Temperature Variability Research Articles

Exploring the Effect of Indoor Thermal Comfort using Iris Dampers: A Justification Study

This study explores the impact of fixed damper openings on indoor thermal comfort in a lab-scaled chamber. Experiments with maximum, medium, and minimum iris damper openings were conducted under various occupancy conditions. Results show that the maximum opening maintained temperatures close to the ideal 24°C with minimal fluctuations. In contrast, medium and minimum openings resulted in higher temperature variability and less efficient air distribution. Statistical analysis highlighted significant differences in temperature stability among the different damper settings. The maximum opening ensured a stable temperature range, while the minimum opening caused noticeable temperature stratification and discomfort, especially with more occupants. The findings indicate that fixed damper openings are inadequate for maintaining consistent thermal comfort due to their lack of adaptability. This underscores the need for advanced control systems that can dynamically adjust damper positions to ensure optimal indoor temperature regulation and improve energy efficiency.

A century-long China homogenized daily surface air temperature dataset (CUG-CMA CHDT)

Daily meteorological observation data of the early period (pre-1950) were critically important for investigating the long-term trends and multi-decadal scale variability of extreme climate events. The high-resolution surface air temperature (SAT) data for time period before 1950 are lacking in China. We extended the SAT observations of China back to 1840 through developing a pre-1950 daily SAT dataset. The early-period daily SAT were manually corrected for the input and clerical errors, and then according to the length or coverage of time, the main series for each of the cities was determined. The observation time system of unknown sites was determined by the minimum difference method. After these operations, the data of all sites were unified into the same format. By using the ridge regressions established based on data from modern reference stations, the missing maximum temperature (Tmax) and minimum temperature (Tmin) were interpolated. The early-period data were combined with modern data to form the long-term daily SAT dataset of 1840–2020 in China. RHtest software was used to detect and adjust the inhomogeneities in the station data series. Finally, the century-long homogenized daily SAT dataset including 45 key city stations in China was obtained. Among the stations, there are 20 stations with observation record more than one hundred years. The length of temperature observation series of 17 stations is between 80 and 100 years. The series length of the remaining 7 stations is between 68 and 80 years. Finally, the angular distance weighting (ADW) method was used to interpolate the data into grid products, and the grid size is 2.5 ° × 2.5 °. The dataset was named CUG-CMA CHDT, which is applicable in monitoring, studies and assessments of regional extreme temperature change and variability in China.

Future increase in extreme El Niño supported by past glacial changes

El Niño events, the warm phase of the El Niño–Southern Oscillation (ENSO) phenomenon, amplify climate variability throughout the world1. Uncertain climate model predictions limit our ability to assess whether these climatic events could become more extreme under anthropogenic greenhouse warming2. Palaeoclimate records provide estimates of past changes, but it is unclear if they can constrain mechanisms underlying future predictions3–5. Here we uncover a mechanism using numerical simulations that drives consistent changes in response to past and future forcings, allowing model validation against palaeoclimate data. The simulated mechanism is consistent with the dynamics of observed extreme El Niño events, which develop when western Pacific warm pool waters expand rapidly eastwards because of strongly coupled ocean currents and winds6,7. These coupled interactions weaken under glacial conditions because of a deeper mixed layer driven by a stronger Walker circulation. The resulting decrease in ENSO variability and extreme El Niño occurrence is supported by a series of tropical Pacific palaeoceanographic records showing reduced glacial temperature variability within key ENSO-sensitive oceanic regions, including new data from the central equatorial Pacific. The model–data agreement on past variability, together with the consistent mechanism across climatic states, supports the prediction of a shallower mixed layer and weaker Walker circulation driving more frequent extreme El Niño genesis under greenhouse warming.

