Energy Budget Research Articles

Anthropogenic heat (AH) emissions in urban environments alter the surface energy budget and significantly influence urban climates. However, these emissions vary spatiotemporally, leading to considerable uncertainty in their estimation. As remote sensing in the urban environment advances, the remotely sensed urban surface temperatures are becoming increasingly available. Yet, assimilating these observations into surface energy modelling for AH estimation has not been fully explored. In this study, a model for AH estimation based on the Kalman filter-surface energy balance (KF-SEB) is developed. Urban meteorological data, including air temperature and building surface temperature, are assimilated into the Kalman filter (KF), yielding sensible heat flux, building heat storage and estimated AH using the surface energy balance (SEB) equation. The KF-SEB model is evaluated using two forward models with predefined AH emissions. The first model is a simple slab model, and the second one is a more complex single-layer urban canopy model (UCM). The results show that the KF-SEB model accurately captures the magnitude and temporal variation of AH, with reduced uncertainties compared to previous studies. This study offers a novel approach to AH estimation based on urban meteorological data and provides important insights into the feedback between urban microclimates and anthropogenic energy use.This article is part of the theme issue 'Urban heat spreading above and below ground'.

Abstract The challenge of distinguishing convective anvil cirrus from in situ cirrus has long limited the quantification of their distinct roles in regulating upper‐tropospheric moisture and modulating Earth's energy budget. In this study, we address this ambiguity by introducing a physically constrained classification framework that applies advanced computer vision techniques to CloudSat‐CALIPSO observations. By tracking the complete physical evolution of cloud systems from their convective origins, this method enables a robust global separation of anvil and in situ cirrus. Our results illuminate stark contrasts in their macro‐ and micro‐properties, governed by fundamentally different mechanisms. Anvil cirrus extent is tightly coupled to dynamic factors, whereas in situ cirrus, while linked to local tropopause thermodynamics, exhibits strong modulation by remote atmospheric influences from the opposite hemisphere. This identified linkage shows a previously unrecognized interhemispheric teleconnection: wherein large‐scale deep convective systems in one hemisphere rapidly influence in situ cirrus formation in the other. We hypothesize that this coupling is mediated by planetary‐scale waves—likely fast‐propagating Kelvin waves that transmit energy across the equator, cooling the remote tropical tropopause layer, with subsequent interactions with the subtropical jet fostering mid‐latitude in situ development. This newly quantified atmospheric coupling provides a pathway for improving representation of cirrus in climate models and suggests a mechanism by which regional shifts in convection under global warming could reshape global cirrus distributions and their radiative impact.

Abstract. We present the first multi-year study of gravity-wave (GW) kinetic Ekin and potential Epot energy spectra in the polar middle atmosphere, based on simultaneous temperature and horizontal-wind measurements by the Doppler Rayleigh–Mie–Raman lidar at the ALOMAR observatory (69° N, 16° E). The analysed 7 year dataset (2017–2023) comprises 61 soundings, each longer than 12 h, totalling 2036 h of observations between 35–60 km. Our results reveal a strong winter-summer contrast that depends on both frequency and vertical wavenumber: winter spectra exhibit significantly higher energies and greater variability, particularly at long periods, while summer spectra are marked by a distinct near-inertial peak, most pronounced in Ekin. We further reveal that the ratio of kinetic to potential energy depends systematically on frequency and vertical wavelength, with near-inertial, short-vertical-scale waves channelling a disproportionate share of energy into kinetic form, indicating that the two-dimensional GW spectrum cannot be treated as fully separable. Frequency spectra also show, for the first time, broken power laws at 35–40 km, merging into a single flatter power law with increasing altitude. These findings provide new constraints on the spectral energy budget at high latitudes in the middle atmosphere and deliver essential benchmarks for validating and improving GW parameterisations in climate and numerical weather prediction models.

