Browsing by Subject "ENERGY-BALANCE"

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  • ISCOLE Res Grp; Zakrzewski-Fruer, Julia K.; Gillison, Fiona B.; Fogelholm, Mikael; Kivelä, Jemina; Räsänen, Sari; Roito, Sanna; Saloheimo, Taru; Valta, Leena (2019)
    BackgroundExisting research has documented inconsistent findings for the associations among breakfast frequency, physical activity (PA), and sedentary time in children. The primary aim of this study was to examine the associations among breakfast frequency and objectively-measured PA and sedentary time in a sample of children from 12 countries representing a wide range of human development, economic development and inequality. The secondary aim was to examine interactions of these associations between study sites.MethodsThis multinational, cross-sectional study included 6228 children aged 9-11years from the 12 International Study of Childhood Obesity, Lifestyle and the Environment sites. Multilevel statistical models were used to examine associations between self-reported habitual breakfast frequency defined using three categories (breakfast consumed 0 to 2days/week [rare], 3 to 5days/week [occasional] or 6 to 7days/week [frequent]) or two categories (breakfast consumed less than daily or daily) and accelerometry-derived PA and sedentary time during the morning (wake time to 1200h) and afternoon (1200h to bed time) with study site included as an interaction term. Model covariates included age, sex, highest parental education, body mass index z-score, and accelerometer waking wear time.ResultsParticipants averaged 60 (s.d. 25) min/day in moderate-to-vigorous PA (MVPA), 315 (s.d. 53) min/day in light PA and 513 (s.d. 69) min/day sedentary. Controlling for covariates, breakfast frequency was not significantly associated with total daily or afternoon PA and sedentary time. For the morning, frequent breakfast consumption was associated witha higher proportion of time in MVPA (0.3%), higher proportion of time in light PA (1.0%) and lower min/day and proportion of time sedentary (3.4min/day and 1.3%) than rare breakfast consumption (all p0.05). No significant associations were found when comparing occasional with rare or frequent breakfast consumption, or daily with less than daily breakfast consumption. Very few significant interactions with study site were found.ConclusionsIn this multinational sample of children, frequent breakfast consumption was associated with higher MVPA and light PA time and lower sedentary time in the morning when compared with rare breakfast consumption, although the small magnitude of the associations may lack clinical relevance.Trial registrationThe International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE) is registered at(Identifier NCT01722500).
  • Abera, Temesgen; Heiskanen, Janne; Pellikka, Petri; Adhikari, Hari; Maeda, Eduardo (2020)
    Bushlands (Acacia-Commiphora) constitute the largest and one of the most threatened ecosystems in East Africa. Although several studies have investigated the climatic impacts of land changes on local and global climate, the main focus has been on forest loss and the impacts of bushland clearing thus remain poorly understood. Measuring the impacts of bushland loss on local climate is challenging given that changes often occur at fragmented and small patches. Here, we apply high-resolution satellite imagery and land surface flux modeling approaches to unveil the impacts of bushland clearing on surface biophysical properties and its associated effects on surface energy balance and land surface temperature. Our results show that bushland clearing leads to an average reduction in evapotranspiration of 0.4 mm day(-1). The changes in surface biophysical properties affected the surface energy balance components with different magnitude. The reduction in latent heat flux was stronger than other surface energy fluxes and resulted in an average net increase in daytime land surface temperature (LST) of up to 1.75 K. These results demonstrate the important impact of bushland-to-cropland conversion on the local climate, as they reveal increases in LST of a magnitude comparable to those caused by forest loss. This finding highlights the necessity of bushland conservation for regulating the land surface temperature in East Africa and, at the same time, warns of the climatic impacts of clearing bushlands for agriculture. (c) 2020 The Authors. Published by Elsevier B.V.
