bluuebunny/crossref_metadata_2025 huggingface dataset:
Forecasting the El Niño type well before the spring predictability barrier
Authors: Ludescher Josef , Bunde Armin , Schellnhuber Hans Joachim
Published: February 2023

The El Niño Southern Oscillation (ENSO) is the most important driver of interannual global climate variability and can trigger extreme weather events and disasters in various parts of the globe. Depending on the region of maximal warming, El Niño events can be partitioned into 2 types, Eastern Pacific (EP) and Central Pacific (CP) events. The type of an El Niño has a major influence on its impact and can even lead to either dry or wet conditions in the same areas on the globe. Here we show that the zonal difference ΔTWP-CP between the sea surface temperature anomalies (SSTA) in the equatorial western Pacific and central Pacific is predictive of the type of an upcoming El Niño. When at the end of a calendar year, ΔTWP-CP is positive, an El Niño event developing in the following year will probably be an EP event, otherwise a CP event. Between 1950 and present, the index correctly indicates the type of 18 out of 21 El Niño events (p = 9.1⋅10-4).For early actionable forecasts, the index has to be combined with a forecast for the actual onset of an El Niño event. The previously introduced climate network-based forecasting approach provides such forecasts for the onset of El Niño events also by the end of the calendar year before onset. Thus a combined approach can provide reliable forecasts for both the onset and the type of an event: at a lead time of about one year, 2/3 of the EP El Niño forecasts and all CP El Niño forecasts in the regarded period are correct. The combined model has considerably more predictive power than the current operational type forecasts with a mean lead time of about 1 month and should allow early mitigation measures.
Particle hygroscopicity in an urban background environment during the ACROSS campaign
Authors: Deshmukh Shravan , Poulain Laurent , Wehner Birgit , Petit Jean-Eudes , Fombelle Pauline , Favez Oliver , Herrmann Hartmut , Pöhlker Mira
Published: February 2023

Hygroscopicity strongly influences aerosol particle properties and multiphase chemistry, which also plays an essential role in several atmospheric processes. Although CCN (cloud condensation nuclei) properties are commonly measured, sub-saturation hygroscopicity measurements remain rare. Within the ACROSS campaign, which took place in the Paris region, France, during the summer of 2022, the particle’s hygroscopic growth at 90 % relative humidity (RH) and chemical composition were concurrently measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA, scanning at 100, 150, 200, and 250 nm) and Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) respectively, at the ACTRIS (the European Aerosol, Clouds and Trace gases Research Infrastructure) SIRTA near facility, a peri-urban site representative of the Greater Paris background conditions. Growth factor probability density distributions (GF-PDF) show two distinct modes: hydrophobic and hygroscopic, indicating that the particles are internally and externally mixed. The hygroscopic mode is always more prominent in the GF-PDF, indicating a change in the particles' mixing state. The dominance of the hygroscopic mode becomes more pronounced with increasing particle size. The mean hygroscopicity parameter values, κ of 100, 150, 200, and 250 nm particles derived from hygroscopicity measurements are respectively 0.23, 0.29, 0.36, and 0.38 during the sampling period. The size dependence is reflected in the averaged values of κ and the GF distributions. A diurnal pattern was observed with an average daytime κ higher than during night-time, which could be linked to aging processes and secondary aerosol formation during the day. The Zdanovskii-Stokes-Robinson (ZSR) mixing rule was applied on the particle chemical to make accurate quantitative predictions of the mean GF of mixed atmospheric aerosol particles.Keywords: Hygroscopicity, Growth factor, hygroscopicity parameter κ.
Stratosphere-troposphere coupling under the extreme conditions of the No-Montreal-Protocol scenario
Authors: Sukhodolov Timofei , Zilker Franziska , Chiodo Gabriel , Egorova Tatiana , Friedel Marina , Rozanov Eugene , Sedlacek Jan , Seeber Svenja , Peter Thomas
Published: February 2023

