A partial migrant relies upon a range-wide cue set but uses population-specific weighting for migratory timing

Background Many birds species range over vast geographic regions and migrate seasonally between their breeding and overwintering sites. Deciding when to depart for migration is one of the most consequential life-history decisions an individual may make. However, it is still not fully understood which environmental cues are used to time the onset of migration and to what extent their relative importance differs across a range of migratory strategies. We focus on departure decisions of a songbird, the Eurasian blackbird Turdus merula, in which selected Russian and Polish populations are full migrants which travel relatively long-distances, whereas Finnish and German populations exhibit partial migration with shorter migration distances. Methods We used telemetry data from the four populations (610 individuals) to determine which environmental cues individuals from each population use to initiate their autumn migration. Results When departing, individuals in all populations selected nights with high atmospheric pressure and minimal cloud cover. Fully migratory populations departed earlier in autumn, at longer day length, at higher ambient temperatures, and during nights with higher relative atmospheric pressure and more supportive winds than partial migrants; however, they did not depart in higher synchrony. Thus, while all studied populations used the same environmental cues, they used population-specific and locally tuned thresholds to determine the day of departure. Conclusions Our data support the idea that migratory timing is controlled by general, species-wide mechanisms, but fine-tuned thresholds in response to local conditions.

Synoptic-scale variability of surface winds and ocean response to atmospheric forcing in the eastern austral Pacific Ocean

In the Southern Hemisphere, macroscale atmospheric systems such as westerly winds and the southeast Pacific subtropical anti-cyclone (SPSA) influence the wind regime of the eastern austral Pacific Ocean. The average and seasonal behaviors of these systems are well known, although wind variability at different time and distance scales remains largely unexamined. Therefore, the main goal of this study was to determine the variabilities of surface winds on a spatiotemporal scale from 40 to 56∘ S, using QuikSCAT, Advanced Scatterometer (ASCAT), and the fifth major global European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA5) surface-wind information complemented with in situ meteorological data. In addition, interactions between the atmospheric systems, together with the ocean–atmosphere response, were evaluated for the period 1999–2018. The empirical orthogonal function detected dominance at the synoptic scale in mode 1, representing approximately 30 % of the total variance. In this mode, low and high atmospheric pressure systems characterized wind variability for a 16.5 d cycle. Initially, mode 2 – which represents approximately 22 % of the variance – was represented by winds from the west/east (43–56∘ S), occurring mostly during spring and summer/fall and winter at an annual timescale (1999–2008) until they were replaced by systems cycling at 27.5 d (2008–2015). This reflects the influence of the baroclinic annular mode in the Southern Hemisphere. Mode 3, representing approximately 15 % of the variance, involved the passage of small-scale low and high atmospheric pressure (LAP and HAP) systems throughout Patagonia. Persistent Ekman suction occurred throughout the year south of the Gulf of Penas and beyond the Pacific mouth of the Strait of Magellan. Easterly Ekman transport (ET) piled these upwelled waters onto the western shore of South America when winds blew southward. These physical mechanisms were essential in bringing nutrients to the surface and then transporting planktonic organisms from the oceanic zone to Patagonian fjords and channels. In the zonal band between 41 and 43∘ S, the latitude of Chiloé Island, upward Ekman pumping and Ekman transport during spring and summer favored a reduced sea surface temperature and increased chlorophyll a (Chl a) levels; this is the first time that such Ekman upwelling conditions have been reported so far south in the eastern Pacific Ocean. The influence of the northward-migrating LAP systems on the ocean–atmosphere interphase allowed us to understand, for the first time, their direct relationship with recorded nighttime air temperature maxima (locally referred to as “nighttime heatwave events”). In the context of global climate change, greater attention should be paid to these processes based on their possible impact on the rate of glacier melting and on the austral climate.