  • McManus, Bettina; Korpela, Riitta; O'Connor, Paula; Schellekens, Harriet; Cryan, John F.; Cotter, Paul D.; Nilaweera, Kanishka N. (2015)
    Background: Several studies in both humans and rodents have examined the use of lactoferrin as a dietary solution to weight gain and visceral fat accretion and have shown promising results in the short term (up to 7 weeks). This study examined the effects of giving lactoferrin over a longer period of time. Methods: For 13 weeks, male C57/BL6J mice were given a diet containing 10 % kJ fat and 20 % kJ casein (LFD) or a diet with 45 % kJ fat and either 20 % kJ casein (HFD) or 20 % kJ lactoferrin (HFD + Lac). Physiological, metabolic, and biochemical parameters were investigated. Gene expression was investigated by Real-Time PCR and microarray. All data was assessed using t-test, ANOVA or ANCOVA. Gene Set Enrichment Analysis was used to interpret microarray data and assess the impact on gene sets with common biological roles. Results: By the end of the trial, HFD + Lac fed mice did not alter energy balance, body composition, bodyweight, or weight gain when compared to the HFD group. Notably, there were no changes in subcutaneous or epididymal adipose leptin mRNA levels between high fat diet groups, however plasma leptin was significantly reduced in the HFD + Lac compared to HFD group (P <0.05) suggesting reduced leptin secretion. Global microarray analysis of the hypothalamus indicate an overall reduction in gene sets associated with feeding behaviour (P <0.01) and an upregulation of gene sets associated with retinol metabolism in the HFD + Lac group compared to the HFD group (P <0.01). Genes in the latter catergory have been shown to impact on the hypothalamic-pituitary-adrenal axis. Notably, plasma corticosterone levels in the HFD + Lac group were reduced compared to the HFD fed mice (P <0.05). Conclusions: The data suggests that prolonged feeding of full-length dietary lactoferrin, as part of a high fat diet, does not have a beneficial impact on weight gain when compared to casein. However, its impact on leptin secretion and accompanying changes in hypothalamic gene expression may underlie how this dietary protein alters plasma corticosterone. The lactoferrin fed mouse model could be used to identify leptin and corticosterone regulated genes in the hypothalamus without the confounding effects of body weight change.
  • Tsakoumis, Emmanouil; Ahi, Ehsan Pashay; Schmitz, Monika (2022)
    Reproduction is an energetically costly event across vertebrates and tightly linked to nutritional status and en-ergy reserves. In mammals, the hormone leptin is considered as a link between energy homeostasis and repro-duction. However, its role in fish reproduction is still unclear. In this study, we investigated the possible role of leptin in the regulation of reproduction in zebrafish, using a loss of function leptin receptor (lepr) strain. Impaired leptin signaling resulted in severe reproductive deficiencies in female zebrafish. lepr mutant females laid significantly fewer eggs, with low fertilization rates compared to wild-type females. Folliculogenesis was not affected, but oocyte maturation and ovulation were disrupted in lepr mutants. Interestingly, the expression of luteinizing hormone beta (lhb) in the pituitary was significantly lower in mutant females. Analysis of candidate genes in the ovaries and isolated fully grown follicles revealed differential expression of genes involved in ste-roidogenesis, oocyte maturation and ovulation in the mutants, which are known to be regulated by LH signaling. Moreover, subfertility in lepr mutants could be partially restored by administration of human chorionic gonad-otropin. In conclusion, our results show that leptin deficiency does not affect early stages of follicular devel-opment, but leptin might be essential in later steps, such as in oocyte maturation and ovulation. To our knowledge, this is the first time that leptin is associated to reproductive deficiencies in zebrafish.
  • Ahola, Aila J.; Mutter, Stefan; Forsblom, Carol; Harjutsalo, Valma; Groop, Per-Henrik (2019)
    We assessed meal timing, meal frequency, and breakfast consumption habits of adult individuals with type 1 diabetes (n = 1007) taking part in the Finnish Diabetic Nephropathy Study, and studied whether they are associated with glycaemic control. Data on dietary intake and blood glucose measurements were retrieved from food records. HbA(1c) was measured at the study visit. In the whole sample, four peaks of energy intake emerged. Energy intake was the greatest in the evening, followed by midday. Altogether 7% of the participants reported no energy intake between 05:00 and 09:59 (breakfast skippers). While breakfast skippers reported lower number of meals, no difference was observed in the total energy intake between those eating and omitting breakfast. In a multivariable model, skipping breakfast was associated with higher mean blood glucose concentrations and lower odds of good glycaemic control. A median of 6 daily meals was reported. Adjusted for confounders, the number of meals was negatively associated with HbA(1c), and the mean of the blood glucose measurements, but positively associated with the variability of these measurements. Our observations support the habit of a regular meal pattern, including consumption of breakfast and multiple smaller meals for good glycaemic control in adults with type 1 diabetes. However, an increase in the blood glucose variability may additionally be expected with an increase in the number of meals eaten.
