was shown that improvement in the aero-sanitary conditions was caused by external factors. It was also shown that changes in the frequency of particular circulation types had influence on the air pollution in urban and industrial agglomerations.

3

Zmienność terminów początku i końca pokrywy śnieżnej o różnym czasie zalegania i ich uwarunkowania cyrkulacyjne

80%

Czarnecka M.

Prace i Studia Geograficzne

|

2011

|

tom 47

4

Cyrkulacyjne uwarunkowania opadów w północno-zachodniej Polsce

80%

Kirschenstein M.

Przegląd Geofizyczny

|

2002

|

tom Z. 1-2

45-59

EN

The aim of this work is the analysis of precipitation totals and frequency in the north-west of Po-land depending on the type of atmospheric circulation. Heavy rains are of remarkable importance for agriculture, forestry, weather forecasts etc. In the north-west of Poland percentage of heavy rains in the annual total is great (nearly 41,2%) with the average annual value 7,3%. The basis for the analysis was mean daily precipitation totals for the 1961-1980 period from 185 pluviographic stations. To determine the influence of types of atmospheric circulation on rainfalls Osuchowska-KlehYs classification was used (1975). The research has shown that atmospheric circulation in seasons of the year can influence on precipitation totals and it's frequency in many ways. The most distinguishing are the types of circulation with heavy rains occurring most often (CB, A, E(0)) as well as the ones with high daily precipitation totals (E(0), CB, A). Furthermore, it should be emphasized that the same type of circulation may condition, by different means, precipitation totals due to the peculiarities of flowing air masses dependent on the season. The north-eastern and eastern cyclonic circulation (E(0)) is a good example here since, among the 13 circulation types defined by Osuchowska-Klein (1975), it is the type that most frequently causes high daily precipitation totals in the warm period of the year, which results from the advection of cold air masses towards the warmer surface. Similar effects emerge with the north-western cyclonic circulation (CB) as throughout the warmer period of the year the circulation is characterized by the onshore advection of cold air masses, while in autumn and winter it brings on warm and humid air from the ocean, along with continuous precipitation. It is worth noticing the eastern circulation during which the rainfalls > 30 occur most frequently. The reason for such heavy and prolonged rainfalls is the advection of very warm air, which leads to intense convection and evolution of thermal thunderstorms.

5

Cechy zmienności opadów w cyklu rocznym na obszarze Svalbardu

80%

Łupikasza E.

Problemy Klimatologii Polarnej

|

2000

|

tom nr 10

41--54

EN

This article discusses the changes in an annual cycle of precipitation observed over many years in the Svalbard area. Monthly precipitation sums recorded at the Isfjord Radio station, Björnöya, Jan Mayen were used to accomplish the analysis. Data presented come from GHCN (Vose et al. 1997), MCDW (1957-1997) and WWR (1929,1944,1947,1959,1968,1979,1981, 1987, 1994, 19(5). The characteristics of the annual precipitation were described using Wilgat's indicator of periodicity of precipitation ( 1949) and Vemic's pluviometric coefficient (Szreffel 1961). Apart from that the amount of the highest and the lowest occurrence of precipitation in each month was calculated during the 10-years moving periods. In addition the annual change of the monthly sums of precipitation was characterised. The analysis of the annual change of the periodicity indicator has proved that during the examined period the precipitation regime on Isfjord Radio station and Jan Mayen do not show clear changes. On Björnöya station from the mid forties periodicity of precipitation has decreased. On all examined stations until the late thirties the value of the pluviometric coefficient were less than 50%. Since the mid forties over half of the amount of precipitation occurred from March to November. The highest sums of precipitation most often occurred in April, May and June. The highest sums of precipitation on Jan Mayen station and Björnöya station occurred mainly in September and October. On Isford Radio station the highest sums of precipitation were recorded chiefly in March. September. February and August.

6

Liczba dni z calodziennymi inwersjami w Krakowie w latach 1994-2005

80%

Walczewski J.

