TY - GEN A1 - Limberger, Oliver A1 - Homeier, Jürgen A1 - Farwig, Nina A1 - Pucha-Cofrep, Franz A1 - Fries, Andreas A1 - Leuschner, Christoph A1 - Trachte, Katja A1 - Bendix, Jörg T1 - Classification of Tree Functional Types in a Megadiverse Tropical Mountain Forest from Leaf Optical Metrics and Functional Traits for Two Related Ecosystem Functions T2 - Forests N2 - Few plant functional types (PFTs) with fixed average traits are used in land surface models (LSMs) to consider feedback between vegetation and the changing atmosphere. It is uncertain if highly diverse vegetation requires more local PFTs. Here, we analyzed how 52 tree species of a megadiverse mountain rain forest separate into local tree functional types (TFTs) for two functions: biomass production and solar radiation partitioning. We derived optical trait indicators (OTIs) by relating leaf optical metrics and functional traits through factor analysis. We distinguished four OTIs explaining 38%, 21%, 15%, and 12% of the variance, of which two were considered important for biomass production and four for solar radiation partitioning. The clustering of species-specific OTI values resulted in seven and eight TFTs for the two functions, respectively. The first TFT ensemble (P-TFTs) represented a transition from low to high productive types. The P-TFT were separated with a fair average silhouette width of 0.41 and differed markedly in their main trait related to productivity, Specific Leaf Area (SLA), in a range between 43.6 to 128.2 (cm2/g). The second delineates low and high reflective types (E-TFTs), were subdivided by different levels of visible (VIS) and near-infrared (NIR) albedo. The E-TFTs were separated with an average silhouette width of 0.28 and primarily defined by their VIS/NIR albedo. The eight TFT revealed an especially pronounced range in NIR reflectance of 5.9% (VIS 2.8%), which is important for ecosystem radiation partitioning. Both TFT sets were grouped along elevation, modified by local edaphic gradients and species-specific traits. The VIS and NIR albedo were related to altitude and structural leaf traits (SLA), with NIR albedo showing more complex associations with biochemical traits and leaf water. The TFTs will support LSM simulations used to analyze the functioning of mountain rainforests under climate change. KW - ecosystem productivity KW - energy fluxes KW - leaf hyperspectra KW - functional traits KW - tree functional types KW - tropical forest Y1 - 2021 U6 - https://doi.org/10.3390/f12050649 SN - 1999-4907 VL - 12 IS - 5 ER - TY - GEN A1 - Knerr, Isabel A1 - Trachte, Katja A1 - Egli, Sebastian A1 - Barth, Johannes A. C. A1 - Bräuning, Achim A1 - Garel, Emilie A1 - Häusser, Martin A1 - Huneau, Frédéric A1 - Juhlke, Tobias R. A1 - Santoni, Sébastien A1 - Szymczak, Sonja A1 - Geldern, Robert van A1 - Bendix, Jörg T1 - Fog - low stratus (FLS) regimes on Corsica with wind and PBLH as key drivers T2 - Atmospheric Research N2 - The French Mediterranean island of Corsica is already today confronted with a clear tendency towards water shortage, leading not only to socio-economical, but also to ecological problems. A potential, but not very widespread source of water is the presence of near-ground clouds, mostly fog. In this study, we investigate fog-low stratus (FLS) frequencies in Corsica, derived from a data set of Meteosat Second Generation SEVIRI, whereby a distinction between fog and low stratus is hardly feasible using remote sensing data. The FLS frequency was studied with respect to its interaction with distinct locally-generated wind and its dependence on the planetary boundary layer height (PBLH) obtained by ERA5 reanalysis (the fifth generation of the European Centre for Medium-Range Weather Forecasts, ECMWF). Results show that radiation FLS is formed in coastal areas at sunrise, with low PBLH. On the other hand, in the interior of the island at sunset, a maximum of advection FLS is formed, fostered by locally-generated and related transport of moisture. On the east side of the island, FLS frequency is lower throughout the year due to frequent lee situations. This situation is reinforced by reduced synoptic moisture transport by westerly winds, so that westerly exposed slopes benefit from moisture input by FLS formation. KW - Corsica KW - Mediterranean KW - Fog Low Stratus KW - Meteosat Second Generation (MSG) KW - Planetary Boundary Layer KW - Locally-generated wind Y1 - 2021 U6 - https://doi.org/10.1016/j.atmosres.2021.105731 SN - 0169-8095 VL - 261 ER - TY - CHAP A1 - Trachte, Katja A1 - Ahmadpour, Somayeh T1 - Europe and the Middle East T2 - Regional Climates Y1 - 2024 U6 - https://doi.org/10.1175/2024BAMSStateoftheClimate_Chapter7.1 VL - 105 (2024) IS - 8 SP - 371 EP - 484 PB - American Meteoroligal Society ER - TY - GEN A1 - Trachte, Katja T1 - Recent progress in atmospheric modeling over the Andes – part II: projected changes and modeling challenges T2 - Sec. Atmospheric Science Y1 - 2024 U6 - https://doi.org/10.3389/feart.2024.1427837 VL - 12 (2024) SP - 1 EP - 21 PB - Frontiers in Earth Science ER - TY - GEN A1 - Trachte, Katja T1 - Recent progress in atmospheric modeling over the Andes – part I: review of atmospheric processes T2 - Atmospheric Science Y1 - 2024 U6 - https://doi.org/10.3389/feart.2024.1427783 VL - 12 (2024) SP - 1 EP - 23 PB - Frontiers in Earth Science ER - TY - JOUR A1 - Ahmed, Rezwan A1 - Zafor, Md. Abu A1 - Trachte, Katja T1 - Land-use and land-cover changes in Cottbus City and Spree-Neisse District, Germany, in the last two decades: a study using remote sensing data and Google Earth Engine JF - Remote Sensing N2 - Regular detection of land-use and land-cover (LULC) changes with high accuracy is necessary for natural resources management and sustainable urban planning. The produced LULC maps from Google Earth Engine (GEE) also illustrate the transformation of the LULC for the respective landscape over time. The selected study area, Cottbus City and the Spree-Neisse district in northeastern Germany, has undergone significant development over the past decades due to various factors, including urbanization and industrialization; also, the landscape has been converted in some areas for post-mining activities. Detection of LULC changes that have taken place over the last few decades thus plays a vital role in quantifying the impact of these factors while improving the knowledge of these developments and supporting the city planners or urban management officials before implementing further long-term development initiatives for the future. Therefore, the study aims to (i) detect LULC changes for the time slices 2002 and 2022, testing machine learning (ML) algorithms in supervised and unsupervised classification for Landsat satellite imageries, and (ii) validate the newly produced LULC maps with the available regional database (RDB) from the federal and state statistical offices, Germany, and the Dynamic World (DW) near real-time 10 m global LULC data set powered by artificial intelligence (AI). The results of the Random Forest (RF) and the Smilecart classifiers of supervised classification using Landsat 9 OLI-2/TIRS-2 in 2022 demonstrated a validation accuracy of 88% for both, with Kappa Index (KI) of 83% and 84%, respectively. Moreover, the Training Overall Accuracy (TOA) was 100% for both years. The wekaKMeans cluster of the unsupervised classification also illustrated a similar transformation pattern in the LULC maps. Overall, the produced LULC maps offered an improved representation of the selected region’s various land-cover classes (i.e., vegetation, waterbodies, built areas, and bare ground) in the last two decades (20022 to 2022). Y1 - 2024 U6 - https://doi.org/10.3390/rs16152773 SN - 2072-4292 VL - 16 IS - 15 SP - 1 EP - 16 PB - MDPI AG ET - 2nd edition ER - TY - GEN A1 - Fenner, Daniel A1 - Christen, Andreas A1 - Grimmond, Sue A1 - Meier, Fred A1 - Morrison, William A1 - Zeeman, Matthias A1 - Barlow, Janet A1 - Birkmann, Jörn A1 - Blunn, Lewis A1 - Chrysoulakis, Nektarios A1 - Clements, Matthew A1 - Glazer, Russell A1 - Hertwig, Denise A1 - Kotthaus, Simone A1 - König, Kai A1 - Looschelders, Dana A1 - Mitraka, Zina A1 - Poursanidis, Dimitris A1 - Tsirantonakis, Dimitris A1 - Bechtel, Benjamin A1 - Benjamin, Kit A1 - Beyrich, Frank A1 - Briegel, Ferdinand A1 - Feigel, Gregor A1 - Gertsen, Carlotta A1 - Iqbal, Nimra A1 - Kittner, Jonas A1 - Lean, Humphrey A1 - Liu, Yiqing A1 - Luo, Zhiwen A1 - McGrory, Megan A1 - Metzger, Swen A1 - Paskin, Matthew A1 - Ravan, Marvin A1 - Ruhtz, Thomas A1 - Saunders, Bethany A1 - Scherer, Dieter A1 - Smith, Stefan Thor A1 - Stretton, Megan A1 - Trachte, Katja A1 - Van Hove, Melania T1 - urbisphere-Berlin campaign: investigating multi-scale urban impacts on the atmospheric boundary layer T2 - Bulletin of the American Meteorological Society N2 - For next-generation weather and climate numerical models to resolve cities, both higher spatial resolution and sub-grid parameterizations of urban canopy-atmosphere processes are required. Key is to