217 research outputs found
Selected Spectral Characteristics of Turbulence over an Urbanized Area in the Centre of Łódź, Poland
We present the turbulence spectra and cospectra derived frommore than five years
of eddy-covariance measurements at two urban sites inŁód´z, central Poland. The fast response
wind velocity components were obtained using sonic anemometers placed on narrow masts
at 37 and 42 m above ground level. The analysis follows Kaimal et al. (Q J R Meteorol Soc
98:563–589, 1972) who established the spectral and cospectral properties of turbulent flow in
atmospheric surface layer on the basis of the Kansas experiment. Our results illustrate many
features similar to those of Kaimal et al., but some differences are also observed. The velocity
(co)spectra from Łód´z show a clear inertial subrange with −2/3 slope for spectra and −4/3
slope for cospectra. We found that an appropriate stability function for the non-dimensional
dissipation of turbulent kinetic energy calculated from spectra in the inertial subrange differs
from that of Kaimal et al., and it can be satisfactorily estimated with the assumption of local
equilibrium using standard functions for the non-dimensional shear production. A similar
function for the cospectrum corresponds well to Kaimal et al. for unstable and weakly stable
conditions. The (co)spectra normalized by their spectral values in the inertial subrange are in
general similar to those of Kaimal et al., but they peak at lower frequencies in strongly stable
conditions. Moreover, our results do not confirm the existence of a clear “excluded region”
at low frequencies for the transition from stable to unstable conditions, for longitudinal and
lateral wind components. The empirical models of Kaimal et al. with adjusted parameters fit
well to the vertical velocity spectrum and the vertical momentum flux cospectrum. The same
type of function should be used for longitudinal and lateral wind spectra because of their
sharper peak than occurs for the Kansas data. Finally, it should be stressed that the above
relationships are well-defined for averaged values. The results for individual 1-h periods are
very scattered and can be significantly different from the generalized functions.Funding for this research was provided by the Polish Ministry of Science and Higher
Education (State Committee for Scientific Research) under grant no. N306 276935 for the years 2008–2012
and grant no. N306 519638 for the years 2010–2013
Atlas parametrów meteorologicznych na stacji pomiarowej w Kopytkowie (Biebrzański Park Narodowy) w roku 2013
Praca wykonana w ramach projektu “Bilans absorpcji i emisji gazów cieplarnianych (metanu,
dwutlenku węgla i pary wodnej) na obszarach bagiennych (studium Biebrzańskiego Parku
Narodowego)”sfinansowanego ze środków Narodowego Centrum Nauki przyznanych na podstawie
decyzji numer DECR2011/01/B/ST10/07550
Singularities of the urban climate of Łódź, Central Poland
Published in: Natural environment of Poland and its protection in Łódź University Geographical Research, edited by E. Kobojek and T.MarszałThe results presented in the work show the selected features of local climate modification caused by urbanisation in Łódź, Central Poland. The city structure is similar to many other mid-European towns, but the influences of urbanisation on local climate are not affected here by other factors. Thus, the outcomes of presented investigations can be generalised for many cities of the region. The findings about the urban heat island are similar to those of other cities and they confirm the general rules about the UHI phenomenon, its spatial distribution and temporal variations (see Arnfield 2003 for a comprehensive review). Similarly, the influence of the city on incoming shortwave radiation in Łódź simply quantify well established relations. More unique are the studies on the albedo and the influence of surface geometry on the absorption of radiation. The influence of the town on humidity is more disputable. On the average, our data confirm the findings on the urban-rural contrasts of these elements, but they also show that unlike the UHI evolution, the diurnal course of humidity differences can take different form even in favourable weather conditions. The measurements of turbulent fluxes of sensible and latent heat, carbon dioxide and methane are unique in Poland and one of the few in Europe; thus they just provide new data and extend our understanding of poorly known processes. At the present stage, it is hard to evaluate if these result are case-specific or more general. The comparison with other cities is problematic because of a small number of similar works – there are several concerning urban energy balance, very few on carbon dioxide flux, and almost none about the flux of methane
Daily and annual cycle of urban heat island occurrence in Łódź
During the period of 1992-1996 the meteorological station belonging to Department of
Meteorology and Climatology, University of Łódź worked in the city centre of Łódź. The
station was equiped with standard instruments and attended as a normal climatological station.
