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The use of long-term (slow variations) for modelling radio propagation behavior in indoor scenarios limits the validity of such models, as most of the environments induced fast variations overlapped with the slow ones. Real world data gathered at different locations in two bands within Fifth Generation FR1 spectrum, 3 GHz and 5 GHz, provide insight on the effect of such fast variations and on the distribution models that would be useful to complement the long term analysis with short term behavior in order to improve the design of such 5G microwave networks. Comparisons among short term performance taking into account both the frequency, the visibility conditions and the environment size, shape and furnishing are presented with the focus on modelling as accurate as possible the narrowband channel. The use of ΔBIC (describing the difference between Bayesian Information Criteria indexes of each fitting) complements and confirms the insight provided by direct inspection on traditional fitting plots. This parameter could be interesting for future network deployments. Ministerio de Innovación y Ciencia | Ref. TEC 2017-85529-C3-3-R Ministerio de Innovación y Ciencia | Ref. PRX21/00115

International audience; Today, more and more velocity observations are available online or on-demand. However, this amount of data is complex to analyze since velocity observations span different temporal baselines. Velocities obtained from a small temporal baseline are close to the derivative of the displacement but are more likely to be contaminated by noise. Velocities obtained from a long temporal baseline approximate the mean velocity between two dates but can be affected by temporal decorrelation. Having short and long temporal baselines provides a data redundancy that needs to be properly considered. In this article, we propose a method that aims to extract short-term velocity time series with a regular temporal sampling from all available displacement observations. The proposed method relies on a temporal inversion based on an improved temporal closure of the displacement observation network. Two criteria are proposed to determine the optimal temporal sampling to study short-term variations. To take the unequal data uncertainty into account, the temporal inversion is done by an Iterative Reweighted Least Square using a well-established weighting function, without preprocessing. The proposed method results in velocity time series with an optimal temporal sampling, an improved temporal coverage, reduced uncertainty and no redundancy. The studied area is the Kyagar glacier, in the North of the Karakoram range which is characterized by strong velocity variations originated from a glacier surge and additional seasonal variability.

Lakes are among the most productive and biodiverse ecosystems in Antarctica, and they behave as important indicators of local climatic and environmental changes. However, few studies have focused on the local drivers of short-term temporal variability in lacustrine biogeochemical variables. In the present study, measurements of physical, chemical, biological and optical characteristics of the shallow endorheic Lake 14 at Edmonson Point (74.33° S, 165.13° E) were made over the ice-free period in December 2006. A significant variation in most variables was observed. Possible drivers for these changes were the loss of the ice cover, an increase in solar irradiance, a change in photosynthetic activity and the evaporative loss of water. By removing relative changes due to evaporative losses, new insights were gained into the driving factors controlling the biogeochemistry and primary productivity in the shallow Antarctic lake. In particular, a decrease in phytoplankton biomass was observed and was probably linked to photoinhibition as revealed by an increase in photoprotective pigments. The absorbance by dissolved organic matter, when weighted with respect to evaporative loss, shows an overall reduction in humic-like absorption, most likely linked to photodegradation.

2009年の6月29日-7月2日と8月22-23日に，周防灘において水温，塩分，クロロフィルα（以下chl. α），濁度の鉛直分布を調べた。6-7月にはchl. αの亜表層極大と海底高濁度層がほぼ調査海域全体に形成されていた。8月にはchl. α の亜表層極大は弱くなり，6-7月と較べて海底高濁度層の発達が顕著で，chl. α濃度の増加も見られた。6-7月と8月の両観測期間は，それぞれ小潮と大潮の時期に相当していたことから，潮汐周期が海底高濁度層の発達に影響を及ぼしている可能性が示唆された。また，両観測期間中に，灘西部の2観測点（水深10mの浅海域と30mの沖合域）において1-3時間毎の連続観測を行って日周変動を調べた。海底高濁度層は水温・塩分（および密度）の急激な変化時に最大値を示し，濁度層の分布パターン・厚さは潮汐周期と底層の水温･塩分･密度分布によく対応していた。さらに，塩分－chl. α，塩分－濁度，chl. α－濁度の関係から，粒状懸濁物を陸（河川）起源，海底高濁度層，亜表層クロロフィル極大，異水塊に由来するものに分別することができた。, During June 28 to July 2 and August 22 to 23 in 2009, we investigated the distributiosn and diurnal variations of temperature, salinity, chlorophyll a (chl.α) and turbidity in Suo-sound, Seto Inland Sea. In June to July observation, the subsurface chl.α maximum layer (SCM) and the bottom turbid layer (BTL) were found throughout the Suo-sound. In August, the SCM almost diminished but the BTL significantly developed compared to June to July observations and chl.α also showed a noticeable increase in the bottom layer. June to July and August observations corresponded with a neap and spring tides, suggesting a close relation between the development of the BTL and the tidal cycle. The turbidity values of BTL showed a maximum when temperature and salinity changed rapidly, and the distribution pattern of the BTL well-corresponded to those of temperature and salinity, particularly in spring tide in August. Particulate matter was classified into four groups such as terrigeous matter, BTL, SCM, and different water mass according to salinity-chl.α, salinity-turbidity, and chl.α-turbidity relationships.

International audience; Not Available

The terrestrial carbon (C) cycle has received increasing interest over the past few decades, however, there is still a lack of understanding of the fate of newly assimilated C allocated within plants and to the soil, stored within ecosystems and lost to the atmosphere. Stable carbon isotope studies can give novel insights into these issues. In this review we provide an overview of an emerging picture of plant-soil-atmosphere C fluxes, as based on C isotope studies, and identify processes determining related C isotope signatures. The first part of the review focuses on isotopic fractionation processes within plants during and after photosynthesis. The second major part elaborates on plant-internal and plant-rhizosphere C allocation patterns at different time scales (diel, seasonal, interannual), including the speed of C transfer and time lags in the coupling of assimilation and respiration, as well as the magnitude and controls of plant-soil C allocation and respiratory fluxes. Plant responses to changing environmental conditions, the functional relationship between the physiological and phenological status of plants and C transfer, and interactions between C, water and nutrient dynamics are discussed. The role of the C counterflow from the rhizosphere to the aboveground parts of the plants, e.g. via CO2 dissolved in the xylem water or as xylem-transported sugars, is highlighted. The third part is centered around belowground C turnover, focusing especially on above- and belowground litter inputs, soil organic matter formation and turnover, production and loss of dissolved organic C, soil respiration and CO2 fixation by soil microbes. Furthermore, plant controls on microbial communities and activity via exudates and litter production as well as microbial community effects on C mineralization are reviewed. A further part of the paper is dedicated to physical interactions between soil CO2 and the soil matrix, such as CO2 diffusion and dissolution processes within the soil profile. Finally, we highlight state-of-the-art stable isotope methodologies and their latest developments. From the presented evidence we conclude that there exists a tight coupling of physical, chemical and biological processes involved in C cycling and C isotope fluxes in the plant-soil-atmosphere system. Generally, research using information from C isotopes allows an integrated view of the different processes involved. However, complex interactions among the range of processes complicate or currently impede the interpretation of isotopic signals in CO2 or organic compounds at the plant and ecosystem level. This review tries to identify present knowledge gaps in correctly interpreting carbon stable isotope signals in the plant-soil-atmosphere system and how future research approaches could contribute to closing these gaps.