  • Thum, Tea; Zaehle, Sönke; Köhler, Philipp; Aalto, Tuula; Aurela, Mika; Guanter, Luis; Kolari, Pasi; Laurila, Tuomas; Lohila, Annalea; Magnani, Federico; Van der Tol, Christiaan; Markkanen, Tiina (2017)
    Recent satellite observations of sun-induced chlorophyll fluorescence (SIF) are thought to provide a large-scale proxy for gross primary production (GPP), thus providing a new way to assess the performance of land surface models (LSMs). In this study, we assessed how well SIF is able to predict GPP in the Fenno-Scandinavian region and what potential limitations for its application exist. We implemented a SIF model into the JSBACH LSM and used active leaf-level chlorophyll fluorescence measurements (Chl F) to evaluate the performance of the SIF module at a coniferous forest at Hyytiala, Finland. We also compared simulated GPP and SIF at four Finnish micrometeorological flux measurement sites to observed GPP as well as to satellite-observed SIF. Finally, we conducted a regional model simulation for the Fenno-Scandinavian region with JSBACH and compared the results to SIF retrievals from the GOME-2 (Global Ozone Monitoring Experiment-2) space-borne spectrometer and to observation-based regional GPP estimates. Both observations and simulations revealed that SIF can be used to estimate GPP at both site and regional scales. At regional scale the model was able to simulate observed SIF averaged over 5 years with r(2) of 0.86. The GOME-2-based SIF was a better proxy for GPP than the remotely sensed fA-PAR (fraction of absorbed photosynthetic active radiation by vegetation). The observed SIF captured the seasonality of the photosynthesis at site scale and showed feasibility for use in improving of model seasonality at site and regional scale.
  • Lu, Yingchang; Day, Felix R.; Gustafsson, Stefan; Buchkovich, Martin L.; Na, Jianbo; Bataille, Veronique; Cousminer, Diana L.; Dastani, Zari; Drong, Alexander W.; Esko, Tonu; Evans, David M.; Falchi, Mario; Feitosa, Mary F.; Ferreira, Teresa; Hedman, Asa K.; Haring, Robin; Hysi, Pirro G.; Iles, Mark M.; Justice, Anne E.; Kanoni, Stavroula; Lagou, Vasiliki; Li, Rui; Li, Xin; Locke, Adam; Lu, Chen; Magi, Reedik; Perry, John R. B.; Pers, Tune H.; Qi, Qibin; Sanna, Marianna; Schmidt, Ellen M.; Scott, William R.; Shungin, Dmitry; Teumer, Alexander; Vinkhuyzen, Anna A. E.; Walker, Ryan W.; Westra, Harm-Jan; Zhang, Mingfeng; Zhang, Weihua; Zhao, Jing Hua; Zhu, Zhihong; Afzal, Uzma; Ahluwalia, Tarunveer Singh; Bakker, Stephan J. L.; Bellis, Claire; Bonnefond, Amelie; Borodulin, Katja; Buchman, Aron S.; Cederholm, Tommy; Choh, Audrey C.; Choi, Hyung Jin; Curran, Joanne E.; de Groot, Lisette C. P. G. M.; De Jager, Philip L.; Dhonukshe-Rutten, Rosalie A. M.; Enneman, Anke W.; Eury, Elodie; Evans, Daniel S.; Forsen, Tom; Friedrich, Nele; Fumeron, Frederic; Garcia, Melissa E.; Gartner, Simone; Han, Bok-Ghee; Havulinna, Aki S.; Hayward, Caroline; Hernandez, Dena; Hillege, Hans; Ittermann, Till; Kent, Jack W.; Kolcic, Ivana; Laatikainen, Tiina; Lahti, Jari; Leach, Irene Mateo; Lee, Christine G.; Lee, Jong-Young; Liu, Tian; Liu, Youfang; Lobbens, Stephane; Loh, Marie; Lyytikainen, Leo-Pekka; Medina-Gomez, Carolina; Michaelsson, Karl; Nalls, Mike A.; Nielson, Carrie M.; Oozageer, Laticia; Pascoe, Laura; Paternoster, Lavinia; Polasek, Ozren; Ripatti, Samuli; Sarzynski, Mark A.; Shin, Chan Soo; Narancic, Nina Smolej; Spira, Dominik; Srikanth, Priya; Steinhagen-Thiessen, Elisabeth; Sung, Yun Ju; Swart, Karin M. A.; Taittonen, Leena; Tanaka, Toshiko; Tikkanen, Emmi; van der Velde, Nathalie; van Schoor, Natasja M.; Verweij, Niek; Wright, Alan F.; Yu, Lei; Zmuda, Joseph