Interannual Temperature Fluctuations Research Articles

RARE: The Regional Arctic Reanalysis

Abstract This paper describes the new Regional Arctic Ocean/sea ice Reanalysis (RARE) with a domain that spans a subpolar/polar cap poleward of 45°N. Sequential data assimilation constrains temperature and salinity using World Ocean Database profiles as well as in situ and satellite SST, and PIOMAS sea ice thickness estimates. The 41-yr (1980–2020) RARE1.15.2 reanalysis with resolution varying between 2 and 5 km horizontally and 1–10 m vertically in the upper 100 m is examined. To explore the impact of resolution RARE1.15.2 is compared to a coarser-resolution SODA3.15.2, which uses the same modeling and data assimilation system. Improving resolution in the reanalysis system improves agreement with observations. It produces stronger more compact currents, enhances eddy kinetic energy, and strengthens along-isopycnal heat and salt transports, but reduces vertical exchanges and thus strengthens upper ocean haline stratification. RARE1.15.2 and SODA3.15.2 are also compared to the Hadley Center EN4.2.2 statistical objective analysis. In regions of reasonable data coverage such as the Nordic seas the three products produce similar time-mean distributions of temperature and salinity. But in regions of poor coverage and in regions where the coverage changes in time EN4.2.2 suffers more from those inhomogeneities. Finally, the impact on the Arctic of interannual temperature fluctuations in the subpolar gyres on the Arctic Ocean is compared. The influence of the subpolar North Pacific is limited to a region surrounding Bering Strait. The influence of the subpolar North Atlantic, in contrast, spreads throughout the Nordic seas and Barents Sea in all three products within two years. Significance Statement The Arctic Ocean/sea ice system plays crucial roles in climate variability and change by controlling the northern end of the oceanic overturning circulation, the equator to pole air pressure gradient, and Earth’s energy balance. Yet the historical ocean observation set is sparse and inhomogeneous, while ocean dynamics has challengingly fine horizontal and vertical scales. This paper introduces a new Regional Arctic Ocean/sea ice Reanalysis (RARE) whose goal is to use the combined constraints of mesoscale ocean dynamics, historical observations, surface meteorology, and continental runoff in a data assimilation framework to reconstruct historical variability. RARE is used to produce a 41-yr ocean/sea ice reanalysis 1980–2020 whose results are described here.

Six decades of North American bird banding records reveal plasticity in migration phenology.

The timing of avian migration has evolved to exploit critical seasonal resources, yet plasticity within phenological responses may allow adjustments to interannual resource phenology. The diversity of migratory species and changes in underlying resources in response to climate change make it challenging to generalize these relationships. We use bird banding records during spring and fall migration from across North America to examine macroscale phenological responses to interannual fluctuations in temperature and long-term annual trends in phenology. In total, we examine 19 species of North American wood warblers (family Parulidae), summarizing migration timing from 2,826,588 banded birds from 1961 to 2018 across 46 sites during spring and 124 sites during fall. During spring, warmer spring temperatures at banding locations translated to earlier median passage dates for 16 of 19 species, with an average 0.65-day advancement in median passage for every 1°C increase in temperature, ranging from 0.25 to 1.26 days °C-1 . During the fall, relationships were considerably weaker, with only 3 of 19 species showing a relationship with temperature. In those three cases, later departure dates were associated with warmer fall periods. Projecting these trends forward under climate scenarios of temperature change, we forecast continued spring advancements under shared socioeconomic pathways from 2041 to 2060 and 2081 to 2100 and more muted and variable shifts for fall. These results demonstrate the capacity of long-distance migrants to respond to interannual fluctuations in temperatures, at least during the spring, and showcase the potential of North American bird banding data understanding phenological trends across a wide diversity of avian species.

