Recent Submissions

  • Image Printing on Stones, Wood, and More

    Ahmed, Abdalla G.M. (ACM, 2023-07-14) [Poster]
  • Development of molecular tools for metabolic engineering in the polyextremophile red microalga Cyanidioschyzon merolae

    Villegas Valencia, Melany; Abualsaud, Fatima; de Freitas, Barbara; Stark, Martha; Rader, Stephen; Seger, Mark; Lammers, Perer; Romero, Gabriel; Gonzales, Ricardo; Fuentes Grunewald, Claudio; Lauersen, Kyle J. (2023-07-02) [Poster]
    Cyanidialean unicellular red algae are polyextremophilic organisms that thrive in thermo-acidic environments (pH of 0.05 to 5.0, up to 60C), dominating acidic hot-springs worldwide. Cyanidioschyzon merolae 10D is been developed as an industrial source of phycobiliproteins due to its high content of thermotolerant and acid tolerant phycocyanin, high biomass productivity and the lack of a rigid cell wall (Yoshida et al., 2021). Moreover, this strain possesses a small genome (16.5 Mb) wherein 90% of genes lack introns, and the nuclear gene targeting has been developed based on homologous recombination (Kuroiwa et al., 2019). Although many genetic tools have been established for C. merolae, the successful transformation and standard screening of colonies can take up to a couple of months. In this study, we demonstrated the transformation of linear and circular plasmids and the stable expression of several fluorescent reporters in the chloroplast, while simultaneously optimizing the transformation workflow, reducing the appearance of positive transformants from 3 months to 6 days and performing high-throughput screening of colonies using fluorescence imaging and flow cytometry. In addition, the outdoor cultivation of C. merolae on a 1.000 L photobioreactor in the Red Sea coast in Thuwal, Saudi Arabia, resulted in the efficient production of valuable biomass (2 g/L). These methods should facilitate the metabolic manipulation of C. merolae and the accumulation of high value recombinant products.
  • Establishing the polyextremophilic red microalga Cyanidioschyzon merolae as a host for synthetic biology and scalable production of valuable biomass

    Villegas, Melany; de Freitas, Barbara; Abualsaud, Fatimah; Stark, Martha; Rader, Stephen; Romero, Gabriel; Gonzales, Ricardo; Fuentes Grunewald, Claudio; Lauersen, Kyle J. (2023-07-02) [Poster]
    The Cyanidiales are a group of unicellular red algae that thrive in thermo-acidic environments (pH 0.05-5.0, up to 60 C) and environments with elevated heavy metal concentrations. Cyanidioschyzon merolae 10D is found in acid hydrothermal systems and it can be cultivated in acidified medium (pH 0.5-3) to high biomass in both lab-scale and outdoor conditions with minimal contamination. This alga may be a powerful candidate for synthetic biology and metabolic engineering for heterologous product generation due to its simple genomic features – a small nuclear genome (16.5 Mb) with few introns (0.5%) and 55% GC content– Moreover, unlike other algae, nuclear transformation and integration of transgenes into chromosomes can occur by homologous recombination. Although molecular tools for the successful transformation of this alga have been recently developed, current methods to generate transformants require weeks to months. Here, we report an optimized transformation and selection protocol for C. merolae 10D, generating single chloramphenicol resistant colonies within 6-8 days. We present an in silico designed and de novo constructed modular plasmid toolkit, its transformation, and benchmark transgene expression by fluorescence imaging, flow cytometry, in-gel fluorescence and Western blotting. The transformation and stable expression of several fluorescent reporters in both linear DNA fragments and circular episomes, as well as the application of metabolic engineering for the production of volatile isoprene in this alga is presented for the first time in this work. Additionally, we demonstrated the use of C. merolae as a system for large-scale cultivation with continuous CO2 injection to produce ~2 g L-1 of valuable biomass in 1000 L tubular photobioreactors in the extreme environment of the mid-Red Sea coast during August 2022. This work aims to show that C. merolae is an emerging algal system for metabolic engineering and synthetic biology mediated sustainable and scalable production of engineered bio-products.
  • Unifying acoustic cavitation through the frequency

