Wyniki wyszukiwania - BazTech

1

Climate indices and drought characteristics in the river catchments of Western Ghats of India

Shetty Swathi, Umesh Pruthviraj, Shetty Amba

Acta Geophysica

|

2024

|

Vol. 72, no. 1

371--384

EN

The study addresses the long-term trend in rainfall, minimum and maximum temperature, and the climate indices for the river catchments located in the diverse climate of the Western Ghats of India. The dry sub-humid Chaliyar catchment and humid Kajvi catchment have shown a dramatic change in the decadal rainfall, with the decade 1950-1960 being the point of change. The monsoon rainfall has decreased in the Chaliyar and Netravati catchments and increased insignificantly in the Kajvi catchment. With the increase in mean temperature, the number of rainy days is decreasing, and intense rainfall is increasing in the pre-monsoon. The increase in minimum temperature is more severe in all three catchments, irrespective of the region’s climate. The decline in rainy days is more figurative in the humid and per-humid catchments and has seen a 16-20% decrease in Rx 1 day, Rx 3 day, and Rx 5 day in the past six decades with an insignificant increase in the dry subhumid catchment. The frightful increase in warm days/nights with a decrease in cool days/nights has been alarming for the extremity of temperature in future years. The significant changes in the forest area in Chaliyar and Kajvi catchment and the increase in a built-up area in Netravati may have a decisive role in the nonseasonal variability in rainfall and temperature along with increasing greenhouse gases. In the case of meteorological drought studied using the Standardized Precipitation Index (SPI), moderate droughts have occurred over the Chaliyar and Kajvi, and extreme droughts over the Netravati catchments with no reduction in the frequency or severity of short-duration extreme rainfall events. The geographical location of the catchment has a greater impact on the characteristics of the rainfall and meteorological drought, and these changes in the hydrological regimes of the catchment have a significant bearing on the water availability in the catchments in the future years.

2

Variations of temperature, salinity and oxygen of the Baltic Sea for the period 1950 to 2020

Stockmayer Vera, Lehmann Andreas

Oceanologia

|

2023

|

Vol. 65 (3)

466--483

EN

Variations of temperature, salinity and oxygen of the Baltic Sea on interannual to decadal timescales were studied for the period from 1950 to 2020. Both observational data and the output of a numerical circulation model of the Baltic Sea were analyzed. In addition, we investigated the influence of atmospheric parameters and river runoff on the observed hydrographic variations. Variability of sea surface temperature (SST) closely follows that of air temperature in the Baltic on all timescales examined. Interannual variations of SST are significantly correlated with the North Atlantic Oscillation in most parts of the sea in winter. The entire water column of the Baltic Sea has warmed over the period 1950 to 2020. The trend is strongest in the surface layer, which has warmed by 0.3–0.4°C decade−1, noticeably stronger since the mid-1980s. In the remaining water column, characterized by permanent salinity stratification in the Baltic Sea, warming trends are slightly weaker. A decadal variability is striking in surface salinity, which is highly correlated with river runoff into the Baltic Sea. Long-term trends over the period 1950–2020 show a noticeable freshening of the upper layer in the whole Baltic Sea and a significant salinity increase below the halocline in some regions. A decadal variability was also identified in the deep layer of the Baltic Sea. This can be associated with variations in saltwater import from the North Sea, which in turn are influenced by river runoff: fewer strong saltwater inflows were observed in periods of enhanced river runoff. Furthermore, our results suggest that changes in wind speed have an impact on water exchange with the North Sea. Interannual variations of surface oxygen are strongly anti-correlated with those of SST. Likewise, the positive SST trends are accompanied by a decrease in surface oxygen. In greater depths of the Baltic Sea, oxygen decrease is stronger, which is partly related to the observed increase of the vertical salinity gradient.