Wiadomości Instututu Meteorologii i Gospodarki Wodnej

|

2006

|

tom 29

|

nr 3-4

69-73

7

Cyrkulacyjne uwarunkowania susz rolniczych w województwie podkarpackim

80%

Ziernicka-Wojtaszek A.

Infrastruktura i Ekologia Terenów Wiejskich

|

2012

|

nr 2/III

PL

Treścią artykułu jest analiza cyrkulacyjnych uwarunkowań suszy rolniczej na obszarze dzisiejszego województwa podkarpackiego w okresie wegetacyjnym IV-X lat 1901-2000. Materiał badawczy stanowią: kalendarz codziennych typów cyrkulacji dla Polski południowej autorstwa Niedźwiedzia i kalendarz warunków meteorologicznych wegetacji roślin uprawnych na obszarze Polski południowo-wschodniej autorstwa Zawory dla okresów miesięcznych. Metoda pracy polegała na określeniu częstości typów cyrkulacji atmosfery w miesiącach uznanych przez korespondentów rolnych za suche z powodu niedoboru opadów. Zagrożenie suszą można wyrazić przez stosunek częstości danego typu cyrkulacji przy występowaniu suszy do ogólnej częstości typów cyrkulacji. I tak w okresie wegetacyjnym typ cyrkulacji antycyklonalnej z adwekcją powietrza z południowego - zachodu SEa w przypadku suszy występuje 1,38 razy częściej, niż ogólna częstość tego typu cyrkulacji, podobnie typ Sa i Ea 1,35 i 1,33 razy częściej. Odpowiednie wartości dla innych typów cyrkulacji wynoszą: dla klina antycyklonalnego Ka - 1,21, sytuacji antycyklonalnej z adwekcją powietrza z kierunku północno-wschodniego NEa i sytuacji centralnej antycyklonalnej Ca - 1,20. Dla sytuacji antycyklonalnej z adwekcją powietrza z kierunku południowo-zachodniego SWa i północnego Na, odpowiednie relacje częstości wynoszą 1,1 i 1,05. Z drugiej strony ważna jest częstość występowania tego typu sytuacji. Można ją uszeregować w następującej kolejności: Ka - 16,7%, Ea - 7,2%, SEa - 5,5%, NWa - 5,5%, NEa - 4,9%, Sa - 4,2%, Na - 4,1%, SWa - 3,4% i Ca - 3,0% (tab. 1).

EN

This article presents the analysis of atmospheric circulation conditions pertaining to agricultural droughts in the Podkarpackie Province during the growing season (1901-2000). The following resource materials have been used: daily calendar of atmospheric circulation types elaborated by T. Niedzwiedz for southern Poland, and growing season meteorological calendar elaborated by T. Zawora for southern Poland for the following monthly periods. The author had to determine the frequency of atmospheric circulation types for months which have been recognized by agricultural specialists as too dry (due to precipitation deficit). Drought hazard may be expressed by the following ratio: frequency of occurrence of a given circulation type during drought conditions to general frequency of circulation types. This method enabled to present detailed results. Firstly during the growing season the anticyclonic circulation type - advection of air from southwest - occurs 1,38 more frequently than the general frequency of this particular circulation type (SEa). The situation is similar for types Sa and Ea (1,35 and 1,33 respectively). When we examine the remaining values we can notice that the frequency coefficient for anticyclonic ridge (Ka) is equal to 1,21, whilst for anticyclonic situation with advection of air from northeast (NEa), and for central anticyclonic situation (Ca) is equal to 1,20. For anticyclonic situation with advection of air from the southwest (SWa) and north the coefficient is 1,1 and 1,05 respectively. It is also important to notice the general frequency of occurrence of these particular circulation types. The author managed to rank them in the descending order: Ka – 16,7%, Ea – 7,2%, SEa – 5,5%, NWa – 5,5%, NEa – 4,9%, Sa – 4,2%, Na – 4,1%, SWa – 3,4 % and Ca – 3,0% (refer to table 1).

8

Wpływ cyrkulacji atmosferycznej na kształtowanie zachmurzenia w Koszalinie

80%

Kirschenstein M.