The Montreal Protocol and its amendments (MPA) have been a major success in preventing serious health damage from the destruction of the stratospheric ozone layer by chlorofluorocarbons (CFCs). Additionally, unabated CFC emissions would have significantly accelerated global warming and affected large-scale tropospheric circulation. CFC-induced ozone depletion would have contributed to global climate change through reduced absorption of UV radiation, resulting in weaker stratospheric circulation, affecting the dynamical coupling to the troposphere. With the Earth System Model SOCOLv4, we study an extreme condition where the MPA is absent to disentangle the radiative and chemical (i.e., ozone-mediated) effects of CFCs and their impacts on stratosphere-troposphere coupling. Our results show that at the end of the 21st century, unabated CFC emissions would have largely destroyed the global ozone layer, which would have strongly affected the large-scale stratospheric and tropospheric circulation. In the stratosphere, contrary to historical ozone destruction, the polar vortices severely weaken due to low-latitude ozone depletion. In the Northern Hemisphere (NH), the weakening of the vortex leads to a pronounced negative phase of the North Atlantic Oscillation (NAO) in boreal winter and spring due to the chemical CFC effect. Similarly, the stratosphere also affects the Southern Annular Mode (SAM) to be in a more negative phase in austral winter and spring. However, tropospheric warming from CFCs largely dominates the overall SAM response to be in a more positive phase, whereas in the NH it compensates for the NAO negative phase. Additionally to the circulation changes, uncontrolled CFC emissions would have led to around 2.5 K additional global surface warming, being partially compensated by a cooling of around 0.6 K due to ozone depletion, leading to an overall warming of around 1.9 K. Our study strongly emphasizes the importance of the MPA for our climate and its mitigation of stratospheric circulation changes and their effects on tropospheric variability.
A dendroprovenance approach to fingerprint the origin of instream wood at the river basin scale
Authors: Gibaja del Hoyo Javier , Monbaron Laetitia , Vennemann Torsten , Vauridel Marceline , Ruiz-Villanueva Virginia
Published: February 2023

Instream large wood (LW) plays an important role in the geomorphic and ecological diversity of a fluvial ecosystem. However, during flood events, LW can also pose a risk to infrastructure and populations by blocking channels, damaging bridges, and other structures. The primary source of LW are forested areas established along rivers and their upstream network. Understanding the origin of LW and the factors that influence its dynamics is key for optimizing river and riparian forest management and reducing the risk associated with flood events.We study a 50km reach of the Rhone River between the city of Geneva and Génissiat dam (France), where the wood material arriving is retained. In this 3000km2 catchment, we aim to infer the origin of the LW that arrives at the reservoir by differentiating between the two main tributaries and providers of LW in the reach: The Arve River (coming from the Alps Mountains) and the Valserine River (from the Jura Mountains).We have explored several methods for inferring the origin of instream wood. By combining them, we gain a more comprehensive understanding of the factors that influence the supply of LW to the watershed and its dynamics within the river system. These methods are based on:Stable isotopes in the cellulose coming from the water molecule (δD and δ18O): they present a spatial distribution due to fractionation happening during evaporation-precipitation processes. The tree absorbs the isotopic signal and stores it in the cellulose, that can be analyzed to distinguish between different source areas.
Chemical composition of wood cellulose: it can be analyzed to provide information about the geology of the area where the tree grew. Techniques such as inductively coupled plasma optical emission spectrometry (ICP-OES) or X-ray fluorescence spectrometry (XRF) are used for this purpose.
Riparian forest composition: some forest characteristics (e.g., tree species, tree diameter, forest density, dead wood present in the floodplain, lateral connectivity with the river, etc.) provide useful information on the areas that are supplying the wood that reaches or will potentially reach the dam.
By combining these approaches, it may be possible to distinguish between different source areas of LW within the catchment and to better understand the factors that influence the supply of LW to the river system. We aim to develop a method that can be applied to similarly scaled mountainous catchments to determine the origin of instream large wood.
Comparison of Meteorological Drought Indices in Georgia (1931-2020)
Authors: Tsitsagi Mariam , Gulashvili Zaza , Bolashvili Nana , Leuchner Michael
Published: February 2023

Recently, the severity of droughts has been increasing due to climate change. Due to the multifaceted nature of droughts (meteorological, hydrological, economic, ecological, etc.), it affects almost all aspects of community life directly or indirectly, both short and long term. Georgia is characterized by diverse terrain and, accordingly, climatic conditions. Most types of climates are present in Georgia except savanna and tropical forests (from humid subtropical to dry subtropical, and climate of eternal snows and glaciers). Therefore, droughts are expressed differently in this small area (67,900 km²). The complexity of different indices used in drought studies depends on the availability of the used data. The purpose of the study was to analyze the intensity of droughts in the short and long term in the territory of Georgia and their distribution for 1931-2020. In this study, we focused on the widespread Standard Precipitation Index (SPI) and Standard Precipitation Evapotranspiration Index (SPEI).  Both indices were calculated based on the data of more than 100 rain gauges located in the study area for several time-scales including 3, 6, 12 and 24 months covering the period from 1931 to 2020. As SPI uses only precipitation data, evapotranspiration is also taken into account in SPEI, which offers a more complete picture of the background of the diversity of Georgia's climate. Daily temperature (for calculation of ET) and precipitation data are used in the research. We calculated the Pearson correlation, R² and RMSE. The correlation of SPI and SPEI allowed us to determine climate type with decisive role of temperature in assessing droughts. The frequency of severe droughts has increased throughout the country, especially in recent decades. This trend is especially striking in the case of the eastern Georgian lowland. In the example of Eastern Georgia‘s precipitation data, another trend was revealed. Here the correlation of SPI and SPEI was relatively low and decreased as the period increases; for example, the correlation for 12- and 24-month periods was lower than for 3- and 6-month periods. This shows that when assessing droughts in East Georgia, it is crucial to take into account the change in temperature along with the change in precipitation. Therefore, in western Georgia, where there is a humid subtropical climate, it is possible to create an idea about the nature of droughts only by using SPI. In the lowland of Eastern Georgia, where it is unlikely to see the accurate picture with only one index, and it is better to use multivariable indices, where along with precipitation, temperature and other data will be taken into account.
Strofio: A Status Update
Authors: Schroeder Jared , Livi Stefano , Allegrini Frederic
Published: February 2023

