bluuebunny/crossref_metadata_2025 huggingface dataset:
A General Framework of Kernel-driven Modeling in the Thermal Infrared Band for Land Surface Temperature Normalization
Authors: Cao Biao , Liu Qinhuo , Du Yongming , Li Hua , Bian Zunjian , Hu Tian , Xiao Qing
Published: March 2020

Land surface temperature (LST) is the direct driving force of turbulent heat fluxes at the surface and atmosphere interface and is widely used in the fields of evapotranspiration estimation (Su et al., 2002) and energy budget (Liang et al., 2019). Remote sensing products offer the only possibility for measuring LST with completely spatially averaged values. The thermal radiation directionality (TRD) effect has been widely concerned in the area of thermal infrared (TIR) remote sensing over 50 years which can lead to the directional brightness temperature (DBT) difference between different viewing directions up to 10 K (Cao et al., 2019). Many models have been proposed to simulate the DBT patterns over different underlying surfaces aimed to achieve the TRD effect correction for the satellite LST products. In practice, it is advised to handle only TRD models having a limited number of input parameters for operational normalization of LST products. The use of TIR kernel-driven models appears a good tradeoff between physical accuracy and operationality. It remains that the existing 4 TIR kernel-driven models (Ross-Li, LSF-Li, Vinnikov, RL) underestimate the hotspot effect, especially for continuous canopies. In this study, a new general framework of TIR kernel-driven modeling is proposed to overcome such issue. It is a linear combination of three kernels (including a base shape kernel, a hotspot kernel and an isotropic kernel) with the ability to simulate the bowl, dome and bell shapes in the solar principal plane. 4 specific models (Vinnikov-RL, LSF-RL, Vinnikov-Chen, LSF-Chen) within the new framework were further developed to assess their fitting abilities for both continuous and discrete vegetation canopies. To evaluate 4 existing models and 4 new models comprehensively, it was prepared 102 groups of 4SAIL/DART generated multi-angle datasets considering 6 different canopy architectures and 17 component temperatures. Results show that the 4 new models behave slightly better than the 4 existing models over discrete canopies (R2 increases from 0.791~0.989 to 0.976~0.996) whereas they significantly improved the fitting accuracy over continuous canopies (R2 increases from 0.661~0.970 to 0.940~0.997). The innovative new general framework with three kernels and four parameters improve the fitting ability significantly since the addition of one more degree of freedom. This new kernel-driven modeling framework is a potential tool to achieve angular correction of LST products.
Erosional-denudational valleys on the Wolin Island cliff coast (Southern Baltic) and their impact on the morphological development of the coast
Authors: Paluszkiewicz Renata , Kostrzewski Andrzej , Winowski Marcin
Published: March 2020

A characteristic feature of the contemporary cliff morphology of the Southern Baltic Baltic are erosional-denudational valleys, which are an important element of the contemporary morphogenetic system. Detailed observations combined with the use of GIS methods were carried out on the Wolin Island. Over a length of about 4 km, several landforms have been distinguished, which are clearly marked in the relief. These forms show the course of NW-SE and are characterized by various morphometric features. Within the studied area, types of valleys with postglacial assumptions as well as fresh erosive cuts were identified. At the turn of the Pleistocene / Holocene, forms of late-glacial genesis were transformed by flushing and erosion processes. Progressive abrasion (cliff top recession rate of 0.22 m / year) has an impact on the further development of the valleys, whose bottoms are currently suspended in relation to the foot of the cliff.

The aim of the study is to present detailed morphometry, lithology of sediments as well as the genesis of separated erosion and denudation valleys.

Based on the research on a selected experimental catchment (recognized as a representative form) located in the edge zone of the cliff, detailed morphological and lithological studies were carried out. In the longitudinal profile of the analyzed valleys, landslides were found in the lower part, which is an effect of an increased dynamics of abrasive processes, while the upper part of the valleys has erosive and denudative character.

Based on the conducted experimental research, it is possible to separate in the longitudinal profile of the valleys the zone of impact of coastal processes from the zone which is shaping by erosion and denudation processes.

Separated erosion and denudation valleys affect both the morphology of the coast and modify the contemporary morphogenetic system of the cliff coast of the Southern Baltic.
GIS and geomatics for hydrogeodiversity assessment of glaciated mountains: examples from the Western Alps (Italy) and the Coast Mountains (Canada)
Authors: Perotti Luigi , Lasagna Manuela , Carraro Gilda , Viani Cristina , Tognetto Federico , Dominico Antonio De Luca , Roberti Gioachino , Giardino Marco
Published: March 2020

This paper aims at the systematization of knowledge related to geodiversity assessment for water resources and its evaluation within high mountain areas. In this environmental context, geological features, landforms and geomorphological processes, soils and water too are particularly sensitive to climatic and environmental changes, thus giving geodiversity a particularly dynamic character.