Słupskie Prace Geograficzne

|

2003

|

nr 01

9

Dynamiczne cechy klimatu Polski - dominujące typy cyrkulacji atmosferycznej

80%

Baranowski D.

Słupskie Prace Geograficzne

|

2003

|

nr 01

10

Opady całkowite i stałe w Arktyce Kanadyjskiej i ich zmienność w okresie 1950-1995

80%

Przybylak R.

Problemy Klimatologii Polarnej

|

2000

|

tom nr 10

13—40

EN

The main aims of this paper are i) to establish the trends in solid and total precipitation as well as in solid to total precipitation ratio (hereinafter SIC ratio) in the Canadian Arctic in recent decades. and ii) to investigate the influence of air temperature and circulation factors (atmospheric and oceanic) on the above-mentioned precipitation characteristics, Recently updated and adjusted data (see Mekis and Hogg 1999) from 16 stations located in the Canadian Arctic (fig. I) were used for the investigation. The southern boundary of the study area was taken after Atlas Arktiki (1985). In addition, the data from two sub-Arctic stations were also used. The majority of the data cover the period from 1950 to 1995. The relationship between air temperature and precipitation in the Canadian Arctic was investigated using i) the sets of 10 individual warmest and 10 individual coldest years chosen from the areally averaged annual Canadian Arctic temperature series, ii) the warmest and coldest l C-year blocks from the same Canadian Arctic series, and iii) the sets of years defined in points i) and ii) but chosen from the individual station temperature series. Next, in the case of the two first approaches, for each station the differences of solid and total precipitation as well as the S/C ratio were calculated between sets of warmest and coldest years. In the third approach, the differences were only computed for the station which was the basis for choosing the warmest and coldest years. The same method was used to investigate the relationships between circulation factors and precipitation in the Canadian Arctic. The precipitation and the SIC ratio differences were calculated here between the sets of years with high and low values of the best known indices (North Atlantic Oscillation (NAO) and Southern Oscillation) characterizing atmospheric circulation or, in the case of the oceanic circulation, between the years with the opposite Arctic Ocean circulation regimes (cyclonic and anticyclonic, see e.g. Proshutinsky and Johnson 1997). The main results of the investigation were as follows: The corrected annual precipitation sums (after the influence of measured errors are deleted ) arc higher than uncorrected values by 26% to 58% depending on the analyzing station (see tab. 2). A statistically significant increase in all kinds of areally averaged seasonal and annual precipitation for the Canadian Arctic occurred over the period 1950 1995 (figs :2 and 3). On the other hand, the S/C ratio did not change significantly, except for summer values (fig. 5) and its behavior was also in accord with small variations noted in air temperature (fig. 4). Solid precipitation occurs usually in all seasons , but the S/C ratio maximum was observed in winter (98.7%) and the minimum in summer (12.5%). The areally averaged annual S/C ratio was 57,3%. An increase in air temperature in the Canadian Arctic most often led to the rise of all kinds of annual precipitation sums, but only when the warmest and coldest years were chosen based on the individual stations. The pattern of the relationship is significantly more complicated and can be even opposite to that presented above, when the sets of the warmest and coldest years are chosen based on the areally averaged annual temperature for the Canadian Arctic (see fig. 6). Significantly more stable results of changes occurred for the S/C ratio, which in warmer periods was usually lower (fig. 7). However, more detailed and reliable investigations of temperature-precipitation relations conducted for individual stations showed that the last statement is true, but only for the southern (warmer) part of the Canadian Arctic (<70°N). During the periods with high positive values of the NAO, a decrease in precipitation is observed in the south-eastern part of the Canadian Arctic (fig. 8), that is, in the area where a strong cooling was also observed (see fig. 12 in Przybylak 2000). During the El Niño events most of the Canadian Arctic had both greater precipitation and a higher SIC ratio than during the La Niña events (fig. 9). The most univocal results of precipitation and SC ratio changes were connected with changes of the Arctic Ocean circulation regimes. In almost the whole study area, a lower precipitation and a SC ratio was noted during the anticyclonic circulation regime in the Arctic Ocean (fig. 11).