Habitat type controls microarthropod community changes across a Magellanic sub-Antarctic elevation gradient

IntroductionElevation gradients are often used as a proxy for climate change as they allow comparisons of ecological responses over much larger temporal and spatial scales than is possible through experimental manipulations.MethodsHere, we tested how microarthropod communities (Collembola and Acari) are affected by climatic differences between sea level and 600 m a.s.l. on Navarino Island, in the Magellanic sub-Antarctic ecoregion of southern Chile (mean annual temperatures of 5.6 vs 3.1°C, respectively). We quantified microarthropod abundance, richness and community trait characteristics in dominant moss (Racomitrium lanuginosum and Polytrichum strictum) and lichen (Usnea trachycarpa, Pseudocyphellaria freycinetii and Stereocaulon alpinum) vegetation growing at both elevations. These moss and lichen genera are characterized by large morphological differences and allow testing of how habitat characteristics affect microarthropod community response across elevation gradients.ResultsCollembola and Acari community composition differed between the low and high elevation sites. Total abundance levels of Acari were maintained in each habitat across elevation, whereas Collembola richness strongly declined (50%) at high elevation in the moss habitats. Acari community differences across elevation were driven by relative abundance changes whereas the Collembola community lost species at higher elevation. An anticipated decline of smaller eudaphic Collembola at high elevation was only observed in the moss Racomitrium, reflecting potentially lower temperature buffering capacity and shelter options compared to Polytrichum. Lichens mostly supported larger epigeic species irrespective of elevation. There were no consistent patterns linking microarthropod communities with habitat water holding capacity or water loss rates across the studied habitats and elevation.DiscussionHabitat type and the genus of moss or lichen were associated with microarthropod community changes across elevation, including examples of declines, increases and no change. These findings highlight that community responses across gradients may not always relate to the generally hypothesized environmental variables (e.g. temperature variability) and that habitat characteristics should be taken into account when using elevation as a proxy for climate change.

Floodplain Restoration and Its Effects on Summer Water Temperature and Macroinvertebrates in Whychus Creek, Oregon (USA)

ABSTRACTStream restoration is a proposed climate adaptation tool; however, outcomes of floodplain restoration on stream temperature have been debated. Despite a growing number of studies that investigated water temperature in restored streams, few have quantified temperature variations in new habitat types created by restored hydrogeomorphic processes to explore the effects on aquatic macroinvertebrates. We evaluated the hypotheses: (1) restoration increases habitat diversity, (2) habitat diversity increases water temperature variability, and (3) restoration increases the diversity of macroinvertebrate assemblage and temperature associations. In August 2021, we collected environmental data to describe the aquatic habitats, water temperature and quality (continuous and discrete), and macroinvertebrates in 40 riffle, pool, and off‐channel sites in a stream being restored, Whychus Creek, Oregon, USA. Our study is a site comparison of three reaches—one restored in 2012, another restored in 2016, and an unrestored (control) that will soon undergo restoration. Evaluations of the hypotheses show: (1) Habitat diversity in restored reaches is effectively three types of aquatic habitats versus only one in the control (riffles), (2) water temperature variability in habitats created by restoration (off‐channel) is high and low, and suggest a range of hyporheic connectivity and flow paths are present, and (3) restoration created a different macroinvertebrate assemblage, with 16 additional taxa in off‐channel habitats, and the range in macroinvertebrate thermal optima is approximately doubled when off‐channel macroinvertebrate thermal optima are accounted for. Our results support the idea that floodplain restoration creates more diverse thermal conditions and different macroinvertebrate communities in restored stream reaches.

Sensitive response of erosion and weathering to the Indian Summer Monsoon changes in South Asia during Dansgaard-Oeschger oscillations

Continental weathering plays a key role in regulating the long-term climate stability via negative feedback. However, whether and how erosion and weathering respond to rapid climate change (e.g millennial scale) in large river basins remains unclear, partly due to the lack of archives with robust age models and high sampling resolution. As one of the largest sediment source-to-sink systems, the Himalaya-Ganga/Brahmaputra River-Bay of Bengal system is considered as an ideal laboratory for examining the weathering-climate relationships over the past. Here we present the elemental and mineralogical data from well age-constrained core sediments in the Bay of Bengal, which document the erosion and weathering conditions in South Asia during the last glacial period. All proxies generally show larger values during glacial interstadials than the stadials, consistent with the millennial variabilities of regional sea surface temperature (SST) and the Indian Summer Monsoon (ISM) strength. We confirm that the erosion and chemical weathering signals in Ganga/Brahmaputra River basins, which sensitively respond to the ISM strength and/or temperature change, could be propagated through the large river systems and faithfully preserved in the South Asian marginal seas, without noticeable time lag on a millennial scale. Our findings provide valuable data for response of erosion and weathering dynamics in a large river basin to rapid climate changes, and highlight the immense potential of monsoon-driven continental silicate weathering in floodplains as a substantial short-term carbon sink, thus underscoring a pivotal natural carbon sequestration mechanism amidst the escalating threat of global warming.