3

Crop Yields under Climate Variability and No-Tillage System in Dry Areas of Morocco

Moussadek Rachid, Laghrour Malika, Mrabet Rachid, Van Ranst Eric

Ecological Engineering & Environmental Technology

|

2023

|

Vol. 24, iss. 1

221--232

EN

In Morocco, the intensive use of agricultural land coupled with irregular precipitation is a serious threat to the country’s food security. Conservation agriculture especially no-tillage (NT) system has shown an important result in the semi-arid regions of Morocco, but its dissemination to other, more humid, agro-ecological zones (precipitation > 350 mm) is still low. For this purpose, a field experiment under NT system has been installed since 2004 in the Zaer Plateau (Central Morocco) to study the adaptation of this system to the irregular rainfall compared to a conventional tillage (CT). Yields (grain and biomass) of crops (wheat and lentil) under NT and CT were analyzed and compared over the years of study. The ANOVA test showed that yields over the seven years were significantly different and that both crop yields under NT system were greater than or equal to those under CT system even though lentil is more vulnerable to extreme climate events under CT and NT systems. Unlike NT, yields under CT were significantly correlated with the rainfall amount received during the crop cycle. This indicates the dependence of CT precipitation, whereas NT is more adaptable to the irregularities of the climate in the study area.

4

Analyzing trend and forecast of rainfall and temperature in Valmiki Tiger Reserve, India, using non parametric test and random forest machine learning algorithm

Roshani, Sajjad Haroon, Saha Tamal Kanti, Rahaman Md Hibjur, Masroor Md, Sharma Yatendra, Pal Swades

Acta Geophysica

|

2023

|

Vol. 71, no. 1

531--552

EN

Assessment of spatiotemporal dynamics of meteorological variables and their forecast is essential in the context of climate change. Such analysis can help suggest possible solutions for flora and fauna in protected areas and adaptation strategies to make forests and communities more resilient. The present study attempts to analyze climate variability, trend and forecast of temperature and rainfall in the Valmiki Tiger Reserve, India. We utilized rainfall and temperature gridded data obtained from the Indian Meteorological Department during 1981–2020. The Mann–Kendall test and Sen’s slope estimator were employed to examine the time series trend and magnitude of change at the annual, monthly and seasonal levels. Random forest machine learning algorithm was used to estimate seasonal prediction and forecasting of rainfall and temperature trend for the next ten years (2021–2030). The predictive capacity of the model was evaluated by statistical performance assessors of coefficient of correlation, mean absolute error, mean absolute percentage error and root mean squared error. The findings revealed a significant decreasing trend in rainfall and an increasing trend in temperature. However, a declining trend for maximum temperature has been observed for winter and post-monsoon seasons. The results of seasonal forecasting exhibited a considerable decrease in rainfall and temperature across the Reserve during all the seasons. However, the temperature will increase during the summer season. The random forest machine learning algorithm has shown its effectiveness in forecasting the temperature and rainfall variables. The findings suggest that these approaches may be used at various spatial scales in different geographical locations.

5

Assessment of evidence based climate variability in Bhagirathi sub basin of India: a geostatistical analysis

Rehman Sufa, Sajjad Haroon, Masroor Md, Rahaman Md Hibjur, Roshani, Ahmed Raihan, Sahana Mehebub

Acta Geophysica

|

2022

|

Vol. 70, no 1

445--463

EN

Climate variability analysis is essential for predicting the behavior of various extreme weather events and making communities resilient. Notwithstanding the profound concerns, climate variability assessment faces numerous challenges due to inadequate and sometimes unavailability of data at spatiotemporal scales. This study makes an attempt to analyse climate variability in the Bhagirathi Sub-basin of India. Six meteorological variables were analysed from fourteen weather stations located in the Sub-basin during 1968–2017. Modified Mann–Kendall test was employed to ascertain the trends in meteorological variables. One-way ANOVA was used to assess the relationship between and within the variables. A total of 432 households were selected for reaffirming climate variability and impact on landscape. Significant trends were detected in highest maximum, mean maximum (Mmax) and mean minimum (Mmin) temperatures, relative humidity (Rh), rainfall and vapour pressure (Vp) at annual and seasonal scales. Stations located in eastern and deltaic Sub-basins registered varying trends in these meteorological variables due to anthropogenic activities-induced land use changes. ANOVA revealed a robust relation among rainfall, Vp, Mmin and Mmax. Perceptions of the sampled households revealed that climate variability has considerably affected food intensity, vegetation, soil, water resources and agricultural pattern. We find modified Mann– Kendall method effective in analysing climate variability in the Sub-basin. Thus, this method can be utilized for effective analysis of climate variability at spatial scales in geographical regions.