11

Oscylacja Północnego Atlantyku a długość okresu wegetacyjnego w Polsce

80%

Marsz A. A. , Żmudzka E.

Przegląd Geofizyczny

|

1999

|

tom Z. 4

199-210

EN

In the paper are discussed correlations of the beginning and the length of a vegetative period in Poland with of the NAO index. Analysis had been led for 8 stations completely representing the differentiation of climate in Poland during the 60 years period (1931-1990). There has been stated statistically significant correlations of the beginning and the length of a vegetative period with the NAO index, and no correlations the end of a vegetative period and the NAO index. For each station existing correlations are described dy linear equations . They show that there are move exact correlations of the beginning and the length of a vegetative period with an average value of the NAO index, being a difference of the air pressure between Gibraltar and SW Iceland for the period from January to March, than with Hurrell index (Lisboa-Stykkisholmur, December-March). Change of the NAO index about ą2dn changes the duration of a vegetative period on the area of Poland from 21 days (Zakopane) to 46 days (Szczecin) on the average about 31 days. It proves, that the changeability of the length of a vegetative period, which is one the most important ecological factor, is also considerably caused by conditions of circulation. Generally, the influence of the NAO on the beginning and the duration of the vegetative period is decreasing from NW and W edges of Poland in the direction of SE and E.

12

Cyrkulacja atmosferyczna nad Europą na powierzchni izobarycznej 500 hPa. Cz. 1 Zima

80%

Wibig J.

Przegląd Geofizyczny

|

1999

|

tom Z. 1-2

15-24

EN

To describe circulation fields in winter months the sets of mean monthly values of 500 hPa geopotential heights in grid points over Europe and North Atlantic were transformed into a new sets orthogonal principal components. The principal component analysis together with varimax rotation were used. Maps of correlation coefficients between a few most important components and original time series present circulation types. Four types present in all months were distinguished. There were the NAO, the scandinavian, the east-european and the blocking type. Also one type present only in December - the east-atlantic one - was distinguished. The NAO type is represented by dipol with one centre of high negative correlations over subpolar region of Atlanitc and the second centre of high positive correlations over subtropical Atlantic. It is closely connected with activities of Icelandic Low and Azorian High, which is confirmed by strong correlations with NAO index by Hurrell (1996). Dipol is also characteristic for east-european type with one centre of correlations over East Europe near Black Sea and the second one over West Europe or British Isles. Remaining type are represented by singular centres of high correlations; in scandinavian type it is over northern part of Scandinavian Peninsula, in blocking type it is over Central Europe and in east Atlantic type it is over eastern part of North Atlantic.

13

Cyrkulacja atmosferyczna nad Europą na powierzchni izobarycznej 500 hPa. Cz. 2 Wiosna, lato, jesień

80%

Wibig J.

Przegląd Geofizyczny

|

1999

|

tom Z. 1-2

25-38

EN

To describe circulation fields the sets of mean monthly values of 500 hPa geopotential heights in grid points over Europe and North Atlantic were transformed into a new sets of orthogonal principal components. The principal component analysis together with varimax rotation were used. Maps of correlation coefficients between a few most important components and original time series were interpreted as circulation types. Six types were distinguished. Three of them: the NAO, the scandinavian and the east-european type, are present in all months of spring, summer and fall. Next two - east-atlantic and blocking type - are on maps in eight months (the east-atlantic type is absent in June and the blocking one is absent in August). The mediterranean type is characteristic for warm months from June to September. During cold season the NAO type is represented by dipol with one centre of high negative correlations over subpolar region of Atlantic andthe second centre of high positive correlations over subtropical Atlantic. In spring and summer the correlation coefficients over subtropical Atlantic are much lower, so at figure 7 can be seen only the region of high correlations near Greenland. Type NAO is closely connected with activities of Icelndic Low and Azorian High, which is confirmed by strong correlations with NAO index by Hurrell (1996). Dipol is also characteristic for east-european type with one centre of correlations over East Europe near Black Sea and the second one over West Europe or British Isles. Remaining type are represented by singular centres of high correlations; in scandinavian type it is over northern part of Scandinavian Peninsula, in blocking type it is over Central Europe, in east Atlantic type it is over eastern part of North Atlantic.(in some months there is a second region of high correlation coefficients of opposite sign over Adriatic Sea) and in mediterranean type over southern Europe.

