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As a cognitively-mediated response, autonomous adaptation at farm-gate levels constitutes reactionary actions by farmers against climate impacts. These actions are shaped by interacting factors such as household characteristics, livelihood scope and resources. It is driven by the goal of adapting cultivated farmlands to climate and for sustaining crop yields. Thus, interest in balancing adaptation goals with protection of vegetation conditions is less of a priority. Lack of research interest in understanding the gap between objectives of reactionary adaptation and protection of surface conditions (vegetation canopies) is a gap in research. In many studies, farm-gate level adaptation is described as a set of zero-feedback actions in response to climate impacts. This perception conceals the stress and impact-engendering attribute of reactionary adaptation. Inspired towards addressing this conceptual gap; this study investigates impact of farmers’ reactionary adaptation on vegetation cover in Keffi, Nasarawa, Nigeria. A twenty-year time-series NDVI and rainfall datasets are linearly regressed to examine the extent of NDVI-rainfall sensitivity. A weak linear relationship between NDVI and rainfall in Keffi for the period, 1999-2018 is observed. At a regression slope of 0.001, R squared, R2=0.129 (implying that only about 13% of the variability in NDVI in Keffi are explained by rainfall amount) and a bivariate regression coefficient, r=0.359; statistical evidence shows that rainfall amount are not significant predictors of NDVI in Keffi. In investigating the possible interference of non-rainfall factors on vegetation productivity (NDVI) in Keffi; a residual trend (RESTREND) analysis was carried out. Regression of residuals from NDVI-Rainfall linear regression produced a R=0.192 with a negative and downwards slope. The downward character of the RESTREND slope is suggestive of non-rainfall factors contained in the residuals. In validating the RESTREND analysis, a comparative analysis between observed and predicted NDVI derived from a reference NDVI value of 0.46 was carried out. The NDVI value of 0.46, is empirically assumed to be average NDVI value expected at a minimum rainfall amount of 850mm/year reported in tropical Savanna ecosystems. Using this empirical relationship, NDVI values were predicted for Keffi. Even at higher rainfall amounts≈1340mm/year, amounts were unable to produce corresponding higher NDVI values; rather a more plausible correlation between reference-derived predicted NDVI values and rainfall was obtained. A further analysis with predicted NDVI values, based on 1999 NDVI value in Keffi returned higher NDVI units than observed NDVI values. This strengthens the attribution of the possible interference of rainfall-NDVI sensitivity by non-rainfall factors like human activities on vegetation productivity. Surface soil analysis to exclude potential impacts of soil nutrients and moisture deficiency on vegetation productivity, showed that soil had insignificant effect on vegetation dynamics. Further inferential analysis, using the inter-annual NDVI and the reclassified bi-decadal NDVI maps showed that spatial vegetation distribution in Keffi were driven by farmers inter-annual rotational cultivation footprints than rainfall variability. With a three-class categorization, “gain, loss and significant loss”, the spatial distribution of vegetation in Keffi between (1999-2008) and (2009-2018) was assessed. Temporal condition (stressed and healthy) across the three classes supports the attribution of farmers’ reactionary adaptation and cultivation practices on the dynamic spatial vegetation distribution. Between 1999 -2018, an increase in areas with significant vegetation loss (42%), so with a decrease of -25% in areas with healthy vegetation was observed. The character of vegetation cover across the two decadal time slices, reflects landuse intensity and unsustainable farming practices. Preferences for modification of cultivation practices and changes in seed by farmers exerts positive feedbacks on vegetation cover. Higher statistical measures, 38.4% (yearly cropping) and 44% (shifting cultivation with less fallow periods) were observed in the chi-square analysis. These measures were higher than 2.0% relating to shifting cultivation with more fallow periods. While 11.6% farmers noted cultural practices as reasons for preferred cultivation methods, 48.4% farmers attributed climate as reason behind cultivation modification. This was higher than 24.4% who linked issues of tenure rights to cultivation practices. With preferences for yield- breaching strategies, the non-receding cultivation and shorter fallow practices in Keffi triggers feedback on vegetation dynamics. Evidence from this study shows that the NDVI-rainfall functional sensitivity in Keffi is plausibly dampened by effects of reactionary farm-gate level adaptation practices.