6

The sensitivity of vegetation in the lower Tigris basin landscapes to regional and global climate variability

Alhumaima Ali S., Abdullaev Sanjar M.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2021

|

Vol. 30, No. 1

159--170

EN

This study investigates the lower Tigris basin’s the normalized difference vegetation index (NDVI) sensitivity in 2000–2016 to regional climate variability reflected by the monthly precipitation and temperature time series of seven global datasets as well as to four global circulation indices. To examine the effect of climate variability on the different ecosystems, the study area has been classified into 10 smaller natural and anthropogenic landscapes based on landforms and land cover patterns. The preliminary analysis showed that the maximum biological productivity reflected by the NDVI of March and April has the highest correlation (0.5–0.8) to the same cumulative amounts of October–March period total precipitation and January–March period mean temperatures according to all datasets. In addition, this article showed there is a correlation between landscapes’ NDVI and global modulation represented by the September–February state of El Nińo-Southern Oscillation (ENSO) (0.55–0.70) and December state of the dipole mode index (DMI) (0.35–0.72). The significant differences in the original precipitation and temperature levels according to the different datasets have urged the use of normalized time series: z-score of temperatures and analogous six-months the standardized precipitation index (SPI). However, the multiple correlation analysis showed that using ERA-

7

Forest cover change detection in relation to climate variability and LULC changes using GIS and RS techniques. A case of the Kafa zone, southwest Ethiopia

Lemma Dejene Beyene, Gebretsadik Kinde Teshome, Debela Seifu Kebede

Journal of Water and Land Development

|

2021

|

no. 51

152--162

EN

Ethiopia has lost sizable forest resources due to rapid population growth and subsequent increase in the demand for agricultural land and fuel woods. In this study, GIS and remote sensing techniques were used to detect forest cover changes in relation to climate variability in the Kafa zone, southwest Ethiopia. Landsat Thematic Mapper (TM) images of 1986 and 1990, Enhanced Thematic Mapper plus (ETM+) image of 2010 and Landsat-8 Operational Land Imager (OLI-8) image of 2018 were acquired at a resolution of 30 m to investigate spatial-temporal forest cover and land use changes. A supervised image classification was made using a maximum likelihood method in ERDAS imagine V9.2 to identify the various land use and land cover classes. Both spectral (normalised difference vegetation index – NDVI) and post classification change detection methods were used to determine the forest cover changes. To examine the extent and rate of forest cover changes, post classification comparisons were made using ArcGIS V 10.4.1. A net forest cover change of 1168.65 ha (12%) was detected during the study period from 1986 to 2018. The drop in the NDVI from 0.06–0.64 in 1986 to (–0.08)–0.12 in 2018 indicated a marked forest cover change in the study area. The correlation of NDVI values with climate data indicated the forest was not in a stable condition. The declining of the forest cover was most likely caused by climate variability in the study area.

8

Seasonality shift and streamfow fow variability trends in central India

Kuriqi Alban, Ali Rawshan, Pham Quoc Bao, Montenegro Gambini Julio, Gupta Vivek, Malik Anurag, Linh Nguyen Thi Thuy, Joshi Yogesh, Anh Duong Tran, Nam Thai Van, Dong Xiaohua