14

Związek parametrów lodowych Zatoki Pomorskiej z typami cyrkulacji atmosferycznej

80%

Girjatowicz J. P. , Chabior M.

Przegląd Geofizyczny

|

1999

|

tom Z. 1-2

61-71

EN

In the present paper there was applied a catalogue of circulations types according to J. Lityński as well as data concerning ice conditions, like the number of days with ice (L), length of ice season (S) and maximum thickness of ice (H) for Świnoujście-sea and Kołobrzeg-sea for winters within 1950/51 - 1989/90. For one month's and several months winter periods the selected circulation types were correlated to the accepted parameters of ice conditions. Equations of linear regression as well as polynomial of the second degree were applied. The statistical significance of relationships was determined with the aid of Fisher-Snedecor's (F) significance test. There was found, that on the number of days with ice (L), length of ice season (S) and maximum height of ice (H) affect mostly the anticyclonic and zero circulation types of eastern component (NE a,o + E a,o), as well as cyclonic and zero circulation types of western component (SW c,o + W c,o + NW c,o). The highest values of correlation coefficient for these directions were obtained in the period from December to February, while relatively high also for December only, what points some prognostic value. For earlier months, in principle, no significant relationships were found. More significant relationship occurred in the of Świnoujście when compared to Kołobrzeg, the highest for maximum thickness of ice (H) and the number of days with ice (L).

15

Wplyw cyrkulacji atmosferycznej na zasolenie wod u poludniowych brzegow Zatoki Pomorskiej

70%

Girjatowicz J. P.

Wiadomości Instututu Meteorologii i Gospodarki Wodnej

|

2002

|

tom 25

|

nr 4

39-50

16

Fale ciepła i chłodu w środkowej Polsce na przykładzie Łodzi

70%

Wibig J. , Uniwersytet Łódzki W. N. G.

Acta Universitatis Lodziensis. Folia Geographica Physica

|

2008

|

tom 8

PL

Artykuł powstał w wyniku prac badawczych prowadzonych w ramach Projektu Zamawianego MNiI (K091/P04/2004/11).

EN

The aim of this work is to analyze the waves of warmth and coldness in central part of Poland basing on a daily maximum and minimum temperature in Łódź between 1931 and 2006. Warm and cold periods were distinguished following daily maximum temperature course (warm and cold days) and daily minimum temperature course (warm and cold nights). A particular day was involved in warm (cold) period, if its daily temperature was higher (lower) than average +1.28 (-l.28) of standard deviation within this calendar day. The value of l.28 was chosen because it counterparts percentile of 90% (10%) if we assume that temperature distribution is normal. The trends of seasonal and annual changeability of the number of cold and warm days and nights as well as maximum length of warm and cold waves were estimated by Sen's method. The most frequently observed were the short waves, such as one- or two days long (Fig. 3 and 9). The average of day numbers, within at least three day-long waves and an their average lasting time of the longest waves had distinct annual cycle with its maximum in summer and minimum in winter. However, the absolute maxima of the waves lengths fell on winter half-year. The longest waves were 18 and 17 days. For comparison, the lengths of the warm and cold nights periods were significantly shorter and were about II and 14 days. The longest cold waves were slightly longer than equivalent waves of warmth. The following years: 1962, 1989, 1992, 1994, 2000, 2002 and 2006 are the years of particularly long warm periods or years of a great number of warm days, and are grouped in last 20 years of analyzed series with the exception of 1962, which represents series center. On the other hand, the years, during which cold waves were exceptionally long or those, which were characterized by a great number of cold days and nights (1954, 1956, 1963, 1979, 1996) were gathered during first 30s of the analyzed period. In spite of this, only some of studied series have statistically significant trend. Lasting time of the longest wave of warmth increased significantly in winter (0.28 of the day per ID years), while the number of waves of warmth grew in summer (0.33 of the day per ID years) and during the whole year (1.79 of the day per ID years). If it is about warm nights, the lasting time of the longest wave increased significantly in winter (0.17 of the day per 10 years) and in autumn (0.20 of the day per 10 years), while the number of the days increased significantly in summer (0.36 of the day per 10 years) and within the whole year (1.61 of the day per 10 years). The length of the longest wave of cold days significantly decreased in winter (0.18 of the day per ID years) and the number of cold days in a year decreased in 0.87 of the day per 10 years. In case of cold nights the lasting time of the longest wave shortened in winter (0.17 of the day per 20 years) and during the whole year (0.2 of the day per 10 years), while the number of cold nights in the year decreased in 1.43 days per 10 years and 0.43 of the day per ID years in spring. The influence of the atmospheric circulation either in macroscale or mesoscale on frequency and intensity of extreme thermal events in Poland is visible only in winter, however it explains no more than 25% of their changeability. Better results are obtained by composite method, which allows to single out such synoptic situations, which favor maintaining strong positive and negative thermal anomalies. Thermal conditions of central Poland primarily depend on baric centers, which centers locate in country's proximity (Fig. 14-17). The correlations between number of days during periods of warm days and nights, and maximum length of waves and northern hemisphere's temperature are positive and statistically significant for all seasons except summer (fable 6). Nonetheless, no more than 25% of the changes might be the direct results of big-scale temperature changes, the rest is influenced by regional or even local factors. The correlations between number of days during periods of cold days and nights and maximum length of waves and northern hemisphere's temperature are negative and statistically insignificant.

