bluuebunny/crossref_metadata_2025 huggingface dataset:
Using backpack mobile laser scanning system for mapping large wood in a forested headwater stream of southwest Japan
Authors: Koyanagi Kenta , Yamada Taku , Ishida Koji
Published: March 2022

Understanding the dynamic of instream large wood (LW) is essential for reducing hydrogeomorphic hazards in populated mountainous catchments. Quantifying the spatiotemporal distribution of LW is generally the most demanding process for investigating LW dynamics in rivers. Over the last two decades, multiple airborne sensors have been applied for mapping LW in relatively large alluvial rivers. However, those existing approaches are not necessarily suitable for remotely sensing LW in forested headwater streams, mainly due to canopy obstruction, weak illumination, and operational difficulty. Therefore, we tested the applicability of a 5-kilogram commercial backpack mobile laser scanning system for detecting and quantifying LW in a forested headwater stream of southwest Japan. Extremely dense point clouds (~15000 pts/m2) were continuously scanned within 150-meter reach of the 2nd-order stream (slope: 0.045) by a 6-minute walk following rainfall-triggered debris flows. Dimension and volume of LW measured from point clouds were compared to associated field and UAV photogrammetry-based mapping data. Based on a surface shape detection algorithm and subsequent manual filtering of falsely detected objects (e.g., riparian trees), 25 cylinders corresponding to 34.9 m3 total volume were delineated from point clouds. While the UAV photogrammetry-based approach was able to quantify only 2.4% of total LW volume, 75.1% of LW volume was successfully reconstructed by backpack mobile laser scanning. The visibility of the UAV photogrammetry-based approach was substantially limited by the dense riparian vegetation of our study reach. However, underestimation of wood piece length and overestimation of wood piece diameter consistently occurred for both remote sensing approaches. Therefore, further efforts would be made to evaluate the sensitivity of individual parameters used in point cloud processing for LW detection and quantification. Considering the mobility of sensors and data availability of near-surface objects, our case study indicates that backpack mobile laser scanning potentially provides a powerful alternative for more continuous, efficient, and frequent LW mapping, particularly in forested headwater streams.
Strong isoprene emission response to temperature in tundra vegetation
Authors: Seco Roger , Holst Thomas , Davie-Martin Cleo L. , Simin Tihomir , Guenther Alex , Pirk Norbert , Rinne Janne , Rinnan Riikka
Published: March 2022

Biogenic emissions of volatile organic compounds (BVOCs) are a crucial component of biosphere-atmosphere interactions. In northern latitudes, climate change is amplified by feedback processes in which BVOCs have a recognized, yet poorly quantified role, mainly due to a lack of measurements and concomitant modelling gaps. Hence, current Earth system models mostly rely on temperature responses measured on vegetation from lower latitudes, rendering their predictions highly uncertain.

We used Proton Transfer Reaction -Time of Flight- Mass Spectrometry (PTR-TOF-MS) and eddy covariance to measure ecosystem-level isoprene fluxes at two contrasting ecosystems in Sweden and Norway during an entire growing season. Measured fluxes showed that tundra isoprene emissions responded vigorously to temperature increases, with Q10 temperature coefficients of up to 20.8; that is 3.5 times the Q10 derived from the equivalent model results. Our results demonstrate that tundra vegetation possesses the potential to substantially boost its isoprene emissions in response to future rising temperatures, at rates that exceed the current Earth system model predictions.
Modelling the impacts of extreme weather events on crop yields using water balance and satellite sensor data
Authors: Gobin Anne , Vannoppen Astrid
Published: March 2022

Managing weather related risks in cropping systems includes strategies to share the risk such as insurance schemes. Advances in satellite sensor technology and interpolated regional weather data enable insights in the relationship between extreme weather events and yields losses which in turn offers possibilities for area-yield insurance schemes.

Extreme weather events  during sensitive phenological stages of the growing season differed significantly (p < 0.05) between low and high crop yields (Gobin, 2012; Gobin, 2018). Spatial return levels confirmed the exceptionality of 2016 and 2018 as extreme wet and dry years with high return periods and yield impacts (Gobin and Van de Vyver, 2021). We investigated the importance of weather data, satellite sensor-derived vegetation indices and water balance simulations in estimating crop yields of winter wheat, potato and sugar beet for the period 2016-2018. The water balance simulations were performed with the Aquacrop model, while the yield simulations were realised with the machine learning technique random forest regression. Results for winter wheat showed that NDVI series did not respond to crop yield affecting weather conditions (Vannoppen and Gobin, 2021). Weather and/or soil water depletion during sensitive phenological stages in combination with the NDVI integral during the growing season explained up to 57 of late potato, 66% of winter wheat, 68% of early potato and 84% of sugar beet yield variability.

Machine learning techniques proved valuable in estimating crop yields thereby elucidating the importance of weather conditions during sensitive crop stages. The crop yield models developed make use of commonly available remote sensing indicators and weather data, and are commensurate with regional scale decision making.