    Viciconte, Giamaria; Guida, Paolo; Truscott, T. T.; Roberts, William L. (2023-06-15) [Poster]
    The present study investigates the cavitation induced by the propagation of acoustic waves in a liquid medium. Traditionally, cavitation or vaporization of a liquid is predicted by the flow velocity and the liquid vapor pressure. Pan et al. showed that cavitation, in a liquid set into motion by an impulsive force, could be better predicted by the acceleration [1, 2]. Using a similar approach, we show that cavitation inception in the presence of an ultrasound device can be characterized by frequency and tensile strength. Visualization of the phenomenon with high-speed cameras synchronized with a hydrophone and an oscilloscope reveals that the vapor pressure is not a proper threshold for high frequencies. The system evolves very quickly toward strong gradients in pressure and the quasi-static assumptions used by traditional models break down. Instead, the system evolves towards a metastable state [3], where the liquid exhibits an elastic behavior and can withstand negative pressures. However, if the tensile strength is considered rather than the vapor pressure then the model and experiments match well for a wide range of frequencies. The result is a new non-dimensional number that scales the tensile strength with the acoustic frequency.
  • Effect of ultrasonic cavitation in the acid leaching process

    Canciani, Chiara; Colleoni, Elia; Sarvothaman, Varaha Prasad; Guida, Paolo; Roberts, William L. (2023-06-14) [Poster]
    The leaching process consists in the release of chemicals in a liquid phase, that can be either a acid or a basic solution. Acid leaching is used in metal extraction from ores in metallurgy or from scraps in recycling. The process consists in two main steps: contact between the solid and the leaching solution, and the separation of the desired substance that is transferred to the liquid phase. To be transferred to the solution, the substance of interest must move across the boundary layer that forms around the particle. In general, leaching times are in the order of hours and require special handling of the solution due to the harsh acids employed (most commonly sulfuric acid). Ultrasonic cavitation is a well-known process intensification tool. The collapse of the bubbles generates micro-jets and shear forces that improve mixing and transport properties in the liquid phase. The presence of solid particles in the liquid phase influences the formation of bubbles, as the particles can offer heterogeneous nucleation sites, enhancing the overall cavitation activity. This work aims to study the effect of ultrasonically-induced cavitation combined with acid leaching on solid particles. This will be achieved by comparing the size and morphology of solid lithium oxide particles after ultrasonically-enhanced and regular acid leaching.
  • Microalgae strains adaptation to harsh desert conditions in Saudi Arabia: results from lab to large scale

    Fuentes Grunewald, Claudio; Romero, Gabriel; Mhedhbi, Emna; Kapoore, Rahul; Gonzalez, Erik; Alammari, Zain; Banjar, Rana; Malibari, Raghdah; Aljahdali, Abdulaziz; Filimban, Akram; Villegas-Valencia, Melanie; Lauersen, Kyle J. (2023-06-13) [Poster]
  • Members of the Cyanidiophyceae can not metabolize phosphite

    Masson, Mauricio Lopez Portillo; Lammers, Peter; Seger, Mark; Wellman, Gordon; Villegas Valencia, Melany; Lauersen, Kyle J. (2023-06-12) [Poster]
    The use of members of Cyanidiophyceae in algal biotechnology concepts has started to gain attention in recent years. These polyextremophilic unicellular red algae were isolated from acidic hot springs where they tolerate and thrive in pH 0.5-2, high salinities, heavy metal concentrations, and temperatures from 42-60 ˚C. These culture conditions minimize the risk of contamination by other microorganisms at scale. The biomass of these organisms is proteinaceous and also contains thermostable phycocyanin. Cultivation of these species is also possible in contaminated acidified wastewater and are exciting candidates for bio-resource circularity processes in extreme environments or from unusual wastewater streams. This work has explored the possibility of genetic transformation of Galdieria sulphuraria 5587.1 (Gs) and enhancing engineering efforts with Cyanidioschyzon merolae 10D (Cm). Genetic engineering in Gs has emerged as a possibility upon a recent report describing the sexual mating cycle of this organism, the homologous recombination of transgenes into its nuclear genome, and its conversion to haploid form in low pH (<1.0) conditions. Here, conversion of Gs to the haploid stage is attempted, and a novel plasmid toolkit for homologous recombination in the algal nuclear genome was developed. This work is complemented by efforts to expand selectable marker options for Cm, which are currently limited to two antibiotics and one auxotrophy. I first characterized the inability of both Cyanidiophyceae to use phosphite (PO3−3) as a sole source of phosphorous and consequently attempted to use the Pseudomonas stutzeri WM88 phosphite NAD+ oxidoreductase (ptxD) as a selectable marker in these species. The work reported here will describe ongoing genetic engineering efforts in these two hosts and their potential for applied algal synthetic biology-mediated bioengineering concepts using acidified waste streams from industrial sources.
  • Engineered Production of Isoprene from the Model Green Microalga Chlamydomonas Reinhardtii