During the last decades mammalian intracranial structures like the ethmoidal region have rarely been a focus of morphological studies, as they required invasive techniques. Contrary, the ontogeny of the fetal nasal capsule could easily be investigated based on histological material. Since the early 21st century modern imaging techniques like high-resolution computed tomography (μCT) reveal non-destructive insights into the mammalian skull. Furthermore, visualization software enables the virtual reconstruction of the tissues and additionally their morphometric analyses. However, the use of morphometric approaches on the nasal cavity is still scarce. Moreover, the turbinal skeleton is generally regarded as a unit, or the rostral respiratory part is compared to the caudal olfactory part; but the distinct olfactory turbinals have been considered only in a few studies.
The present study focuses on the highly diverse facial shape of the dog (Canis lupus familiaris) that evolved during domestication. Due to human-controlled breeding and care the natural selective pressure in prehistoric dogs has been replaced continually by artificial selection. As a consequence, harmful mutations on gene loci which e.g., control facial length growth got fixed within an extremely short time. According to veterinarian studies the turbinals of short snouted breeds continue their growth after the elongation of the facial bones has stopped prematurely. However, such investigations are based on low-resolution CT or MRT data and the morphological descriptions are vague. Referring to the elongation of the face in dolichocephalic breeds no former study has dealt with the detailed morphology of their turbinal skeleton so far.
The current study is based on comparative anatomical, morphometric, morphofunctional, and ontogenetic patterns of the dog’s turbinal skeleton. The 32 macerated skulls and four histological serial sections represent eleven breeds which cover different snout lengths (brachycephalic, mesaticephalic, dolichocephalic; according to two length indices), functional groups (scent hound, sighthound, companion/toy), and breeding histories (ancient pure-breeding associated with an unchanged appearance, modern time fashion breeding). The nasal cavity of the selected skulls was μCT-scanned and virtual 3D models of the turbinal skeleton were reconstructed. The breeds have been compared with each other in their number of olfactory turbinals, in the morphology of all turbinals and the lamina semicircularis as well as in their morphometrics and ontogeny. Based on morphological and ontogenetic patterns a new terminology of the interturbinals was established. The morphometric data covers the measurement of the relative turbinal surface area (IAT) and the calculation of the surface density (SDEN) and the turbinal complexity (TC). For the latter parameter a new morphometric approach was developed. For the ontogenetic comparison histological serial sections of perinatal dog stages have been consulted. As the dog’s ancestor macerated skulls of three adult Eurasian wolves (Canis lupus lupus) function for outgroup comparison and represent the grundplan with which the breeds are compared.
The results support former studies concerning a species-specific number of the fronto- and ethmoturbinals: in the Eurasian wolf and all postnatal dogs under study three ethmoturbinals and three frontoturbinals are observed. Additionally, two types of interturbinals are distinguished, namely four prominent interturbinals which are present in nearly all individuals and show a homologous pattern, and a variable number of additional interturbinals which differ in their shape among the dogs. Generally, longer snouted breeds have more additional interturbinals, so the total number of olfactory turbinals is increased to a maximum of 16 in the borzoi, whereas several short snouted breeds have only nine olfactory turbinals due to the loss of additional interturbinals and one prominent interturbinal. Regarding ontogeny the growth of the respiratory and the olfactory turbinals and the lamina semicircularis is highly associated with the growth of the facial bones after birth. As the viscerocranium of brachycephalic breeds is subjected to a postnatal growth inhibition the ethmoidal region stops growing prematurely, too. The turbinals of both functional parts develop less accessory lamellae that results in the reduction of the three morphometric parameters IAT, SDEN, and TC. The increase of all these three parameters with increasing snout length proves a correlation between both variables in the maxilloturbinal, all olfactory turbinals, and the lamina semicircularis in the dog. With the help of the perinatal dog stages plesiomorphic patterns which are present in all adult specimens (e.g., separation of ethmoturbinal I into two laminae, the presence of the uncinate process) were distinguished from less established morphological traits which get preferably reduced in association with brachycephaly (e.g., the anterior process of the posterior lamina of ethmoturbinal I, the caudal processes of frontoturbinal 1 and 2 within the frontal sinus due to the latter’s reduction). Obviously, the driving mechanism behind these and further variations are mutations on gene loci which control ontogenetic processes: the in other studies already described postnatal growth inhibition in the dermal bones of the midface of brachycephalic breeds seems to have a similar effect on the ethmoidal region. The results of the present study serve as basis for the evaluation how far the bony turbinals’ morphology, morphometrics, and ontogeny might be associated with physiological, genetic, neurological, and phylogenetic patterns. Additionally, the growth patterns of the hard tissues need to be compared to those of the soft tissues (i.e. the nasal epithelium).