Strofio is a neutral mass spectrometer designed to measure the chemical composition of Mercury’s exosphere. Neutral species enter the instrument through one of two inlets before they are ionized via electron impact. The product ions are then guided by dozens of individually programmed electrodes toward the detector. A rotating electric field determines the time-of-flight (TOF) of each particle before they collide with a microchannel plate (MCP). Upon launch, one of the system’s electrodes (D5) suffered an anomaly that disrupted communications between the commanded value and the value reported in telemetry. This particular electrode is responsible for steering the particles into the MCP. Laboratory tests with the engineering model confirm mission requirements are satisfied regardless of the electrode state with the caveat being a reduced first-order mass range; however, second-order manipulation can extend the mass range to pre-anomaly standards. I will present the latest advances we have made in optimizing the instrument in its current state.
Hydrogeophysical imaging of an aquifer in the Talysh mountain area, Azerbaijan
Authors: Jodry Clara , Bayramov Kamal , Alizada Gunel , Karimova Nigar
Published: February 2023

Underground water resources face an increase stress due to human activities and global climate change. To ensure sustainable and effective management of water resources, it is important to identify and characterize hydrogeologic systems and associated processes. In Azerbaijan, the groundwater is unevenly distributed due to a wide variety of climate conditions and the lowland areas depend mainly on water supply from the mountain areas to subsist. Especially since the alluvial plain aquifers undergo over consumption and pollution due to industrial and agricultural activities.Our study focusses on the Talysh Mountain area in the Lesser Caucasus basin, where aquifers are characterized by alluvial terrain over volcanic-sedimentary tuff. This implies a high flow rate and quick discharge to low land. Yet, this area is also characterized by higher precipitation than evaporation which makes it favorable to host consequent groundwater aquifer. Geophysics has proved many times that it can bring valuable information to hydrogeological issue in subsurface environment such as unconsolidated ground or weathered hard rock aquifers. Thus, this project aims to characterized the underground structure (lithology, weathering profiles, fault and fissures, etc.) of a mountain aquifer in the region with Electrical Resistivity Tomography (ERT). We realized three separate measurements along the Lenkaran river which should enable us to image the 2D heterogeneity at the catchment scale and identify preferential pathways which influence the hydrodynamic circulations.All three tomographies display two main resistivity layers which seem to be linked to the location along the river. The first layer shows resistivities in between 100 Ω.m with 3 m thickness upstream to 600 Ω.m and 6 m thickness downstream. The second layer is less resistive as a whole and goes from 60 Ω.m upstream to 15 Ω.m downstream. The resistivity limit in-between these two layers is rather abrupt and appear more linear downstream whereas the two profiles up stream display a non-linear limit. We interpret the first layer as dry alluvial sediments over a sedimentary tuff with an irregular top limit. The difference of resistivity from upstream to downstream could be linked to small changes in the lithology as well as variations of water content.To help interpret further the hydrodynamic circulations in the region, these geophysical images will need to be associated with two essential data: groundwater levels and rainfall. Hydrogeology and hydrogeophysics campaign are rarely applied in Azerbaijan, especially in mountain areas, and existing data are either not available or date back to the 1960’s. This study represents the first step in developing environmental geophysics research in Azerbaijan and help put light on key environmental issues in the country.
Symmetry statistics of mineral – paragenetic mode pairs
Authors: Bermanec Marko , Vidović Noa , Gavryliv Liubomyr , M. Hazen Robert , R. Hummer Daniel , M. Morrison Shaunna , Prabhu Anirudh , R. Williams Jason
Published: February 2023

