Search results for "ANNUAL CYCLE"

2020

Abstract. The vertical distribution and seasonal variation of water vapour volume mixing ratio (H2O VMR), of relative humidity with respect to ice (RHice) and particularly of regions with ice-supersaturated air masses (ISSRs) in the extratropical upper troposphere and lowermost stratosphere are investigated at northern mid-latitudes over the eastern North American, North Atlantic and European regions for the period 1995 to 2010. Observation data originate from regular and continuous long-term measurements on board instrumented passenger aircraft in the framework of the European research programme MOZAIC (1994–2010), which continues as the European research infrastructure IAGOS (from 2011). …

Influence of the Laurentian Great Lakes on Regional Climate*

2013

Abstract The influence of the Laurentian Great Lakes on climate is assessed by comparing two decade-long simulations, with the lakes either included or excluded, using the Abdus Salam International Centre for Theoretical Physics Regional Climate Model, version 4. The Great Lakes dampen the variability in near-surface air temperature across the surrounding region while reducing the amplitude of the diurnal cycle and annual cycle of air temperature. The impacts of the Great Lakes on the regional surface energy budget include an increase (decrease) in turbulent fluxes during the cold (warm) season and an increase in surface downward shortwave radiation flux during summer due to diminished atmo…

The genetic regulation of avian migration timing: combining candidate genes and quantitative genetic approaches in a long-distance migrant

2021

Abstract Plant and animal populations can adapt to prolonged environmental changes if they have sufficient genetic variation in important phenological traits. The genetic regulation of annual cycles can be studied either via candidate genes or through the decomposition of phenotypic variance by quantitative genetics. Here, we combined both approaches to study the timing of migration in a long-distance migrant, the collared flycatcher (Ficedula albicollis). We found that none of the four studied candidate genes (CLOCK, NPAS2, ADCYAP1 and CREB1) had any consistent effect on the timing of six annual cycle stages of geolocator-tracked individuals. This negative result was confirmed by direct ob…

Condensation nuclei measurements at theGeorg von Neumayer-Station (F.R.G.), Coastal Antarctica

1991

The analysis of nearly continuous records of surface-based atmospheric condensation nucleiconcentration (CNC) since 1984 up to the present at the Georg von Neumayer-Station (GvN) shows clearly: u - an annual cycle of CNC with low values in winter time; - a significantly increasing frequency of CNC of more than 1000 particles per cm3 over the years.

Geochemical insight into differences in the physical structures and dynamics of two adjacent maar lakes at Mt. Vulture volcano (southern Italy)

2013

[1] We report on the first geochemical investigation of the Monticchio maar lakes (Mt. Vulture volcano, southern Italy) covering an annual cycle that aimed at understanding the characteristic features of the physical structures and dynamics of the two lakes. We provide the first detailed description of the lakes based on high-resolution conductivity-temperature-depth (CTD) profiles, chemical and isotopic (H and O) compositions of the water, and the amounts of dissolved gases (e.g., He, Ar, CH4, and CO2). The combined data set reveals that the two lakes, which are separated by less than 200 m, exhibit different dynamics: one is a meromictic lake, where the waters are rich in biogenic and man…

When the seasons don't fit: Speedy molt as a routine carry-over cost of reproduction

2013

The failure of animals to fit all life-cycle stages into an annual cycle could reduce the chances of successful breeding. In some cases, non-optimal strategies will be adopted in order to maintain the life-cycle within the scope of one year. We studied trade-offs made by a High Arctic migrant shorebird, the red knot Calidris canutus islandica, between reproduction and wing feather molt carried out in the non-breeding period in the Dutch Wadden Sea. We compared primary molt duration between birds undertaking the full migratory and breeding schedule with birds that forego breeding because they are young or are maintained in captivity. Molt duration was ca. 71 days in breeding adults, which wa…

Scavengers on the move: behavioural changes in foraging search patterns during the annual cycle

2013

Background: Optimal foraging theory predicts that animals will tend to maximize foraging success by optimizing search strategies. However, how organisms detect sparsely distributed food resources remains an open question. When targets are sparse and unpredictably distributed, a Lévy strategy should maximize foraging success. By contrast, when resources are abundant and regularly distributed, simple Brownian random movement should be sufficient. Although very different groups of organisms exhibit Lévy motion, the shift from a Lévy to a Brownian search strategy has been suggested to depend on internal and external factors such as sex, prey density, or environmental context. However, animal re…

Last Interglacial Hydroclimate Seasonality Reconstructed From Tropical Atlantic Corals

2018

The seasonality of hydroclimate during past periods of warmer than modern global temperatures is a critical component for understanding future climate change scenarios. Although only partially analogous to these scenarios, the last interglacial (LIG, Marine Isotope Stage 5e, ~127–117 ka) is a popular test bed. We present coral δ18O monthly resolved records from multiple Bonaire (southern Caribbean) fossil corals (Diploria strigosa) that date to between 130 and 118 ka. These records represent up to 37 years and cover a total of 105 years, offering insights into the seasonality and characteristics of LIG tropical Atlantic hydroclimate. Our coral δ18O records and available coral Sr/Ca-sea surf…

Weakening of annual temperature cycle over the Tibetan Plateau since the 1870s

2017

The annual cycle of extra-tropical surface air temperature is an important component of the Earth's climate system. Over the past decades, a reduced amplitude of this mode has been observed in some regions. Although attributed to anthropogenic forcing, it remains unclear when dampening of the annual cycle started. Here we use a residual series of tree-ring width and maximum latewood density from the Tibetan Plateau >4,000 m asl to reconstruct changes in temperature seasonality over the past three centuries. The new proxy evidence suggests that the onset of a decrease in summer-to-winter temperature difference over the Tibetan Plateau occurred in the 1870s. Our results imply that the influen…

Holidays? Not for all. Eagles have larger home ranges on holidays as a consequence of human disturbance

2019

Human-wildlife conflicts are the object of raising concern in conservation biology. People living in urban areas are rapidly increasing worldwide and consequently the temporal pattern of occupation of natural areas for recreation is changing as well, resulting in an ever-increasing concentration of people during weekends and holidays. This is particularly evident in affluent societies, where more recreationists visit natural areas on holidays and weekends, causing disturbance to wildlife in the so-called “weekend effect”. Here, we tested the response to disturbance of 30 Bonelli's eagles tracked by high-frequency GPS/GSM telemetry. We analysed daily home-range size, a measure of changing be…