Synoptic scale variability of surface winds and expected changes in the ocean–atmosphere dynamics of the eastern Austral Pacific Ocean

In the southern hemisphere, macroscale atmospheric systems such as the westerly winds and the Southeast Pacific Subtropical anti-cyclone (SPSA) influence the wind regime of the eastern Austral Pacific Ocean. The average and seasonal behaviors of these systems are well known, although wind variability at different time and distance scales was previously unexamined. The main goal of this study was, therefore, to determine the space and time scale variabilities of surface winds from 40° to 56° S, using QuikSCAT, ASCAT, and ERA-Interim surface wind information, complemented by in situ meteorological data. In addition, interactions between atmospheric systems, together with the ocean–atmosphere dynamics, were evaluated, from 1999 to 2015. The empirical orthogonal function detected dominance at the synoptic scale in mode 1, representing approximately 30 % of the total variance. In this mode, low and high atmospheric pressure systems characterized wind variability, with a cycle length of 16.5 days. Initially, mode 2, representing approximately 22 % of the variance, was represented by westerly winds (43° to 56° S), which occurred mostly during spring and summer, with an annual time scale (1999–2008), until they were replaced by systems cycling at 27.5 days (2008–2015), reflecting the influence of the Southern Hemisphere's baroclinic annular mode. Mode 3, representing approximately 15 % of the variance, involved passage of small scale, low and high atmospheric pressure (LAP, HAP) systems throughout Patagonia. Persistent Ekman suction south of the Gulf of Penas, and up to and beyond the Pacific mouth of the Magellan Strait, occurred throughout the year. Easterly Ekman transport (ET) piled these upwelled waters onto the western shore of South America, when the winds blew southward. These physical mechanisms were essential in bringing nutrients to the surface, and then transporting planktonic organisms from the oceanic zone into Patagonian fjords and channels. In a variation, between 41° and 43° S, surface wind from the SPSA produced offshore ET during spring and summer, causing reduced sea surface temperature, and increased chlorophyll-a; this is the first time that such upwelling conditions have been reported so far south, in the eastern Pacific Ocean. The influence of northward migrating LAP systems on the ocean–atmosphere interphase allowed us to understand, for the first time, their direct relationship with recorded night time air temperature maxima (locally referred to as Nighttime heat wave events). In the context of global climate change, greater attention should be paid to these processes, based on their possible impact on the rate of glacier melting, and on the austral climate.

Black Sea Baric Depression

This work is meant to demonstrate that, in the special synoptic conditions, on the surface of the Black Sea, a baric depression is being formed. This depression is formed when the Black Sea's water temperature is higher than the surrounding continental ground's temperature. There are situations when the baric depression of the Black Sea occurs because of the consequences of the movement of another baric depression from the east of the Mediterranean Sea to its north-east side. Due to the high atmospheric pressure of the continental zone that's surrounding the Black Sea, the baric depression will get a retrograde movement, towards the north or northwest. Eventually, this depression occludes in the eastern continental zone of Europe or even near the Baltic Sea. During a retrograde movement of a baric depression, the atmospheric precipitations will fall in big quantities, in many situations, causing floods.

The impact of high and low atmospheric pressure in the Jordanian environment on some physiological variable for runners .

<p>The study aimed at identifying the impact of difference between the areas of high atmospheric pressure in the Jordanian environment on some physiological variable ( estimating maximal oxygen consumption , estimating rate of Energy expenditure, and hemoglobin ,vital capacity), for runners .</p><p> The study sample consisted of (16) athletes who practice ( middle and long – distance running). A number of statistical methods were used to answer the questions of the study ( arithmetic means , standard deviations , Mann.Whiteny test ,and the result of Kolmogorov – Smirnov tests ) .</p><p> The study result concluded that there was apriority for the measurements which were conducted on the training groups of low atmospheric pressure in comparison with the other group, with regard to the variables (maximal oxygen consumption , rate of Energy expenditure, and hemoglobin). The study result also showed that there was apriority for the measurements which were conducted on the training groups of high atmospheric pressure in comparison with the other group, regarding to the variables (maximal oxygen consumption , rate of Energy expenditure, and hemoglobin).in the areas of high atmospheric pressure.</p><p>The study result also suggested that ther were no statistically significant differences between two training groups with regard to the study variables of (maximal oxygen consumption , rate of Energy expenditure, and hemoglobin ,vital capacity), were measured in of high atmospheric pressure areas .</p><p>The study recommended about building sports facilities that simulate the areas of low atmospheric pressure , because of the expected role that the factors would play in improving some physiological variables .</p>