Typical synoptic situations for thunderstormy days observed over the majority of Poland, and with the highest probability of thunderstorms occurence in the country

Ponencia presentada en: VI Congreso Internacional de la Asociación Española de Climatología celebrado en Tarragona del 8 al 11 de octubre de 2008.[EN]In the present study, we have performed an analysis of synoptic situations in thunderstorm days, during which the thunderstorm phenomenon was noted at at least 80% of meteorological stations located in Poland or at which the probability of an occurrence of days with this phenomenon was the highest and whose frequency explains the occurrence of days with thunderstorms on the highest level. The analysis of synoptic maps from the period 1951-2000 made the isolation of two different synoptic situations characteristic for days with thunderstorms occurring over the entire area of Poland possible. As well two synoptic situation with the highest probability of thunderstorms occurrence and which frequency explains the best the occurrence of days with thunderstorms have been distinguished.[ES]En este estudio realizamos un análisis de las situaciones sinopticas en dias de tormenta, definidas como aquellas que aparecen en al menos el 80% de los observatorios meteorológicos polacos o en que la probabilidad de un acontecimiento de días con este fenómeno era la más alta y cuya frecuencia explica el acontecimiento de días con tormentas al mayor nivel. El análisis de mapas sinópticos a partir del período 1951-2000 permitió el aislamiento de dos situaciones sinópticas características de días con tormentas que ocurren sobre el conjunto de Polonia. También se han identificado dos situación sinópticas con la mayor probabilidad de ocurrencia de tormentas y cuya frecuencia explica el mejor el acontecimiento de días con tormentas

Warunki mikroklimatyczne we wnętrzu boru sosnowego na Mierzei Łebskiej

The observed regularities concerning the differentiation of the temperature of individual layers of the pine forest point to the assumption by the tree crowns of the role of the active surface, which is served by the soil surface in the area devoid of vegetation. This is supported among others by the higher values of air temperature to a height of 6 m above ground level between 12.00–15.00 hours, this means during the maximum of the intensity of solar radiation (Molga 1970). Moreover the lowest values of air temperature appears to a bottom part of the pine forest above ground level between 15.00–8.00 hours. The inversion of temperature near the ground is a natural phenomenon in the night hours, particularly at dawn. If no compact vegetation layer is present, it comes into being during calm nights and in the predawn hours above the active surface (above the ground) due to the radiation of heat from the ground zone to higher layers of the atmosphere. Appearance of the cool layer in the bottom part of pine forest under the hight of 6–8 m above ground level during the points to the assumption of the role of the active surface by pine crowns at this very height (Molga 1970; Paszyński et al. 1999). Differences in temperature between the open area and the forest interior or the layer of air above the forest point to the differentiation of energy exchange processes, this being dependent on the nature of the active surface. The forest area is characterised by a clearly lower albedo value than the area of the grey sand dune upon which the MAWS 201 station is located. In addition, forest areas may accumulate a greater amount of heat during the day than the sandy soil covered with grassy vegetation. The stored heat, the quantity of which depends both on the heat capacity and the albedo value, is transferred to the atmosphere in the night. Thus, the layer of atmosphere above the forest is usually warmer at night than the air located above the ground not covered with dense and tall vegetation. During the day, the soil is considerably warmer than the active surface of the forest, which results from the lower heat capacity of the soil. For this reason, a considerably greater quantity of energy radiates in a longwave form than in the case of the forest, and thus the temperature of air above the ground during the day is higher (Paszyński et al. 1999). During the day, the interior of the forest is in turn cooler than the areas devoid of vegetation due to considerably weaker solar radiation reaching the forest bed. At night, however, due the emission of additional quantities of heat from the tall vegetation and the more difficult emission of energy from the forest soil to the atmosphere above the forest (due to its absorption by the vegetation), the temperature of air inside the forest is usually higher than in the area devoid of vegetation (Geiger 1942; Molga 1970). The distribution of humidity in individual layers of the researched forest community does not differ considerably from the results of research carried out on this topic by other authors. The greater content of water vapour in the air inside the forest in comparison with the open area results directly from the considerable intensity of evaporation of the lower active surface of the forest. The maintenance of the greatest air humidity in the lower zone of pine crowns is most probably connected with their additional transpiration (apart from the transpiration of vegetation of the forest bed) and low wind velocities, which make it possible for water vapour to gather and remain in this zone (Molga 1970).A6115716