The association between short-term temperature variability and mortality in Virginia

The objective of this study is to determine the relationship between short-term temperature variability on neighboring days and mortality. The change in maximum temperature in Northern Virginia, Richmond, Roanoke, and Norfolk, Virginia, on neighboring days was calculated from airport observations and associated with total mortality over a multi-county area surrounding each weather station. The association between day-to-day temperature change and mortality, lagged over a 28-day period, was analyzed using distributed lag non-linear models that controlled for air quality, temporal trends, and other factors. Days following large temperature declines were associated with an increased risk of mortality in three of the four locations, and temperature increases were linked to higher mortality risk in two cities. For example, the relative risk of mortality for a 12°C daily temperature decline (1st percentile) was 1.74 [0.92, 3.27] in Roanoke and 1.16 [0.70, 1.92] in Richmond. The net effect of short-term temperature increases was smaller, with the largest relative risk of 1.03 [0.58, 1.83] for a 12°C increase (99th percentile) in maximum temperature in Norfolk. In Richmond and Roanoke, there was an observed lagged effect of increased mortality (maximum relative risks varying from 1.08 to 1.10) that extended from 5 to 25 days associated with large temperature declines of 15°C or more. In contrast, there was a strong and immediate (lag 0–3 day) increase in the risk of mortality (1.10 to 1.15) in northern Virginia and Norfolk when the temperature increase exceeded 10°C (short-term warming). In general, consecutive day warming had a more immediate mortality impact than short-term cooling, when the peak mortality is lagged by one week or more. However, cooling of at least 10°C after a hot (summer) day reduced mortality relative to comparable cooling following a cold (winter) day, which is associated with high mortality. This differential mortality response as a function of temperature suggests that there is some relationship between average temperature, temperature variability, and season. The findings of this study may be useful to public health officials in developing mitigation strategies to reduce the adverse health risks associated with short-term temperature variability.

Atlantyk Północny a klimat Europy. Mechanizmy wpływu. Część 1

The work discusses the mechanisms operating within the climate system leading to variability and changes in the atmospheric climate over Europe. The first part discusses the operation of the main factor regulating the variability of atmospheric circulation, which is the North Atlantic thermohaline circulation (NA THC). The variability of NA THC, through its influence on the shaping of the mid-tropospheric circulation and the distribution of geopotential heights, determines the variability of the lower circulation, and thus the variability of climatic elements over Poland and Europe. The analysis showed that the variability of NA THC largely explains the variability of sunshine duration, air temperature and relative humidity, but does not satisfactorily explain the variability of other climatic elements.

Temperature variability regulates the interactive effects of warming and pharmaceutical on aquatic ecosystem dynamics

Climate warming and pharmaceutical contaminants have profound impacts on population dynamics and ecological community structure, yet the consequences of their interactive effects remain poorly understood. Here, we explore how climate warming interacts with pharmaceutical-induced boldness change to affect aquatic ecosystems, built on an empirically well-informed food-chain model, consisting of a size-structured fish consumer, a zooplankton prey, and a fish predator. Climate warming is characterized by both daily mean temperature (DMT) and diurnal temperature range (DTR) in our model. Results show that DMT and high levels of species’ boldness are the primary drivers of community instability. However, their interactive effects can lead to diverse outcomes: from predator collapse to coexistence with seasonality-driven cycles and coexistence with population interaction-driven cycles. The interactive effects are significantly modulated by daily temperature variability, where moderate DTR counteracts the destabilizing interactive effects by increasing consumer reproduction, while large temperature variability considerably reduces consumer biomass, destabilizing the community at high mean temperatures. Our analyses disentangle the respective roles of DMT, DTR and boldness in mediating the response of aquatic ecosystems to the impacts from pharmaceutical contaminants in the context of climate warming. The interactive effects of the environmental stressors reported here underscore the pressing need for studies aimed at quantifying the cumulative impacts of multiple environmental stressors on aquatic ecosystems.