Heterogeneous ice nucleation is a key process for ice cloud formation, snowfall, and freezing of water bodies. Ice nucleating particle (INP) cloud feedbacks are one of the largest sources of uncertainties in Earth’s Energy Budget. Although INPs are essential in the development of mixed-phased and glaciated clouds, their composition, sources, and cloud feedbacks remain poorly constrained. Previous studies have shown mixed results on the potential of light-absorbing particles (LAP), such as black carbon (BC) and high latitude dust (HLD), serving as INPs. However, many of these studies use laboratory or model-generated particles that may not represent the complex morphology and behaviors of ambient light-absorbing particles sufficiently. Here, we use in situ surface snow samples, collected during Spring 2018 in Svínafellsjökull, Iceland. The samples were analyzed by an immersion freezing mechanism for their ice nucleation activity (INA). Portions of the filtered samples were concentrated by lyophilization to observe the potential enhancement of INA. We investigated environmental samples of deposited aerosols to better understand the role activity of HLD and BC in ice nucleating activity in mixed-phase clouds in Iceland. We found concentrations of 16 ± 27 ng g−1 and 33 ± 66 × 106 ng g−1 for BC and HLD, respectively. However, we found that isolated methanol-soluble organic aerosols have a more prominent role than BC and HLD in Iceland. We conclude that BC and HLD are insignificant INP but that they can inhibit INA from other INP.

Mixing and heat transfer rates are typically enhanced in high-pressure transcritical turbulent flow regimes. This is largely due to the rapid variation of thermophysical properties near the pseudo-boiling region, which can significantly amplify velocity fluctuations and promote flow destabilisation. The stability conditions are influenced by the presence of baroclinic torque, primarily driven by steep, localised density gradients across the pseudo-boiling line; an effect intensified by differentially heated wall boundaries. As a result, enstrophy levels increase compared with equivalent low-pressure systems, and flow dynamics diverge from those of classical wall-bounded turbulence. In this study the dynamic equilibrium of these instabilities is systematically analysed using linear stability theory. It is shown that under isothermal wall transcritical conditions, the nonlinear thermodynamics near the pseudo-boiling region favour destabilisation more readily than in subcritical or supercritical states; though this typically requires high-Mach-number regimes. The destabilisation is further intensified in non-isothermal wall configurations, even at low Brinkman and significantly low Mach numbers. In particular, the sensitivity of neutral curves to Brinkman number variations, along with the modal and non-modal perturbation profiles of hydrodynamic and thermodynamic modes, offer preliminary insight into the conditions driving early destabilisation. Notably, a non-isothermal set-up (where walls are held at different temperatures) is found to be a necessary condition for triggering destabilisation in low-Mach, low-Reynolds-number regimes. For the same Brinkman number, such configurations accelerate destabilisation and enhance algebraic growth compared with isothermal wall cases. As a consequence, high-pressure transcritical flows exhibit increased kinetic energy budgets, driven by elevated production rates and reduced viscous dissipation.

Abstract Diurnal warm layers (DWLs) develop under relatively weak winds and strong solar radiation and have important consequences for ocean surface transport and air–sea interactions. In this paper, we investigate DWLs during 3 consecutive days in the subtropical South Atlantic using observations from an underwater glider equipped with a turbulence microstructure package, a series of drifters at two different depths, and a 1D turbulence model. The observations and modeling show that the DWLs create a near-surface stratification that partially decouples the surface current from the mixed layer below. However, we find that turbulent entrainment of momentum from below the DWL is important in the evolution of the surface current. We further derive buoyancy, potential, and kinetic energy budgets and identify the dominant terms. The upper-ocean potential energy budget is dominated by the incoming solar radiation, with only a small contribution from turbulent mixing. Turbulent shear production, however, is found to be an important influence on the upper-ocean mean kinetic energy, receiving a similar fraction of the wind work as the acceleration of the diurnal jet. The DWL evolution and energy budgets are corroborated with simulations from a freely evolving 1D turbulence model, which additionally shows that the exchange of mean kinetic energy with the surface wave field due to rotation is of minor importance to the development of the DWLs we observe.