Changes in lake ice cover on the Morskie Oko Lake in Poland (1971-2007)

On the basis of data from the period 1971-2007, and by applying trend analysis, a study on formation, disappearance and duration of lake ice cover on the Morskie Oko Lake in the Tatra Mountains in southern Poland was carried out. The results show decreasing trends in the maximum thickness of winter lake ice cover and in duration of lake ice phenomena, while air temperature recorded at the same period at the foot of the Tatra Mountains shows increasing trend. There are strong relationships between the course of lake ice phenomena and air temperature

Variability of summer meteorological and biometeorological conditions in the Ebba Valley region (Central Spitsbergen)

Variability of summer meteorological and biometeorological conditions on the topoclimatic scale in the 2008–2010 summer season in the Ebba Valley region (Central Spitsbergen) was investigated. Three measurement sites, representing different altitudes and topography, as well as different types of active surfaces typical of Spitsbergen, were chosen, where automatic, hourly recorded, measurements were taken. The mean diurnal course of the basic meteorological and biometeorological parameters (i.e. air surface temperature, relative humidity, wind speed and wind direction, global solar radiation, wind chill temperature, cooling power, etc.), was computed for each of the three sites, which demonstrated spatial and temporal variability of biometeorological and weather conditions. Furthermore, four relevant weather types which may appear in the summer in different environments represented by the three measurement sites were distinguished. They can be defined as follows: type 1 – cold and windy weather, type 2 – cold and wet weather, type 3 – sunny weather (moderately windy and relatively warm), type 4 – warm and cloudy weather. The characteristics and occurrence of each of these types were described.517211Badania Fizjograficzn

Lokalne zróżnicowanie parametrów wiatru na Mierzei Łebskiej (Słowiński Park Narodowy)

The daily course of wind speed and direction over chosen active surfaces close to the sea shore on the Łeba Bar have been analysed. Measurements took place in the vicinity of the field station of the Department of Climatology, Adam Mickiewicz University in the period from the 1st of July until 25th of August 2009. Two measurement posts, representing different morphological and plant zones were chosen: 1) the frontal dune, 2) coniferous forest, and additionally, the measurements from an automatic meteorological station, located at the grey dune in the topographic low behind the frontal dune, were used. The daily cycle of wind speed changes, with its maximum in the early afternoon and minimum at night, was identified at both measurement posts. Wind speed decreases towards the land interior. The difference of a few hundred meters distance from the sea shore between posts 1 and 2 causes substantial decrease in wind speed. Additionally, the topography of the second post, which is located in the forest, in the depression behind the frontal dune, strongly reduces wind speed. The breeze circulation was weak during the measurement period while the macroscale western circulation was dominant with shorter periods when the eastern flow dominated. The effect of the night breeze was expressed by southern deviation of wind direction and the daily breeze in the afternoon, whereas in the evening the northern directions dominated.A6111912

Topoclimatic differentiation of the area of the Słowiński National Park, northern Poland.