In dieser Dissertation wird die Parametrisierung von subgitterskaligen (SGS) Prozessen in Atmosphärenmodellen untersucht. Die Arbeit befasst sich mit den stochastisch angetriebenen Flachwassergleichungen, im ersten Teil in einer räumlichen Dimension und im zweiten Teil in zwei Dimensionen. Die Einteilung in aufgelöste und SGS-Variable erfolgt in beiden Fällen über lokale räumliche Mittel der Ursprungsvariable und deren Abweichungen vom lokalen Mittel.
Im eindimensionalen Fall liegt zwischen den Variablen eine deutliche Separation der charakteristischen Zeitskalen vor, wodurch die Anwendung der stochastischen Moden Reduktion (SMR) ermöglicht wird. Die SMR generiert ein reduziertes Modell der aufgelösten Variable mit einer stochastischen SGS-Parametrisierung, im Folgenden auch Schließung genannt. Die SMR-Schließung basiert auf den Grundgleichungen des Flachwassermodells und ist numerisch effizient einsetzbar, da sie nur eine geringe Anzahl von benachbarten Zellen koppelt. Sie verbessert die Ergebnisse des reduzierten Modells und übertrifft die Ergebnisse zweier zum Vergleich untersuchter empirischer stochastischer Schließungen. Den größten Zugewinn liefert sie im Energiespektrum, insbesondere für kleine Skalen. Das Ergebnis der SMR-Schließung kann verbessert werden, indem die Amplitude der stochastischen Schließungskomponente gedämpft wird. Die SMR-Schließung ist skalenabhängig im Sinne der räumlichen Modellauflösung. Untersucht wird die Schließung bei Halbierung und Viertelung der räumlichen Auflösung, wo sie ihre Überlegenheit gegenüber den empirischen Schließungen wiederholt bestätigt.
Im Unterschied zum eindimensionalen Fall ist in zwei Dimensionen auch die Corioliskraft enthalten und eine räumliche Divergenz der Schwerewellen möglich. Zwischen der aufgelösten und der SGS-Variable kommt es erneut zu einer Separation der charakteristischen Zeitskalen. Die Separation ist allerdings weniger stark ausgeprägt als im eindimensionalen Fall. Grund hierfür ist das Auftreten einer lang korrelierten geostrophisch balancierten Mode, welche auch auf die SGS-Variable projiziert. Das Vorgehen zur Bestimmung der SMR-Schließung für das zweidimensionale Modell verläuft analog zum eindimensionalen Fall. Es werden die Ergebnisse des hoch aufgelösten Referenzmodells und zweier Modelle ohne SGS-Schließung verglichen.
State-of-the-art climate models contain, to a significant degree, empirical components. In particular, subgrid-scale (SGS) parameterizations are usually highly tuned against observations or high-resolution model data. While this enables the models to minimize the error during hindcasts, it is not guaranteed that it yields a benefit for climate projections because of climate change. In this thesis the Fluctuation-Dissipation theorem (FDT) is used to update the statistics of the system in the presence of an external forcing. If the empirical parameters are tuned objectively to the data (i.e., they depend on the statistics of the data), then they might be updated with the FDT. This ansatz is tested within a framework of a semi-empirical model (SEM) based on the leading variance patterns of a quasigeostrophic three-layer model (QG3LM) and supplemented by a purely data-driven parameterization. We show that the FDT is able to successfully update the tuning parameters of the data-driven SGS closure, resulting in a systematic improvement in model performance in comparison to an untreated SEM. Ideally, SGS parameterizations should contain little to no tuning parameters. Thus, complementary to the FDT approach we investigate a stochastic SGS closure constrained by first principles that is calculated using the stochastic mode reduction (SMR). The SMR allows for an analytic derivation of the SGS closure from the model equations while requiring only minimal tuning. We successfully apply the SMR to the QG3LM and construct the reduced stochastic model (RSM). Furthermore, we show that the RSM is more robust against an external forcing than the SEM. Additionally, we find that, under appropriate conditions, the FDT is able to update the empirical parts of the RSM. Yet, only for the response in mean streamfunction the RSM provides useful results, while the response in covariance of the streamfunction is incorrect for most cases. Nevertheless, we obtain a remarkably accurate response in both moments for the RSM in an idealized setting. In combination with the results of the FDT study this indicates that the considered RSM is too low dimensional and encourages us to investigate the response of larger RSMs in the future.