Ocean Complexity Shapes Sea Surface Temperature Variability in a CESM2 Coupled Model Hierarchy

Abstract To improve understanding of ocean processes impacting monthly sea surface temperature (SST) variability, we analyze a Community Earth System Model, version 2, hierarchy in which models vary only in their degree of ocean complexity. The most realistic ocean is a dynamical ocean model, as part of a fully coupled model (FCM). The next most realistic ocean, from a mechanically decoupled model (MDM), is like the FCM but excludes anomalous wind stress–driven ocean variability. The simplest ocean is a slab ocean model (SOM). Inclusion of a buoyancy coupled dynamic ocean as in the MDM, which includes temperature advection and vertical mixing absent in the SOM, leads to dampening of SST variance everywhere and reduced persistence of SST anomalies in the high latitudes and equatorial Pacific compared to the SOM. Inclusion of anomalous wind stress–driven ocean dynamics as in the FCM leads to higher SST variance and longer persistence time scales in most regions compared to the MDM. The net role of the dynamic ocean, as an overall dampener or amplifier of anomalous SST variance and persistence, is regionally dependent. Notably, we find that efforts to reduce the complexity of the ocean models in the SOM and MDM configurations result in changes in the magnitude of the thermodynamic forcing of SST variability compared to the FCM. These changes, in part, stem from differences in the seasonally varying mixed layer depth and should be considered when attempting to quantify the relative contribution of certain ocean mechanisms to differences in SST variability between the models.

Non-equilibrium thermal models of lithium batteries

Temperature fluctuations impact battery performance, safety, and health. Industry-standard cell-level models of these phenomena ignore thermal gradients within the electrodes’ active material, i.e., assume the latter to be in “thermal equilibrium”. We present a “non-equilibrium” thermal model that explicitly accounts for spatial variability of temperature with the active material (and the carbon-binder domain). We investigate the conditions, expressed in terms of the heat-generation rate and the thermal properties of a cell’s liquid (electrolyte) and solid (active material and CBD) phases, under which the thermal equilibrium assumption breaks down and our model should be used instead. The differences between these two thermal models are investigated further by coupling them with an industry-standard electrochemical model. The resulting thermal–electrochemical model demonstrates the importance of thermal gradients within the active material at high C-rates (discharge current densities) and for large grain sizes. Under these conditions, the equilibrium assumption underestimates internal temperature by as much as 50%. These two thermal models are then applied to a commercial NMC battery with multiple units. Our non-equilibrium model predicts the battery surface temperature that is in good agreement with measurements, while the equilibrium model underestimates the observed temperature.

Montane peatland response to drought: Evidence from multispectral and thermal UAS monitoring

This paper investigates the response of mid-latitude montane peatlands to climate warming, focusing on changes occurring in a montane peat bog during a drought period. Unmanned Aerial Systems (UAS) equipped with multispectral and thermal sensors were used for high-resolution monitoring to analyze qualitative changes within the peat bog and their spatial distribution. The study was conducted in the Rokytka mountain peat bog in Šumava National Park, Czech Republic, which is one of the largest mountain peat bog complexes in Central Europe. Monitoring took place during the 2019 vegetation season, coinciding with the peak of the 2015–2019 drought. The recurrent UAS imaging campaigns were complemented by continuous hydrological and hydropedological monitoring and in-situ calibration measurements. The findings revealed diverging responses of montane peatlands to climate change across different functional zones of the peat bog. UAS thermal mapping identified distinct land surface temperature variations across various vegetation categories under different conditions. Notably, ponds and waterlogged areas displayed a stabilizing effect on land surface temperature variability, though they exhibited different absolute temperatures. In contrast, shallow waterlogged areas exhibited surface temperatures akin to dry open peat areas. Multispectral UAS monitoring demonstrated significant transitions among the peat bog zones in response to heat and drought propagation. The most pronounced changes occurred in shallow waterlogged areas, which shrank notably from 22.8% to 4.5%, while bare peat expanded from 26.8% to 45.5% during the 2019 drought season. High-resolution thermal and multispectral monitoring has revealed the scope and magnitude of the intra-peatland responses to drought and heat waves and serves as a sensible indicator of environmental changes of peatlands. It has disclosed a large cumulative effect of change in an environment composed of highly heterogeneous and subtle structures. The results highlighted the effectiveness of UAS monitoring in understanding the extent of change in montane peatlands as a fragile environment exposed to the effects of climate change.