A multidimensional (regional, local; present, past) approach was developed for analyzing components of geomorphological and hydrogeological systems, both at superficial and underground level, in order to establish a conceptual model and a specific procedure for the evaluation of geodiversity.

Spatial and temporal dimensions of glaciated mountain landscapes of the Italian Western Alps (Monte Rosa, Maggiore Lake, Sesia Val Grande UNESCO Global Geopark) and the Coast Mountains of Canada (Mount Meager, Lillohet Valley, Sea-to-Sky Corridor) were mapped and interpreted by means of: 1) detailed interpretation of DEM-derived data, 2) proper selection of Geomatics survey and monitoring tools and 3) targeted application of GIS analytical methods. The selection and processing operations of the elements considered for this evaluation led to the identification of areas characterized by greater values of hydrogeodiversity. Here, the link between surface and underground hydrodynamics becomes closer and intense, thus conditioning the local landscape setting and the interactions of its natural and human components.

The conceptual model and related workflow proved to be useful for both a) enhanced accuracy of models of a diversity of geomorphological and hydrogeological elements and processes of mountain regions and b) improved “targeted” knowledge on hydrogeodiversity and increased awareness on related geoheritage.

The proposed GIS and Geomatics framework allowed the hydrogeodiversity assessment going well beyond the limit of classical geomorphological and hydrogeological techniques. Difficulty of quantitative analysis over large areas was overcome, and small landscape features and other “hidden” hydrogeological markers could be taken into account. The results of the research strengthened the possibility of strategic management of geological, geomorphological and hydrological heritages within the study areas. In fact, we identified different landscapes and local peculiarities determined by mutual influences between geology and hydrological dynamics and mapped their possible interaction with human activities and infrastructures within areas of enhanced climate change effects.
The role of climate information for the urban transition towards sustainability
Authors: Langendijk Gaby , Rechid Diana , Jacob Daniela
Published: March 2020

Urban areas are prone to climate change impacts. A transition towards sustainable urban systems is relying heavily on useful, evidence-based climate information on urban scales. 

However, many of the urban climate models and regional climate models are currently either not scale compliant for cities, or do not cover essential parameters and/or urban-rural interactions under climate change conditions. Furthermore, although e.g. the urban heat island may be better understood, other phenomena, such as moisture change, are little researched. Our research shows the potential of regional climate models, within the EURO-CORDEX framework, to provide climate information on urban scales for 11km and 3km grid size. The city of Berlin is taken as a case-study. The results show that the regional climate models simulate a difference between Berlin and its surroundings for temperature and humidity related variables. There is an increasing urban dry island in Berlin towards the end of the century, as well as an increasing urban heat island. The study shows the potential of regional climate models to provide climate change information on urban scales.

For climate information to underpin the urban transition this information will need to be put in a decision-making context. As an example, the research aims to understand connections to the health sector on how to integrate the information in order to manage e.g. the dispersion of pollen in cities, assisting in mitigating pollen allergies. The research showcases an interdisciplinary way forward to firstly produce climate information on urban scales and secondly how to connect it to city sectors in a suitable manner to underpin the transition to sustainable urban systems. 

 
Quantifying the influence of low vegetation on vertical uncertainties of 3D point clouds derived from UAV-based ground surface measurements
Authors: Fischer Sebastian , Hormes Anne , Adams Marc S. , Zieher Thomas , Bremer Magnus , Rutzinger Martin , Otto Jan-Christoph
Published: March 2020

The use of unmanned aerial vehicles (UAV) for ground surface measurements in natural hazard studies has strongly increased in recent years. Multi-temporal 3D point clouds derived from light detection and ranging (LiDAR) sensors and photogrammetric techniques including structure-from-motion (SfM) and dense image matching (DIM) have become important tools for monitoring the activity of geomorphic processes. However, due to georeferencing errors and measurement inaccuracies, change detection with centimeter precision remains challenging, especially in study areas covered by vegetation. This study aims at quantifying the influence of low vegetation on the vertical uncertainties of 3D point clouds in a study area mostly covered by meadows and pastures with different grass heights. 3D point clouds derived from UAV-SfM and UAV-LiDAR are compared to terrestrial ground surface measurements of a differential global navigation satellite system (dGNSS) receiver in order to quantify the vertical uncertainties and to detect advantages/disadvantages of the different sensors. The results indicate that neither method is able to detect the ground surface under dense low vegetation with centimeter precision, and that surface displacement rates derived from multi temporal analyses can be highly influenced by changes in vegetation height between surveys.
Spatial variation and temporal trends of solar radiation over Morocco based on ground observations and CMSAF data records.
Authors: Moutia Sara
Published: March 2020