Characterizing the types of crystalline structures that form in different environments helps us to better interpret the geologic record and deepens our understanding of mineral stability. To this end, the Dolivo – Dobrovol’sky symmetry index provides a convenient way to quantify the statistical trends in the symmetry of minerals over time (Bermanec et al. 2022). Behavior of the Dolivo - Dobrovol’sky symmetry index was investigated for different paragenetic modes of minerals (Hazen and Morrison 2022). Two datasets were used and compared (code and datasets are available on https://github.com/NoaVidovic/pgm-mineral-pairs-pg). The first one used only minerals, and each mineral was considered just once. In contrast, in the mineral–paragenetic mode pair dataset, minerals were counted once for each of the paragenetic modes in which they occurred.The paragenetic mode dataset incorporates a number of properties associated with each of more than 60 modes of formation, including relative age and order of that mode’s first appearance, estimated minimum and maximum temperature and pressure of formation, and duration. Paragenetic mode order does not substantially affect the symmetry index of minerals. However, some trends are evident when inspecting the properties of given paragenetic modes. The symmetry indices show a strong correlation with the maximum temperature, maximum pressure, and minimum pressure of paragenetic modes they belong to (Hazen et al. 2022) with correlation coefficients of 69%, 84% and 95%, respectively when using the mineral dataset. These trends show that minerals formed at higher temperature display higher overall symmetry. Trends for pressure are enigmatic: correlations show that minerals formed at higher minimum pressure tend to favor lower symmetry, whereas minerals formed at higher maximum pressure tend to favor higher symmetry.When using the mineral–paragenetic mode dataset, the correlation coefficients are significantly lower at 42%, 30% and 89% for maximum temperature, maximum pressure, and minimum pressure, respectively. The lower correlation coefficients obtained using the mineral–paragenetic mode pairs might indicate that the paragenetic mode is not as important in terms of trends in symmetry as initially thought. On the other hand, considering a much higher correlation coefficient for the mineral dataset, perhaps there is a more dominant effect where certain P-T conditions tend to favor certain types of symmetry at equilibrium.
Record reduction in European forest canopy greenness during the 2022 drought
Authors: Buras Allan , Meyer Benjamin , Rammig Anja
Published: February 2023

According to climate projections, extreme summer drought conditions as those striking Central and Southern Europe in 2022 will become more frequent under climate change. Consequently, studying forests’ response to such extreme conditions may reveal important insights on how forests will cope with anticipated climate conditions. Of particular interest are questions related to forest-type specific drought sensitivities (e.g. broadleaved vs. coniferous, Mediterranean vs. temperate) and the existence of legacy effects from previous droughts (e.g. the extreme 2018 drought, see Buras et al 2020).While many approaches exist to address these questions at local scale, satellite borne remote sensing offers the opportunity to tackle these topics at large scale. Here, the MODIS mission provides a valuable source of information due to a relatively long observational period since the year 2000 at sufficient spatial resolution (250 m x 250 m) and a high sampling frequency (daily images which are used to compute 16-day maximum value composites). In context of monitoring forests' response to environmental conditions, MODIS NDVI renders a frequently considered data source since it reflects canopy greenness and consequently mirrors – among others – early leaf coloration and senescence as direct responses of trees to extreme drought. Yet, MODIS NDVI time-series need to pass a multi-step processing chain to mask poor-quality pixels, remove remaining outliers, gap-fill, and finally apply a pixel-specific standardization to achieve relative measures of canopy greenness. The recently launched European Forest Condition (EFCM, Buras et al 2021) provides correspondingly processed data, which can be used to monitor forest canopy condition in Europe through space and time.Here, we present first insights on the impact of the 2022 drought on European forest ecosystems based on the EFCM. Preliminary results indicate the drought 2022 to supersede previous droughts with regards to the spatial extent of severely affected pixels, thus breaking the former record from the 2018 drought (Buras et al 2020) just four years later. Our analyses suggest that legacy effects from previous years have contributed to this development. Moreover, we found different drought sensitivities of different forest types. In combination, these factors draw a complex picture of forests climate-change resilience, which we here seek to disentangle. Corresponding knowledge will likely provide valuable empirical information to improve model-based projections of tree-species performance under anticipated climate change.Buras A, Rammig A and Zang C S 2020 Quantifying impacts of the 2018 drought on European ecosystems in comparison to 2003 Biogeosciences 17 1655–72Buras A, Rammig A and Zang C S 2021 The European Forest Condition Monitor: Using Remotely Sensed Forest Greenness to Identify Hot Spots of Forest Decline Frontiers in Plant Science 12 2355
The Italian Automated Lidar Ceilometer Network ALICENET: retrievals and applications in support to urban air quality monitoring
Authors: Bellini Annachiara , Diémoz Henri , Di Liberto Luca , Gobbi Gian Paolo , Barnaba Francesca
Published: February 2023

ALICENET is the Italian network of Automated Lidar-Ceilometers (ALCs) coordinated by CNR-ISAC, operationally running (24/7) several systems across the country, including main urban areas. Particulate matter and atmospheric dynamics monitoring through profiling remote sensing techniques is explored within the H2020 RI-URBANS project (WP1) and, in this framework, ALC-based products will be made available to the scientific and stakeholder communities. These include, among others, aerosol extinction and mass concentration profiles, directly usable by the research community as well as by environmental, meteorological, health and aviation safety agencies.In this work, the ALICENET data processing is applied and showcased for three RI-URBANS pilot sites: Milan, Rome (Italy) and Paris (France). These are characterized by different aerosol and atmospheric conditions: Milan is strongly influenced by high anthropic emissions and transport dynamics within the Po Basin, Rome is an example of urban conditions in the Mediterranean area, and Paris is representative of aerosol conditions affected by both local and continental sources. The ALC-retrieved aerosol quantities are compared with both advanced in-situ/remote sensing observations and modeled fields  to identify potential upscaling issues of the data inversion procedure.The work will focus  on the added value of the aerosol profile products for air quality monitoring in urban sites.
Investigation of numerical continuation methods for marine ice-sheet systems formulated as contact problems
Authors: Gregov Thomas , Pattyn Frank , Arnst Maarten
Published: February 2023