The interaction of ambient ozone and personal temperature variability on blood markers of inflammation, oxidative stress, coagulation, endothelial function, and stress hormones

The interaction between ozone and temperature on cardiovascular biomarkers has not been thoroughly examined. A panel study was conducted among 40 college students with four equal interval follow-ups in Hefei, Anhui Province, China between August and October 2021. Real-time concentrations of ozone were collected from a nearby monitoring device. Temperature variability parameters included diurnal temperature range (DTR), the standard-deviation of temperature (SDT), and temperature variability (TV). A set of cardiovascular biomarkers were measured, including markers of inflammation (Granulocyte-macrophage colony-stimulating factor, GM-CSF and serum amyloid A, SAA), coagulation (D-dimer and ADAMTS13), oxidative stress (Myeloperoxidase, MPO and Growth differentiation factor-15, GDF-15), endothelial function (vascular endothelial growth factor A, VEGFA), and stress hormone (5-hydroxytryptamine, 5-HT). Linear mixed-effect models were conducted to analyze the associations between ozone, temperature variability, and all blood markers. The results showed significant associations among ozone, DTR, SDT, TV, and blood markers, suggesting harmful effects on markers. For instance, a 10-μg/m3 increase in ozone at lag 2d was associated with higher levels of SAA by 19.65% (95%CI: 13.70, 25.60), VEGFA by 10.90% (95%CI: 4.57, 17.22), GDF-15 by 5.33% (95%CI: 0.59, 10.06), and GM-CSF by 2.52% (95%CI: 1.70, 3.34), but 13.09% lower D-dimer (95%CI: 6.99, 19.19). We also found statistically significant interaction between ozone and TV exposures for GM-CSF and SAA. This study shows that ambient ozone and personal TV exposures may independently have acute effects on markers of inflammation, oxidative stress, coagulation, endothelial function, and neuroendocrine stress response. Simultaneous exposure to these factors may also lead to interactive effects on inflammation markers. These findings offer valuable insights for developing comprehensive strategies in cardiovascular disease control and prevention.

Biennial variability of boreal spring surface air temperature over India

In this study, we report significant biennial variability or oscillation (BO) in the boreal spring (March–May) Surface Air Temperature (SAT) over India and unravelled the causative mechanisms. The positive phase of the BO exhibit significant seasonal warming over India, whereas seasonal cooling is observed during the negative phase of BO. Heat wave days are more during the positive phase of BO compared to negative or neutral phase. The positive (negative) phase of BO is generally coherent with the central (eastern) Pacific warming (cooling) years. The anomalous low-level divergence associated with low-level anticyclonic circulation induces less cloudiness and intense surface solar radiation ovr India during the positive phase, favouring surface warming. The evolution of some positive and/or negative phases of BO without any large scale forcing from the equatorial Pacific suggested the possibility of alternate pathways. The strong anomalous upper-level (at 200 hPa) anticyclonic circulation provoked by mid-latitude Rossby waves is found contributing to the positive phase, thereby highlighting the role of dominant mid-latitude pathways in the biennial SAT variability in addition to El Niño forcing. The sinking motion associated with persistent high, and the associated adiabatic compression also supported surface heating during the positive phase of BO. On the other hand, the mid-latitude Rossby wave induced upper-level cyclonic circulation is found contributing to the negative phase. The sinking motion associated with persistent high, and the associated adiabatic compression also supported surface heating during the positive phase of BO. In contrast, negative soil temperature anomalies and high latent heat flux release to the atmosphere supported surface cooling during the negative phase.