Acta Geophysica

|

2020

|

Vol. 68, no. 5

1461--1475

EN

A better understanding of intra/inter-annual streamfow variability and trends enables more efective water resources planning and management for current and future needs. This paper investigates the variability and trends of streamfow data from fve stations (i.e. Ashti, Chindnar, Pathgudem, Polavaram, and Tekra) in Godavari river basin, India. The streamfow data were obtained from the Indian Central Water Commission and cover more than 30 years of mean daily records (i.e. 1972–2011). The streamfow data were statistically assessed using Gamma, Generalised Extreme Value and Normal distributions to under stand the probability distribution features of data at inter-annual time-scale. Quantifable changes in observed streamfow data were identifed by Sen’s slope method. Two other nonparametric, Mann–Kendall and Innovative Trend Analysis methods were also applied to validate fndings from Sen’s slope trend analysis. The mean fow discharge for each month (i.e. January to December), seasonal variation (i.e. Spring, Summer, Autumn, and Winter) as well as an annual mean, annual maximum and minimum fows were analysed for each station. The results show that three stations (i.e. Ashti, Tekra, and Polavaram) demonstrate an increasing trend, notably during Winter and Spring. In contrast, two other stations (i.e. Pathgudem, Chindnar) revealed a decreasing trend almost at all seasons. A signifcant decreasing trend was observed at all station over Summer and Autumn seasons. Notably, all stations showed a decreasing trend in maximum fows; remarkably, Tekra station revealed the highest decreasing magnitude. Signifcant decrease in minimum fows was observed in two stations only, Chindnar and Pathgudem. Findings resulted from this study might be useful for water managers and decision-makers to propose more sustainable water management recommendations and practices.

9

Eco-biostratigraphic advances in late Quaternary geochronology and palaeoclimate : the marginal Gulf of Mexico analogue

Antonarakou Assimina, Kontakiotis George, Karageorgis Aristomenis P., Besiou Eva, Zarkogiannis Stergios, Drinia Hara, Mortyn Graham P., Tripsanas Efthymis

Geological Quarterly

|

2019

|

Vol. 63, No. 1

178--191

EN

This study combines high-resolution planktonic foraminiferal eco-biostratigraphy and palaeoclimatic data from the high-sedimentation-rate core J PC-26 from the northwestern margin of the Gulf of Mexico (GoM). The eco-biozones recognized (GOMPFE1-12) being correlated with published Mg/Ca-based sea surface temperatures. This updated palaeoclimatic and stratigraphic reference record facilitates correlations with the Greenland ice core events and their climatic relationships, and also provides a solid stratigraphic framework for correlations with other palaeoclimatic and palaeoceanographic records in the circum-GOM/Caribbean region. This multidisciplinary approach underlines the utility of supporting conventional dating methodologies with different constraints, and further reveals a powerful tool for reliably correlating marine records between comparable deep-sea marginal settings and coeval sequences of this region.

10

The water resources of tropical West Africa: problems, progress, and prospects

Ndehedehe Christopher E.

Acta Geophysica

|

2019

|

Vol. 67, no. 2

621--649

EN

West Africa plays key roles in global climate and shows one of the strongest variations in hydro-climatic conditions. As it turns out, the region appears to be underrepresented in the existing compendium of Earth science and hydrology-focused journal papers when it comes to significant discussion on terrestrial hydrology and freshwater science. This prominent gap is largely precipitated by increasing number of constraints that include lack of considerable and robust investments in gauge measurements for meteorological and hydrological applications, poor funding of research institutions and other disincentives, among other factors. In this manuscript, the challenges and problems in large-scale terrestrial hydrology-focused investigation in West Africa are reviewed. Using a dossier of some recent contributions in the field of remote sensing hydrology, this review also highlights some of the progress in terrestrial hydrology and the opportunities that exist for hydro-geodetic research in West Africa that leverage on sustained investments in satellite geodetic missions. It is noted that West Africa is still a pristine environment for hydrology-focused research and can benefit from recent advancements in sophisticated space agency programs such as the Gravity Recovery and Climate Experiment, which undoubtedly has revolutionized terrestrial hydrology research around the world for nearly two decades. Given the poor density of gauge stations and limited ground observations, hydrological research in West Africa is expected to benefit more from independent space observations and multi-resolution data. This is because the lack of sufficient in-situ data for the parameterizations and adequate initialization of outputs from hydrological models and reanalysis data for hydrological applications results in poor representation of the West African land surface and hydrological state variables. To further improve our contemporary understanding of West Africa’s terrestrial hydrology, the continued evaluation/validation of these observations and space-borne measurements is advocated.