The main advantage of remote sensing products is that they are reasonably good in terms of temporal and special coverage, and they are available in a near real time. Therefore, an understanding of the strengths and weaknesses of satellite data is useful to choose it as an alternative source of information with acceptable accuracy.  On the first hand, this study assesses an Inter-comparison between CMSAF Sunshine Duration (SD) data records and ground observations of 30 data sets from 1983 to 2015. the correlation is very significant and the satellite data fits very closely to in situ observations. On the other hand, trend analysis is applied to SD and Solar Incoming Direct radiation (SID) data, a number of stations show a statistically significant decreasing trend in SD and also SID shows a decreasing trend over Morocco in most of regions especially in summer. The results indicate a general tendency of decrease in incoming solar radiation mostly during summer which could be of some concern for solar energy.
Using objective comparisons of observed and simulated precipitation to help guide the improvement of Earth System Models
Authors: Gleckler Peter , Pendergrass Angeline
Published: March 2020

In this presentation we discuss a community-based effort to establish the benchmarking of simulated precipitation in Earth System Models.   We first summarize the impetus and outcomes of a recent workshop dedicated to the topic.    This includes the identification of a tiered system of objective tests (metrics) for the following climatological characteristics:  the mean state, seasonal cycle, variability across time scales, intensity/frequency distributions, extremes and drought.   Preliminary results are shown gauging model performance changes across multiple generations of CMIP.   The performance tests we describe are part of an open-source analysis framework being made available to model developers to help them make judgements about the quality of simulated precipitation during the model development process.
Climate-groundwater dynamics inferred from GRACE and the role of hydraulic memory
Authors: Taylor Richard , Opie Simon , Brierley Chris , Shamsudduha Mohammad , Cuthbert Mark
Published: March 2020

Groundwater is the largest store of freshwater on Earth after the cryosphere and provides a substantial proportion of the water used for domestic, irrigation and industrial purposes. Knowledge of the relationship between groundwater and climate is limited and undermined by the scale, duration, and accessibility of observations. Here we examine a 14-year period (2002-2016) of GRACE observations to investigate climate-groundwater dynamics of 14 tropical and sub-tropical aquifers selected from WHYMAP’s 37 large aquifer systems of the world. GRACE-derived changes in groundwater storage resolved using GRACE JPL Mascons and the CLM Land Surface Model are related to precipitation time series and regional-scale hydrogeology. We show that aquifers in dryland environments exhibit long-term hydraulic memory through a strong correlation between groundwater storage changes and annual precipitation anomalies integrated over the time series; aquifers in humid environments show short-term memory through strong correlation with monthly precipitation. This classification is consistent with estimates of Groundwater Response Times calculated from the hydrogeological properties of each system, with long (short) hydraulic memory associated with slow (rapid) response times. The results suggest that groundwater systems in dryland environments may be less sensitive to seasonal climate variability but vulnerable to long-term trends from which they will be slow to recover. In contrast, aquifers in humid regions may be more sensitive to seasonal climate disturbances such as ENSO-related drought but may also be relatively quick to recover. Exceptions to this general pattern are traced to human interventions through groundwater abstraction. Hydraulic memory is an important factor in the management of groundwater resources, particularly under climate change. 
Solving the erosion transport equation on three dimensional catchments
Authors: Kuraz Michal , Mayer Petr
Published: March 2020

Modeling the kinematic wave equation and sediment transport equation enables a deterministic approach for predicting surface runoff and resulting sediment transport. Both the kinematic wave equation and the sediment transport equation are first order differential equations. Moreover the kinematic wave equation is a quasilinear problem. In many engineering applications this set of equations is solved on one-dimensional representative cross-sections. However, a proper selection of representative cross-section(s) is  cumbersome. On the other hand integrating this set of equations on real catchment topography  yields difficulties for standard variational methods such as continous Galerkin method. These difficulties are two-fold (1) the nonlinearity of the kinematic wave, and (2) the absence of diffusion term, which acts as a stabilization term for convection-diffusion equation. In a theory, the Peclet number of numerical stability reaches infinity. 

In this contribution we will focus on a stable numerical approximation of this convection-only problem using least square method. With this method we are able to reliably solve both the kinematic wave equation and the sediment transport equation on computational  domains representing real catchment topography. Several examples representing real-world scenarios will be given.
New GGOS JWG3 on Improved understanding of space weather events and their monitoring
Authors: Garcia-Rigo Alberto , Soja Benedikt
Published: March 2020

Multiple space geodetic techniques are capable of measuring effects caused by space weather events. In particular, space weather events can cause ionospheric disturbances correlated with variations in the vertical total electron content (VTEC) or the electron density (Ne) of the ionosphere.

In this regard and in the context of the new Focus Area on Geodetic Space Weather Research within IAG’s GGOS (International Association of Geodesy; Global Geodetic Observing System), the Joint Working Group 3 on Improved understanding of space weather events and their monitoring by satellite missions has been created as part of IAG Commission 4, Sub-Commission 4.3 to run for the next four years.