Abstract This study investigates the influence of equatorial Rossby (ER) waves on modulating the eastward propagation of the Madden–Julian oscillation (MJO). Using classification methods, the standing and jumping MJO clusters are identified as those impeded by ER waves. In these clusters, MJO convection splits and shifts poleward, in contrast to the continuously propagating MJO, which moves through the MC without disruption. Column-integrated moist static energy (MSE) budget analysis and time-scale separation were conducted to understand the dynamic mechanisms underlying the different behaviors among the MJO clusters. The results revealed that the positive MSE tendency anomalies east of the MJO convection, which facilitate the eastward propagation of the MJO, are mainly contributed by the horizontal and vertical advection. However, these positive anomalies straddle to the equator in the standing and jumping MJO clusters, leading convection to propagate poleward. The differences in MSE tendency anomalies are primarily contributed by two nonlinearly rectified terms: meridional advection of the low-frequency background MSE by the MJO-scale winds [] and the vertical transport of low-frequency background MSE by the MJO-filtered vertical velocity []. These differences arise from the destruction of the front Walker cell and the anomalous poleward flows to the east of MJO convection by the ER waves. The variations in ER wave intensity among the MJO clusters are associated with differences in the background vertical shear of zonal wind. This study provides new insights into the mechanisms driving MJO propagation and the sophisticated interactions between ER waves and the MJO. Significance Statement Understanding the evolution of tropical weather systems is essential for improving global weather and climate forecasts. This study investigates how equatorial Rossby (ER) waves influence the Madden–Julian oscillation (MJO), a critical driver of intraseasonal variability in the tropics. By classifying MJO events based on their propagation characteristics, the research identifies how ER waves disrupt the MJO’s eastward propagation, inhibiting its convection from moving across the Maritime Continent as expected. The study further reveals the mechanisms behind this disruption and the factors influencing ER wave intensity. These findings offer new insights into tropical atmospheric dynamics and provide the potential to enhance MJO simulations and improve intraseasonal predictability in climate models.

Abstract The strengthening of the zonal sea surface temperature (SST) gradient observed in the tropical Pacific in recent decades is a regional climate change signal that may be outside the range of historical simulations with comprehensive climate models. Given the important role that this change has on other aspects of climate, a series of idealized surface energy balance calculations with imposed parameters are performed to build a baseline understanding of the sensitivities that govern these changes. I quantify the requisite magnitudes of five perturbations that reach a new equilibrium with a mean SST warming of about 0.5 K and about 0.4 K more west Pacific warming than east Pacific warming, based approximately on the observed trends. A characteristic magnitude of zonal asymmetry in a surface energy tendency that can bring changes in line with observed trends is ≈3 W m−2. Strengthened zonal SST gradients can arise from a more zonally asymmetric ocean heat flux that increases by ≈20% K−1 using that implied by ERA5’s surface fluxes, a spatially varying radiative forcing with a west–east contrast of ≈3.3 W m−2, a more amplifying surface radiative feedback in the west than in the east with a contrast of ≈4 W m−2 K−1, a surface-air relative humidity (RH) contrast that increases RH in the west and decreases it in the east by ≈0.5% K−1, or a more zonally asymmetric wind speed that increases by ≈16% K−1. The “storylines” of forced surface energy budget change identified here are valuable in determining the plausibility of mechanisms that may be absent or underestimated in coupled climate model simulations. Significance Statement What is the magnitude of changes in energy fluxes in the tropical Pacific that could provoke the recent several decades of observed sea surface temperature trends? This urgent question of climate science is addressed using surface energy balance calculations with the various input terms perturbed in an idealized manner. These calculations provide an essential order-of-magnitude baseline for evaluating how novel mechanisms that are absent or weak in comprehensive climate model simulations might affect the pattern of historical trends.