During my PhD, I was applying the clumped isotope technique to modern brachiopods and fossil belemnites, and I conducted methodological work. Carbonate clumped isotope thermometry is a tool to reconstruct carbonate precipitation temperatures. In contrast to oxygen isotope thermometry, i.e., the δ18O-thermometer, the carbonate clumped isotope thermometer does not require an estimate for the oxygen isotope composition of the seawater, as it considers the fractionation of isotopes exclusively amongst carbonate isotopologues. The ∆47 value of a carbonate expresses the abundance of the 13C–18O bond bearing carbonate isotopologue, within the carbonate, relative to its random distribution. In thermodynamic equilibrium, the ∆47 value of a given carbonate is solely a function of the carbonate precipitation temperature. However, kinetic isotope fractionations, i.e., vital effects, driven by diffusion, pH or incomplete oxygen isotope exchange between water and dissolved inorganic carbonate species can cause the carbonate to be precipitated with isotopic compositions that are offset from those predicted for thermodynamic equilibrium.
Brachiopods serve as important geochemical archives of past climate conditions. To investigate the nature and significance of kinetic controls on brachiopod shell δ18O and ∆47 values, in collaboration with the BASE-LiNE Earth ITN, I analysed the bulk and clumped isotope compositions of eighteen modern brachiopod shells, collected from different geographic locations and water depths that cover a substantial range of growth temperatures. Growth temperatures and seawater δ18O values for each brachiopod were independently determined. Most of the analysed brachiopods exhibit combined offsets from clumped and oxygen isotope equilibrium, and there is a significant negative correlation between the offset values. The observed correlation slope between offset ∆47 and offset δ18O point to the importance of kinetic effects associated with Knudsen diffusion and incomplete hydration and hydroxylation of CO2 (aq), occurring during biomineralisation. The correlations between the growth rates of the analysed brachiopods and both the offset ∆47 and the offset δ18O values provide further arguments for the presence of kinetic effects. In conclusion, the oxygen and clumped isotope composition of modern brachiopod shells are affected by growth rate-induced kinetic effects that hinder their use for palaeoceanography.
In der vorliegenden Arbeit wurde ein neuer optischer Aufbau für das Laserlabor der Abteilung Kristallographie im FB 11 an der Goethe-Universität Frankfurt beschrieben. Mit Hilfe dieses Aufbaus konnten verschiedene spektroskopische Methoden genutzt werden, um die - von Druck und Temperatur abhängige - Phasenstabilität von Calcium- und Eisencarbonaten zu untersuchen. Mit Hilfe von Raman-Spektroskopie konnte das Phasendiagramm von Calciumcarbonat (CaCO3) teilweise neu bestimmt werden. Fluoreszenzuntersuchungen an dotierten CaCO3 Proben ergaben, dass sich Europium-dotierter Calcit zunächst in eine amorphe Form umwandelt, bevor er bei ca. 15 GPa in eine amorphe 'aragonitische' Form umgewandelt wird. Die Umwandlung ist nicht reversibel. Laserheizexperimente bei 18.5 GPa an dotiertem Siderit (FeCO3) führten zur Bildung eines neuen Hochdruck-Hochtemperatur FeCO3 -Polymorphs. Die Strukturlösung erfolgte mit Hilfe von Röntgendaten, die am Deutschen Elektronen-Synchrotron (DESY) in Hamburg gewonnen wurden. Schließlich wurde eine neue Methode zur Bestimmung von Temperaturen in Laserheizexperimenten beschrieben. Sie beruht auf der Abschwächung eines Fluoreszenzsignals durch die Temperatur, welche durch die Wechselwirkung eines Heizlasers mit der Probe erzeugt wird.
Das Wissen über die Wolkenmikrophysik und die Wechselwirkung zwischen Niederschlag und Aerosol ist ein wichtiger Baustein zur Optimierung von Klima- und Wettermodellen. Ein Großteil des Niederschlags in den mittleren Breiten fällt aus Mischphasenwolken, die aus unterkühlten Tröpfchen und Eispartikeln bestehen. Die Eispartikel bilden sich an speziellen Aerosolpartikeln, die als Eiskeime (INP) wirken können. Die Wahrscheinlichkeit eines Aerosols als Eiskeim zu wirken, nimmt mit abnehmender Temperatur und steigender Wassersättigung zu. Mineralstaubpartikel sind die häufigsten Eiskeime, die ab Temperaturen ≤−15°C aktiv sind, biologische Partikel wirken schon bei wärmeren Bedingungen. Große Wissenslücken bestehen noch bei der globalen Konzentration von Eiskeimen, inklusive deren geographischer und jahreszeitlicher Variabilität.