Within JWG3, we expect investigating different approaches to monitor space weather events using the data from different space geodetic techniques and, in particular, combinations thereof. Simulations will be beneficial to identify the contribution of different techniques and prepare for the analysis of real data. Different strategies for the combination of data will also be investigated, in particular, the weighting of estimates from different techniques in order to increase the performance and reliability of the combined estimates. Furthermore, existing algorithms for the detection and prediction of space weather events will be explored and improved to the extent possible. Furthermore, the geodetic measurement of the ionospheric electron density will be complemented by direct observations from the Sun gathered from existing spacecraft, such as SOHO, ACE, SDO, Parker Solar Probe, among others. The combination and joint evaluation of multiple datasets with the measurements of space geodetic observation techniques (e.g. geodetic VLBI) is still a great challenge. In addition, other indications for solar activity - such as the F10.7 index on solar radio flux, SOLERA as EUV proxy or rate of Global Electron Content (dGEC)-, provide additional opportunities for comparisons and validation.

Through these investigations, we will identify the key parameters useful to improve real-time/prediction of ionospheric/plasmaspheric VTEC, Ne estimates, as well as ionospheric perturbations, in case of extreme solar weather conditions. In general, we will gain a better understanding of space weather events and their effect on Earth’s atmosphere and near-Earth environment.
Concrete Damage Assessment by Coda Waves: Wave propagation simulations to support experimental investigations
Authors: Saydak Leslie Anne , Saenger Erik H.
Published: March 2020

Concrete is a strongly heterogeneous and densely packed composite material. Due to the high density of scattering constituents and inclusions, ultrasonic wave propagation in this material consists of a complex mixture of multiple scattering, mode conversion and diffusive energy transport. For a better understanding of the effect of aggregates, porosity and of crack distribution on elastic wave propagation in concrete and to optimize inverse techniques it is useful to simulate the wave propagation and scattering process explicitly in the time domain. For this purpose, we use the rotated staggered grid (RSG) finite-difference technique for solving the wave equations for elastic, anisotropic and/or viscoelastic media. This study is part of the CoDA project (DFG project 398216472, FOR 2825), which aims to develop a novel method based on ultrasonic coda wave interferometry (CWI) for the assessment of safety and durability of reinforced concrete structures. For this purpose, the coda technique is a suitable method to detect small changes in concrete members. In order to distinguish changes in the coda signal in terms of their origin (i.e. mechanical load, temperature, moisture), wave propagation simulations are performed to support the experimental investigations within the project. The idea is to create realistic digital twins for the experiments on two different scales: The specimen scale and the structural scale. In this study, high-performance simulations of ultrasonic wave propagation within concrete structures on the specimen scale were performed and evaluated using coda wave interferometry (CWI).
Hydrologic-hydraulic coupling for flash flood real-time simulation: Application to the October 2015 French Riviera floods
Authors: Charpentier-Noyer Maryse , Bourgin François , Kirstetter Geoffroy , Delestre Olivier , Brigode Pierre
Published: March 2020

The vulnerability of the French Riviera to hydro meteorological hazards has been dramatically illustrated by the flash floods of October 3, 2015: 20 people were killed and the cost of the direct damages were higher than 600 million euros. Due to their fast dynamics, flash floods are difficult to predict and leave little time for forecasting. In this context, it is needed to improve real-time simulations to enable a short-range anticipation of the consequences of these phenomena. The main goal of this work was to test a hydrologic-hydraulic coupling in order to assess whether this coupling can be used for real-time forecasting purposes. The coupling is composed for the hydrological part of the event-based spatially distributed rainfall-runoff model Cinecar and for the hydraulic part of the Basilisk software, which is based on 2D hydraulic modelling (finite volume methods for shallow water equations) with adaptive grid refinement. The main interest of this coupling method is the compromise obtained between calculation time and precision. The rainfall-runoff model is run on the upstream part of the domain and feeds the hydraulic model applied in the downstream part. The rainfall-runoff model makes it possible to estimate very quickly the streamflow temporal evolution, while the hydraulic model, although much slower when applied at high spatial resolution (up to 4m), makes it possible to have water level and velocity at any point of the downstream area. The application of this coupling approach is presented for three basins severely affected by the October 2015 flash floods: the Brague (68 km²), the Frayère (22 km²) and the Riou de l’Argentière (48 km²) catchments. The results obtained for the three basins are compared with information gathered from post-event surveys, particularly the high water level marks. A particular attention is also put on computation times in order to evaluate the possibilities of real-time simulation. The results show promising performances both in terms of calculation time but also in terms of accuracy of the simulated flood areas and water levels.
Combining global and local models and data for sector-specific water scarcity risk assessments in mega-cities
Authors: Hendriks Dimmie , Vermooten Sophie , van Aalst Maaike , Mulder Niels , Morales Irato Diana , Hüsken Lieke , Faneca Sànchez Marta
Published: March 2020

An increasing number of mega-cities, such as Cape Town and São Paulo, are confronted with increasing droughts as well as an increase in water demand. Inevitably, this leads to an increasing pressure on the available water resources and associated risks and economic impact for the water dependent sectors, such as drinking water supply, industry, energy production, agriculture, and nature.