 

Gobin, A., 2012. Impact of heat and drought stress on arable crop production in Belgium. Natural Hazards and Earth System Sciences 12: 1911–1922. https://doi.org/10.5194/nhess-12-1911-2012

Gobin, A., 2018. Weather related risks in Belgian arable agriculture. Agricultural Systems 159: 225-236. https://doi.org/10.1016/j.agsy.2017.06.009

Gobin, A., Van de Vyver, H., 2021. Spatio-temporal variability of dry and wet spells and their influence on crop yields. Agricultural And Forest Meteorology, 308-309, Art.No. 108565. https://doi.org/10.1016/j.agrformet.2021.108565

Vannoppen, A., Gobin, A., 2021. Estimating Farm Wheat Yields from NDVI and Meteorological Data. Agronomy-Basel, 11 (5), Art.No. 946. https://doi.org/10.3390/agronomy11050946
ENSO modulation of MJO and its impacts on South America: enhancement of extreme events
Authors: Grimm Alice M , Fernandes Lais G
Published: March 2022

The changes in the Madden-Julian Oscillation (MJO) and its impacts on the South American monsoon season during different El Niño-Southern Oscillation (ENSO) states (El Niño – EN, La Niña – LN, neutral – NT) are analyzed in the global context of the MJO propagating anomalies of convection and circulation. The background ENSO-related anomalies influence several aspects of MJO (relative occurrence of phases, propagation, convection and teleconnections), and therefore modify the MJO impacts on South America (SA), such as precipitation anomalies and frequency of extreme events, as well as their temporal distribution throughout the MJO cycle. Changes include: (1) a delay in the peak of the teleconnections between central-eastern Pacific and SA, from MJOphase8 in LN to MJOphase1 in EN; (2) enhanced MJO convection in the central-east subtropical South Pacific in MJOLNphases7+8 and a little further east in MJOENphases8+1, in a region efficient in generating tropics-extratropics teleconnections via Rossby wave to SA, producing rainfall anomalies over Central-East SA (CESA), especially the South Atlantic Convergence Zone (SACZ), strongest one phase earlier in LN (MJOLNphase8) than in EN (MJOENphase1), and a little shifted east in the latter than in the former; (3) enhancement of the extratropical teleconnection via Rossby wave and its impacts over subtropical CESA in both EN and LN (with regard to NT), suggesting that both ENSO states generate forcing in the source region that more efficiently triggers stronger Rossby waves than forcing in NT ENSO years, indicating nonlinear ENSO effects on MJO anomalies over SA; (4) predominant increase (or reduction) in the frequency of extreme events over densely populated SA regions where both ENSO and MJO contribute in the same direction, with the greatest increase over CESA (including SACZ) during EN, in MJOENphase1, and over Southeast SA (SESA), in MJOENphase3; (4) enhanced amplitude in both states, EN and LN, of the first continental intraseasonal dipole-like mode of precipitation variability between CESA and SESA, with maximum opposite anomalies in CESA, the center with largest amplitude, in phases 1 and 4 for EN, and phases 8 and 5 for LN. Significant effects can also be observed in other regions, such as northeast and northwest SA.
Response of a small mountain river to a sediment pulse tracked using sub-canopy UAV surveys
Authors: McDowell Conor , Carina Helm , David A. Reid , Marwan Hassan
Published: March 2022

Remotely piloted aircrafts (UAVs) and Structure-from-Motion photogrammetry (SfM) have become a widely used approach for producing high-resolution topographical measurements of river systems. This approach has the benefit of capturing data over large spatial scales while requiring little time in the field. In small, forested rivers, the dense canopy has hindered the use of remote sensing techniques, limiting topographic data collection to more time-consuming and lower-resolution methods. This complicates monitoring the response of these systems to individual floods, as in many situations there is not enough time to complete more time-consuming surveys between events.

In this study, we pilot the use of sub-canopy UAV surveys (flown at 1-3 m altitude) to monitor the response of a small mountain stream (1-3 m wide) in British Columbia to a sediment pulse generated by the removal of an upstream culvert. Using eleven surveys flown over a three-year period, we track the downstream propagation of the pulse and the subsequent responses in bed topography and roughness along the 240 m reach. We observe a “build-and-carve” response of the channel, where some channel segments aggrade during the first floods after pulse generation, whereas others undergo little morphologic activity. In subsequent floods, these aggradational segments rework through the carving of well-defined channels that release this aggraded sediment downstream. These “build-and-carve” segments serve as temporary storage reservoirs that caused the pulse to fragment as it progressed downstream. The locations of these storage reservoirs were set by the initial channel morphology and the movement of in-stream wood and debris. This study highlights the importance of temporary sediment storage reservoirs for fluvial morphodynamics and provides some insights and suggestions for the future monitoring of forested river systems using sub-canopy drone surveys.
Renku: a platform for collaborative, reusable and reproducible research
Authors: Roškar Rok
Published: March 2022