    Yahya, Razan; Wellman, Gordon; Overmans, Sebastian; Lauersen, Kyle (2023-06-11) [Poster]
    Isoprene (C5H8) is the volatile hemiterpene monomer of the natural polymer rubber and has been recognized as feedstock for the chemical industry. Isoprene is naturally produced by a wide range of species via the methyl erythritol 4-phosphate (MEP) isoprenoid biosynthesis pathway. In the algal chloroplast, sunlight energy is used in the conversion of CO2 into G3P and pyruvate for cellular carbon. These 3-carbon compounds are used by the MEP pathway to make the 5-carbon isopentyl- and dimethylallyl pyrophosphate (IPP and DMAPP, respectively) precursors of carotenoid pigments and cellular sterols. Isoprene synthases (IspSs) produce isoprene by cleavage of the pyrophosphate group of DMAPP to yield molecular isoprene. In this work, we benchmarked expression of four IspSs from different plant species in a high-density cultivation enabled strain of model green microalga Chlamydomonas reinhardtii (UPN22): Ipomoea batatas (IbIspS), Eucalyptus globulus (EgIspS), Pueraria montana (PmIspS) and Populus alba (PaIspS). Of the tested synthases, IbIspS yielded the highest and most stable isoprene yields in alga. To further enhance isoprene production, up- and downstream portions of the MEP and carotenoid pathways were perturbed to investigate their in uence on isoprene yields. The 1- deoxyxylulose 5-phosphate synthase from Salvia pomifera (SpDXS) and isopentenyl diphosphate isomerase from Saccharomyces cerevisiae (ScIDI) were overexpressed to modify upstream ux to DMAPP. Carotenoid biosynthesis was perturbed through overexpression of the Daucus carota lycopene beta cyclase (DcLCYB) and the C. reinhardtii beta carotene ketolase (CrBKT). A synergistic effect of CrBKT and ScIDI co-expression with IbIspS was found to result in robust isoprene generation from the eukaryotic alga. Using 20-photobioreactors, the interplay of light and temperature was used to determine that culture temperature, rather than incident light, had the greatest effect on isoprene yields from the algal host.
  • Pathway engineering and synthetic transgene design to produce diverse fragrant sesquiterpenoids from the green microalga Chlamydomonas reinhardtii

    Gutiérrez, Sergio; Overmans, Sebastian; Wellman, Gordon; Lauersen, Kyle J. (2023-06-11) [Poster]
    Terpenoids are a diverse class of natural compounds with many applications, such as flavors and fragrances. Sesquiterpenoids (C15) are fragrant components of incenses and perfumes, which are widely used in the Middle East region. Some, however, are acquired unsustainably from slow-growing plants such as Aquilaria sp. trees, members of which are considered endangered. Alternative sources of these compounds are desired, and heterologous production of sesquiterpenoids in engineered microbes is a favorable alternative. The photosynthetic model green microalga Chlamydomonas reinhardtii has recently been used as an alternative cell factory to generate heterologous sesquiterpenoids from CO2 as a carbon source. Our goal in this work was to investigate production of a range of heterologous sesquiterpenoids in C. reinhardtii while modifying its native isoprenoid pathway to channel carbon flow towards these products. A strategy of terpenoid pathway modification was employed wherein a β-carotene ketolase (BKT) was expressed to perturb carotenoid biosynthesis and the host squalene synthase (SQS) was knocked down to reduce metabolic pull on FPP. The modifications resulted in a synergistic effect that increased patchoulol (C15-OH) production from 191 ± 25 μg/L to 2330 ± 230 μg/L using a cytosolic localized patchoulol synthase. Using algal optimized synthetic transgene designs, 22 sesquiterpenoid synthases from various species were then systematically expressed and compared in this strain to produce aristolochene (n=4), guaiene (n=6), santalene (n=3), valencene (n=1), valerianol (n=1), zizaene (n=2), cadinol (n=1), and bisabolol (n=1). The findings suggest that the alga can be engineered to possess a sizable pool of FPP to synthesize non-native sesquiterpenes. For each SqTPS isoform, variable sesquiterpenoid yields were observed and the optimal synthase identified for each product. These results indicated that C. reinhardtii can be used as a green cell factory to generate heterologous high-value specialty sesquiterpenoids through metabolic engineering.
  • Building a living library from the Kingdom of Saudi Arabia