The primary objective of the study was to elaborate a synthetic topoclimatic map of the area of the Słowiński National Park (SNP). The spatial scopes of individual types of topoclimate were distinguished using the method proposed by Paszyński (1999). Pursuant to this method, the topoclimatic classifi cation – and subsequently topoclimatic charting – is performed on the basis of an analysis of the exchange of energy between the atmosphere and its base. The research conducted allowed us to determine that the SNP contains 12 types of local climate, and also to designate the spatial scopes thereof

Charakterystyka topoklimatyczna fragmentu wybrzeża klifowego w rejonie Białej Góry (Woliński Park Narodowy)

W opracowaniu wykorzystano pomiary: albedo, bilansu promieniowania, temperatury i wilgotnooeci wzglêdnej z siedmiu stanowisk obserwacyjnych rozlokowanych w profilu poprzecznym do brzegu morskiego od pla¿y do buczyny na wysoczyŸnie morenowej. Stwierdzono zró¿nicowany przebieg dobowy analizowanych elementów meteorologicznych, zale¿ny od konfiguracji i pokrycia terenu. Punkty pomiarowe zlokalizowane na obszarze ods³oniêtym charakteryzuj¹ siê wiêkszymi amplitudami temperatury i wilgotnooeci powietrza ni¿ usytuowane na terenie zalesionym czy na stokach klifu. Wystawienie na bezpooerednie promieniowanie s³oneczne powoduje znaczny wzrost temperatury przy pogodzie bezchmurnej. Ods³oniêcie terenu pozwala te¿ na wiêksze wypromieniowanie w zakresie d³ugofalowym w nocy, co obni¿a poranne minimum temperatury. Specyficzn¹ termik¹ charakteryzuje siê obszar pla¿y.Wyniki pomiarów potwierdzaj¹ oddzia³ywanie Ba³tyku, który znacz¹co zmniejsza dobow¹ amplitudê temperatury powietrza. Termika analizowanych stanowisk pomiarowych jest oecioele powi¹zana z wartooeci¹ bilansu radiacyjnego, która g³ównie zale¿y od natê¿enia bezpooeredniego promieniowania S³oñca docieraj¹cego do pod³o¿a, albedo oraz pojemnooeci cieplnej gruntu.6072

Točnost prognoza temperature zraka dobivenih odabranim kratko- i dugoročnim numeričkim modelima prognoze vremena iznad Poljske

The article discusses the results of air temperature forecasts from four short-term and two long-term forecasts of numerical weather prediction models. The analysis covered the results of model simulations from January 2015 to January 2016 and compared them at 14 meteorological stations in Poland. The comparison was made based on the most commonly used measures for continuous parameters i.e., ME (mean error), MAE (mean absolute error), RMSE (root mean square error), MSE (mean square error), BIAS and Pearson correlation. In the short time horizon, the best results in the context of the MAE, RMSE, MSE and correlation values were obtained by the Unified Model, although the diagnosed differences between the models are small. All models in the 0–72 h projection horizon reached a correlation of 0.95–0.97 and an MAE in the range of 1.5 °C to 2.1 °C. In the case of long-term forecasts, the HIRLAM model was slightly better than the GFS model. Clearly, in both cases, there is a marked decrease in quality after the fourth and in the following forecast lead days.U članku se razmatraju rezultati prognoze temperature zraka pomoću četiri kratkoročna i dva dugoročna numerička modela prognoze vremena. Analiza je obuhvatila rezultate simulacija modela od siječnja 2015. do siječnja 2016., koji su uspoređeni s podacima 14 meteoroloških postaja u Poljskoj. Usporedba je izrađena na temelju najčešće korištenih mjera za kontinuirane parametre, tj ME (srednja pogreška), MAE (srednja apsolutna pogreška), RMSE (korijen srednje kvadratne pogreške), MSE (srednja kvadratna pogreška), BIAS i Pearsonova korelacija. Za ovako kratak vremenski interval, u kontekstu vrijednosti MAE, RMSE, MSE i korelacije, najbolji rezultati dobiveni su ujedinjenim modelom, iako su utvrđene razlike među modelima male. Svi modeli su u prognostičkom vremenu od 0 do 72 h dostigli korelaciju od 0,95 do 0,97 i MAE u rasponu od 1,5 °C do 2,1 °C. U slučaju dugoročnih prognoza model HIRLAM bio je nešto bolji od GFS modela. Jasno je da u oba slučaja dolazi do znatnog smanjenja kvalitete nakon četvrtog i sljedećih prognostičkih dana