The Influence of Current Temperature Fluctuations on the Economic Activity of the Baikal Region1

ABSTRACT This article reviews a number of characteristics of the heating season in the Baikal region’s south both over many years and interannually. It uncovers a 6- to 10-day reduction in the heating seasons of recent decades (from 1991 through 2017) as compared to long-term data up to 1960. It also shows noticeable growth in outside temperature during the heating season: 3.9°C in Chita, 4.1°C in Irkutsk, and 5.0°C in Ulan-Ude. In the aggregate, changes in these indicators influenced the 15–19 percent decrease in the index of fuel consumption. An analysis of interannual fluctuations in heating season characteristics from 1991 through 2017 uncovered that anomalously low temperatures have greater magnitudes and are seen more frequently than anomalously warm winters. The index of fuel consumption varied by 14—20 percent interannually. This is comparable to long-term fluctuations (to 1960). It is demonstrated that against the background of ongoing warming, abrupt interannual temperature fluctuations are showing an ambiguous effect on economic activity in the Baikal region.

Microbial Diversity in a North Western Mediterranean Sea Shallow Coastal Lagoon Under Contrasting Water Temperature Conditions

Temperature and light mainly drive seasonal dynamics of microbial planktonic diversity in coastal ecosystems; however, disentangling their effects is challenging because they are always tightly coupled. Shallow coastal lagoons exhibit intense temperature changes throughout the year and high interannual temperature fluctuations, offering the opportunity to study temperature effects on microbial community diversity and succession. Weekly sampling at 16s and 18s rRNA gene OTU diversity associated with high-frequency meteorological and hydrological monitoring was conducted in the northwestern Mediterranean Thau Lagoon (South of France) from winter to spring in 2015 and 2016. While 2015 was a normal climatic year, 2016 had the warmest winter ever recorded in southern France. Water temperature was found to be the main driver of community diversity and succession from winter to spring. During the normal temperature year of 2015, bacterial communities were dominated by Proteobacteria and Bacteroidetes, archaeal community by Thaumarachaeota, and unicellular eukaryotes mainly by picochlorophytes (Bathycoccus prasinos, Micromonas bravo, and Ostreococcus spp.) in winter and diatoms (Chaetoceros spp.) in spring. The unusually warm year 2016 benefited Actinobacteria (ML602J-51), Cyanobacteria (Synechococcus), the picoeukaryote Ostreococcus spp., and several dinoflagellates. Our results suggest that in a warmer ocean, smaller organisms will dominate microbial communities in shallow coastal waters, potentially affecting ecosystem services.

Effects of Interannual Environmental Changes on Juvenile Fish Settlement in Coastal Nurseries: The Case of the Adriatic Sea

This study tested generality in the settlement and recruitment patterns of juvenile fish in the coastal Mediterranean as driven by interannual environmental differences. A multivariate analysis of juvenile fish community data, sampled over three consecutive years, was conducted to elucidate the interannual changes of new settlers’ occurrence and abundance in different nurseries along the eastern Adriatic coast. Sites were assigned to four groups of nurseries based on water type (marine or transitional) and geographical position (north or south). Statistically significant interannual differences were found in temperature but not in salinity. In general, species occurrence significantly fluctuated between years and seasons. The highest total abundance of juveniles was observed in the significantly warmer year 2018 within all study groups. Defined groups expressed significant annual differences in species richness and abundance related to variations in water temperature and salinity as environmental factors for the same consecutive years. Nurseries within transitional waters in the north are more prone to interannual water temperature changes. The associated community composition differed most from those recorded in southern marine waters, where groups were mostly defined by salinity influence and were least sensitive to interannual temperature fluctuations. The cold and rainy spring in 2019 caused late settlement and longer retention of specific economically and ecologically important fish species in the nurseries. The results suggested that settlers’ delay or retention due to negative temperature deviation in the spawning period were linked to the nurseries located in the northern transitional waters that are under a stronger coastal influence. These delays can have ecological consequences on population dynamics and on inter- and intraspecific relationships within specific nursery communities.

СОВРЕМЕННОЕ РАСПРОСТРАНЕНИЕ И ПОТЕНЦИАЛЬНЫЙ АРЕАЛ ВИДА GENTIANOPSIS BARBATA (FROEL.) MA НА ЮЖНОМ УРАЛЕ И СОПРЕДЕЛЬНЫХ ТЕРРИТОРИЯХ

The aim of the study is to analyse the distribution and the potential range of Gentianopsis barbata (Froel.) Ma in the Southern Urals. Maxent software was used for modeling. BIOCLIM (CHELSA) climate variables as well as the variables of a digital elevation model were used as predictors for modeling. The results of the potential range modeling have shown that despite being confined to habitats with a high moisture regime, high habitat suitability for this species is found mainly in areas with a fairly arid climate. At the same time, the main habitats of G. barbata are connected with slightly saline wet meadows located in floodplains of steppe rivers, along lake shores and mainly used as hayfields. Thus, moisture variability associated with interannual fluctuations in temperature and precipitation can weaken competition with other species and create suitable conditions for seed regeneration of this annual and biennial species.