Marine ice sheets are complex systems whose response to external forcing is the subject of much attention in the scientific community. In particular, the West Antarctic ice sheet, which could have a significant impact on future sea-level rise, is a major concern. One method of studying the response of marine ice sheets consists in investigating the relationship between the parameters and the equilibrium states of such systems. However, this is typically done by varying these parameters and letting the ice sheets evolve to new steady states, i.e., through transient simulations, which are computationally expensive.An alternative is to consider continuation methods, where the equilibrium state of a system is studied directly as a function of the parameters. Such an approach has already been used in glaciology to study the mechanical behaviour of 1D marine ice sheets (Mulder et al., 2018), highlighting the hysteresis phenomena that had previously been obtained theoretically (Schoof, 2007). However, this study, because it only considers 1D geometries, does not allow to take into account the effect of lateral drag and of complex bedrock geometries, which are two factors that have the potential to stabilize the grounding line (Gudmundsson, 2013, Sergienko and Wingham, 2021).Here we consider the continuation problem in the context of 2D marine ice sheets. This introduces several mathematical difficulties, notably related to the treatment of the distinction between grounded and floating parts. Mathematically, the problem takes the form of a contact problem between the bedrock and the lower part of the ice sheet. This leads to a system of equations that is not differentiable, which is challenging to solve numerically. We address these challenges in the context of the continuation problem, and propose several solutions, including a norm-based approach that is inspired from earlier studies (Mittelmann, 1987). Finally, we present some preliminary results which show that our numerical method is promising.
GCM-based future projections of European weather types obtained by Self‑Organizing-Maps and a novel GCM selection technique
Authors: Wehrmann Sibille , Mölg Thomas
Published: February 2023

The interdisciplinary research project "BayTreeNet" examines the reactions of forest ecosystems to climate dynamics. To establish a relationship between tree growth and climate, it is important to know that in the mid-latitudes, local climate phenomena often show a strong dependence on the large-scale climate weather types (WT), which significantly determine the climate of a region through frequency and intensity. Different WT show various weather conditions at different locations, especially in the topographically diverse region of Bavaria. The meaning of every WT is the physical basis for the climate-growth relationships established in the dendroecology sub-project to investigate the response of forests to individual WT at different forest sites. Complementary steps allow interpretation of results for the past (20th century) and projection into the future (21st century). One hypothesis is that forest sites in Bavaria are affected by a significant influence of climate change in the 21st century and the associated change in WT.The automated classification of large-scale weather patterns is presented by Self-Organizing-Maps (SOM) developed by Kohonen, which enables visualization and reduction of high-dimensional data. The poster presents the SOM-setting which was used to classify the WT and the results of past environmental conditions (1990-2019) for different WT in Europe based on ERA5 data. Morover, it shows a future projection until 2100 for European WT and their respective environmental conditions. The projections are based on a novel GCM selection technique for two scenarios (ssp1-2.6 and ssp5-8.5) to obtain a range of the most likely conditions.
The Oligocene and Miocene sands in the deep Levant Basin: Provenance and sediment routing
Authors: Glazer Adar , Avigad Dov , Morag Navot , Gerdes Axel
Published: February 2023