M.; Pellikka, Niina; Forrester, Terrence; Grarup, Niels; Jackson, Anne U.; Kristiansson, Kati; Kuulasmaa, Teemu; Kuusisto, Johanna; Lichtner, Peter; Luan, Jian'an; Mahajan, Anubha; Mannisto, Satu; Palmer, Cameron D.; Ried, Janina S.; Scott, Robert A.; Stancakova, Alena; Wagner, Peter J.; Demirkan, Ayse; Doring, Angela; Gudnason, Vilmundur; Kiel, Douglas P.; Kuhnel, Brigitte; Mangino, Massimo; Mcknight, Barbara; Menni, Cristina; O'Connell, Jeffrey R.; Oostra, Ben A.; Shuldiner, Alan R.; Song, Kijoung; Vandenput, Liesbeth; van Duijn, Cornelia M.; Vollenweider, Peter; White, Charles C.; Boehnke, Michael; Boettcher, Yvonne; Cooper, Richard S.; Forouhi, Nita G.; Gieger, Christian; Grallert, Harald; Hingorani, Aroon; Jorgensen, Torben; Jousilahti, Pekka; Kivimaki, Mika; Kumari, Meena; Laakso, Markku; Langenberg, Claudia; Linneberg, Allan; Luke, Amy; Mckenzie, Colin A.; Palotie, Aarno; Pedersen, Oluf; Peters, Annette; Strauch, Konstantin; Tayo, Bamidele O.; Wareham, Nicholas J.; Bennett, David A.; Bertram, Lars; Blangero, John; Bluher, Matthias; Bouchard, Claude; Campbell, Harry; Cho, Nam H.; Cummings, Steven R.; Czerwinski, Stefan A.; Demuth, Ilja; Eckardt, Rahel; Eriksson, Johan G.; Ferrucci, Luigi; Franco, Oscar H.; Froguel, Philippe; Gansevoort, Ron T.; Hansen, Torben; Harris, Tamara B.; Hastie, Nicholas; Heliovaara, Markku; Hofman, Albert; Jordan, Joanne M.; Jula, Antti; Kahonen, Mika; Kajantie, Eero; Knekt, Paul B.; Koskinen, Seppo; Kovacs, Peter; Lehtimaki, Terho; Lind, Lars; Liu, Yongmei; Orwoll, Eric S.; Osmond, Clive; Perola, Markus; Perusse, Louis; Raitakari, Olli T.; Rankinen, Tuomo; Rao, D. C.; Rice, Treva K.; Rivadeneira, Fernando; Rudan, Igor; Salomaa, Veikko; Sorensen, Thorkild I. A.; Stumvoll, Michael; Tonjes, Anke; Towne, Bradford; Tranah, Gregory J.; Tremblay, Angelo; Uitterlinden, Andre G.; van der Harst, Pim; Vartiainen, Erkki; Viikari, Jorma S.; Vitart, Veronique; Vohl, Marie-Claude; Volzke, Henry; Walker, Mark; Wallaschofski, Henri; Wild, Sarah; Wilson, James F.; Yengo, Loic; Bishop, D. Timothy; Borecki, Ingrid B.; Chambers, John C.; Cupples, L. Adrienne; Dehghan, Abbas; Deloukas, Panos; Fatemifar, Ghazaleh; Fox, Caroline; Furey, Terrence S.; Franke, Lude; Han, Jiali; Hunter, David J.; Karjalainen, Juha; Karpe, Fredrik; Kaplan, Robert C.; Kooner, Jaspal S.; McCarthy, Mark I.; Murabito, Joanne M.; Morris, Andrew P.; Bishop, Julia A. N.; North, Kari E.; Ohlsson, Claes; Ong, Ken K.; Prokopenko, Inga; Richards, J. Brent; Schadt, Eric E.; Spector, Tim D.; Widen, Elisabeth; Willer, Cristen J.; Yang, Jian; Ingelsson, Erik; Mohlke, Karen L.; Hirschhorn, Joel N.; Pospisilik, John Andrew; Zillikens, M. Carola; Lindgren, Cecilia; Kilpelainen, Tuomas Oskari; Loos, Ruth J. F. (2016)
    To increase our understanding of the genetic basis of adiposity and its links to cardiometabolic disease risk, we conducted a genome-wide association meta-analysis of body fat percentage (BF%) in up to 100,716 individuals. Twelve loci reached genome-wide significance (P <5 x 10(-8)), of which eight were previously associated with increased overall adiposity (BMI, BF%) and four (in or near COBLL1/GRB14, IGF2BP1, PLA2G6, CRTC1) were novel associations with BF%. Seven loci showed a larger effect on BF% than on BMI, suggestive of a primary association with adiposity, while five loci showed larger effects on BMI than on BF%, suggesting association with both fat and lean mass. In particular, the loci more strongly associated with BF% showed distinct cross-phenotype association signatures with a range of cardiometabolic traits revealing new insights in the link between adiposity and disease risk.