    Freitas, Barbara Bastos; Barsotti, Adriana; Lauersen, Kyle J. (2023-06) [Poster]
    Algal biodiversity is still underexplored and requires increased attention as each isolate may hold unique value for different human-use applications. As the Kingdom of Saudi Arabia (KSA) is looking to diversify its sustainable technologies, the development of technologies using, and bio-prospecting of, local algae strains may hold value for a number of industries and enhance resource circularity. Sourcing local strains is of importance for their adaptedness to the sometimes harsh environments of this region in outdoor cultivation concepts and to avoid issues of species invasiveness or risks to biodiversity. The abiotic factors of this region, high irradiance, high temperatures, and minimal water sources have likely yielded microbes with specialized biochemistries with adaptive features like tolerance to UV and light radiation as well as high temperatures. Algal biodiversity has been generally underexplored in the KSA. This work presents our efforts to isolate, cultivate, characterize and generate a living library of KSA species that can be grown in salt water or waste(fresh)water resources. We aim to establish an algae library that can be accessed by stakeholders who wish to conduct work with algae in KSA. Samples have been collected from hot springs, volcanic sites, desert soil, cement production facilities, aquaculture farms, and the Red Sea. Isolation protocols to date include plate-spreading and serial dilution in ambient temperatures, 25 °C and ~100 µE to isolate monocultures. Greater than fifty individual isolates have been achieved since Spring 2022. Isolates include green algae, cyanobacteria, Euglenophyta, and diatoms. Preliminary growth data has been obtained for the local context in photobioreactors programed to emulate Spring, Summer, Winter, and Fall weather conditions at the mid Red Sea coast in addition to controls. Our living library and preliminary growth data highlight the unexplored biodiversity of algae and lay a foundation for next-stage circular resource bioprocesses in this region.
  • Hunting for Chlamydomonas in different regions of Saudi Arabia

    Freitas, Barbara Bastos; Barsotti, Adriana; Lauersen, Kyle J. (2023-06) [Poster]
    Most regions of the Kingdom of Saudi Arabia (KSA) can be considered extreme environments for biological growth, this geography includes regions of elevated light and temperatures, extreme pH, hyper salinity, and heavy metals. Despite these inhospitable conditions, photosynthetic organisms can survive, so long as some irrigation is provided, and we have found that photosynthetic microorganisms are readily isolatable from the local context. As algal biodiversity has generally been underexplored in the KSA, we decided to develop a living libraryof locally isolated algal species from this region for all algal biotechnology and phycology applications. We have been collecting environmental samples from desert regions, hot springs, the Red Sea, as well as volcanic areas, and so far, we have identified by morphology two potential Chlamydomonas strains from different environments within the KSA. Sequencing and growth profiles in simulated weather conditions using photobioreactors are being carried out. The growth will be benchmarked in two control conditions, constant light, 12 h:12 h light: dark, both at 25°C and 325 μmol photons m−2 s−1, and 4 different temperature and light conditions that each represents one of the four seasons from each of February (Winter), May (Spring), August (Summer), and November (Autumn) in Thuwal, Saudi Arabia. Upon genetic confirmation of these isolates as Chlamydomonas, they will be deposited at the Chlamydomonas resource center and shared with the global community as alternative strains from this unusual environment.
  • Engineering production of specialty fragrant C15 sesquiterpenoids from the green algal Chlamydomonas reinhardtii