Here, we present the WaterLOUPE approach (https://deltares.nl/waterloupe) to estimating water scarcity risk for mega-cities and their surrounding catchment that combines the global model PCR-GLOBWB and global datasets (e.g. Shared Socioeconomic Pathways and OECD Economic Outlook) with local datasets and local expert knowledge. Data and models provide the required information to estimate the water scarcity hazard, level of exposure of the relevant sectors and their vulnerability. With our approach we estimate sector-specific risks at the spatial scale of sub-catchments or municipalities. Moreover, the water scarcity risk is provided both for the current situation and future climatic and socio-economic scenarios.

Our approach has been tested, both technically and through stakeholder workshops, in several case studies (São Paolo, Cape Town, Cali, and Tel Aviv-Yafo). The results of our sector-specific water scarcity risk calculations have shown to reflect the local situation of water users in mega-cities very well. As such, the outcomes of the approach have provided a useful knowledge base that enables stakeholders in the catchment to discuss water scarcity risk, which is a first step to collaboration on mitigation and adaptation strategies to decrease water scarcity risks in mega-cities.

Overall, it can be concluded that although climate change tends to decrease water availability, the main drivers of the water scarcity risk are socioeconomical and are related to the strong growth of water demand and the high vulnerability of specific water users. Generally, it was found that water scarcity risks for poor households, small scale farmers, local businesses and nature are relatively high, also under moderate drought conditions. On the other hand, the risks for industries and non-poor households are low to moderate even in more drought prone areas or periods. In most cases the level of water scarcity risk is expected to increase in the future, underlining the urgency for mega-cities to develop actionable and inclusive strategies to mitigate and adapt to the new normal of increasing water stress.
Methodology of preliminary safety assessments in the site selection procedure in Germany
Authors: Rühaak Wolfram , Kreye Phillip , Hoyer Eva-Maria , Wolf Johanna , Panitz Florian , Gawletta Dennis
Published: March 2020

In Germany, the site selection for a repository for radioactive waste in deep geological formations was (re-) started in 2017 with the Repository Site Selection Act coming into force. The Site Selection Act envisages preliminary safety assessments as a measure to ensure the safety of a considered site.

The focus of the presentation will be the methodology of the preliminary safety assessments as it is derived from the legal requirements. In this context, the Federal Ministry for Environment, Nature Conservation and Nuclear Safety published the draft of the regulation on the safety requirements for the disposal of high-level radioactive waste in summer 2019. Article 2 of this regulation contains the requirements for the implementation of preliminary safety assessments in the site selection procedure. One essential aspect is the systematical identification and characterization of uncertainties. We will discuss the key features of the handling of uncertainties in the site selection procedure, especially with regard to numerical reactive transport modelling. The German Site Selection Act is divided into several steps with increasing level of detail. The identification and quantification of uncertainties plays a major role to improve quality and plausibility in each step. Well-prepared explorations for instance, need to be addressed in a way to minimise data uncertainties. In addition, the handling of uncertainties in safety assessments on an international level is evaluated.
Different climate response of three tree ring proxies of Pinus sylvestris from the Eastern Carpathians, Romania
Authors: Nagavciuc Viorica , Roibu Cătălin-Constantin , Ionita Monica , Mursa Andrei , Cotos Mihai-Gabriel , Popa Ionel
Published: March 2020

The aim of this study was to compare the climatic responses of three tree rings proxies: tree ring width (TRW),
maximum latewood density (MXD), and blue intensity (BI). For this study, 20 cores of Pinus sylvestris covering
the period 1886–2015 were extracted from living non-damaged trees from the Eastern Carpathian Mountains
(Romania). Each chronology was compared to monthly and daily climate data. All tree ring proxies had a
stronger correlation with the daily climate data compared to monthly data. The highest correlation coefficient
was obtained between the MXD chronology and daily maximum temperature over the period beginning with the
end of July and ending in the middle of September (r=0.64). The optimal intervals for the temperature signature
were 01 Aug – 24 Sept for the MXD chronology, 05 Aug – 25 Aug for the BI chronology, and both 16 Nov
of the previous year – 16 March of the current year and 15 Apr – 05 May for the TRW chronology. The results
from our study indicate that MXD can be used as a proxy indicator for summer maximum temperature, while
TRW can be used as a proxy indicator for just March maximum temperature. The weak and unstable relationship
between BI and maximum temperature indicates that BI is not a good proxy indicator for climate reconstructions
over the analysed region.
HITRAN2020: An overview of what to expect
Authors: Hargreaves Robert , Gordon Iouli , Rothman Laurence , Hashemi Robab , Karlovets Ekaterina , Skinner Frances , Conway Eamon , Tan Yan , Hill Christian , Kochanov Roman
Published: March 2020

The HITRAN database is an integral component of numerous atmospheric radiative transfer models and it is therefore essential that the database contains the most appropriate up-to-date spectroscopic parameters. To this end, the HITRAN2020 database is scheduled to be released at the end of this year.  The compilation of this edition (as is the tradition for the HITRAN database) exemplifies the efficiency and necessity of worldwide scientific collaborations. It is a titanic effort of experimentalists, theoreticians and atmospheric scientists, who measure, calculate and validate the HITRAN data.