  • Helbig, Manuel; Waddington, James M.; Alekseychik, Pavel; Amiro, Brian; Aurela, Mika; Barr, Alan G.; Black, T. Andrew; Carey, Sean K.; Chen, Jiquan; Chi, Jinshu; Desai, Ankur R.; Dunn, Allison; Euskirchen, Eugenie S.; Flanagan, Lawrence B.; Friborg, Thomas; Garneau, Michelle; Grelle, Achim; Harder, Silvie; Heliasz, Michal; Humphreys, Elyn R.; Ikawa, Hiroki; Isabelle, Pierre-Erik; Iwata, Hiroki; Jassal, Rachhpal; Korkiakoski, Mika; Kurbatova, Juliya; Kutzbach, Lars; Lapshina, Elena; Lindroth, Anders; Lofvenius, Mikaell Ottosson; Lohila, Annalea; Mammarella, Ivan; Marsh, Philip; Moore, Paul A.; Maximov, Trofim; Nadeau, Daniel F.; Nicholls, Erin M.; Nilsson, Mats B.; Ohta, Takeshi; Peichl, Matthias; Petrone, Richard M.; Prokushkin, Anatoly; Quinton, William L.; Roulet, Nigel; Runkle, Benjamin R. K.; Sonnentag, Oliver; Strachan, Ian B.; Taillardat, Pierre; Tuittila, Eeva-Stiina; Tuovinen, Juha-Pekka; Turner, Jessica; Ueyama, Masahito; Varlagin, Andrej; Vesala, Timo; Wilmking, Martin; Zyrianov, Vyacheslav; Schulze, Christopher (2020)
    Peatlands and forests cover large areas of the boreal biome and are critical for global climate regulation. They also regulate regional climate through heat and water vapour exchange with the atmosphere. Understanding how land-atmosphere interactions in peatlands differ from forests may therefore be crucial for modelling boreal climate system dynamics and for assessing climate benefits of peatland conservation and restoration. To assess the biophysical impacts of peatlands and forests on peak growing season air temperature and humidity, we analysed surface energy fluxes and albedo from 35 peatlands and 37 evergreen needleleaf forests-the dominant boreal forest type-and simulated air temperature and vapour pressure deficit (VPD) over hypothetical homogeneous peatland and forest landscapes. We ran an evapotranspiration model using land surface parameters derived from energy flux observations and coupled an analytical solution for the surface energy balance to an atmospheric boundary layer (ABL) model. We found that peatlands, compared to forests, are characterized by higher growing season albedo, lower aerodynamic conductance, and higher surface conductance for an equivalent VPD. This combination of peatland surface properties results in a similar to 20% decrease in afternoon ABL height, a cooling (from 1.7 to 2.5 degrees C) in afternoon air temperatures, and a decrease in afternoon VPD (from 0.4 to 0.7 kPa) for peatland landscapes compared to forest landscapes. These biophysical climate impacts of peatlands are most pronounced at lower latitudes (similar to 45 degrees N) and decrease toward the northern limit of the boreal biome (similar to 70 degrees N). Thus, boreal peatlands have the potential to mitigate the effect of regional climate warming during the growing season. The biophysical climate mitigation potential of peatlands needs to be accounted for when projecting the future climate of the boreal biome, when assessing the climate benefits of conserving pristine boreal peatlands, and when restoring peatlands that have experienced peatland drainage and mining.