The Renku platform developed at the Swiss Data Science Center integrates state-of-the-art data science and open source software tools to enable collaborative, reproducible and reusable data science. Data, code, workflows and computational environments in every project are versioned from the start, allowing researchers to focus on their task of discovery rather than worrying about preserving their work. In addition, Renku provides a hosted solution for running those computational environments, which allows researchers to share their fully reproducible work instantly with others. Renku treats all aspects of the data analysis process (code, data, workflows) as nodes in an indexed, searchable Knowledge Graph, meaning that datasets, algorithms or full workflows can be discovered, shared and reused. In this talk we will describe how Renku lowers the bar for researchers to participate in open-science and provides scientific communities with tools to gain a deeper understanding of pathways of discovery within their disciplines.
Examining the Sensitivity of the Accuracy of EFSO to Ensemble Size
Authors: Wu Ting-Chi , Terasaki Koji , Kotsuki Shunji , Miyoshi Takemasa
Published: March 2022

Data assimilation plays a critical role in the advancement of numerical weather prediction (NWP) via ingesting information of atmospheric observations from various platforms. As more and more observations become available, it is important to quantify the impact of assimilated observations on a forecast to help improve the use of these observations. Currently several approaches exist to estimate observational impact on the forecast skills. Ensemble Forecast Sensitivity to Observations (EFSO) is one such approach that extends upon the adjoint-based FSO method by utilizing ensemble of forecasts in replacement of an adjoint model. However, like any ensemble-based methods, EFSO also suffers from sampling error due to the use of limited-sized ensemble. This is more severe when we take ensemble-based correlations between different times. In recent years, the rapid advancement of supercomputing has facilitated the use of large number of ensemble members in NWP. Many studies have demonstrated the use of large ensembles in the context of data assimilation, however, the use of large ensemble to quantify observation impact via EFSO is yet to be explored. In this study, we implemented the EFSO method for a global atmospheric data assimilation system that consists of the Non-hydrostatic Icosahedral Atmospheric Model (NICAM) with the Local Ensemble Transform Kalman Filter (LETKF), namely the NICAM-LETKF. Using a total of 1024 ensemble members, we can examine the sensitivity of ensemble size to the accuracy of EFSO estimated error reduction via sub-sampling. We will present results from a series of EFSO experiments with the 1024-member NICAM-LETKF to conclude our findings.    
Evidence for the long-term climate model predicted-stratospheric circulation changes in the ERA5 reanalysis over 1960-2020
Authors: Diallo Mohamadou , Eichinger Roland , Iglesias-Suarez Fernando , Ploeger Felix
Published: March 2022

The recent release of the long-term ERA5 reanalysis data spanning from 1950 to present offers new opportunities for analysing trends and variability of stratospheric dynamics. For the first time, a 60 year period (1960-2020) can be analysed in reanalysis data and compared with chemistry-climate model simulations. The analyses of stratospheric circulation trends and seasonalities over this long time period can help us to better understand the long-term evolution of the Brewer-Dobson circulation (BDC), and the related inter-model differences and model dependencies. Therefore, this way an improved credibility in future projections of the BDC can be obtained.
We find that the global trend patterns of the temperature, zonal wind and residual vertical velocity agrees well between ERA5 and the multi model mean. However, differences occur in the width and altitude of the maximum trend. The tropical upwelling mass flux time series in the lower stratosphere of models and reanalysis disagrees at the beginning of the period, but they converge after around 1980. The agreement of the time series increases with altitude, where the QBO dominates the signal. Moreover, we find a generally good agreement in the zonal wind trends, although some differences are detected in the subtropical jet strength and upward shift, as well as in the polar vortex region where the models exhibit larger changes than ERA5. Another striking difference is the temperature trend in the tropical upper troposphere/lower stratosphere, where models show a more extended warming trend into the lower stratosphere. In this presentation, we show these results, put them in relation to what had been shown in previous studies for other time periods and discuss possible explanations for the differences as well as implications for the further evolution of the BDC.
Climate change impact on precipitation-phase partitioning and streamflow for glacierized catchments in Nepal
Authors: Vijayan Nair Anju , Wi Sungwook , Gleason Colin , Kayastha Rijan Bhakta , Nikolopoulos Efthymios I.
Published: March 2022