    Gutiérrez, Sergio; Overmans, Sebastian; Wellman, Gordon; Lauersen, Kyle J. (2023-05-30) [Poster]
    Terpenoids, a family of natural compounds with various uses, are produced by many organisms, including plants, bacteria, and mammals. However, these specialty chemicals are currently being sourced in an unsustainable manner from slow-growing plants, such as the fragrant products of the Aquilaria tree, known in the Middle East as oud and bakhour. Heterologous production of terpenoids in engineered microorganisms provides a desirable alternative source for these chemicals, which can be produced in controlled cultures rather than through native plant harvesting. Recent research has utilized the photosynthetic model green microalgae, Chlamydomonas reinhardtii, as an alternative cell chassis to produce heterologous terpenoids. This organism is interesting because it utilizes CO2 as a carbon source and light as an energy source through photosynthesis. The research presented here aimed to analyze the production of various heterologous sesquiterpenoids using C. reinhardtii as a cell chassis by modifying its native pathway to direct carbon flow toward these products to increase their production rates. A terpenoid pathway modification strategy was used in which the host squalene synthase (SQS) was knocked down to decrease the native metabolic pull on farnesyl pyrophosphate (FPP), and a beta-carotene ketolase (BKT) was induced to perturb carotenoid biosynthesis. The modifications resulted in a synergistic effect on FPP availability, increasing patchoulol production 12-fold (191 ± 25 μg/L to 2330 ± 230 μg/L). Using this strain, the production of fragrant terpenoid chemicals, including aristolochene (n=4), guaiene (n=6), santalene (n=3), valencene (n=1), valerianol (n=1), zizaene (n=2), cadinol (n=1), and bisabolol (n=1) were evaluated. Optimized synthetic transgene designs enabled their expression in the alga. The findings show that the alga can be genetically manipulated to make non-native terpenoids by improving its pool of FPP and may be an alternative source of fragrant specialty chemicals, which could prevent the unsustainable harvesting of the Aquilaria tree for cosmetic applications.
  • Exporting Institutional Repository Metadata as Dataset

    Garcia, Marcelo; Grenz, Daryl M.; Baessa, Mohamed A. (2023-05) [Poster]
    Exporting the metadata of publications from KAUST affiliate faculty member.
  • Improving SO2 emissions over the Middle East.

    Ukhov, Alexander; Stenchikov, Georgiy L. (Copernicus GmbH, 2023-02-26) [Poster]
    The Middle East is one of the most polluted regions on Earth. Besides strong natural air pollution caused by frequent dust storms, anthropogenic emissions of SO2 from power and desalination plants significantly deteriorate air quality and, as a consequence, reduce life expectancy. Additionally, sulfate aerosol formed through the chemical oxidation of SO2 has an effect on climate and cloud formation. Therefore, accurate modeling of SO2 emissions is crucial, especially in such harsh conditions as the Middle East. In this work, we attempt to improve existing SO2 emissions using inversion modeling, a high-resolution regional WRF-Chem model, and satellite observations of SO2 columns available from OMI and TOMS instruments. Obtained SO2 emission dataset is planned to be open to the community.
  • Multiple effects contributed to the intensive shaking recorded in the 6 February 2023 Kahramanmaraş (Türkiye) earthquake sequence

    Jonsson, Sigurjon; Aspiotis, Theodoros; Aquib, Tariq Anwar; Cano, Eduardo; Castro Cruz, David; Espindola Carmona, Armando; Li, Bo; Li, Xing; Liu, Jihong; Matrau, R.; Nobile, Adriano; Palgunadi, Kadek Hendrawan; Parisi, Laura; Ribot, Matthieu; Suhendi, Cahli; Tang, Yuxiang; Yalcin, Bora; Avşar, Ulaş; Klinger, Yann; Mai, Paul Martin (Copernicus GmbH, 2023-02-26) [Poster]
    The Kahramanmaraş earthquake sequence caused strong shaking and extensive damage in central-south Türkiye and northwestern Syria, making them the deadliest earthquakes in the region for multiple centuries. The rupture of the first mainshock (M7.8) initiated just south of the East Anatolian Fault (EAF) and then ruptured bilaterally hundreds of km of the EAF, causing major stress changes in the region and triggering the second mainshock (M7.6) about 9 hours later. We mapped the surface ruptures of the two mainshocks using pixel-offset tracking of Sentinel-1 radar images and find them to be ~300 km and 100-150 km long. The distribution of aftershocks indicates that the fault ruptures may have been even longer at depth, or about ~350 km and ~170 km, respectively. The pixel-tracking results and finite-fault modeling of the spatially variable fault slip show up to 7 and 8 m of surface fault offsets at the two faults, respectively, and that fault slip was shallow in both events, mostly above 15 km. In addition, our back-projection analysis suggests the first mainshock ruptured from the hypocenter to the northeast towards the EAF (first ~15 sec), then continued along it to the northeast (until ~55 sec), and also to the southwest towards the Hatay province, later at high rupture speeds (until ~80 sec). Furthermore, strong motion recordings show PGA values up to 2g and are particularly severe in Hatay, where multiple stations show over 0.5g PGA values. Both events are characterized by abrupt rupture cessation, generating strong stopping phases that likely contributed to the observed high shaking levels. Together the results show that directivity effects, high rupture speed, strong stopping phases, and local site effects all contributed to the intensive shaking and damage in the Hatay province.
  • Strong ground motions due to directivity and site effects inflicted by the February 6 2023 earthquake doublet, along the East Anatolian Fault