Harmony in Nature: Exploring the Multisensory Impact of Classical Gardens on Individuals' Well-Being.

Objectives: Chinese classical gardens, designated as a vital world cultural heritage, embody a lasting legacy transcending generation. Despite the cultural importance of these gardens, a notable research gap exists in deciphering the nuanced emotional and physiological responses triggered by individual elements within classical garden landscapes. Our research question aims to uncover the specific emotional and physiological impacts of key garden elements-plants, architecture, waterscape, and rockery-on visitors, with a particular focus on the Humble Administrator's Garden. These elements serve as the primary subjects for video capture at four sites. Study Design: A within-subject design experiment was used. Methods: Videos were recorded at these sites, encompassing visual, auditory, and tactile elements. Ninety-five participants watched these videos in an indoor setting. While viewing, we measured participants' physiological responses, including heart rate variability, skin conductance, and skin temperature, will be monitored alongside subjective assessments obtained through self-reported questionnaires such as the Emotional Perception Scale and State-Trait Anxiety Scale. Results: Findings suggest that while all landscape types evoke positive emotions, natural elements exert a more profound influence. Additionally, the Large Rockery emerges as a focal point, indicating enhanced emotional relaxation through auditory and tactile stimuli, particularly among younger individuals. Conclusions: This research contributes to the broader understanding of how classical gardens impact human emotions and well-being, offering insights that can inform future landscape design and promote mental health in diverse cultural contexts.

Diversity pattern of Symplocos tree species in China under climate change scenarios: Toward conservation planning

Symplocos, a genus rich in endemic and keystone species in China's subtropical forests, plays a vital role in maintaining biodiversity. Climate change impacts on Symplocos trees affect ecosystem composition, dynamics, and functions. This study delves into the potential ramifications of climate change on the distribution and richness of Symplocos species across China under different climatic conditions. A comprehensive analysis was conducted using occurrence records of 29 species of Symplocos, focusing on habitat suitability modeling and spatial analysis, to demonstrate the possible effects of climate change on the distribution and diversity patterns of Symplocos species in China. Environmental data, including bioclimatic variables, were collected, and the future climate scenarios were projected using the combined average of the two global climate models. Four modeling algorithms were applied in an ensemble species distribution models to assess the distribution of Symplocos species and decipher the pattern of species richness and endemism. The results indicate high accuracy and performance of the models with a mean AUC of 0.94 and TSS of 0.77, particularly the random forest. The analysis identified key bioclimatic variables influencing Symplocos species distribution, with precipitation patterns (precipitation of driest month and precipitation of warmest quarter) and temperature variability (temperature mean diurnal range) playing significant roles. Predictions suggest a reduction in Symplocos species richness over the next six decades, particularly in southern and southwestern China, with potential gains in other regions. Overall, this study highlights the vulnerability of Symplocos species to climate change and underscores the importance of proactive conservation efforts and forest plantations to mitigate future loss in Symplocos species diversity.

Analysis of Urbanization Impact on Land Surface Temperature Variability by Using Landsat Imagery

Analysis of Urbanization Impact on Land Surface Temperature Variability by Using Landsat Imagery

Interplay and feedback between tectonic regime, faulting, sealing horizons, and fluid flow in a hydrocarbon-hosting extensional basin: The Val d'Agri Basin case, Southern Italy