Selective breeding boosts oyster resilience to ocean acidification via energy budget modulation.

Context . Neptunes and sub-Neptunes are typically modeled under the assumption that the interior is adiabatic and consists of distinct layers. However, this assumption is oversimplified, as formation models indicate that composition gradients can exist. Such composition gradients can significantly affect the planetary thermal evolution by inhibiting convection. In non-convective layers, the heat transport is governed by multiple processes, and each is relevant in different regions within the planet. Aims . We investigate how the evolution and internal structure of Neptunes and sub-Neptunes is affected when considering non-convective layers and the sensitivity of the results on the assumed thermal conductivity. Methods . We simulated the planetary evolution of such objects with an appropriate implementation for the conductivity by considering thermal transport via radiation, electrons, and vibrational conductivity. We considered planetary masses of 5, 10, and 15 M ⊕ ; three different initial energy budgets; and two different primordial composition profiles. Results . We find that the assumed conductivity significantly affects the planetary thermal evolution. We show that the commonly used conductivity assumption is inappropriate for modeling this planetary type. Furthermore, we find that the inferred radii deviate by ~20% depending on the assumed conductivity. The uncertainty on the primordial entropy in planets with non-convective layers leads to a difference of ~25% in the radii. This shows that the theoretical uncertainties are significantly larger than the observed ones and emphasizes the importance of these parameters. Conclusions . We conclude that the characterization and modeling of intermediate-mass gaseous planets strongly depend on the modeling approach and the model assumptions. We demonstrate that the existence of composition gradients significantly affects the inferred radius. We suggest that more data on thermal conductivities, particularly for partially ionized material and mixtures, as well as better constraints on the primordial thermal state of such planets are necessary.

This study focuses on the Alentejo and Algarve regions of southern Portugal, which is characterized by a typical Mediteranean climate. In the Mediterranean region, evaporation plays a significant role in reservoir water budgets. Therefore, estimating water surface evaporation is essential for efficient reservoir water management. This study aims to (i) assess the reservoir evaporation pattern in southern Portugal from meteorological offshore measures, (ii) benchmark various indirect methods for evaluating reservoir evaporation at a monthly scale, and (iii) provide recommendations on the most suitable indirect method to apply in operational practices. This study presents meteorological data collected from floating weather stations on instrumented platforms across nine reservoirs in Alentejo and Algarve. This is the first time that so many offshore local measurements have been made available in a Mediterranean climate region. The reservoir evaporation was estimated by the Energy Budget (Bowen Ratio) method, having concluded that monthly evaporation rates across the nine reservoirs ranged from 0.8 mm d­−1 in winter to 4.6 mm d­−1 in summer, with an annual average of 2.7 mm d­−1. Annual evaporation values ranged from 750 to 1230 mm, showing a positive gradient from the northern Alentejo region to the southwest Algarve region. To evaluate the performance of five empirical and semi-empirical evaporation indirect methods, a benchmarking analysis was conducted. The indirect methods studied are Mass Transfer (MT), Penman (PEN), Priestley and Taylor (PT), Thornthwaite (THOR), and Pan Evaporation (PE). Regarding the MT method, an N function of a reservoir superficial area is presented for the Mediterranean climate regions. In the Pan Evaporation method, the pan coefficient was considered equal to one. The benchmarking analysis revealed that all studied methods produced estimates that had good correlation with the Energy Budget method’s results across all reservoirs. All the methods showed small biases at the monthly scale, particularly in the dry semester. The estimates’ evaporation variability depended on the reservoir. Overall, the evaluation of evaporation methods concluded that (i) the stakeholders should considerer having an evaporation pan offshore; (ii) to manage the water balance of the studied reservoirs, the manager must apply the method with the best performance, depending on the data available; (iii) to manage other reservoirs located in the Mediterranean climate region, the manager must compare reservoir characteristics and the data available in order to choose the most suitable method to apply.