The change in climate, characterized by spatial and temporal variations in precipitation and temperature, significantly impacts the hydrological processes and water resources availability. Quantifying long-term changes in climatic variables and their effect on streamflow are crucial for understanding watershed hydrology and developing effective climate adaptation and water management strategies. In this study, we aim to quantify the changes in precipitation, temperature, and streamflow over the last 70 years (1950-2020) for two glacierized catchments in Nepal: Marsyangdi and Budigandaki River Basins. We utilize a distributed hydrological model (HYMOD_DS) forced by the most recent release of the ERA5 Land reanalysis product. Our investigation focuses on evaluating the impact of spatiotemporal changes in precipitation phases (either snow or rainfall) on streamflow characteristics. Specifically, we analyze the temporal trends and changes in the distribution of snow and rainfall and resulting streamflow separated into surface runoff and baseflow at daily and seasonal scales. The ERA5 Land reanalysis indicates a decrease in mean annual total precipitation for the period 1950-1980 and an increasing trend afterward. Annual mean temperature exhibits a rising trend for the entire period. Streamflow simulations for both basins revealed a significantly increased total flow over the last 20 years, primarily due to an increase in rainfall-induced streamflow. The results from this study will provide critical insight into the hydrology of glacierized basins and serve as a reference for water resources planning under climate change.
Estimation of fine sediment transport processes by forest management using Pb-210ex, Cs-137 and Cs-134
Authors: Onda Yuichi , Kinoshita Motosuke , Kato Hiroaki , Gomi Takashi , Chiu Chen-Wei
Published: March 2022

While thinning practices are essential for forest maintenance and management, it has been suggested that the amount of sediment discharge from forests to rivers increases with the practices.  In Karasawayama, Tochigi Prefecture, Japan, different types of thinning were carried out in 2011-12, and continuous observation of water and sediment runoff before and after thinning has been carried out. So far, through connectivity analysis, Lopez-Vincente (2017) estimated that work roads can be a major runoff pathway for sediment produced by thinning practices. On the other hand, radionuclides are known to be effective in estimating the source of sediment production. In this catchment, 8kBq/m2 of Cs-137 and Cs-134 were newly deposited due to the Fukushima Daiichi Nuclear Power Plant accident during the observation period. Therefore, the purpose of this study was to estimate the source of fine sediment production from the slope scale to the watershed scale before and after thinning, utilizing Cs-134 of Fukushima origin and changing the end-members of the source sediment production in each year for more detailed source estimation. In addition, by using Pb-210ex, Cs-137, and Cs-134 at the same time, we can distinguish the production sources more clearly. In the field, SS samplers and turbidimeters were installed in the river to observe the amount and concentration of sediment, and soil erosion plots were set up in the forest and along the work road to collect sediment and measure the radioisotope concentration with Ge semiconductor detectors.

As a result of the analysis, the amount of sediment in the watershed where row thinning was conducted increased rapidly in the year of thinning and one year later. On the other hand, in the watershed where point thinning was conducted, there was no significant increase in sediment discharge. In the production source estimation, we were able to clearly distinguish between work roads and river banks by using Cs-134/Cs-137 as the horizontal axis and Cs-134/Pb-210ex as the vertical axis. The tracer analysis showed that the contribution of sediment production from the working road increased during the thinning period in the row-thinning catchment, but no such trend was observed in the point-thinning catchment.
Large-scale evaluation of temporal trends in ANN behaviour for daily flow forecasts in Canadian catchments.
Authors: Snieder Everett , Khan Usman
Published: March 2022

Modelling accurate rainfall-runoff (RR) simulations is a longstanding contest in hydrological research. These models often treat the RR relationship as stationary; in other words, model parameters are assumed to be fixed, time-invariant values. In reality, the RR relationship is continuously changing due to factors such as climate change, rapid urban growth, and construction of hydraulic infrastructure. Therefore, there is a need for hydrological models to be able to adapt to these changes.

The suitability of machine learning (ML) models for flow forecasting has been well established over the past 3 decades. One advantage of such models is their ability to rapidly and continuously adapt to the non-stationary relationship between rainfall and runoff generation. However, changes in model performance and model adaptation in an operational context have not received much attention from the research community.

We present a large-scale framework for daily flow forecasting models in Canada (>100 catchments). In our framework, local artificial neural network (ANN) ensembles models are automatically trained to forecast flow on an individual catchment basis using openly available daily hydrometeorological timeseries data. The collection of catchments taken from across Canada have highly heterogenous soil groups, land use, and climate. We propose several experiments that are designed to evaluate the robustness of ANN-based flow forecasting across time. Using the most recent year of observations for validation, we evaluate the effects of incrementally providing increasing amounts of historic observations. Similarly, we quantify changes to ANN model parameters (weights and biases) across increasing historic training data. Finally, we analyse feature importance across time using multiple feature importance algorithms. Our research aims to provide guidance on initial model training and adaptive learning, as ML-based approaches become increasingly adapted for operational use.
AnnAGNPS-MODFLOW integration for evaluation of agricultural practice impacts on surface and groundwater resources
Authors: Momm Henrique , Bingner Ronald , Moore Katy , Herring Glenn
Published: March 2022