Understanding the factors that govern past fluid circulation in tectonically active and/or hydrocarbon-rich basins is crucial for elucidating present-day fluid-flow scenarios. We investigate the circulation of paleo-fluids in the extensional-transtensional Val d'Agri Basin (southern Italy), home to a giant oil field and significantly affected by both natural and human-induced seismicity. Our aim is to understand how faulting and the variable thickness of the clay-rich tectonic mélange, which constitutes the seal of the hydrocarbon reservoir, influenced past fluid flow under different tectonic regimes. To achieve this, we combined multiscale structural observations with isotope (C, O, clumped, and Sr) and Rare Earth and Yttrium (REY) analyses of fault-related calcite mineralizations. Using analytical methodologies that allow the analysis of sub-milligram samples for carbonate clumped isotopes, we provided a detailed characterization of the variability in precipitation temperatures and composition of parental fluids in both space and time. Our results reveal five main types of parental fluids, ranging from meteoric to intraformational and deep crustal, which were differently involved in the tectonic evolution of the Val d'Agri Basin. During orogenic shortening, vertical fluid circulation was mostly limited and compartmentalized, whereas post-orogenic extensional faulting promoted the ascent of deep fluids. Our findings indicate that the sealing properties of the mélange were likely enhanced locally by increased thickness but were also compromised by fault activity and associated seismic events. Fluid circulation in the study area has been influenced by the prevailing tectonic regime (compressive vs. extensional), stratigraphic-structural architecture, properties of impermeable horizons, and seismic events. The model proposed for the Val d'Agri Basin elucidates past processes that are useful for understanding current fluid circulation in the basin itself and can be applied to other basins where fluid circulation is partly manipulated by human activities.

Tidal pumping and intertidal groundwater springs create pronounced spatiotemporal thermal variability in a coastal lagoon

AbstractIntertidal groundwater springs provide thermally stable, nutrient‐rich freshwater that causes fine‐scale variability in water temperature and salinity and promotes biodiversity in coastal estuaries and lagoons. In this study, we combined three thermal sensing techniques to elucidate summer water temperature patterns at the mouths of intertidal groundwater springs and the ambient coastal lagoon in Prince Edward Island, Canada. Thermal infrared imagery captured the spatiotemporal variability in relative temperatures of the lagoon channel and cold‐water plumes from the springs. Thermal anomalies due to the springs were detected at the surface throughout a tidal cycle, suggesting that the thermal plumes were buoyant. Fiber‐optic distributed temperature sensing paired with temperature loggers near the spring outlets recorded groundwater temperatures at low tide (~ 7°C) but ambient lagoon temperatures (up to 26°C) at high tide due to the vertical thermal gradient in the stratified water column. Calculated estuarine Richardson numbers throughout the study confirm intertidal spring buoyancy due to salinity differences. The fiber‐optic distributed temperature sensing results revealed pronounced variations in temperature as evidenced by spatial (3.7°C) and temporal (5.5°C) standard deviations over the cable length during the study and lower mean lagoon bed water temperatures at high tide (22.5°C) than low tide (24.3°C) due to heat advection from tidal pumping. Lagoon temperatures fluctuate at diurnal (solar) and semi‐diurnal (tidal) frequencies. The findings emphasize the efficacy of a multi‐technology approach to reveal fine‐scale and dynamic thermal processes that drive temperature patterns and habitat distribution in coastal lagoon ecosystems and highlight the thermal influence of intertidal springs.

Spatial variability of temperature inside atoll lagoons assessed with Landsat-8 satellite imagery

Sea Surface Temperature (SST) maps are necessary for managing marine resources in a climate change context, but are lacking for most of the 598 world's atolls. We assessed the feasibility of using the Landsat-8 (L8) satellite to infer SST maps for four French Polynesia atolls of aquaculture interest in Tuamotu Archipelago, namely Takaroa, Raroia, Tatakoto, and Reao. Specifically, we (1) used sensors to measure in situ the range of spatial temperature differences recorded in these four atoll lagoons; (2) calibrated and assessed the performances of SST algorithms to estimate lagoon temperature from L8 signals; (3) generated temperature maps for the lagoons and compared spatial patterns of temperature obtained from these maps with patterns highlighted by in situ sensors. Good agreements between satellite and in situ temperature data were obtained, with better results achieved when using an atoll-by-atoll optimization (average bias = −0.26 °C; RMSE = 0.55 °C). However, we also show that the range of temperature inside atoll lagoons is low, and of the same order of magnitude than RMSE achieved with SST algorithms. Because of the L8 overpass time (∼9 a.m.) and the revisit time (16 days), L8 SST could not capture the entire range of spatial differences measured in situ in the four lagoons, but could capture spatial gradients and fronts better than with few in situ sensors. Considering the achieved accuracies and the actual temperature differences at the four study sites, we discuss the usefulness of L8 derived SST maps to assist fishery and aquaculture management in atoll lagoons, as well as the possible generalization to other lagoons.