better understand intra-urban variability and urban-rural differences in atmospheric boundary layer (ABL) dynamics. This includes upwind-downwind effects due to cities’ influences on the atmosphere beyond their boundaries. To address these aspects a network of >25 ground-based remote-sensing sites was designed for the Berlin region (Germany), considering city form, function, and typical weather conditions. This allows investigation of how different urban densities and human activities impact ABL dynamics. As part of the interdisciplinary European Research Council Grant urbisphere, the network was operated from Autumn 2021 to Autumn 2022. Here we provide an overview of the scientific aims, campaign setup, and results from two days, highlighting multi-scale urban impacts on the atmosphere in combination with high-resolution numerical modeling at 100 m grid-spacing. During a spring day, the analyzes show systematic upwind-city-downwind effects in ABL heights, largely driven by urban-rural differences in surface heat fluxes. During a heatwave day, ABL height is remarkably deep, yet spatial differences in ABL heights are less pronounced due to overall dry soil conditions, resulting in similar observed surface heat fluxes. Our modeling results provide further insights into ABL characteristics not resolved by the observation network, highlighting synergies between both approaches. Our data and findings will support modeling to help deliver services to a wider community from citizens to those managing health, energy, transport, land-use and other city infrastructure and operations. Y1 - 2024 U6 - https://doi.org/10.1175/BAMS-D-23-0030.1 SN - 0003-0007 SN - 1520-0477 VL - 105 PB - American Meteorological Society ER - TY - GEN A1 - Häusser, Martin A1 - Aryal, Sugam A1 - Barth, Johannes A. C. A1 - Bendix, Jörg A1 - Garel, Emilie A1 - Geldern, Robert van A1 - Huneau, Frédéric A1 - Juhlke, Tobias R. A1 - Knerr, Isabel A1 - Santoni, Sébastien A1 - Szymczak, Sonja A1 - Trachte, Katja A1 - Bräuning, Achim T1 - Xylem formation patterns from Mediterranean to subalpine climate conditions reveal high growth plasticity of pine species on Corsica T2 - Trees N2 - Investigating seasonal wood formation is crucial to understand tree growth responses to climate impact. The present study quantifies the variability of xylogenesis along an elevation gradient on the Mediterranean island of Corsica, where two native pine species (Pinus nigra Arnold ssp. laricio Maire and Pinus pinaster Aiton) grow from the upper tree line to sea level, partly in sympatry. We extracted microcores from 35 trees at 5 sites along an East–West transect from the coasts (10 m asl) to the island's central mountain ridge (1600 m asl) during bi-weekly sampling campaigns between 2017 and 2019. We applied generalised additive models to detect radial growth differences in elevation and species along with minimum temperatures for growth initiation. We found that trees in low elevations experienced over 2 months longer growth periods with higher maximum growth rates than in high elevations. The results show a 1-month delay for the beginning of tracheid formation between the low, mid and high-elevation belts but comparable timing for its termination. At the sites where both species co-occur, P. nigra accumulates more radial cells in a shorter time than P. pinaster. Trees at the two contrasting coastal sites have similar growth period lengths, but exhibit a time shift of over a month. Minimum temperatures around growth initiation vary between 3.1 °C for P. nigra and 9.9 °C for P. pinaster. These findings emphasise the high plasticity in the growth behaviour of one of the most widespread tree genera in Mediterranean and temperate zones. KW - Generalised additive models (GAM) KW - Corsican black pine KW - Maritime pine KW - Cambial dynamics KW - Xylogenesis KW - Mediterranean Y1 - 2023 U6 - https://doi.org/10.1007/s00468-023-02402-8 SN - 0931-1890 SN - 1432-2285 VL - 37 IS - 4 SP - 1027 EP - 1039 PB - Springer Berlin Heidelberg ER - TY - GEN A1 - Murkute, Charuta A1 - Sayeed, Mostafa A1 - Pucha-Cofrep, Franz A1 - Carrillo-Rojas, Galo A1 - Homeier, Jürgen A1 - Limberger, Oliver A1 - Fries, Andreas A1 - Bendix, Jörg A1 - Trachte, Katja T1 - Turbulent energy and carbon fluxes in an Andean Montane Forest—energy balance and heat storage T2 - Forests N2 - High mountain rainforests are vital in the global energy and carbon cycle. Understanding the exchange of energy and carbon plays an important role in reflecting responses