Influence of temperature fluctuations on equilibrium ice sheet volume

Abstract. Forecasting the future sea level relies on accurate modeling of the response of the Greenland and Antarctic ice sheets to changing temperatures. The surface mass balance (SMB) of the Greenland Ice Sheet (GrIS) has a nonlinear response to warming. Cold and warm anomalies of equal size do not cancel out and it is therefore important to consider the effect of interannual fluctuations in temperature. We find that the steady-state volume of an ice sheet is biased toward larger size if interannual temperature fluctuations are not taken into account in numerical modeling of the ice sheet. We illustrate this in a simple ice sheet model and find that the equilibrium ice volume is approximately 1 m SLE (meters sea level equivalent) smaller when the simple model is forced with fluctuating temperatures as opposed to a stable climate. It is therefore important to consider the effect of interannual temperature fluctuations when designing long experiments such as paleo-spin-ups. We show how the magnitude of the potential bias can be quantified statistically. For recent simulations of the Greenland Ice Sheet, we estimate the bias to be 30 Gt yr−1 (24–59 Gt yr−1, 95 % credibility) for a warming of 3 °C above preindustrial values, or 13 % (10–25, 95 % credibility) of the present-day rate of ice loss. Models of the Greenland Ice Sheet show a collapse threshold beyond which the ice sheet becomes unsustainable. The proximity of the threshold will be underestimated if temperature fluctuations are not taken into account. We estimate the bias to be 0.12 °C (0.10–0.18 °C, 95 % credibility) for a recent estimate of the threshold. In light of our findings it is important to gauge the extent to which this increased variability will influence the mass balance of the ice sheets.

Geographic variations in spring and autumn phenology of white ash in a common garden

Geographic variations in plant phenology are known to be affected by climatic differences over space, but the role of adaptation variability of plant populations is less well understood. In this study, I examined the geographic variations in spring and autumn phenology of white ash (Fraxinus americana L.) in a common garden and related observations over a 2-year period (2013 and 2014) to climatic and geographic factors of their provenances. Spring leaf-out of trees with northern provenances occurred later in 2013, but slightly earlier in 2014, than those with southern provenances. This difference was potentially caused by the counterbalancing effect of chilling and forcing in response to interannual temperature fluctuations. In both years, leaf senescence of white ash occurred significantly earlier for trees with northern than southern provenances, reflecting strong adaptation to a photoperiod gradient. The growing season length for white ash, therefore, is constrained by spring and fall phenology through different environmental cues. Spring phenology exerted a greater influence on the interannual variability of growing season length. Identifying these detailed adaptive patterns facilitates a better understanding of phenological change over space and allows development of genotype-sensitive phenological models to predict the ecological impact of climate change.

Seasonal variation in parasite infection patterns of marine fish species from the Northern Wadden Sea in relation to interannual temperature fluctuations

Marine environmental conditions are naturally changing throughout the year, affecting life cycles of hosts as well as parasites. In particular, water temperature is positively correlated with the development of many parasites and pathogenic bacteria, increasing the risk of infection and diseases during summer. Interannual temperature fluctuations are likely to alter host–parasite interactions, which may result in profound impacts on sensitive ecosystems.In this context we investigated the parasite and bacterial Vibrionaceae communities of four common small fish species (three-spined stickleback Gasterosteus aculeatus, Atlantic herring Clupea harengus, European sprat Sprattus sprattus and lesser sand eel Ammodytes tobianus) in the Northern Wadden Sea over a period of two years.Overall, we found significantly increased relative diversities of infectious species at higher temperature differentials. On the taxon-specific level some macroparasite species (trematodes, nematodes) showed a shift in infection peaks that followed the water temperatures of preceding months, whereas other parasite groups showed no effects of temperature differentials on infection parameters.Our results show that even subtle changes in seasonal temperatures may shift and modify the phenology of parasites as well as opportunistic pathogens that can have far reaching consequences for sensitive ecosystems.