The difference between air temperature in a city centre (Tu) and on the outskirts of Łódź
on the local airport Łódź-Lublinek (Tr) was used to define the intensity of urban heat island.
Its significant diurnal and annual periodicity have been observed. The biggest positive
differences have always been noticed during the summer nights when the weather conditions
are most suitable to the creation and duration of heat surplus in city. During winter, UHI
is a scarcity and its intensity is much less significant in average (it is caused by rise of wind's
speed during this season). The relations between intensity of um in Łódź, wind speed and
cloudiness have also been analyzed.W latach 1992-1996 działała w centrum Łodzi Miejska Stacja Meteorologiczna Zakładu
Meteorologii i Klimatologii UL, wyposażona w standardowe przyrządy i obsługiwana w reżimie
pracy stacji klimatologicznej. Dla określenia intensywności miejskiej wyspy ciepła wykorzystano
różnicę temperatury powietrza pomiędzy stacją śródmiejską a stacją zamiejską - w tym przypadku
lotniskową stacją synoptyczną Lódź-Lublinek (fu-Tr). Występowanie miejskiej wyspy ciepła cechuje
się wyraźną cyklicznością dobową i roczną. Największe dodatnie różnice notowano zawsze
w terminie nocnym w okresie lata - najczęściej występują wówczas warunki do tworzenia się
i trwania przez całą noe nadwyżki ciepła w mieście. W zimie mwc zaznacza się rzadziej, a jej
intensywność nie jest z reguły duża, co wynika ze wzmoźonej prędkości wiatru o tej porze roku.
Określono związek natężenia miejskiej wyspy ciepła w Łodzi z wielkościPraca została wykonana przy finansowym wsparciu Komitetu Badań Naukowych - grant nr 6P04E 036 08
Hydrochemical zoning of valley peatlands as a result of water supply conditions: examples from Poland
The chemical composition of water from two peatlands was investigated. Both peatlands, which are nature reserves, are located in central Poland in the Widawka and Rawka River valleys. The study concerned groundwaters, peat waters from different depths, and waters from draining ditches. The research permitted determination of the hydrochemical zoning of the peatlands resulting from the complex character of the water supply. The hydrochemical interpretation of surface waters outflowing alongside the ditches, in terms of their similarity to particular zones, provides an insight into the water-feeding structure of the peatlands. In the evaluation, hydrochemical indicators were applied, which have been used in hydrogeological studies. They are based on equivalent concentrations of the major ions: sodium, calcium, chlorides, and sulphates, selected from other hydrochemical elements by means of principal component analysis (PCA), conducted individually for each peatland. The analyses showed a high contribution of unconfined and confined groundwaters to the water supply, with clearly distinguishable zones, in terms of their transit through the structures of the peatlands
Ekstremalne warunki opadowe w Łodzi w okresie 1931-1995
W opracowaniu analizowano szereg dobowych sum opadu z Łodzi z okresu 1931-1995.
Przedstawiono roczny bieg częstości występowania dni bez opadu i z opadem w poszczególnych
przedziałach wartości. Stwierdzono, że pojawienie się opadu zależy w większym stopniu od
charakteru cyrkulacji niż od kierunku napływu mas. Badano długoletnią zmienność częstości
dni bez opadu, dni z sumą opadu powyżej 10 mm i największej dobowej sumy opadu w roku.