    Aspiotis, Theodoros; Aquib, Tariq Anwar; Castro Cruz, David; Li, Bo; Li, Xing; Liu, Jihong; Matrau, R.; Palgunadi, Kadek Hendrawani; Parisi, Laura; Suhendi, Cahli; Tang, Yuxiang; Klinger, Yann; Jonsson, Sigurjon; Mai, Paul Martin (Copernicus GmbH, 2023-02-26) [Poster]
    Two powerful earthquakes (magnitudes 7.8 and 7.6) struck south-central Türkiye on February 6, 2023, causing significant damage across an extensive area of at least ten provinces in Türkiye as well as in multiple cities in northwestern Syria, making them one of the deadliest earthquakes in Türkiye for multiple centuries. The first mainshock started close to the well-known East Anatolian Fault (EAF) and then rupturing more than 300 km of that fault, whereas the second large earthquake occurred nine hours later around 90 km north of the first mainshock, on an east-west trending fault. In this study, we analysed recorded strong ground motions from the two events to better understand the factors contributing to the devastation caused by the earthquakes. For this, we collected 250 and 200 strong ground motion records for the first and the second event, respectively, from the Disaster and Emergency Management Authority (AFAD) in Türkiye. Maximum peak ground accelerations (PGA) of 2g were observed at a distance of 31 km northeast of the first mainshock epicenter and 0.6g for the second event 65km west to its epicenter. In addition, we find particularly high amplitude ground motions in the Hatay province for the first event, which is consistent with the extent of damage reported in that region. High shaking levels in Antakya and other parts of Hatay can be explained by a combination of strong directivity and local site effects. The results of our analysis imply that the PGA values derived from two local ground motion models (GMMs), adopted for the 2018 Turkish hazard map, are underestimated in comparison to observed strong motion recordings. In addition, we also compared observed peak and spectral ground motion characteristics with estimated seismic hazard values (10% probability to exceed in 50 years) in the East Anatolian Fault region (extracted from the 2018 Turkish seismic hazard map). Furthermore, we compare the recorded response spectra with the Turkish design code for several locations around the main faults. The results show that the observations greatly exceed the hazard values and code guidelines in the Hatay province.
  • The first network of Ocean Bottom Seismometers in the Red Sea to investigate the Zabargad Fracture Zone