Remote Sensing of Climatic Anomalies and West Nile Virus Incidence in the Northern Great Plains of the United States

The northern Great Plains (NGP) of the United States has been a hotspot of West Nile virus (WNV) incidence since 2002. Mosquito ecology and the transmission of vector-borne disease are influenced by multiple environmental factors, and climatic variability is an important driver of inter-annual variation in WNV transmission risk. This study applied multiple environmental predictors including land surface temperature (LST), the normalized difference vegetation index (NDVI) and actual evapotranspiration (ETa) derived from Moderate-Resolution Imaging Spectroradiometer (MODIS) products to establish prediction models for WNV risk in the NGP. These environmental metrics are sensitive to seasonal and inter-annual fluctuations in temperature and precipitation, and are hypothesized to influence mosquito population dynamics and WNV transmission. Non-linear generalized additive models (GAMs) were used to evaluate the influences of deviations of cumulative LST, NDVI, and ETa on inter-annual variations of WNV incidence from 2004–2010. The models were sensitive to the timing of spring green up (measured with NDVI), temperature variability in early spring and summer (measured with LST), and moisture availability from late spring through early summer (measured with ETa), highlighting seasonal changes in the influences of climatic fluctuations on WNV transmission. Predictions based on these variables indicated a low WNV risk across the NGP in 2011, which is concordant with the low case reports in this year. Environmental monitoring using remote-sensed data can contribute to surveillance of WNV risk and prediction of future WNV outbreaks in space and time.

Climate variability in north-western Italy during the second half of the 20th century

We analyse a large set of daily temperature and precipitation time series measured by a dense observational network in north-western Italy, in the period from 1952 to 2002. We find that average temperatures display a significant increase of about 1 °C over the period of observation. The increase is particularly evident for maximum daily temperatures in winter and summer months. By contrast, precipitation time series display no significant trend over the last fifty years. We also determine the statistical properties of interannual fluctuations in temperature and precipitation, and quantify their correlation with large-scale atmospheric patterns and global indices such as the North Atlantic Oscillation (NAO), the Scandinavian pattern (SCAN) and European Blocking (EB). The positive phase of the Scandinavian pattern and the presence of frequent blocking episodes are found to be significantly correlated with increased summer and fall precipitation and cold temperatures in the study area.

VARIABILITY IN TEMPERATURE AND HISTORICAL PATTERNS IN REPRODUCTION IN THE FUCUS DISTICHUS COMPLEX (HETEROKONTOPHYTA; PHAEOPHYCEAE): IMPLICATIONS FOR SPECIATION AND THE COLLECTION OF HERBARIUM SPECIMENS1

Natural and anthropogenic‐induced fluctuations in temperature can have profound effects on an organism's reproduction. The potential of herbarium collections for detecting changes in the timing of reproduction associated with interannual fluctuations in temperature from 1905 to 2003 was assessed in several taxa in the Fucus distichus (L.) emend. Powell complex from northern New England. Data were also used to evaluate whether air and/or sea temperature and North Atlantic Oscillation indices can cause overlap in the reproductive seasonalities of these taxa, a potential mechanism that prevents speciation. For all taxa, there was much variability in reproductive seasonalities among years. Discerning potential correlations with air or sea temperature was difficult because of a suspected bias to collect reproductive specimens at times when most of the population was nonreproductive. Nevertheless, there was a trend for seawater temperature to explain aseasonal reproduction for some taxa. Moreover, the existing archive (1895–2003) shows that the reproductive seasons of these taxa often overlap, and we suggest that interannual variability in temperature may often inhibit speciation. Suggestions also include archive of both reproductive and vegetative materials as well as coordinated sampling in critical biogeographic regions. No one investigator or institution can accomplish this, but phycological societies could organize and sustain such efforts.