The Levant Basin in the Eastern Mediterranean contains a ~3 km-thick, predominantly siliciclastic section of Oligocene-Miocene age, which hosts large hydrocarbon reservoirs (“Tamar Sands Play”). A fundamental question raised with respect to this siliciclastic section concerns its origin and the sedimentary pathways into the deep basin. Here we present an advanced provenance study, including detrital zircon U-Pb-Hf and heavy mineral assemblage investigations, of Oligocene-Miocene siliciclastic sediments retrieved from four boreholes across the Levant Basin. Our investigations reveal a preponderance of Neoproterozoic and older Precambrian zircons with mostly negative εHf values. This U-Pb-Hf pattern indicates that the studied sediments were mainly reworked from Paleozoic-Mesozoic sandstones of Afro-Arabia with variable derivation from the juvenile basement of the Arabian-Nubian Shield. Comparison of the detrital signal in various stratigraphic levels of the Levant Basin shows that Early Oligocene and Early Miocene sand intervals are typified by a large proportion of pre-900 Ma zircons (ca. 50%), by a relatively small proportion of Neoproterozoic zircons with positive εHf values (ca. 25%), and by abundant detrital apatite peloids in the heavy mineral fraction. Resembling Miocene clastic sequences preserved in Israel, these characteristics are taken by us to indicate a dominant provenance in the Arabian side of the Red Sea Rift. On the other hand, Late Oligocene-lowest Early Miocene and Middle-Late Miocene intervals are typified by a mild proportion of pre-900 Ma zircon (ca. 35%) and by a larger proportion of Neoproterozoic zircons with positive εHf values (ca. 35%), they also contain scarce Mesozoic-Cenozoic zircons. These similarities to the Nile Delta sediments are taken by us to indicate a dominant provenance in NE Africa. Overall, our findings suggest that the Levant Basin was fed by varying proportions of sediments derived both from Arabia via the Levant continental margin and from NE Africa via the Nile Delta. While Early Oligocene and Early Miocene sediments, including the main section of the “Tamar Sands”, were chiefly derived from Arabian sources, Late Oligocene-lowest Early Miocene and Middle-Late Miocene sediments mainly sourced from NE Africa. The mere absence of Paleozoic and Mesozoic-aged detrital zircons, abundant in the Eurasian side of the Eastern Mediterranean, suggests that sand sourcing in the overriding plate of the Arabian-Eurasian collision belt did not reach the Levant Basin.
Scale-dependent differences of areal reduction factors: from minutes to hours
Authors: Alpers Jannick , Müller-Thomy Hannes , Nistahl Patrick , Schröter Kai
Published: February 2023

Design rainfall is required for numerous applications in hydrology. If based on rain gauge time series, an adoption in space without further processing leads to an overestimation of spatial rainfall extreme values. Areal reduction factors (ARF) reduce point extreme values in space to achieve more realistic areal rainfall extreme values. The necessity of reduction increases with higher temporal resolution. However, the low density of most rain gauge networks hinders the estimation of representative ARF. In this study ARF are derived from 5 min rainfall time series of the high-density WegenerNet in Austria with 143 rain gauges distributed over 300 km² (~ 0.5 gauges per km²).ARF dependency on area (up to 81 km²), rainfall duration (5 min to 6 hours), return period (1 year to 10 years), seasonality (four seasons) and altitude (260 m to 400 m) are studied. The results provide new insights into the research field, especially for the short durations. In addition to providing explicit ARF values, the main conclusions are:ARF decrease with increasing areal extent considered for all durations.
ARF decrease with increasing temporal resolution for all return periods.
While ARF for hourly values (and coarser) decrease with increasing return period, the opposite is found for shorter durations.
ARF vary strongly between seasons, with lowest values found for spring.
Altitude-dependency of ARF increases with areal extent considered, whereby ARF values increase with altitude.
The resulting ARF data set is unique with its applicability for high-resolution extreme values as needed for urban hydrology. The results are assumed to be transferable to other regions with similar hydro-climatologic characteristics.
Characteristics of ionospheric wavenumber structures in COSMIC-2 RO observations
Authors: Joshi Lalit Mohan
Published: February 2023

High-rate radio occultation (RO) in COSMIC2 (FORMOSAT7) enables us to investigate the continuous variability of the ionosphere at a Spatio-temporal resolution which was unthinkable a few decades ago. We present unique characteristics of ionospheric wavenumber structures observed using COSMIC2 RO data, not reported before. Altitude-longitude maps of normalized electron density of local time ionosphere in the Equatorial Ionization Anomaly (EIA) region, indicate wavenumber structures with vertically tilted phase fronts. The longitudinal extent of a tilted wavenumber 4 (WN4) phase front approximates its zonal wavelength in the local-time ionosphere, i.e., ~900 in longitudes. WN4 filtered component indicates a more significant tilt (when visible), with a larger longitudinal extent of a wavenumber structure in the vertical plane. High latitudinal resolution investigation of wavenumber structure presents a significant difference in the characteristics of wavenumber structures at different geomagnetic latitudes within the EIA region. During the daytime WN4 structure in the EIA crest region is out of phase with respect to that in the EIA trough region. However, the two were observed to be in phase with each other during the nighttime. These characteristics also vary with altitude. Above 400 km WN4 structure in the EIA crest and trough region is seen to be in phase with each other at all local times. CREST. These results highlight that, while the direct role of non-migrating tides, which provides the vertical tilt to the wavenumber structure, maybe the dominant mechanism, however, electrodynamical transport of plasma in the EIA region driven by eastward zonal electric field during the daytime also plays a significant role in the formation of wavenumber structure. During the nighttime, in the absence of the fountain effect, wavenumber structures are driven by the direct forcing of non-migrating tides within the EIA region. The results will be presented and discussed in light of existing knowledge of the formation of wavenumber structures and the impact of non-migrating tides on the local-time ionosphere.
GIS-based analysis for regional exploration in the geothermal province of intraplate volcanism in the Center of Mexico
Authors: Macedo Serrano Ernesto , Prol Ledesma Rosa María
Published: February 2023