  • Houlahan, Kathleen E.; Prokopec, Stephenie D.; Moffat, Ivy D.; Lindén, Jere; Lensu, Sanna; Okey, Allan B.; Pohjanvirta, Raimo; Boutros, Paul C. (2015)
    In some mammals, halogenated aromatic hydrocarbon (HAH) exposure causes wasting syndrome, defined as significant weight loss associated with lethal outcomes. The most potent HAH in causing wasting is 2,3,7,8-tetrachlorodibenzo-rho-dioxin (TCDD), which exerts its toxic effects through the aryl hydrocarbon receptor (AHR). Since TCDD toxicity is thought to predominantly arise from dysregulation of AHR-transcribed genes, it was hypothesized that wasting syndrome is a result of to TCDD-induced dysregulation of genes involved in regulation of food-intake. As the hypothalamus is the central nervous systems' regulatory center for food-intake and energy balance. Therefore, mRNA abundances in hypothalamic tissue from two rat strains with widely differing sensitivities to TCDD-induced wasting syndrome: TCDD-sensitive Long-Evans rats and TCDD-resistant Han/Wistar rats, 23 h after exposure to TCDD (100 mu g/kg) or corn oil vehicle. TCDD exposure caused minimal transcriptional dysregulation in the hypothalamus, with only 6 genes significantly altered in Long-Evans rats and 15 genes in Han/Wistar rats. Two of the most dysregulated genes were Cyp1a1 and Nqo1, which are induced by TCDD across a wide range of tissues and are considered sensitive markers of TCDD exposure. The minimal response of the hypothalamic transcriptome to a lethal dose of TCDD at an early time-point suggests that the hypothalamus is not the predominant site of initial events leading to hypophagia and associated wasting. TCDD may affect feeding behaviour via events upstream or downstream of the hypothalamus, and further work is required to evaluate this at the level of individual hypothalamic nuclei and subregions. (C) 2014 The Authors. Published by Elsevier Ireland Ltd.
  • Järvi, Leena; Rannik, Üllar; Kokkonen, Tom; Kurppa, Mona; Karppinen, Ari; Kouznetsov, Rostislav D.; Rantala, Pekka; Vesala, Timo; Wood, Curtis R. (2018)
    The eddy covariance (EC) technique is the most direct method for measuring the exchange between the surface and the atmosphere in different ecosystems. Thus, it is commonly used to get information on air pollutant and greenhouse gas emissions, and on turbulent heat transfer. Typically an ecosystem is monitored by only one single EC measurement station at a time, making the ecosystem-level flux values subject to random and systematic uncertainties. Furthermore, in urban ecosystems we often have no choice but to conduct the single-point measurements in non-ideal locations such as close to buildings and/or in the roughness sub-layer, bringing further complications to data analysis and flux estimations. In order to tackle the question of how representative a single EC measurement point in an urban area can be, two identical EC systems - measuring momentum, sensible and latent heat, and carbon dioxide fluxes - were installed on each side of the same building structure in central Helsinki, Finland, during July 2013-September 2015. The main interests were to understand the sensitivity of the vertical fluxes on the single measurement point and to estimate the systematic uncertainty in annual cumulative values due to missing data if certain, relatively wide, flow-distorted wind sectors are disregarded. The momentum and measured scalar fluxes respond very differently to the distortion caused by the building structure. The momentum flux is the most sensitive to the measurement location, whereas scalar fluxes are less impacted. The flow distortion areas of the two EC systems (40-150 and 230-340 degrees) are best detected from the mean-wind-normalised turbulent kinetic energy, and outside these areas the median relative random uncertainties of the studied fluxes measured by one system are between 12 % and 28 %. Different gap-filling methods with which to yield annual cumulative fluxes show how using data from a single EC measurement point can cause up to a 12 % (480 g C m(-2)) underestimation in the cumulative carbon fluxes as compared to combined data from the two systems. Combining the data from two EC systems also increases the fraction of usable half-hourly carbon fluxes from 45 % to 69 % at the annual level. For sensible and latent heat, the respective underestimations are up to 5 % and 8 % (0.094 and 0.069 TJ m(-2)). The obtained random and systematic uncertainties are in the same range as observed in vegetated ecosystems. We also show how the commonly used data flagging criteria in natural ecosystems, kurtosis and skewness, are not necessarily suitable for filtering out data in a densely built urban environment. The results show how the single measurement system can be used to derive representative flux values for central Helsinki, but the addition of second system to other side of the building structure decreases the systematic uncertainties. Comparable results can be expected in similarly dense city locations where no large directional deviations in the source area are seen. In general, the obtained results will aid the scientific community by providing information about the sensitivity of EC measurements and their quality flagging in urban areas.