11

IV Naukowo-Samorządowa Konferencja „Gospodarka wodna w dobie zmian klimatu”

Wroński S., Turowski L., Kunicka M., Marciniak Ż.

Gospodarka Wodna

|

2016

|

Nr 5

151--157

12

Wpływ warunków klimatycznych na system fluwialny i melioracje wodne w pradolinach w rejonie Łowicza i Koźmina (Polska Środkowa)

Kobojek E.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

|

2015

|

Vol. 24, No. 4

381--390

PL

Artykuł przedstawia wpływ warunków klimatycznych na system fluwialny i meliorację w ostatnich 200 latach. Badania przeprowadzono w pradolinach w środkowej Polsce. Doliny te są bardzo ważnymi elementami nizinnego krajobrazu. Na przełomie wieków XVIII i XIX dna pradolin były zabagnione i kształtowane przez rzeki wielokorytowe. System rzeczny był związany z okresem większych opadów małej epoki lodowej. Takie warunki środowiskowe były bardzo uciążliwe dla gospodarki, dlatego podjęto decyzje o regulacji rzek i melioracji w pierwszej połowie XIX wieku. Prace melioracyjne przeprowadzono jeszcze w dwóch etapach w XX wieku (1928–1932 i 1961–1974). Prace wykonano w wilgotniejszych okresach i po dużych powodziach.

EN

This article presents the influence of climatic conditions on the fluvial system and reclamation in the last 200 years. The research has been conducted in proglacial valleys in Middle Poland. These valleys are extremely important element of the lowland landscape. Between the 18th and 19th century valley floors were paludified and formed by multichannel river system. That river system was connected with periods of higher rain-fall, related to the Little Ice Age. Such natural conditions were troublesome for the economy which is why it was undertaken to regulate the river and reclamation in the first half of the 19 th century. The reclamation was conducted in two stages of the 20th century (1928–1932 and 1961–1974). The operation was realized in wet periods and after major floods.

13

Seasonal temperature extremes in Potsdam

Kundzewicz Z.W., Huang S.

Acta Geophysica

|

2010

|

Vol. 58, no. 6

1115-1133

EN

The awareness of global warming is well established and results from the observations made on thousands of stations. This paper complements the large-scale results by examining a long time-series of highquality temperature data from the Secular Meteorological Station in Potsdam, where observation records over the last 117 years, i.e., from January 1893 are available. Tendencies of change in seasonal temperature- related climate extremes are demonstrated. "Cold" extremes have become less frequent and less severe than in the past, while “warm” extremes have become more frequent and more severe. Moreover, the interval of the occurrence of frost has been decreasing, while the interval of the occurrence of hot days has been increasing. However, many changes are not statistically significant, since the variability of temperature indices at the Potsdam station has been very strong.

14

Charakterystyka okresu wegetatywnego w rejonie Bydgoszczy w latach 1949-2008

Żarski J., Dudek S., Kuśmierek-Tomaszewska R., Banaszewska D.

Ekologia i Technika

|

2009

|

R. 17, nr 3

120-126

PL

Celem pracy było opracowanie charakterystyki okresu wegetacyjnego w rejonie Bydgoszczy na podstawie 60-letniej (1949-2008), nieprzerwanej serii pomiarów temperatury powietrza, wykonywanych w Stacji Badawczej UTP Bydgoszcz w Mochełku ( =53°13', =17°51', h=98,5 m npm). Na podstawie temperatur wyznaczono daty początku, końca oraz długości trwania okresu wegetacyjnego w oparciu o metodę rachunkową i wzory Gumińskiego, przyjmując próg termiczny okresu wegetacyjnego 5,0°C. Stwierdzono, iż okres wegetacyjny w rejonie Bydgoszczy rozpoczyna się przeciętnie 30 marca i trwa 219 dni do 3 listopada. Wykazano bardzo dużą niestabilność czasową charakterystyk okresu wegetacyjnego, właściwą dla umiarkowanego i przejściowego klimatu Polski. Zbliżonego do średnich warunków okresu wegetacyjnego w rejonie Bydgoszczy możemy spodziewać się w około 40% lat, czyli przeciętnie raz na 2,5 roku. W pozostałych latach charakterystyki okresu wegetacyjnego wykazują odstępstwo od normy, przy czym bardziej niestabilna jest data początku okresu wegetacyjnego, w porównaniu z dalą jego końca. Stwierdzono, ze w ostatnim 60-leciu w rejonie Bydgoszczy nie nastąpiła żadna, dająca się udowodnić statystycznie zmiana, dotycząca zarówno długości trwania okresu wegetacyjnego, jak i jego kalendarzowych dat początku i końca.