Pokazano, że najwyższe dobowe sumy opadu pojawiają się w dniach o cyrkulacji EoRecord of daily precipitation totals from Łódź from the period 1931-1995 has been
analysed. The annual courses of frequencies of days without precipitation and with precipitation
in particular ranges were presented. It was shown that occurrence of precipitation is stronger
related to the character of circulation than to direction of air mass advection. Long-term
variability of frequencies of days without precipitation, days with totals exceeding 10 mm/day
and long-term variability of the highest daily total during the year were analysed. It was
shown that the highest daily totals occur in day with circulation of type Eo
Intensywność miejskiej wyspy ciepła w Łodzi w okresie zimowym oraz jej prosty model
W opracowaniu przedstawiono dobowy bieg intensywności miejskiej wyspy ciepła w Łodzi
w okresie zimowym. Bazę doświadczalną stanowią wyniki pomiarów temperatury powietrza na
dwóch posterunkach, miejskim i zamiejskim, z okresu od 26 grudnia 1996 do 4 lutego 1997.
Do analizy wybrano 17 nocy z dobrze rozwiniętą miejską wyspą ciepła. W ciągu nocy róźnice
między temperaturą w centrum Łodzi a terenami zamiejskimi wzrastają początkowo bardzo
gwałtownie, następnie łagodnie osiągają maksimum tuź przed wschodem słońca. Podobieństwo
przebiegów temperatury na obu stacjach umoźliwiło skonstruowanie prostego modelu czasowego
rozwoju intensywności miejskiej wyspy ciepła bazującego na zmianach temperatury na obszarach
zamiejskich.W latach 1992-1996 działała w centrum Łodzi Miejska Stacja Meteorologiczna Zakładu
Meteorologii i Klimatologii UL, wyposażona w standardowe przyrządy i obsługiwana w reżimie
pracy stacji klimatologicznej. Dla określenia intensywności miejskiej wyspy ciepła wykorzystano
różnicę temperatury powietrza pomiędzy stacją śródmiejską a stacją zamiejską - w tym przypadku
lotniskową stacją synoptyczną Lódź-Lublinek (fu-Tr). Występowanie miejskiej wyspy ciepła cechuje
się wyraźną cyklicznością dobową i roczną. Największe dodatnie różnice notowano zawsze
w terminie nocnym w okresie lata - najczęściej występują wówczas warunki do tworzenia się
i trwania przez całą noe nadwyżki ciepła w mieście. W zimie mwc zaznacza się rzadziej, a jej
intensywność nie jest z reguły duża, co wynika ze wzmoźonej prędkości wiatru o tej porze roku.
Określono związek natężenia miejskiej wyspy ciepła w Łodzi z wielkością zachmurzenia ogólnego
i prędkością wiatru w poszczególnych terminach obserwacyjnych.During the period of 1992-1996 the meteorological station belonging to Department of
Meteorology and Climatology, University of Łódź worked in the city centre of Łódź. The
station was equiped with standard instruments and attended as a normal climatological station.
The difference between air temperature in a city centre (Tu) and on the outskirts of Łódź
on the local airport Łódź-Lublinek (Tr) was used to define the intensity of urban heat island.
Its significant diurnal and annual periodicity have been observed. The biggest positive
differences have always been noticed during the summer nights when the weather conditions
are most suitable to the creation and duration of heat surplus in city. During winter, UHI
is a scarcity and its intensity is much less significant in average (it is caused by rise of wind's
speed during this season). The relations between intensity of um in Łódź, wind speed and
cloudiness have also been analyzed
Preliminary results of measurements of absolute short wave radiation and UV radiation in Łódź
Celem opracowania jest prezentacja pierwszej serii pOIn1arow (styczeń-lipiec 1997 r.)