to climate change. In this study, an eddy covariance (EC) measurement system installed in the high Andean Mountains of southern Ecuador was used. As EC measurements are affected by heterogeneous topography and the vegetation height, the main objective was to estimate the effect of the sloped terrain and the forest on the turbulent energy and carbon fluxes considering the energy balance closure (EBC) and the heat storage. The results showed that the performance of the EBC was generally good and estimated it to be 79.5%. This could be improved when the heat storage effect was considered. Based on the variability of the residuals in the diel, modifications in the imbalances were highlighted. Particularly, during daytime, the residuals were largest (56.9 W/m 2 on average), with a clear overestimation. At nighttime, mean imbalances were rather weak (6.5 W/m 2 ) and mostly positive while strongest underestimations developed in the transition period to morning hours (down to −100 W/m 2 ). With respect to the Monin–Obukhov stability parameter ((z − d)/L) and the friction velocity (u*), it was revealed that the largest overestimations evolved in weak unstable and very stable conditions associated with large u* values. In contrast, underestimation was related to very unstable conditions. The estimated carbon fluxes were independently modelled with a non-linear regression using a light-response relationship and reached a good performance value (R 2 = 0.51). All fluxes were additionally examined in the annual course to estimate whether both the energy and carbon fluxes resembled the microclimatological conditions of the study site. This unique study demonstrated that EC measurements provide valuable insights into land-surface–atmosphere interactions and contribute to our understanding of energy and carbon exchanges. Moreover, the flux data provide an important basis to validate coupled atmosphere ecosystem models. KW - energy balance closure KW - heat storage KW - carbon fluxes KW - eddy covariance KW - Andes Mountains Y1 - 2024 U6 - https://doi.org/10.3390/f15101828 SN - 1999-4907 VL - 15 IS - 10 PB - MDPI ER - TY - GEN A1 - Trachte, Katja A1 - Raffelsbauer, Volker T1 - Trees with anisohydric behavior as main drivers of nocturnal evapotranspiration in a tropical mountain rainforest T2 - PLoS ONE Y1 - 2023 U6 - https://doi.org/10.1371/journal.pone.0282397 VL - 18 (3) SP - 1 EP - 21 ER - TY - GEN A1 - Grigusova, Paulina A1 - Limberger, Oliver A1 - Murkute, Charuta A1 - Pucha-Cofrep, Franz A1 - Gonzalez-Jaramillo, Victor Hugo A1 - Fries, Andreas A1 - Windhorst, David A1 - Breuer, Lutz A1 - Dantas de Paula, Mateus A1 - Hickler, Thomas A1 - Trachte, Katja A1 - Bendix, Jörg T1 - Radiation partitioning in a cloud-rich tropical mountain rain forest of the S-Ecuadorian Andes for use in plot-based land surface modelling T2 - Dynamics of atmospheres and oceans : planetary fluid, climatic and biogeochemical systems N2 - Understanding the partitioning of downward shortwave radiation into direct and diffuse components is essential for modeling ecosystem energy fluxes. Accurate partitioning functions are critical for land surface models (LSMs) coupled with climate models, yet these functions often depend on regional cloud and aerosol conditions. While data for developing semi-empirical partitioning functions are abundant in mid-latitudes, their performance in tropical regions, particularly in the high Andes, remains poorly understood due to scarce ground-based measurements. This study analyzed a unique dataset of shortwave radiation components from a tropical mountain rainforest (MRF) in southern Ecuador, developing and testing a locally adapted partitioning function using Random Forest Regression. The model achieved high accuracy in predicting the percentage of diffuse radiation (%Dif; R²=0.95, RMSE = 5.33, MAE = 3.74) and absolute diffuse radiation (R²=0.99, RMSE = 5.30, MAE = 14). When applied to simulate upward shortwave radiation, the model outperformed commonly used partitioning functions achieving the lowest RMSE (8.62) and MAE (5.82) while matching the highest R² (0.97). These results underscore the importance of regionally adapted radiation partitioning functions for improving LSM performance, particularly in complex tropical environments. The adapted LSM will be further utilized for studies on heat fluxes and carbon sequestration. Y1 - 2025 U6 - https://doi.org/10.1016/j.dynatmoce.2025.101553 SN - 0377-0265 VL - 110 SP - 1 EP - 16 PB - Elsevier CY - Amsterdam ER -