EN

The study is a climatological characteristic of a growing season variability in the region of Bydgoszcz. The work is based on 60-year period of a constant air temperatur measurements taken in the Research Centre of the Faculty of Agriculture UTP, in Mochelek (cp=53o13', X=17o51', h=98,5 m a.s.l.). Diurnal air temperature was the fundamental element to estimate the date of beginning, end and the duration of growing season using an arithmetic method and the equations by Gumiński. The temperature of 5,0°C was a thermal level of the growing season. It was found that the growing season in the region of Bydgoszcz begins on the 30th of March and lasts 219 days until the 3rd of November. A great instability of growing season factors was confirmed during the analyzed period, which is typical for the moderate and transition climate in Poland. Therefore, in 40% of years (one per 2,5 year ) the mean conditions of growing season can be expected. For the rest of the time some deviations from the climatological standard norm were proved. However, the date of beginning is more instable compared to the date of its end. It was ascertained that during the last 60-year period there were no statistically confirmed changes of the duration, the date of beginning and the date of end of growing season in the region of Bydgoszcz.

15

Dwutlenek węgla a zmiany klimatu

Lityński J.

Przegląd Geofizyczny

|

2006

|

Z. 1

5-23

PL

Przeprowadzono weryfikację dwóch hipotez dotyczących przepływu dwutlenku węgla między powierzchnią Ziemi i atmosferą. Hipoteza IPCC zakładająca pochłanianie przez powierzchnię niezależne od stężenia CO2 (P = const) nie sprawdza się. Nasza hipoteza P = aS prowadzi do równania różniczkowego S' + aS = W" + Wx(t), gdzie S jest stężeniem CO2, a- współczynnikiem pochłaniania, W" - wydzielaniem naturalnym przez powierzchnię (stałym), Wx(t) rosnącą w czasie produkcją CO_2 przez człowieka. Istniejące prostolinijne odcinki krzywych: stężenia S(t) i produkcji przez człowieka Wx(t) (1845- -1920 oraz 1970-2004) pozwalają na analityczne rozwiązanie problemu. Rozwiązaniami szczególnymi wyjściowego równania różniczkowego spełniającymi warunki brzegowe są funkcje: Sj = C, + m,t/a oraz S2 = C2 + m^/a. Stąd można wyznaczyć współczynnik pochłaniania: a = 0,038 rok~1. Funkcje te spełniają równanie wyjściowe, w którym była użyta hipoteza P = aS i dają rozwiązanie pokrywające się z krzywą pomiarową. Jest to dowodem, że hipoteza P = aS jest prawdziwa. Na rys. 7(b) pokazano, jak zmieniałoby się stężenie CO2, gdyby ludzka produkcja ustaliła się na obecnym poziomie (7,1 GTC /rok), a na rys. 8 dokonano przeglądu czterech różnych wariantów. W tabeli 1 zestawiono czynniki, które wpłynęły na bilans energetyczny powierzchni Ziemi w ubiegłym stuleciu, a w tabeli 2 czynniki prognozowane na następne stulecie.