  • Lindberg, Fredrik; Grimmond, C. S. B.; Gabey, Andrew; Huang, Bei; Kent, Christoph W.; Sun, Ting; Theeuwes, Natalie E.; Järvi, Leena; Ward, Helen C.; Capel-Timms, I.; Chang, Yuanyong; Jonsson, Per; Krave, Niklas; Liu, Dongwei; Meyer, D.; Olofson, K. Frans G.; Tan, Jianguo; Wastberg, Dag; Xue, Lingbo; Zhang, Zhe (2018)
    UMEP (Urban Multi-scale Environmental Predictor), a city-based climate service tool, combines models and tools essential for climate simulations. Applications are presented to illustrate UMEP's potential in the identification of heat waves and cold waves; the impact of green infrastructure on runoff; the effects of buildings on human thermal stress; solar energy production; and the impact of human activities on heat emissions. UMEP has broad utility for applications related to outdoor thermal comfort, wind, urban energy consumption and climate change mitigation. It includes tools to enable users to input atmospheric and surface data from multiple sources, to characterise the urban environment, to prepare meteorological data for use in cities, to undertake simulations and consider scenarios, and to compare and visualise different combinations of climate indicators. An open-source tool, UMEP is designed to be easily updated as new data and tools are developed, and to be accessible to researchers, decision-makers and practitioners. (C) 2017 The Authors. Published by Elsevier Ltd.
  • Liu, Heping; Blanken, Peter D.; Weidinger, Tamas; Nordbo, Annika; Vesala, Timo (2011)
    Understanding seasonal variations in the evaporation of inland waters (e.g., lakes and reservoirs) is important for water resource management as well as the prediction of the hydrological cycles in response to climate change. We analyzed eddy covariance-based evaporation measurements from the Ross Barnett Reservoir (32◦26N, 90◦02W; which is always ice-free) in central Mississippi during the cool months (i.e., September–March) of 2007 and 2008, and found that the variability in cold front activities (i.e., passages of cold fronts and cold/dry air masses behind cold fronts) played an important role in modulating the exchange of sensible (H) and latent (λE) heat fluxes. Our analysis showed that 2007’s warmer cool season had smaller mean H and λE than 2008’s cooler cool season. This implies that the warmer cool season did not accelerate evaporation and heat exchange between the water surface and the atmosphere. Instead, more frequent cold fronts and longer periods of cold/dry air masses behind the cold fronts in 2008 resulted in overall larger H and λE as compared with 2007, this primarily taking the form of sporadic short-term rapid ‘pulses’ of H and λE losses from the water’s surface. These results suggest that future climate-induced changes in frequency of cold fronts and the meteorological properties of the air masses behind cold fronts (e.g., wind speeds, temperature, and humidity), rather than other factors of climate change, would produce significant variations in the water surface’s energy fluxes and subsequent evaporation rates.
  • Guan, Yanlong; Lu, Hongwei; Yin, Chuang; Xue, Yuxuan; Jiang, Yelin; Kang, Yu; He, Li; Heiskanen, Janne (2020)
    Extensive research has focused on the response of vegetation to climate change, including potential mechanisms and resulting impacts. Although many studies have explored the relationship between vegetation and climate change in China, research on spatiotemporal distribution changes of climate regimes using natural vegetation as an indicator is still lacking. Further, limited information is available on the response of vegetation to shifts in China's regional climatic zones. In this study, we applied Mann-Kendall, and correlation analysis to examine the variabilities in temperature, precipitation, surface soil water, normalised difference vegetation index (NDVI), and albedo in China from 1982 to 2012. Our results indicate significant shifts in the distribution of Koppen-Geiger climate classes in China from 12.08% to 18.98% between 1983 and 2012 at a significance level of 0.05 (MK). The percentage areas in the arid and continental zones expanded at a rate of 0.004%/y and 0.12%/y, respectively, while the percentage area in the temperate and alpine zones decreased by -0.05%/y and - 0.07%/y. Sensitivity fitting results between simulated and observed changes identified temperature to be a dominant control on the dynamics of temperate (r(2)= 0.98) and alpine (r(2)= 0.968) zones, while precipitation was the dominant control on the changes of arid (r(2) = 0.856) and continental (r(2) = 0.815) zones. The response of the NDVI to albedo infers a more pronounced radiative response in temperate (r = -0.82, p