The regional evaluation of the intraplate volcanism province is attempted using the Play Fairway Analysis. This province is characterized by recent alkaline volcanism that is not related with the previous Farallon Plate subduction of the present Cocos Plate subduction. This volcanism is constrained to the main structures related with the Basin and Range processes of extensional tectonism.A geographic information system is constructed by including geological and geophysical data. Thematic maps are developed with the information that is considered relevant for the location of areas with favorable conditions to host geothermal systems, with or without surface manifestations, i.e. including the blind geothermal systems. This work includes information of the occurrence of recent volcanism (age less than 2 Ma), geological structures, seismic activity, shallow Curie Point Depth, surface heat flow, crustal thickness, hydrothermal manifestations (hydrothermal alteration, thermal fluids discharge, etc.). Data integration is performed using a “Knowledge driven” model with three different geothermal play models producing play fairway evaluations. The presence of several areas with high favorability was identified to lead future detailed exploration in the field.
Meso- to Submesoscale Turbulence in the Ocean
Authors: Leimann Ilmar , Griesel Alexa , Walter Maren , Dräger-Dietel Julia , Epke Moritz
Published: February 2023

The energy cycle in ocean models is still biased due to the large uncertainty regarding how processes in the mesoscale and submesoscale regimes are represented. Since mesoscale turbulence is largely geostrophic, it features an energy transfer towards larger scales. In contrast, submesoscale turbulence can contain both geostrophic and ageostrophic dynamics which makes the direction of the energy flux less clear. Measuring the kinetic energy spectrum in the ocean is challenging, since gridded satellite data are unable to resolve the subdeformation scales, and shipboard measurements are limited to a few regions. Lagrangian floats are globally available, can connect a range of scales from 10 m to 1000 km and hence are a unique source of information on meso- to submesoscale turbulence.We estimate the kinetic energy spectral flux from SSH data which gives only the geostrophic part, compared to spectral fluxes from a submesoscale permitting ocean model with a focus on the North Atlantic.The kinetic energy spectral fluxes are found to exhibit both inverse and forward cascade, with a higher inverse cascade in turbulent areas and maximum inverse wavenumber increasing with latitude.In addition, we calculate velocity structure functions from the surface drifter data to bridge different scales, with the goal to compare and contrast the spectral estimates of different data sets. Velocity structure functions are the moments of velocity increments between two points and provide information about the properties of turbulent dynamics at different scales.
Exploring Domain Size for WRF High-Resolution Urban Rainfall Simulation
Authors: Du Sichan , Zhuo Lu , Kendon Elizabeth J. , Han Dawei
Published: February 2023

Abstract: With climate change, rainfall is expected to get more intense, leading to cities being increasingly at risk of urban flooding. Understanding local climate change over cities has therefore become a priority for the scientific community and city planners on building resilient cities and mitigating hydrometeorological disasters. Very high resolution (km-scale, ‘convection-permitting’) climate models are required to adequately represent cities and local rainfall extremes. Here we assess the Weather Research and Forecasting (WRF) model for simulating urban rainfall. Despite the wide application of WRF in rainfall simulations (including urban areas), there are limited investigations on the impact of the domain size and how to search for a suitable domain size over a particular city region.To fill this knowledge gap, Newcastle upon Tyne is selected as the study area to simulate a summer heavy rainfall event with ERA5 (a fifth-generation dataset of global reanalysis developed by the European Centre for Medium-Range Weather Forecasts) as the input data and a radar product from the UK Met Office for validation. Accordingly, different domain sizes with the convection-permitting resolutions from 1 km to 4.5 km (increment: 0.5 km) are explored, and the hourly model outputs are compared with the radar observation data.This study has proposed and tested a method to decide the most suitable domain size. By using eight assessment indexes (including pattern, cumulative time series, hourly time series, particular values (max/min/mean) as well as the seven statistical indicators of each data and overall data), there are two preliminary conclusions: 1) 200 km × 200 km is the best domain size for the single domain simulation; 2) For 200 km × 200 km or smaller domain sizes, higher resolution produces better results, but for 250 km × 250 km or large domain sizes, resolution sensitivity is opposite. Regarding next steps, the above procedure will be further investigated by applying it to more extreme rainfall case studies and to other cities in order to assess whether results here are generally applicable, and therefore the optimal domain configuration can be usefully applied to produce reliable urban rainfall simulations.
Ecosystem temperature management under water scarcity
Authors: Yakir Dan , Muller Jonathan , Rotenberg Eyal
Published: February 2023