The Lower Mississippi River Alluvial Plain, referred to as the Delta, is an important agricultural region in the southeastern United States. Recent trends in crop type conversion and higher crop yields resulted in increased irrigation demand for surface and groundwater, which can lead to aquifer levels dropping. Estimates of continued increased irrigation adoption are compounded by future climatic estimates suggesting hotter summers with higher unpredictability in precipitation amounts. In these conditions, the long-term sustainability of this system depends on understanding complex surface-groundwater flow interactions at different temporal and spatial scales, and the impacts of agricultural conservation practices on water use. In this study, a description of the development of the integrated AnnAGNPS-MODFLOW technology is provided. The proposed system was evaluated in the Upper Sunflower River watershed, located in the Delta region of Mississippi, to characterize existing conditions through comparison with observed streamflow and well water levels. Additionally, the system was used to evaluate the impact of alternative irrigation and management strategies on water levels in the aquifer at field and watershed scales. The proposed technology provides a management tool critical to understanding and evaluating the impact of agricultural practices, irrigation, and aquifer recharge strategies that are important to sustaining Delta water resources in a changing climate.
Insights from landowners on Australia's Black Summer bushfires: impacts on soil and vegetation, perceptions, and behaviours
Authors: Ondik Mercedes , Ooi Mark , Muñoz-Rojas Miriam
Published: March 2022

The 2019-2020 bushfire season (the Black Summer) in Australia was unprecedented in its breadth and severity as well as the disrupted resources and time dedicated to studying it.  Right after one of the most extreme fire seasons on record had hit Australia, a once-in-a-century global pandemic, COVID-19, occurred. This pandemic caused world-wide lockdowns throughout 2020 and 2021 that prevented travel and field work, thus hindering researchers from assessing damage done by the Black Summer bushfires. Early assessments show that the bushfires on Kangaroo Island, South Australia caused declines in soil nutrients and ground coverage up to 10 months post-fire, indicating higher risk of soil erosion and fire-induced land degradation at this location. In parallel to the direct impacts the Black Summer bushfires had on native vegetation and soil, the New South Wales Nature Conservation Council observed a noticeable increase in demand for fire management workshops in 2020. What was observed of fires and post-fire outcomes on soil and vegetation from the 2019-2020 bushfire season that drove so many citizens into action? In collaboration with the New South Wales Nature Conservation Council and Rural Fire Service through the Hotspots Fire Project, we will be surveying and interviewing landowners across New South Wales to collect their observations and insights regarding the Black Summer. By engaging landowners, this project aims to answer the following: within New South Wales, Australia, what impact did the 2019-2020 fire season have on a) soil health and native vegetation and b) human behaviours and perceptions of fire in the Australian landscape. The quantity of insights gained from NSW citizens will provide a broad assessment of fire impacts across multiple soil and ecosystem types, providing knowledge of the impacts of severe fires, such as those that occurred during the Black Summer, to the scientific community. Furthermore, with knowledge gained from reflections from citizens, the Hotspots Fire Project will be better able to train and support workshop participants, while expanding the coverage of workshops to improve support of landowners across the state. Data regarding fire impacts on soil, ecosystems, and communities has been collected by unknowing citizen scientists all across New South Wales, and to gain access to that data, we need only ask.
A Global Assessment of the Spatial-Temporal Origin of Soil Water Taken up by Vegetation
Authors: Miguez Macho Gonzalo , Fan Ying
Published: March 2022

Vegetation modulates Earth’s water, energy and carbon cycles and provides a key link between water stores in the deep soil and the atmosphere. How its functions may change in the future largely depends on how it copes with droughts. There is evidence that in places-times of drought, vegetation shifts water uptake to deeper soil and rock moisture and groundwater. We differentiate and assess plant use of four types of water source: precipitation (P) in current month, past P stored in deeper unsaturated soils/rocks, past P stored in locally recharged groundwater, and groundwater from P fallen on uplands via river-groundwater convergence toward lowlands. We examine global and seasonal patterns and drivers in plant uptake of the four sources using inverse modeling and isotope-based estimates. We find that globally and annually, 70% (std 24%) of plant transpiration relies on current month P, 18% (std 15%) on deep soil moisture, only 1% (std 3%) on locally recharged groundwater, and 10% (std 22%) on groundwater or river water from upland more distant sources; (2) regionally and seasonally, recent P is only 19% in semi-arid, 32% in Mediterranean, and 17% in winter-dry tropics in the driest months; (3) at landscape scales, deep soil moisture, taken up by deep roots in the deep vadose zone, is critical in uplands in dry months, but groundwater and river water from uplands is up to 47% in valleys where riparian forests and desert oases are found. Because the four sources originate from different places-times, move at different spatial-temporal scales, and respond with different sensitivity to climate and anthropogenic forces, understanding space-time origin of plant water source can inform ecosystem management and Earth System Models on the critical hydrologic pathways linking precipitation to vegetation.
Water Quality Transit Time (WQTT) for Continuous Velocity/Discharge Measurement in Large and Small Waterways
Authors: Sentlinger Gabriel
Published: March 2022