całkowitego promieniowania UV w Łodzi, ze szczególnym uwzględnieniem dobowego biegu
promieniowania w różnych warunkach meteorologicznych. Kształt krzywych obrazujących
dzienny przebieg wartości natężenia promieniowania całkowitego - le> promieniowania UV
- I•• oraz stosunku I,.fIe (w %) zdeterminowany jest głównie czynnikami astronomicznymi,
przezroczystością atmosfery, stopniem zachmurzenia nieba. Najwyższa średniodobowa wartość
le wystąpiła podczas bezchmurnej pogody w czerwcu (30 czerwca 1997 r.) - 487 W/m2,
a I,. = 35,5 W/m2• W dniach o dużym zachmurzeniu wartości ulegają zmniejszeniu (np. 19
lipca 1997 r. le =49 W/m2, a I•• = 3,2 W/m2). W bezchmurne dni stosunek I,.fIe wynosi
średnio 3--4%, podczas gdy w dni pochmurne udział nadfioletu wzrasta powyżej 6%.The paper presents the preliminary results of the measurements of DV radiation intensity,I uv' and the total short wave radiation,le'(in W/m 2)in Łódź. The data were collected in the city centre for
the period January-July 1997.
The aim of the work is comparison
of daily courses of IuY'le andthe ratio Iuvfle (in%) during various
weather conditions. The daily courses of Iw and le are similar,
depending on sun position, cloudiness or air transparency.
The radiation is higher during
clear weather reaching maximum daily mean values on 30 June 1997
le=487W/mz and I uv= 35.5W/m2•\ During cloudy weather these
values are lower(le= 49W/m2 and
Iw = 3.2 W/m 2 on 19 July 1997). For fine weather the ratio Iuvfle has well marked daily course with average 3-4% where as cloudy conditions disturb this course and lead to the ratio even more than 6
Simulation of the mean urban heat island using 2D surface parameters: empirical modeling, verification and extension.
The spatial distribution of the annual mean urban heat island (UHI) intensity was simulated applying
empirical models based on datasets from urban areas of Szeged and Debrecen, using simple and easily determinable urban
surface cover variables. These two cities are situated on the Alf¨old (Great Hungarian Plain) and have similar topographic
and climatic conditions. Temperature field measurements were carried out, Landsat satellite images were evaluated, and then
one- and multiple variable models were constructed using linear regression techniques. The selected multiple-parameter
models were verified using independent datasets from three urban settlements. In order to obtain some impression of the
mean UHI patterns in other cities with no temperature measurements available, the better model was extended to urban
areas of four other cities situated in geographical environments similar to Szeged and Debrecen. The main shortcoming
of typical empirical models, namely that they are often restricted to a specific location, is overcome by the obtained
model since it is not entirely site but more region specific, and valid in a large and densely populated area with several
settlements
Reorganization of language centers in patients with brain tumors located in eloquent speech areas – A pre- and postoperative preliminary fMRI study
Introduction
The aim of this study was to determine in pre- and postsurgical fMRI studies the rearrangement of the Broca's and Wernicke's areas and the lateralization index for these areas in patients with brain tumors located near speech centers. Impact of the surgical treatment on the brain plasticity was evaluated.
Materials and methods
Pre- and postoperative fMRI examinations were performed in 10 patients with low grade glial, left-sided brain tumors located close to the Broca's (5 patients) or Wernicke's area (5 patients). BOLD signal was recorded in regions of interest: Broca's and Wernicke's areas, and their anatomic right-sided homologues.
Results
In the preoperative fMRI study the left Broca's area was activated in all cases. The right Broca's area was activated in all the patients with no speech disorders. In the postoperative fMRI the activation of both Broca's areas increased in two cases. In other two cases activation of one of the Broca's area increased along with the decrease in the contralateral hemisphere.
In all patients with temporal lobe tumors, the right Wernicke's area was activated in the pre- and postsurgical fMRI. After the operation, in two patients with speech disorder, the activation of both Broca's areas decreased and the activation of one of the Wernicke's areas increased.
Conclusions
In the cases of tumors localized near the left Broca's area, a transfer of the function to the healthy hemisphere seems to take place. Resection of tumors located near Broca's or Wernicke's areas may lead to relocation of the brain language centers
- …