The HITRAN line-by-line lists for almost all 49 molecules have been updated in comparison to HITRAN2016 (Gordon et al., 2017), the previous compilation. The extent of these updates depend on the molecule, but range from small adjustments for a few lines of an individual molecule to complete replacements of line lists and the introduction of new isotopologues. Many new vibrational bands have been added to the database, thereby extending the spectral coverage and completeness of the datasets. In addition the accuracy of the parameters for major atmospheric absorbers has been substantially increased, often featuring sub-percent uncertainties.

Furthermore, the amount of parameters has also been significantly increased. For example, HITRAN2020 will now incorporate non-Voigt line profiles for many gases, broadening by water vapour (Tan et al., 2019), as well as updated collision induced absorption sets (Karman et al., 2019). The HITRAN2020 edition will continue taking advantage of the new structure and interface available at www.hitran.org (Hill et al., 2016) and the HITRAN Application Programming Interface (Kochanov et al., 2016).

This talk will provide a summary of these updates, emphasizing details of some of the most important or drastic improvements.

References:

Gordon, I.E., .et al., (2017), JQSRT 203, 3–69.  (doi:10.1016/j.jqsrt.2017.06.038)

Hill, C., et al., (2016), JQSRT 177, 4–14.  (doi:10.1016/j.jqsrt.2015.12.012)

Karman, T., et al. (2019), Icarus 328, 160–175.  (doi:10.1016/j.icarus.2019.02.034)

Kochanov, R.V., et al.,( 2016), JQSRT 177, 15–30.  (doi:10.1016/j.jqsrt.2016.03.005)

Tan, Y., et al., (2019), J. Geophys. Res. Atmos. 124, 11580-11594. (doi:10.1029/2019JD030929)

 
The Various Aspects of the Large- scale Atmospheric Circulation Response to the Northern Hemispheric Ocean Western Boundary Currents
Authors: Omrani Nour-Eddine , Ogawa Fumiaki , Nakamura Hisashi , Keenlyside Noel , Lubis Sandro , Matthes Katja
Published: March 2020

Semi-idealized Atmospheric General Circulation-Model (AGCM) experiments are used, in order to study the different aspects of the hemisphere-scale wintertime troposphere/stratosphere-coupled circulation that are maintained by the North Atlantic and Pacific Ocean Western Boundary Currents (OWBCs). Here we show that the North Atlantic and Pacific OWBCs jointly maintain and shape the wintertime hemispheric circulation and its leading mode of variability Northern Annular Mode (NAM). The OWBCs energize baroclinic waves that reinforce quasi-annular hemispheric structure in the tropospheric eddy-driven jetstreams and NAM variability. Without the OWBCs, the wintertime NAM variability is much weaker and its impact on the continental and maritime surface climate is largely insignificant. Atmospheric energy redistribution caused by the OWBCs acts to damp the near-surface atmospheric baroclinicity and compensates the associated oceanic meridional energy transport in agreement with the Bjerknes compensation. Furthermore, the OWBCs substantially weaken the wintertime stratospheric polar vortex by enhancing the upward planetary wave propagation, and thereby affecting both stratospheric and tropospheric NAM-annularity. It is shown that the impact of OWBCs on northern hemisphere circulation has significant implication for stratosphere/troposphere dynamical coupling, time-scales on the NAM, frequency of Sudden stratospheric warming and potential formation of polar stratospheric clouds.

 

Reference:

Omrani et al., 2019: Key Role of the ocean Western Boundary currents in shaping the Northern Hemisphere climate, Scientific Reports, https://doi.org/10.1038/s41598-019-39392-y

 
Irrigation efficiency and optimization: the Optirrig model
Authors: Cheviron Bruno , Serra-Wittling Claire , Delmas Magalie , Belaud Gilles , Molle Bruno , Dominguez-Bohorquez Juan-David
Published: March 2020

A possible way to save agricultural water is to improve global irrigation efficiency, defined as the ratio between the irrigation water volume used for crop transpiration and the total irrigation water volume. Higher irrigation efficiency leads to higher irrigation productivity ("more crop per drop") and profitability in relation to irrigation water costs: higher financial expectations for the same water and energy costs or identical financial expectations for lesser water and energy costs.

Improvements of irrigation efficiency may be sought either from better performing material (contextual relevance, technical quality or durability) or from optimized irrigation strategies with multiple levers of action (dates, doses, scheduling or trigger criteria, leaning on weather forecasts or not) and expected constraints (availability, quota, prefecture decrees).