Non-contact and automated flow measurement in open channels is becoming more popular as techniques improve to measure surface velocity, reducing costs and risk to hydrographers.  However, these methods rely on estimates of bulk-to surface ratio estimates, as well as channel wetted area.  This study considers the accuracy and application of paired Up and Downstream Water Quality (WQ) measurements to estimate the Transit Time (TT) and average bulk velocity.  Combined with results from both the Automated Salt Dilution (AutoSalt) and Water Quality Mixing Model (WQMM) systems, we can calibrate the waterway for wetted area at a given water level, and hence estimate discharge from transit time velocity on a continuous basis using only temperature and conductivity insitu sensors.  This low-cost method can used to build or validate rating curves, measure peak and low flow events, and conduct cost-effective hydrological assessments over large regions for any size waterway,  to support climate change study and adaptation.  This method also has application to flood wave propagation and Initial Dilution Zone (IDZ) studies. Results from a large and a small waterway, along with uncertainty, is discussed.
A decade of atmospheric composition observations in the undersampled Central Andes
Authors: Andrade Marcos , Aliaga Diego , Blacutt Luis , Forno Ricardo , Gutierrez René , Velarde Fernando , Moreno Isabel , Ticona Laura , Wiedensohler Alfred , Krejci Radek , Ramonet Michel , Laurent Olivier , Whiteman David , Mohr Claudia , Laj Paolo
Published: March 2022

Ten years of almost continuous observations at the highest Global Atmosphere Watch Regional station in the world are presented here. The Chacaltaya observatory (5240 m asl, 16.3ºS, 68.1ºW) was set up in December 2011. It is currently the only operational station characterizing optical and chemical properties of climate-relevant aerosol and gases in Bolivia and in a radius of about 1500 kilometers from the station. The observations show a clear influence of the well-marked dry and wet meteorological seasons. In addition, the impact on the Andean mountains of long and mid-range transport of biomass burning products from the lowlands is clearly recorded in different parameters measured at the station. Furthermore, the nearby presence of the largest metropolitan area in the region (~1.8 million inhabitants) is observed almost on a daily basis, and therefore different campaigns were carried out to characterize the area and its influence on our measurements. Specific results from these campaigns are discussed elsewhere. Finally, the topographic complexity represents an important challenge for modeling efforts in order to understand sources and sinks (and associated processes) of the observed parameters, requiring not only high spatial resolution and the correct choice of model options, but a novel way of interpreting these results. The decade of collaboration of an international consortium made it possible to keep the station running successfully. The challenge is now to preserve its functioning for the coming decades in a region with historically few high-quality observations while disrupting environmental and socio-economic changes take place.
Operational Framework for Near-real Time Daily Drought Monitoring Using Global Remotely Sensed Precipitation Products and In-situ Datasets
Authors: Prat Olivier , Coates David , Leeper Ronald , Nelson Brian , Bilotta Rocky , Ansari Steve , Huffman George
Published: March 2022

We present an operational near-real time drought monitoring framework on a global scale that uses quantitative precipitation estimates (QPEs) from gridded Satellite Precipitation Products (CMORPH-CDR, IMERG) and in-situ datasets (NClimGrid). The Standardized Precipitation Index (SPI) is computed daily for various time scales from the reprocessed, bias-corrected CMORPH-CDR. The near-real time availability of CMORPH-CDR permits for a daily update of global drought conditions starting in 1998. It provides a global daily SPI at a 0.25x0.25 degree spatial resolution. The global SPI is publicly available via the Global Drought Information System (GDIS) dashboard. The GDIS website includes an interactive map hosted within the NOAA GeoPlatform (ArcGIS Online). It provides 45 layers of drought indices and indicators in addition to the global daily CMORPH SPI (https://gdis-noaa.hub.arcgis.com/pages/drought-monitoring).

The pipeline assembled to produce CMORPH-SPI is extended to IMERG (Integrated Multi-satellitE Retrievals for GPM) to generate a daily global IMERG-SPI at a higher spatial resolution (0.1x0.1deg) from 2000 to the present. The 6-fold increase in spatial resolution comes at a higher computational cost which is alleviated by accessing cloud-scale computing resources such as Microsoft Planetary Computer and Azure that allows to optimize the process and reduce considerably the computation time. Similarly, we use the high resolution gridded in-situ precipitation dataset NClimGrid to generate a daily high resolution NClimGrid-SPI over CONUS (5x5-km). Because of NClimGrid longer period of record, it allows accessing daily drought conditions from 1950 up to the present day.