Im Zentrum der Experimente, die für diese Arbeit durchgeführt wurden, steht der Eiskeimzähler FRIDGE (Frankfurt Ice Deposition Freezing Experiment). Je nach Aufbau und Anwendung des Instruments werden zwei verschiedene Ansätze zur Aktivierung von Eiskeimen verfolgt. Die ursprüngliche und namensgebende Methode in Form einer Vakuum-Diffusionskammer wurde zur Untersuchung von Eisnukleation via Depositionsgefrieren (an INP_D) entwickelt (Klein et al., 2010). Danielczok (2015) nutzte einige Bestandteile des Analysegeräts, um auch Immersionsgefrieren (an INP_I) in Form von Tröpfchengefrieren à la Vali (1971) zu studieren. In der vorliegenden Arbeit wurde diese Anwendungsmöglichkeit von FRIDGE weiterentwickelt. Ein zentraler Schritt war dabei die präzise Charakterisierung des Gefrierverhaltens von Tröpfchen aus Reinstwasser ohne zusätzliches Aerosol. Die Einbeziehung dieses sogenannten Hintergrundgefrierens, das für jedes Instrument und Messverfahren spezifisch ist, ermöglichte es, die Minimaltemperatur, für die zuverlässige Ergebnisse produziert werden können, von −22°C auf −29°C herabzusetzen. Der dadurch hinzugewonnene Temperaturbereich ist für Eisnukleation in Mischphasenwolken äußerst relevant.
Beide Anwendungsmethoden wurden im Rahmen des Fifth International Workshop on Ice Nucleation – Phase 2 (FIN-02) sowie bei einer weiteren Kampagne zur Messung von Eisnukleation an Cellulosepartikeln mit über zwanzig anderen Eiskeimzählern verglichen. Mit FRIDGE als Diffusionskammer wurde für die Mehrheit der untersuchten Aerosoltypen eine zufriedenstellende Übereinstimmung mit den anderen Instrumenten beobachtet. Die Experimente mit gefrierenden Tröpfchen in FRIDGE erzielten ausnahmslos Ergebnisse, die inmitten der Werte der anderen Instrumente lagen. Die erfolgreiche Validierung – besonders der neuen Anwendungsmethode – war das erste Ziel dieser Arbeit und die notwendige Voraussetzung für die anschließenden Feldmessungen.
Atmosphärische Eiskeimkonzentrationen wurden in mehrwöchigen Feldmesskampagnen an drei sehr unterschiedlichen Orten und atmosphärischen Bedingungen untersucht: an der Hochalpinen Forschungsstation Jungfraujoch (JFJ), am Storm Peak Laboratory (SPL) in den Rocky Mountains und am Cyprus Atmospheric Observatory (CAO) in Zypern. Am JFJ wurde eine INP-Konzentration beobachtet, die um den Faktor 20 niedriger als an den anderen beiden Stationen war. Der Grund dafür war, dass sich das Jungfraujoch die meiste Zeit der Messungen in der freien Troposphäre befand. Dementsprechend waren die Bedingungen an der Station von aerosolpartikelarmer Luft mit wenigen Eiskeimen geprägt. An zwei Standorten wurde Mineralstaub als ein Parameter, der die lokale INP-Konzentration positiv beeinflusst, identifiziert. Sowohl am JFJ als auch am CAO erhöhte ferntransportierter Saharastaub die INP-Konzentration.
Die Kombination der zwei Analysemethoden, die Aerosolproben aus derselben Luft entweder in trockenem Ausgangszustand oder in Tröpfchen suspendiert untersuchen, offenbarte eine interessante Eigenschaft der INP. Es herrschte eine offensichtliche Parallelität von INP_D- und INP_I- Konzentrationen. Bei fast allen Messungen waren INP_I etwa 10-mal häufiger als INP_D. Die Aussage trifft gleichermaßen auf sehr niedrige Konzentrationen am JFJ wie auch auf hohe Konzentrationen am SPL und CAO zu. Die einzige Ausnahme bilden Cellulosepartikel. Daraus lässt sich schließen, dass INP_D und INP_I dieselben Partikel sind, die je nach Aktivierungskonditionen Eisnukleation unterschiedlich effektiv hervorrufen.