ABSTRACTAnimals are increasingly exposed to multiple co‐occurring stressors. Environmental factors such as seasonal time constraints (TC), predation risk, and pollutants strongly influence fitness‐related traits in aquatic organisms. Yet, the interactive effects of such stressors, especially across life stages, remain unclear. We examined immediate and delayed effects of predator cue exposure during the post‐overwintering egg stage and the larval stage, both subjected to early‐ or late‐season photoperiods, and how these factors interacted with subsequent larval exposure to predator cues and copper in the damselfly Lestes sponsa. Copper was used due to its known effects as a pesticide on aquatic invertebrates. We measured immediate effects of egg predator cue on egg hatching (development time), carry‐over effects on larval survival and growth rate, and behavioural (activity, resting, freezing, feeding) and physiological (oxidative damage, cellular energy allocation) traits after larval exposure to metal and predator cues. Several pairwise stressor interactions occurred, but none were modified by a third stressor. Predator cues during the egg stage delayed hatching under strong TC and led to sex‐specific carry‐over effects: males had reduced growth under strong TC. Copper increased oxidative damage only under weak TC, suggesting that strong TC can induce a hormetic antioxidant response. Short‐term copper exposure did not affect survival, behaviour, or net energy budget. However, predator exposure during the egg stage modified energy allocation, increasing it under weak TC and reducing it under strong TC, indicating context‐dependent trade‐offs. Behavioural responses were shaped by predator cues and TC; fast‐growing larvae under strong TC increased activity and feeding, while predator‐exposed individuals reduced these behaviours. These findings show how environmental stressors interact across life stages and traits, shaping plastic, sex‐specific responses. By integrating natural and anthropogenic stressors with life‐history timing, our study advances understanding of how ecological and evolutionary processes shape stress responses.

Assessing the asymmetric effects of clean and dirty energy budgets on load capacity factor: Evidence from top investing countries.

Abstract. The radiative effect of cirrus, contrails, and contrail cirrus affects the energy budget of the Earth and climate change. Those clouds, and especially contrails, are heterogeneous and their holes and sides exert three-dimensional radiative effects. This study uses the htrdr Monte Carlo radiative transfer code to investigate the sensitivity of the cloud radiative effect (CRE) to the geometrical dimensions and optical depth of optically thin ice clouds (cloud optical depth <4), with particular emphasis on three-dimensional radiative effects. When the Sun is at zenith, an increase in cloud optical depth causes a linear increase in shortwave (SW) CRE but a saturation of longwave (LW) CRE, causing the net CRE to change sign from positive to negative. The optical depth at which this change in sign occurs depends on the cloud geometry. 3D effects make the one-dimensional SW and LW CREs more positive for the Sun at zenith, reaching the same order of magnitude as the 1D CRE itself for clouds with high aspect ratios. The angular dependence of ice crystal scattering strongly increases shortwave CRE when solar zenith angle increases. 3D effects change sign from positive at zenith to negative at large zenith angles as the Sun's rays interact more with the cloud sides. Integrating instantaneous CRE and 3D effects over selected days of the year indicates compensation of SW with LW 3D effects for some cloud orientations, but 3D effects remain important in some cases. These results suggest that the 3D structure of cirrus and contrails needs to be considered to finely quantify their CRE and radiative forcing.