EN

We conducted the verification of two hypotheses dealing with the exchange of CO2 between the Earth's surface and the atmosphere. The IPCC hypothesis according to which the absorption is not dependant on the concentration of CO2 (P = const) does not prove to be true (fig. 5). Our hypothesis p = aS leads to the differential equation: S' + aS = W" + Wx(t), where S is the concentration of CO2, a is the coefficient of absorption, W" is the natural emission by the surface (constant), Wx(t) is the growing production by man in time. The existing linear sections of the curves: the concentration curve S(t) and man's production curve Wx(t) (1845-1920 as well as 1970-2004) allow for the analytical solution of the problem. Particular solutions of the basic differential equation fulfilling the border conditions are functions: S, = Q + m^/aas well as S2 = C2 +m2t/a. Based on this we can appoint the coefficient of absorption: a = 0,038 year -'. Each of functions S, and S2 fulfils a basic equation in which the hypothesis P - aS was used, giving a solution covered in the measuring curve. This proves that the hypothesis P = aS is true. Fig. 7(b) shows how the concentration of CO2 would change if the anthropogenic production would remain at the current level (7,1 GTc/year) and fig. 8 gives an overview of four different models. Table 1 gives an overview of the factors which affected the energy balance of the earth surface in the last century and table 2 gives an analogical overview of the predicted factors for the next century.

16

Intense precipitation and high river flows in Europe - observations and projections

Kundzewicz Z. W.

Acta Geophysica Polonica

|

2005

|

Vol. 53, nr 4

385--400

EN

Several destructive floods have occurred in the last decade in Europe, causing record high material damage. The question of detection and attribution of changes in various flood-related indices attracts increasing interest. Among the mechanisms that can impact flood risk are changes in socio-economic systems, which influence terrestrial systems, and changes in the climatic system. The atmosphere's water holding capacity (and hence potential for intense precipitation) increases with temperature and more intense precipitation has been documented in the warming world. However, a general and coherent increase in high river flows has not been detected. Results of change detection studies of daily river flow in Europe show that the overall maxima (for the 1961-2000 period) occurred more frequently in the subperiod 1981-2000 than in the subperiod 1961-1980. Regional changes in the timing of floods have been reported in many areas of Europe, with increasing incidence of late autumn and winter floods (caused by rain) and fewer spring snowmelt floods. Also, the number of ice-jam related inundations has decreased. On the other hand, intensive and long-lasting summer precipitation episodes have led to disastrous floods in Central Europe (cf. the 1997 Odra/Oder flood, the 2001 Vistula flood, and the most destructive 2002 deluge on the Labe/Elbe), and river flooding has been recently recognized as a major hazard in the region. Significant differences between future projections and the reference period, indicating the likelihood of increasing flood hazard, have been identified in both intense precipitation and high flows.

17

Wielkość zachmurzenia w Polsce a epoki cyrkulacyjne

Żmudzka E.

Przegląd Geofizyczny

|

2004

|

Z. 1-2

25-42

EN

The aim of this paper is to determine long-term variation of certain characteristics of mean cloudiness in an annual course in Poland in years 1951-2000. Atmospheric circulation is seen as a determining factor of the cloudiness variation. The annual course of cloudiness is characterized by seasonal values, annual range and by winter and summer deviations from 50-year-means. The analysis performed shows distinctly that years of nephological changes in Poland are also years of boundaries between circulation epochs in different divisions of the second half of the 20th century (half of 60., half of 70. and around year 1983). This is because cloudiness is an element of climate determined mainly by circulation processes acting in a macro-scale. Most of the cloudiness variations in Poland can be explained by direct influence of atmospheric circulation; the west and the meridional components of atmospheric circulation on Central Europe and atmospheric pressure in the centre of this area can explain from 29% (turn of autumn and winter) up to 70% (July) of variability of mean monthly cloudiness values. In autumn and in the average situation in a course of a year the cloudiness depends mainly on the direction of air-mass flow - the meridional component. The role of the pressure values is similar to that of the west component. In other seasons the cloudiness is mainly determined by the atmospheric pressure in the centre of the Central Europe. Among directions of circulation in summer more important is a zonal component, however in spring and in winter - the meridional one. Complexity and seasonal diversification of circulation influence on cloudiness values (essential are: the atmospheric pressure pattern, direction of air-mass flow, frequency of fronts passes and their characters,...) and also often complex character of the circulation epochs make changes in characteristics of cloudiness in a course of a year in each epochs being not unequivocal (similarly as in a situation of air temperature and precipitation).