Air-sea feedbacks between the Mediterranean Sea and the atmosphere on various temporal and spatial scales play a major role in the Mediterranean regional climate system and beyond. The Mediterranean Sea is a source of moisture due to excess evaporation and, on a long-term average, is associated with a warming of the lower atmosphere in contact with the sea surface due to heat loss at the air-sea interface. The complex air-sea interactions and feedbacks in the Mediterranean basin strongly modulate the sea surface fluxes and favor several cyclogenetic activities under certain meteorological conditions. Examples of such cyclonic activities are medicanes (Mediterranean hurricanes) and Vb-cyclones. Medicanes are mesoscale, marine, and warm-core Mediterranean cyclones that exhibit some similarities to tropical cyclones, while Vb-cyclones are extra-tropical cyclones, that propagate from the Western Mediterranean Sea and travel across the Eastern European Alps into the Central European region. Extremely strong winds and heavy precipitation associated with these cyclones can lead to severe destruction and flooding. Changes in the intensity and frequency of these cyclones are also projected under changing future climate conditions, where the Mediterranean region has been identified as a hotspot in terms of rising temperatures.
The development of high-resolution regional climate models (RCMs) has progressed our understanding of the processes characterizing the Mediterranean climate. However, large uncertainties still exist regarding the estimates of air-sea fluxes, which, in turn, affect the simulation of the Mediterranean climate. Several factors can be attributed to such discrepancies, such as data quality, temporal and spatial resolution, and the misrepresentation of physical processes. To overcome some of these inconsistencies and deficiencies of the existing climate simulations, a new high-resolution atmosphere-ocean regional coupled model (AORCM) has been developed to simulate the air-sea feedback mechanisms. This coupled model incorporates the coupling of RCM COSMO-CLM (CCLM) and the regional ocean model NEMO-MED12 for the Mediterranean Sea (MED) as well as NEMO-NORDIC for the North- and Baltic Sea (NORDIC). Several experiments were performed using both the coupled and uncoupled models to investigate the impact of air-sea interactions and feedbacks on sea surface heat fluxes, wind speed, and on the formation of Mediterranean cyclones (i.e., medicanes and Vb-cyclones). These experiments were performed using different horizontal atmospheric grid resolutions to analyze the effect of resolution on sea surface heat fluxes, wind speed, and the development of medicanes.
The results of the present study indicate that a finer atmospheric grid resolution ([is as appreciated as]9 vs. [is as appreciated as]50 km) improved the wind speed simulations (particularly near coastal areas) and subsequently improved the simulations of the turbulent heat fluxes. Both parameters were better simulated in the coupled simulations than in the uncoupled simulations, but coupling introduced a warm SST bias in winter. Radiation fluxes were slightly better represented in coarse-grid simulations than in fine-grid simulations. However, the higher-resolution coupled model could reproduce the observed net outgoing total surface heat flux over the Mediterranean Sea. In addition to that sub diurnal SST variations have a strong effect on sub-daily heat fluxes and wind speed but minor effects at longer timescales. Regarding the impact of atmospheric grid resolution ([is as appreciated as]50, 25, and [is as appreciated as]9 km) and ocean coupling on medicanes, it was detected that the coupled model with a finer atmospheric grid ([is as appreciated as]9 km) was able to not only reproduce most medicane events, but also improved the track length, warm core, and wind speed compared to the uncoupled model. The coupled model with the coarse-grid ([is as appreciated as]50 and [is as appreciated as]25 km) did not show any improvement in simulating medicanes compared to the uncoupled model. The spectral nudging technique, applied on the wind components above 850 hPa in the interior domain to keep large-scale circulation close to the driving data (i.e., ERAInterim reanalysis), improved the accuracy of the times and locations of generated medicanes, but no improvement was found in the track length and intensity.
Concerning the role of the Mediterranean Sea coupling on Vb cyclones, the investigation showed that atmosphere-ocean coupling had an overall positive impact, although with a strong case-by-case variation, on the trajectories and intensity of Vb-cyclones as a result of the variation in moisture source for each event. In general, all model configurations could replicate Vbcyclones, their trajectories, and associated precipitation fields. The average structure of the precipitation field was best represented in the coupled simulations. Coupling of the North- and Baltic Seas also showed an improvement in some of the simulated Vb-cyclones.
The atmosphere-ocean coupling showed an overall positive impact on the simulation of sea surface heat fluxes and Mediterranean cyclones (medicanes and Vb-cyclones). Moreover, the representation of sea surface heat fluxes, wind speed, and medicane features was more realistic when using a finer atmospheric grid resolution (less than 10 km). The present study suggests that the combination of a finer atmospheric grid resolution together with atmosphere-ocean coupling is advantageous in simulating the Mediterranean climate system.