    Parisi, Laura; Augustin, Nico; Mai, Paul Martin; Jonsson, Sigurjon (Copernicus GmbH, 2023-02-26) [Poster]
    The Red Sea (RS) is an ideal natural laboratory to study the transition from continental rifting to seafloor spreading because it is one of the youngest rift basins on Earth. The RS is an ultra-slow spreading rift with an opening rate that decreases from 15 mm/yr in the south, at the Nubian-Arabian-Danakil triple junction, to 7 mm/yr in the north where it connects to the Dead Sea transform fault. While the southern RS has a well-developed seafloor spreading ridge with an axis parallel to the rift bounding faults, images of the northern RS seafloor provide limited information because of thick evaporite layers covering the main tectonic features. Nevertheless, the northern rift axis is geometrically different as it is more oblique to the bounding faults than in the south. Furthermore, the transition between the southern and northern RS is sharp with a ~100 km rift axis offset, named Zabargad Fracture Zone (ZFZ). However, the current knowledge of the seismic activity, transform fault configuration, and the crustal and upper mantle structure of the ZFZ area is too limited to assess the seismic hazard associated with this rift offset and understand the role of the ZFZ in the RS development. To fill this gap, we deployed the first broadband seismic network in the Red Sea, within the ZFZ, from November 2021 to November 2022. This network included 12 Lobster OBSs from the DEPAS pool (equipped with Güralp CMG-40T-OBS sensors), 2 additional Trillium Compact sensors deployed directly on the seafloor mounted on minimalist frames through a collaboration with the company Fugro, as well as 2 Trillium Compact Horizon and 2 posthole sensors deployed on islands and inland in Saudi Arabia, respectively. The overall data recovery rate is above 90%. Also, our preliminary data analysis confirms some of the known issues of the Lobster OBSs and their sensors (strong self-noise at periods >10 s of the Güralp sensors and high-frequency harmonic noise due to head-buoy cable strumming). Furthermore, we conducted a systematic comparison of the noise recorded by different station configurations. We find that while Lobster OBSs with a head-buoy cable set free to strum generate strong noise at about 10 Hz and its overtones, Lobster OBSs with tight cable still display harmonic noise from 10 to 40 Hz that increases during bad weather conditions, probably due to resonance of other OBS elements. The Fugro OBSs, despite their minimalist deployment setup, show noise at 40 Hz that also resonates in bad weather. All the OBSs also display a peak of noise between 0.5 and 5 Hz (separated from the secondary microseismic peak). While such a noise peak is not recorded by the inland stations, it is well exhibited by the two island stations suggesting that this is due to locally ocean-generated seismic waves, but not by the OBS frames. At periods >10 s, the Fugro OBSs perform as well as the island and inland stations. In fact, waveforms of teleseismic earthquakes recorded by the Fugro OBSs and island and inland stations have comparable signal-to-noise ratios.
  • The effect of ash, water vapor, and heterogeneous chemistry on the evolution of a Pinatubo-size volcanic cloud

    Abdelkader, Mohamed; Stenchikov, Georgiy L.; Pozzer, Andrea; Tost, Holger; Lelieveld, Jos (Copernicus GmbH, 2023-02-26) [Poster]
    We employ the ECHAM5/MESSy2 atmospheric chemistry general circulation model (EMAC)that incorporates calculations of gas-phase and heterogeneous chemistry coupled with the ozone cycle and aerosol formation, transport, and microphysics to calculate the 1991 Pinatubo volcanic cloud. We considered simultaneous injections of SO2, volcanic ash, and water vapor. We conducted multiple ensemble simulations with different injection configurations to test the evolution of SO2, SO4, ash masses, stratospheric aerosol optical depth, surface area density (SAD), and 24the stratospheric temperature response against available observations. We found that the volcanic cloud evolution is sensitive to the altitude where volcanic debris is initially injected and the initial concentrations of the eruption products that affect radiative heating and lofting of the volcanic cloud. The numerical experiments with the injection of 12 Mt SO2, 75 Mt of volcanic ash, and 150 Mt of water vapor at 20 km show the best agreement with the observation of aerosol optical depth and stratospheric temperature response. Volcanic water injected by eruptive jets and/or intruding through the tropopause accelerates SO2 oxidation. But the mass of volcanic water retained in the stratosphere is controlled by the stratospheric temperature at the injection level. For example, volcanic materials are released in the cold point above the tropical tropopause, and most of the injected water freezes and sediments as ice crystals. The water vapor directly injected into the volcanic cloud increases the SO2− mass and stratospheric aerosol optical depth by about 5%. The coarse 4ash comprises 98% of the ash injected mass. It sediments within a few days, but aged submicron ash could stay in the stratosphere for a few months providing SAD for heterogeneous chemistry. The presence of ash accelerates SO2 oxidation by 10%–20% due to heterogeneous chemistry, radiative heating, lofting, and faster dispersion of volcanic debris. Ash aging affects its lifetime and optical properties, almost doubling the radiative ash heating. The 2.5-year simulations show that the stratospheric temperature anomalies forced by radiative heating of volcanic debris in our experiments with the 20 km injection height agree well with observations and reanalysis data. This indicates that the model captures the long-term evolution and climate effect of the Pinatubo volcanic cloud. The volcanic cloud’s initial lofting, facilitated by ash particles’ radiative heating, controls the oxidation rate of SO2. Ash accelerates the formation of the sulfate layer in the first 2 months after the eruption. We also found that the interactive calculations of OH and heterogeneous chemistry increase the volcanic cloud sensitivity to water vapor and ash injections. All those factors must be accounted for in modeling the impact of large-scale volcanic injections on climate and stratospheric chemistry.
  • Future projection of the African easterly waves in a high-resolution AGCM