Introduction. Earth observation by low Earth orbit (LEO) satellites plays a critical role in supporting various sectors of the national economy. To increase the efficiency of this technology, optimizing the video data downlink —particularly with respect to the satellite’s elevation angle relative to the ground station — is essential.Problem Statement. The communication link margin varies depending on the selected signal waveform, whilechanges in the satellite’s elevation angle alter the propagation path length and, consequently, the energy characteristics of the downlink. For small satellites such as CubeSats, which have limited onboard power, the potential to transmit high-data-rate video within a brief communication window — depending on modulation mode — has not been sufficiently studied.Purpose. This study aims to enhance the performance of Earth remote sensing systems by improving the energy efficiency and throughput of satellite-to-ground video transmission in the X-band.Materials and Methods. The analysis applies microwave communication theory to evaluate the energy budget of the downlink, incorporating Adaptive Coding and Modulation (ACM) techniques supported by the DVB-S2/S2X standard. The study considers various modulation and coding (MODCOD) schemes and output power levels at diff erent satellite elevation angles.Results. The energy margin of the LEO satellite downlink has been calculated, enabling an assessment of thefeasibility of using DVB-S2X for video transmission from Earth observation satellites. The findings have shownthat at low elevation angles, a connection can be established using the most robust mode (QPSK 1/4), supporting a data rate of 38 Mbps. At elevation angles exceeding 50 degrees, higher-order modulation such as 32APSK 9/10 becomes feasible, achieving data rates up to 384 Mbps.Conclusions. The study has demonstrated that applying the DVB-S2(X) standard to CubeSat-class Earth observation missions enables more efficient and adaptive use of the X-band downlink channel. This approach has improved flexibility and throughput of video data transmission, especially when tailored to satellite elevation angles.

Prey quality, measured as energy density and energy content, is a key functional trait in predator-prey relationships. While the effects of interspecific differences in prey quality on predators have been examined previously, the consequences of intraspecific variation remain less understood. To examine how within-species variation in prey quality influences predator foraging, we modelled the effects of prey size, maturity and sampling season and region on the quality of Engraulis mordax, Sardinops sagax and Doryteuthis opalescens-three common prey species for top predators in the California Current Ecosystem (CCE). We contextualized our findings using documented energy budgets of the California sea lion (Zalophus californianus), a consumer of these species and an important ecosystem indicator in the CCE. We found significant within-species variation in prey quality related to size, maturity, season and region, with stronger effects in fish than squid. These patterns likely reflect prey life history and regional and seasonal oceanographic conditions that influence energy storage. Under static prey availability and predator energy demands, daily biomass requirements driven by intraspecific variation in prey quality were comparable to previous estimates based on interspecific differences. By integrating predator bioenergetics with prey energy content models, we found that the number of prey required can vary by tens of thousands depending on prey size-rendering smaller individuals an impractical energy source for non-filter-feeding predators. Even accounting for size, predators may need to consume up to twice as many individuals when foraging on lower-quality prey from certain regions, seasons or maturity stages compared to higher-quality conspecifics. Our findings highlight the critical importance of incorporating intraspecific variation in prey quality into bioenergetics frameworks that inform predator foraging predictions. As climate change and resource exploitation intensify, integrating functional traits and energetic trade-offs into predator-prey studies will be essential for anticipating predator responses and evaluating ecosystem resilience.

Abstract An exciplex, a charge‐transfer state formed at a donor–acceptor (D–A) heterojunction, plays a crucial role in organic photonic devices. Although binding energy significantly influences the exciplex energy and is often decisive in the relative alignment to Frenkel exciton levels, its exact determination remains challenging due to the disordered arrangement of heterodimers in amorphous mixture, leading to heterogeneous energy broadening. In this study, the distribution of the binding energies in organic D–A mixtures is investigated, focusing on the impact of different acceptor molecules in different shapes. A model is introduced that incorporates molecular size and ionic charge localization as key parameters, which successfully reproduces the statistical results of the exciplex binding energies in amorphous mixtures using TD‐DFT calculations. Furthermore, the model predicts that large molecules with ionic charges confined to their edges exhibit low exciplex binding energies, whereas smaller molecules with delocalized ionic charges across their molecular planes result in higher binding energies, which is consistent with experimental observation. These findings provide valuable insights for designing exciplex hosts for photonic applications, particularly for blue OLEDs, which are critical for advancing display technology, where the energy budget for developing higher‐energy exciplexes than a deep blue emitter is rather limited.