Numerical simulation of ice-ocean variability in the Barents Sea region

A dynamic–thermodynamic sea ice model has been coupled to a three-dimensional ocean general circulation model for the purpose of conducting ocean climate dynamical downscaling experiments for the Barents Sea region. To assess model performance and suitability for such an application, the coupled model has been used to conduct a hindcast for the period 1990–2002. A comparison with available observations shows that the model successfully tracks seasonal and inter-annual variability in the ocean temperature field and that the simulated horizontal and vertical distribution of temperature are in good agreement with observations. The model results follow the seasonal and inter-annual variability in sea ice cover in the region, with the exception that the model results show too much ice melting in the northern Barents Sea during summer. The spatial distribution of the winter simulated sea ice cover is in close agreement with observations. Modelled temperatures and ice concentrations in the central Barents Sea are biased too high and too low, respectively. The probable cause is too high inflow of Atlantic Water into the Barents. The seasonal and inter-annual fluctuations in temperature and sea ice cover in the central Barents are, however, in excellent agreement with observations. Salt release during the freezing process in the numerical simulation exhibits considerable inter-annual variability and tends to vary in an opposite manner to the net inflow volume flux at the western entrance of the Barents Sea. Overall, the model produces realistic ice-ocean seasonal and inter-annual variability and should prove to be a useful tool for dynamical downscaling applications.

Effects of climatic variability on the thermal properties of Lake Washington

We conducted a statistical analysis of a long‐term (1964–1998) record of intra‐ and interannual temperature fluctuations in Lake Washington, Washington. Lake Washington has experienced a warming trend, with overall increases of 1.5 (0.045°C yr−1) and 0.9°C (0.026°C yr−1), respectively, for temperature data weighted over the surface (0–10 m) and entire lake volume. This warming trend was greatest for the period from April to September and was smallest and nonsignificant for November–February. A principal‐components analysis of the long‐term mean monthly temperature time series identified two independent modes of interannual variability. The first mode represented the months of the year when the lake warms and is warmest (e.g., March–October) and explained 54% of the variability in the overall time series. The second mode represented the months when the lake cools and is coldest (November–February) and explained 24% of the variability. The March–October mode was positively correlated with interannual variability in air temperatures and the Pacific Decadal Oscillation (PDO), multivariate r2 = 0.65. The November–February mode was positively correlated with air temperature, PDO, relative humidity, solar radiation, and wind speed (r2 = 0.83). A heat budget model indicated that long‐term trends had a secondary role and interannual variability dominated, with exceptions being net long‐wave atmospheric radiation and surface‐emitted radiation, for which the long‐term trend explained ;25% and 53% of the total variance, respectively. An increase in incoming long‐wave radiation fluxes was mainly associated with the increase in minimum daily temperatures (0.06°C yr−1, r2 = 0.47), especially during the March–October mode, when the linear trend accounted for 85% of the variability.

Temperature and the recruitment of Atlantic cod (Gadus morhua)

Variability in the recruitment of fish has been attributed to either changes in the environment or variations in the size of reproductive stocks. Disentangling the effects of environment and stock has proven to be problematic and has resulted in recurrent controversy between studies supporting either hypothesis. In the present study, we examine the relationship between interannual changes in temperature and variation in recruitment for nine Atlantic cod (Gadus morhua) stocks in the North Atlantic. We show that for individual stocks, the relationship often appears weak and statistically not significant. On the other hand, by combining in a single metaanalysis the results from individual stocks, we demonstrate that recruitment of Atlantic cod is linked to interannual fluctuations in temperature in such a way that for stocks located in warm water the relationship is negative, for stocks located in cold water the relationship is positive, and there is no relationship for stocks located in the middle of the temperature range.

A ship of opportunity section to the North Pole: upper ocean temperature observations

During August 1990 XBT temperature profiles were collected in the upper 500 m of the water column along three sections in the Barents, Kara and Laptev Seas and two across the Eurasian Basin of the Arctic Ocean. The shelf sections showed at several locations winter bottom water with temperatures near the freezing point. The subsurface boundary current along the continental slope in the Eurasian Basin, consisting of warm Atlantic Water, was unusually warm when compared to climatological and recent synoptic data. This warming in 1990 may be linked to strong interannual temperature fluctuations of the inflowing Atlantic Water in Fram Strait. A second topographically steered flow above the Arctic Mid Ocean Ridge was detected by tracing fossil intrusive structures created in the Laptev Sea and modified by double diffusive fluxes.