18

Mit efektu cieplarnianego

Boryczka M.

Przegląd Geofizyczny

|

2004

|

Z. 1-2

43-56

EN

Global warming is mostly believed to be caused by the anthropogenic factor of atmosphere's greenhouse effect - increasing carbon dioxide (CO2) content, resulting from carbon combustion. The 1990 IPCC Report forecasted the rise of temperature on Earth in 2030 by 1.5-4.5°C (after the doubling of pre-industrial atmospheric 280 CO(2) ppm content, in the 2xCO(2) scenarios), and the 1995 IPCC Report estimated a 1-3.5°C rise in 2100 (taking into account the sulphate aerosols). Climate warming, however, is mainly affected by natural causes, i.e. increased Sun activity and lower volcanic activity on Earth. It is still unknown which portion of the advancing warming process is caused by the results from the increasing amount of solar energy reaching Earth, and which depends on the anthropogenic nature of atmosphere's greenhouse effect. The following factors point to the prevalence of natural factors: similar regression lines of standardised Sun activity values (Wolf's numbers) and air temperature in Warsaw between 1779-2000, synchronic variations of mean Northern Hemisphere air temperature between 1856-2002, 11-year running means of Wolf's numbers, synchronic fluctuations of Wolf's numbers and centre of mass position of the four biggest planets, and weak correlation between extreme air temperatures and CO(2) concentration evaluated based on carbon combustion amount. Further evidence of natural causes for climate warmings comes from the synchronicity of changes in carbon dioxide concentration and paleotemperature within the last 160 000 years and 450 000 years, reconstructed basing on Antarctic ice cores. Warmings occur every 100 000 years. They are triggered by solar radiation increase in large latitudes, resulting from changes in Earth's orbit and Earth's axis slant (based on the commonly accepted Milankovic theory). "Parallelism" of changes in CO(2) concentration and paleotemperature indicates that the atmospheric carbon dioxide content is shaped by sine changes of solar radiation reaching Earth - through fluctuations of ocean temperatures. Hence, it is more credible to claim that "atmospheric CO(2) concentration increases along with the amount of solar radiation reaching Earth (i.e. when it gets warmer)"

19

Elementarne podejście do problemu cykliczności w zjawiskach klimatycznych

Walanus A., Prokop P.

Przegląd Geofizyczny

|

2004

|

Z. 1-2

57-69

EN

The paper presents an elementary approach to the problem of periodicity in climatic data. The basic method applied in this study is the Fourier analysis (FFT). The periodicity was searched on the basis of long term instrumental precipitation data for 46 European stations for the period of 1832-1992, and for W-E and N-E transects for the period 1864-1992. The evidence of cycles in the range 2 to 128 years was examined in terms of their being of natural variability of climate system, or the result of external forcing. The complexity of the climate system with large number of degrees of freedom, and the unstable nature of atmospheric circulation causing difficulties in distinguish real periodicity from noise. The result show that it is relatively easy to obtain quasi-periodicity in climatic data however it is very difficult to find them statistically significant. We can said that disturbances in climate system can produce a quasi-periodic response which behaves sometimes as an oscillation before disappearing back into the noise or appearing in other place and other time.

20

The major Baltic inflow in January 2003 and preconditioning by smaller inflows in summer/autumn 2002 : a model study

Meier H. E. M., Döscher R., Broman B., Piechura J.

Oceanologia

|

2004

|

No. 46 (4)

557-579

EN

Using the results of the Rossby Centre Ocean model (RCO) the Baltic inflows in summer/autumn 2002 and January 2003 have been studied. The model results were extracted from a long simulation with observed atmospheric forcing starting in May 1980. In RCO a bottom boundary layer model was embedded. Both the smaller inflows and the major inflow in January 2003 are simulated in good agreement with observations. We found that a total of 222 km3 water entered the Baltic in January; the salinity of 94 km3 was greater than 17 PSU. In August/September 2002 the outflow through the Sound and inflow across the Darss Sill were simulated. The net inflow volume amounted to about 50 km3.