Comparisons between the generated SPIs (CMORPH-SPI, IMERG-SPI, NClimGrid-SPI) are conducted with a focus on the influence of the different resolutions, sensors characteristics, and SPI formulations (two parameter Gamma distribution: McKee et al. 1993; three parameter Pearson III distribution: Guttman 1999). When possible, an evaluation of the remotely sensed and in-situ SPIs is performed against existing droughts monitoring tools such as the US Drought Monitor (USDM). Finally, we present the results of the implementation of a drought relief module that quantifies the precipitation amount that would be needed (i.e. rainfall deficit) for drought relief as a function of the accumulation period considered.
A Numerically-integrated Approach for Residential Flood Loss Estimation at the Community Level
Authors: Mostafiz Rubayet Bin , Assi Ayat Al , Friedland Carol , Rohli Robert , Rahim Md Adilur
Published: March 2022

Evaluating average annual loss (AAL) is an essential component of assessing and minimizing future flood risk. A robust method for quantifying flood AAL is needed to provide valuable information for stakeholder decision-making. Several recent studies suggest that the numerical integration method can provide meaningful AAL estimates since this technique includes the full loss‐exceedance probability of flood. While past research focuses on applying the numerical integration method on a single, one-family residential house, calculations across space are necessary for assessing community vulnerability. This research develops a computational framework in MATLAB for integrating across the full loss-exceedance probability curve through space to evaluate flood AAL for multiple single-family homes, including loss to the structure, content, and time spent in refurbishing it (i.e., use), over a case-study census block in Jefferson Parish, Louisiana, USA. To further inform flood mitigation planning, the AAL is also calculated for one, two, three, and four feet of freeboard and separately for each owner-occupant type of residence (i.e., homeowner, landlord, and tenant). Although previous studies provided essential information related to the structure and content loss for one type for ownership-occupant type (homeowner), the wider scope of this study allows for consideration of the use loss and the remaining ownership-occupant types. Results show that individual building AAL varies within a community because of its building attributes. Besides, results highlight the difference of AALs by owner-occupant type, with homeowners generally bearing the highest total AAL and tenants incurring the lowest total AALs. A simple elevation of only one foot can decrease the AAL by as much as 90 percent. A sensitivity analysis underscores the importance of using the exact values of the base flood elevation (BFE) compared to rounding to the nearest integer and excluding damage lower than first flood height (FFH) in the depth-damage functions (DDFs). Expanding the application of the numerical integration method to a broad-scale study area may enhance validity and accuracy as compensating errors are likely to make bulk estimates more reasonable, which might augment its utility at the community level. In general, such techniques improve resilience to flood, the costliest natural hazard, by assisting in better understanding of risk with and without mitigation efforts. 

 
A potential driver of Eurasian winter cooling in CESM large ensemble
Authors: Jun Ye-Jun , Son Seok-Woo , Kim Hera
Published: March 2022

Despite the ongoing global warming, Eurasian winter surface air temperature (SAT) has been decreasing in recent decades. This study investigates the nature of Eurasian winter cooling and its reproductivity in the Community Earth System Model Large Ensemble simulation (CESM-LE). It is found that Eurasian winter cooling and the related atmospheric circulation change are not captured by the model ensemble mean. When 40 ensemble members are divided into two groups, ensembles with Eurasian cooling tend to show a positive sea surface temperature (SST) trend over the western Pacific warm pool, whereas the other group has the opposite SST trend. The causal relationship between tropical SST warming and Eurasian winter cooling is further tested by conducting a series of linear baroclinic model experiments. These experiments reveal that the warm pool warming and the resultant convection can effectively excite the Rossby wave train that resembles atmospheric circulation change shown in the Eurasian cooling ensembles. Specifically, a cyclonic circulation forms over the Aleutian region through the teleconnection and it is followed by an anticyclonic circulation over Siberia resulting from mass redistribution. This result indicates that Eurasian winter cooling in CESM-LE is possibly determined by the internal variability of tropical SST. It also suggests that the recent Eurasian winter cooling has been likely influenced by tropical climate variability.
Experimental study on the conditions of inclusions capturing during diamond growth in the upper mantle
Authors: Chertkova Nadezda , Spivak Anna , Burova Anastasiia , Zakharchenko Egor , Litvin Yuriy , Safonov Oleg , Bobrov Andrey
Published: March 2022

Primary inclusions in natural diamonds provide unique information about deep-seated mantle minerals and fluids. Findings of the VI and VII modifications of H2O-ice as inclusions in diamonds show the presence of aqueous fluids at different depths in the diamond-bearing mantle (Kagi et al., 2000; Tschauner et al., 2018). In this work, we apply various experimental techniques for the investigation of mineral associations and H2O phases, captured as inclusions in diamonds, in the pressure range from 4 to 8 GPa and at temperatures from 500 °C to 1250 °C. In situ observations using diamond anvil cell (DAC) technique revealed crystallization of ice VII in association with ilmenite and olivine minerals upon cooling from 890 °C at 4 GPa, in agreement with the data, obtained from natural samples by Tschauner et al. (2018). Heating of this assemblage to 1200 °C at 6 GPa results in the formation of another mineral association, which includes ilmenite, pyroxene and clinohumite. Obtained experimental results can be used to reconstruct the pressure and temperature conditions of mineral and fluid inclusions capturing upon diamond growth and transfer in the lithosphere.  