It is even possible to handle these two issues at once by

(i) evaluating the irrigation water losses attributable to material (e.g. accidental pipe rupture or unavoidable intrinsic losses when using rainguns, spatial heterogeneity of water delivery),

(ii) evaluating the losses due to inadequate irrigation strategies (drainage or evaporation of irrigation water, excessive irrigation water storage in soils, losses due to wind drift)

(iii) gathering all losses in a "cascade scheme" that organizes them in phenomenological and chronological manner, somehow assuming successive losses "from the canal to plant roots",

(iv) exploring numerous irrigation scenarios that would allow reducing losses, improving efficiency and finally finding the minimal irrigation water amount required to reach the target agricultural yield (or fulfil a typical set of contradictory constraints, e.g. irrigation quota vs. objectives in crop yield profitability and possibly no drainage)  

This was the scope of the recent development of the "Efficiency" module of the Optirrig model built for the generation, analysis and optimisation of crop irrigation scenarios.
Calibration and Validation of Earth-Observing Sensors Using The Radiometric Calibration Test Site (RadCaTS) at Railroad Valley, Nevada, USA
Authors: Czapla-Myers Jeffrey , Anderson Nikolaus
Published: March 2020

The Radiometric Calibration Test Site (RadCaTS) was developed by the University of Arizona to provide satellite operators and the scientific community with daily ground-based data that are appropriate for the radiometric calibration and surface reflectance product validation of Earth-observation sensors. It is located at Railroad Valley, Nevada, USA, which has been used by the University of Arizona since 1996. The primary goal of RadCaTS is to provide data that can be used for the independent, accurate, and timely analysis of both the radiometric calibration and surface reflectance validation of Earth-observation sensors that operate in the solar-reflective region (400 nm to 2500 nm). RadCaTS is currently being used to monitor low-Earth orbit sensors such as Terra and Aqua MODIS, SNPP and NOAA-20 VIIRS, Landsat 8 OLI, Sentinel-2A and -2B MSI, Sentinel-3A and -3B OLCI and SLSTR, as well as geosynchronous sensors such as GOES-16 and ‑17 ABI. RadCaTS is currently one of four automated test sites that make up the CEOS WGCV IVOS Radiometric Calibration Network (RadCalNet), which seeks to harmonize the ground-based calibration and validation measurements from international organizations. This work presents current results from RadCaTS, as well as a comparison with results obtained from the RadCalNet data portal, which became publicly available at no cost to registered users in June 2018.
Mapping Arctic Observing Systems and In Situ Data Collections
Authors: Hamre Torill , Monsen Frode , Sagen Hanne , Olaussen Tor I. , Geyer Florian , Pirazzini Roberta
Published: March 2020

Climate change in the Arctic is significant and will have far-reaching consequences for marine life and sustainable societal and industrial development in this region. Sustained direct (in situ) measurements of key physical and biogeochemical parameters in Arctic waters are required to estimate the state and monitor changes in the marine environment. Since in situ data is most frequently collected in research projects funded by national, regional or international programmes, there is no common overview of what data are collected in which area, for which time period, by which organisation, or where the data are stored. The H2020 INTAROS project has conducted a survey of Arctic in situ observing systems, in situ and remote sensing data collections. Based on the questionnaires from this survey we have developed a user-friendly web-based system for collecting and maintaining information about Arctic in situ observing systems and data collections in a project funded by the Norwegian Ministry of Climate and Environment. This system, called arcmap, is developed using open source technologies and frameworks, such as wq (https://wq.io/) and Django REST (https://www.django-rest-framework.org/). Arcmap enables users to register and maintain information about their Arctic in situ observing systems and data collections. The information is stored in a relational database, which offers a flexible query language for extracting subsets and aggregates of information based on user defined criteria. Building on this database, statistics can be generated on for example spatial and temporal coverage, parameters observed and targeted application areas, nationality of owners of observing systems and data collections, funding sources and periods, maturity of data management. Using these statistical measures different aspects of sustainability for current and planned Arctic observing systems can be analysed. This allows us to identify patterns and gaps in collection of important environmental variables and to follow the evolution of observing systems over time. The presentation will focus on the current functionality of arcmap and outline possible future enhancements.
Reconstructing global continental motions through time using data assimilation: a proof of concept.
Authors: Bocher Marie , Tetley Michael
Published: March 2020

Kinematic plate tectonic reconstructions are central to our understanding of the dynamics of the solid Earth over hundreds of millions of years. These reconstructions are typically based on a combination of qualitative geological and paleontological observations supplemented with quantitative geophysical data, such as paleomagnetism. As a result, reconstructing plate and continental motion generally involves largely manual processes to integrate regional tectonic histories into a geometrically self-consistent global model. Further, with this methodology it is very difficult to quantify the uncertainties of the resulting time-dependent plate configurations and motions. To overcome these difficulties, ensemble-based data assimilation methods present a promising approach to paleogeographic reconstruction as they provide a formal statistical framework to assimilate time-dependent geoscientific data of variable nature and source within a dynamical model whilst providing quantitative estimates of uncertainties on the proposed trajectory.