17

Zwiazki typow cyrkulacji atmosferycznej z warunkami opadowymi na wybrzezu polskim ze szczegolnym uwzglednieniem Wybrzeza Zachodniego

70%

Girjatowicz J. , Swiatek M.

Folia Universitatis Agriculturae Stetinensis. Agricultura

|

1999

|

tom 79

67-72

18

Proba wydzielenia sezonow cyrkulacyjnych nad Europa Srodkowa

70%

Nowosad M.

Annales Universitatis Mariae Curie-Skłodowska. Sectio E. Agricultura

|

2007

|

tom 62

|

nr 1

57-67

19

Dobowe amplitudy temperatury powietrza w Polsce i ich zależność od typów cyrkulacji atmosferycznej (1971-1995)

70%

Baranowski D.

Słupskie Prace Geograficzne

|

2005

|

nr 02

20

Epoki cyrkulacyjne XX wieku i zmienność typów cyrkulacji atmosferycznej w Polsce

70%

Degirmendzić J. , Kożuchowski K.

Przegląd Geofizyczny

|

2000

|

tom Z. 3-4

221-239

EN

A brief survey of classifications of the circulation epochs, ie. Periods of time when definite macro-forms of circulation prevail over the Northern Hemisphere, were included in this paper. All classifi-cations refer to the period from the end of XIXth century to the last decade of XXth century. Authors present conception of such classification procedure for the period 1901-1998 on the basis of mean seasonal values of the Zonal Index (ZI), assessing circulation conditions between the 350 and 650 N and seasonal values of the NAO. By means of the Ward's clustering method we were able to distinguish four groups of years within which: strong zonal flow prevails during the whole year (A), strong zonal flow dominates only in winter (B), weak zonal circulation affects only winter conditions (C) and weak zonal flow consti-tutes the characteristic feature of the circulation condition during the whole year (D). The occur-rence of the years classified as type B and C was particularly useful and allowed us to distinguish 7 circulation epochs. Definite seasonal patterns of intensity of the zonal flow expressed by values of the ZI and the NAO were ascribed to this epochs. During the epoch of 1987-1998 the strongest zonal circulation prevailed, whereas the least intense zonal flow occurred from 1957 to 1970. The changes in frequency of circulation types in Poland (according to Osuchowska-Klein, 1978, 1991) with reference to hemispheric circulation epochs were analysed. On the whole, considerable increase in ration between western and eastern types of circulation during the period of 1987-1998 and 1911-1927 is observed however during the epoch of 1971-1986 eastern types dominate.