Effects of climate change on the metabolic ecology of small yellow croaker (Larimichthys polyactis) based on dynamic energy budget (DEB) model.

In the context of a changing climate, identifying a sustainable food production system that incorporates cleaner technologies with low C-sequestration and minimal energy inputs is crucial for long-term sustainability. The objective of study was to develop an innovative, energy-efficient system for mustard cultivation with reduced carbon footprint and economic viability by optimizing nitrogen (N) management. The experiment included nine nitrogen management strategies plus one unfertilized treatment as control, arranged in a randomized complete block design in three replicates. Results demonstrated that sensor-based nitrogen application using the GreenSeeker (GS) significantly augmented economic yield by 19.3% and 64.5%, and proved more profitable, boosting net monetary returns and benefit-cost ratio by 125.1% & 36.2% and 58.8% & 24.4%, respectively compared to the recommended dose of fertilizer (RDF) and control, and saved 18.7% of nitrogen. The yield of mustard seeds increased significantly, ranging from a minimum of 3.70% (with RDN75 + foliar spray @ 1.5% KNO₃) to a maximum of 19.31% under the GreenSeeker (GS) treatment. Further, N foliar spray treatments at N100 level registered for per cent negative changes in N efficiency (−6.90 to −1.46%) over RDF. Nearly half (46.25%) of the total energy consumption was attributed to fertilizer nitrogen, diesel fuel, threshing, and irrigation contributing 17.7%, 11.4%, 9.68%, and 7.40%, respectively. The GS guided N application consumed comparably lowest energy (5.91% less) than RDF. The energy indices viz. energy input (−5.98%), energy output (+7.25%), energy use efficiency (6.51%), energy profitability (5.51), energy productivity (+18%), respectively were achieved higher by precise N administration using sensor based GS. In contrast, the specific energy (1.39 MJ kg-1), energy intensiveness, direct and non-renewable energy usage were highest under RDN100 over RDN75 in conjunction with FS of different N sources (U, NCU and KNO3). Congruently, human energy profitability was varied from 0.34 to 9.78%, respectively over RDF. Carbon-related metrics showed that RDN100 produced higher carbon inputs, outputs, net carbon gains, and spatial carbon footprints compared to RDN75. However, GS-based management outperformed RDF, with lower carbon input (−8.1%), higher carbon output (+10.9%), greater net carbon gain (+16.5%), and the lowest carbon footprint (0.30 kg CE kg ⁻ ¹) versus RDF 0.39 kg CE kg ⁻ ¹. Furthermore, CO₂ emissions were approximately 81% higher in fertilized plots (1921 kg CO₂-e ha ⁻ ¹) compared to unfertilized ones. Overall, the study concludes that sensor-based precise nitrogen management using GS is an innovative, sustainable, and energy-efficient approach that reduces the carbon footprint, combat climate change, and supports food security.

The prevailing linear model of physical activity (PA) and total energy expenditure (TEE) has been challenged by models that predict an upper limit of TEE linked to a compensatory reduction elsewhere in the energy budget in response to increased PA. We determined the equation of best fit between PA and TEE and explored relationships between PA and behavioral and physiological compensation. Using linear and nonlinear modeling, we observed a positive linear relationship between PA and TEE either without or after adjustment for fat-free mass (R2= 0.3492, TEE = 0.00685*PA + 7.124: R2=0.3667, TEE_ADJ(FFM) = 0.00511*PA + 8.598). Higher PA was associated with lower sedentary time (R2= 0.7207, %SPA= -0.0211*X + 91.261). There was no association between PA, TEE, or resting metabolic rate and adjusted biomarkers of immune, reproductive, or thyroid function after Bonferroni correction. The findings of this observational study do not support the constrained/compensated model but affirm the conventional additive relationship between PA and TEE across a broad range of PA levels.