This work was supported by grant No. 20-77-00079 from the Russian Science Foundation.
Stakeholder Perceptions of Multi-hazards and Implications for Urban Disaster Risk Reduction in Istanbul
Authors: Menteşe Emin Yahya , Trogrlić Robert Šakić , Hussein Ekbal , Thompson Harriet , Öner Emine , Yolcu Aslıhan , Malamud Bruce D.
Published: March 2022

Istanbul is a large urban area exposed to many natural hazards, including earthquakes, landslides, tsunami, flooding, and drought. In addition to the potential risk from these single hazards, their interrelationships can  amplify overall risk, potentially overwhelming the capacity of governments, communities, and systems limits. Here, in order to investigate how multi hazards and their interrelationships are understood and considered in the decision making process in Istanbul, we have conducted two workshops and three interviews with 22 expert practitioners with a wide range of natural hazard relevant roles in Istanbul institutions.

We focused our activities on: (i) Identifying multi-hazard interrelationships relevant for Istanbul of tomorrow and creating multi-hazard interrelationship scenarios. (ii) Understanding the usefulness of multi-hazard thinking in the context of different stakeholders, and (iii) Exploring barriers and opportunities for the integration of multi-hazard thinking into operational practice. We find in the Istanbul urban context that (i) single hazards are calculated, examined, and incorporated within urban development and planning process at a significant level, (ii) the participants’ perception of multi-hazard is mostly focused on cascading single hazards where one triggers another, excluding increasing probability and compound hazard interrelationships, (iii) that although multi-hazard approaches are taken into account at some levels in Istanbul, the main focus is still mainly on single hazards, (iv) there is a lack of interaction amongst many  hazard related institutions that are often single-hazard focused, thus hindering disaster risk reduction in a holistic and integrated way.

Among the multi hazard types, earthquakes induced hazards such as landslides, tsunami and floods are highlighted by the participants often. It is notable that climate change related scenarios such as heavy rainfalls and heatwaves are also mentioned during conversations. Our results show that multi-hazard scenarios have the potential to improve DRR in Istanbul as there are some studies that already address the multi hazard perspective to a certain extent and knowledge on potential multi hazards is significant among experts. However, changes in policies, legislative environment, and  governance arrangements are needed, as well as further physical characterisation of interrelationships. 
The effects of (supra-, en-, and sub-glacial) sediment on mountain glaciers
Authors: Anderson Leif S. , Delaney Ian , Scherler Dirk , Herman Frédéric
Published: March 2022

In mountainous environments, steep hillslopes tend to erode rapidly. These hillslopes, where present above glaciers, trundle rocks onto glacier surfaces below them. The loose rocks (debris) are subsequently transported along with glacial ice as it moves down valley. Debris can be so abundant that it produces continuous blankets across glaciers. Where debris cover is extensive it reduces ice melt and lowers the surface slope of glaciers. This feeds back to reduce basal sliding, thus impacting bedrock erosion. The erosion of bedrock produces loose sediment that is transported down valley along with the ice and by subglacial water flow.

Here, using a coupled numerical model, we tie three realms of sediment transport (supraglacial, englacial, and subglacial) with feedbacks between ice dynamics and surface melt. The model runs in 2D (x, z) using the shallow-ice approximation and a simple formulation for melt under debris. Our simulations use glaciological parameters meant to loosely represent glaciers in the Khumbu region of Nepal. We present numerical experiments to reveal the first order effects of debris cover on erosion and landscape evolution.
Root-zone “Periscope” and its applications for investigating plant-soil water relations and transpiration modelling 
Authors: Guan Huade , Deng Zijuan , Wang Hailong , Xu Xiang , Yang Yuting , Liu Na , Luo Zidong , Zhang Cicheng , Hutson John , Zhang Xinping , He Xinguang , Simmons Craig
Published: March 2022

Since the first stoma appeared about 400 million years ago, moisture exchange between lands and the atmosphere extends into the root zone. However, due to its invisibility from the surface, root distribution and its temporal variation are difficult to estimate, which greatly hinders investigation of root zone moisture dynamics, soil-plant water relations, and transpiration modelling. Plant water potential reflects dynamic water condition in vegetation, which is determined by moisture supply in the root zone, atmospheric demand, and plant physiological control. Thus, dynamic water potential can provide a “periscope” to observe root zone hydraulic conditions. Based on this hydraulic connection in the soil-plant-atmosphere continuum (SPAC), plant individuals work very likely as “observation wells” to the whole root zone at predawn, and as “pumping test wells” in daytime. Meanwhile, stable isotopic composition of water in plant xylem approximately reflects the isotopic signature of bulk root accessible moisture. These hydraulic and isotopic root-zone periscopes provide information to estimate root-zone and plant hydraulic states and their dynamics, and hydraulic properties. In this presentation, we will show how this root-zone periscope concept, based on continuous monitoring of plant water potential, sapflow, and/or isotopic composition of xylem water, has been successfully applied in SPAC model development, root water uptake model improvement, transpiration model parameterisation, as well as investigation of ecohydrological separation.