Efficient heat dissipation under high radiation load is critical to plant functioning. It includes processes that are clearly observed in dry ecosystems but likely extend to other environments where it will be further enhanced by climate change. We observed that despite near-zero evaporation during the seasonal drought in a semi-arid pine forest, leaf temperatures were within the physiological range at about 35C. At the same time, exposed soil at the same site reached temperatures up to 70C. These leaf temperatures were also similar to that in an irrigated plot where evapotranspiration (ET) was enhanced by x10. A detailed energy budget demonstrates that heat dissipation under drought relies on a large sensible heat flux (H) that must depend, in turn, on reducing aerodynamic resistance to heat transfer. At the canopy scale, a “convector effect” of the high-roughness dry canopies generates a massive H that increases the depth of the planetary boundary layer and induces secondary circulations. Model simulation at larger scales indicated that such a process could modify local and regional climatic conditions. Assessing the global FLUXNET data from different environments further indicates that relying on H as a major heat dissipation process is not limited to dry ecosystems and is not dictated solely by the radiation load.  
Detection, characterization and trends of Marine Heat waves in the global worming scenario: the CAREHeat Project
Authors: Santoleri Rosalia ,   CAREheat team
Published: February 2023

Marine Heat Waves (MHWs), persistent and anomalously sea water temperature warm events, are known to have significant impacts on marine ecosystems as well as on air-sea exchanges. As global ocean temperatures continue to rise, MHWs have become more widespread, threatening marine ecosystems and their services for food-provision, livelihoods and recreation. Detecting and predicting the occurrence, intensity and duration of these extreme events, and understanding their impacts on marine ecosystems is a key step towards developing science-based solutions for sustainable development.The project “deteCtion and threAts of maRinE Heat waves – CAREHeat”, funded by ESA in the framework of the Ocean Health initiative, aims at improving the current MHW detection and characterization methodology, as well as advancing the understanding of the physical processes involved, and the corresponding ecological and biogeochemical changes.This is being to be achieved following a multidisciplinary approach capitalizing on the large potential offered by satellite Earth observations, complemented with in situ field measurements, physical and biogeochemical ocean reanalyses, biogeochemical modelling and emerging machine learning technologies. In this presentation an overview of the CAREHeat Project activities and its preliminary results will be provided. In particular the assessment of the major gaps in scientific knowledge, existing products and tools in MHW detection will be discussed. A first version of the CAREHeat MHW Global Atlas covering the entire satellite era (1981-today) will be presented and analysed to investigate the year-to year MWH variability in spatial extension, intensity, duration and rate of evolution.Specific work has also been done to investigate the impact of sea temperature trends and prominent climate modes, as El Nino Southern Oscillation (ENSO), in order to disentangle the slow-varying SST component and quasi-periodic oscillations from the abrupt changes that are characteristics of these extreme events.A first preliminary analysis of the impact of MWHs on marine ecosystem will be presented.  Up to date about the project research and results can be found visiting the  CAREHeat website (www.careheat.org) or on Twitter (@ careheat_)
Evaluation of satellite products for drought characterization and impact assessment on water resources in the Tensift Basin (Morocco)
Authors: Naim Mohamed , Bonaccorso Brunella
Published: February 2023

Effective drought characterization and monitoring are urgent challenges especially in arid and semi-arid regions. The Tensift basin is in the center-west of Morocco and is exposed to recurrent droughts. The effects of climate change, which has already led to several economic, agricultural, hydrological and social losses over the past decades, exacerbate the situation. The objective of this study is to characterize the drought in the Tensift basin and to assess its impact on water resources by using the potential of satellite products. For this purpose, satellite products and reanalysis data were selected for the evaluation of observed data in the study area. These datasets were used due to the availability of long-term data, near real-time data series, relatively high spatial and temporal resolutions and open access data. In particular, precipitation and temperature retrieved by ERA5-Land (https://cds.climate.copernicus.eu) and CHIRPS (https://www.chc.ucsb.edu/data) datasets, as well as the corresponding data observed by in-situ stations, were used and statistically analyzed and evaluated by common metrics (R, R², BIAS, RMSE, and the Nash and Sutcliffe Efficiency) to compare their performance and accuracy. The obtained results showed that most meteorological stations agree with satellite and reanalysis products, with some slight errors. Based on these results, several drought indices during the period 1982-2021 have been calculated at several spatio-temporal scales to determine the impacts of drought on water supply. The results show that the Tensift Basin suffered from multiple droughts over the past 40 years. The years 2000 and 2015, 2017, 2019, 2020, 2021 were common drought periods by either the Standardized Precipitation Index (SPI) and the Standardized Precipitation and Evapotranspiration Index (SPEI); however, the Vegetation Condition Index (VCI), which was provided by NOAA-AVHRR data (https://www.star.nesdis.noaa.gov), indicate more dry years than the other indices. The drought indices provide a powerful tool to monitor drought and its impacts on water resources. These tools could potentially allow decision makers to better manage water resources as to minimize drought impacts. Furthermore, the considered drought indices could be used separately or in combination within a drought early-warning system in the study area for drought monitoring and forecasting.Keywords: Drought, Water supply, Satellite products, Tensift basin, Remote sensing, Reanalysis data