To develop this concept, we apply a particle filter to reconstruct the time-dependent motion of continents on Earth. We start with a kinematic-stochastic model of continental drift: the motion of continents is governed by random rigid rotations, where velocity, rate of rotation (around polygon centroid) and rate of motion change are drawn randomly. Each of the probability density functions is chosen using geometrical and geodynamical arguments. This stochastic-kinematic model is then used to compute possible continent motion trajectories. We integrate this forward model into a data assimilation framework to incorporate paleomagnetic data, starting from present day and moving backward through time. From observing system simulation experiments using this technique, results suggest the number of ensemble members needed is of the order of several thousands to obtain accurate reconstructions of continent motions. Leveraging these experiments, we present the results of applying this method to a global paleomagnetic dataset spanning the last 100 Ma.
3D Reconstruction of Volcanic Ash Clouds Using Simulated Satellite Imagery
Authors: Etchells Tom , Berthoud Lucy , Calway Andrew , Watson Matthew
Published: March 2020

Volcanic ash suspended in the atmosphere can pose a significant hazard to aviation, with the potential to cause severe damage or shutdown of jet engines. Forecasts of ash contaminated airspace are generated using atmospheric transportation and dispersion models, among the inputs to these models are eruption source parameters such as cloud-top height and cloud volume. A potential method to measure these source parameters is space carving – a technique to generate 3D hull reconstructions of clouds using multi-angle imagery.

This paper investigates the potential for 3D space carving reconstruction using multi-angle satellite imagery.  This builds on previous work where the authors have applied this technique to ground-based and drone-based imagery. A satellite-based imaging platform has advantages such as global coverage and being safely removed from any damaging effects of a volcanic eruption. However, the accuracy of any potential reconstruction will be affected by the distances and restricted viewing angles of a satellite in orbit.

To assess the general suitability of a satellite-based system for reconstruction, as well as different configurations of the system, a method for simulating satellite imagery and applying a space carving reconstruction scheme was developed. This method allows the analysis of the effects of orbital dynamics (altitude, inclination, etc.), spatial resolutions, and imaging rates on the efficacy of the 3D reconstruction of ash clouds. The model utilises an input ‘ground-truth’ voxel-based plume model as the imaging target and generates simulated satellite images based on the user defined orbital and camera properties. These simulated images are then used for reconstruction and the resultant plume can be compared against the ground-truth model.

A range of possible observation schemes (controlling number and distribution of images and limits on viewing angles) have been modelled over a range of possible orbital paths and the accuracy of the space carving reconstruction has been measured. Spatial resolution limits for the accurate reconstruction of various plume sizes can be calculated. Limitations of the model are presented, including the sensitivity to the size and shape of the input plume model and the impact of the perfect feature identification in the simulated images. Further work includes the use of additional input models and improvements and validation of the image simulation method.

The methods presented in this study demonstrate the potential of satellite-based 3D reconstruction methods in the forecasting of ash dispersion, leading to potential improvements in airspace management and aviation safety.
Ocean role in the winter sea ice openings north of Svalbard
Authors: Herbaut Christophe , Houssais Marie-Noelle , Blaizot Anne-Cecile
Published: March 2020

The winter trend in the sea ice coverage in the Atlantic sector of the Arctic Ocean has been linked to the Atlantic Water heat transport, providing significant skill to decadal prediction (Yeager et al, 2015, Årthun et al., 2019). The Atlantic Water meets the sea ice north of Svalbard where it has the potential to melt significant amounts of ice and contribute to the formation of a cool, fresh surface layer (Rudels et al., 2004). In this study we investigate the origin of the intra-seasonal variability of winter sea ice melt north of Svalbard and evaluate its contribution to recurrent sea ice openings in this region. 

Based on outputs of a simulation with a high resolution regional ice-ocean model over the period 1995-2017, a number of large, short-term ice melt events could be identified in winter which can contribute up to 40% of the total winter ice melt. Most of these events show enhanced signature along the Atlantic Water path. However different types of events have been established depending on the scenario responsible for enhanced sea ice melt. Enhanced melt can happen concomitantly to large ice edge convergence over preexisting warm surface waters, a scenario which predominates during close-up of large ice openings. Large melt rates can also be driven by entrainment of warm water into the mixed layer in response to strong winds or to enhanced advection of warm water during episodes of increased transport in the boundary current. The latter process is however less efficient than entrainment. We conclude that increased southerly winds, which can sustain altogether ice edge retreat and efficient ice melt through entrainment and advection of heat into the region, create optimal conditions for major ice openings such as those observed north of Svalbard.