    Raj, Jerry; Bangalath, Hamza Kunhu; Stenchikov, Georgiy L. (Copernicus GmbH, 2023-02-22) [Poster]
    African Easterly Waves (AEWs) are a significant control of West African rainfall and the associated Mesoscale Convective Systems (MCSs) and squall lines embedded within them. More than 40% of the total MCSs over the region are associated with AEWs and these MCSs account for approximately 80% of the total annual rainfall over the Sahel. Approximately 60% of all Atlantic hurricanes and 80% of major hurricanes have their genesis associated with AEWs. Simulating the features of AEWs, such as their westward propagation off the east Atlantic coast, is challenging for coarse-resolution climate models. In this study, we use High-Resolution Atmospheric Model (HiRAM) to simulate AEWs and analyze their future projections by the end of the 21st century. The simulations are performed globally at a horizontal resolution of 25km. The model uses shallow convective parameterization for moist convection and stratiform cloudiness. Future projections are conducted using representative concentration pathway 8.5. AEWs are separated with respect to their periods as 3–5 and 6–9-day period AEWs, and bandpass filtering is used to filter the waves from the mean flow. HiRAM simulates the structure and propagation of the waves well; however, it tends to overestimate the associated precipitation. In the future, the AEW precipitation and intensity of the circulation will considerably increase. The northward extent of the AEW track also shows a significant increase in the future. Enhanced baroclinic overturning and eddy available potential energy generated due to diabatic heating is also observed in the future.
  • Impact of Forestation and Land-use Changes on Desert Climate

    Dufour, Ambroise; Mostamandi, Suleiman; Johansen, Kasper; Lopez Valencia, Oliver Miguel; Stenchikov, Georgiy L. (Copernicus GmbH, 2023-02-22) [Poster]
    Growing forests is an effective way of removing CO2 from the atmosphere. Forestation projects were started in China, Germany, and the Middle East. Saudi Arabia announced its ambitious “Saudi Green Initiative,” intending to plant ten billion trees. Given the insufficient rainfall to support the initiative, vegetated areas will require irrigation, effectively increasing evaporation. In addition, those areas have a lower albedo than bare land, absorbing more solar radiation. Enhancing precipitation due to the recycling of evaporated water is important as it reduces the amount of freshwater required for irrigation. In this study, we focus on the regional climate impact of irrigated forested or vegetated areas on temperature and precipitation over the Arabian Peninsula to quantify their effect on livability and evaluate the water recycling potential. First, we studied the climate effect of irrigated farming developing over vast areas in Saudi Arabia since the 1980s. The agricultural areas were mapped using available satellite-based observations from the Landsat platforms, which capture optical and thermal data every 16 days at a resolution of 30 m to 100 m. Second, we projected the climate impact of widespread forestation over the Arabian Peninsula. The analysis of the long-term precipitation changes caused by irrigated farming is hindered by the lack of in situ observations and the limitations of global-scale observation data sets. Most reanalysis products have contradictory evaporation trends and indicate an overall reduction in rainfall since the 1980s. The recycled precipitation cannot be estimated reliably because of reanalysis increments and background rainfall variability. Presumably, the local increase in rains occurs downstream of the irrigated areas rather than over them. Along with the analysis of observations, we conducted numerical experiments mimicking the effect of irrigated agricultural fields using a non-hydrostatic regional meteorological model (WRF), covering the whole Arabian Peninsula by a 9x9 km2 grid, with 3x3 km2 nesting over the irrigated areas. Irrigation water is accounted for by tagging moisture evaporated from agricultural regions. The amount of tagged water vapor falling as rain represents recycled precipitation. The simulated evaporation and local temperature response strongly depends on the level of irrigation. Large-scale subsidence suppresses the local deep convection over most parts of the Arabian Peninsula. Strong turbulence quickly mixes evaporated water vapor within a six km thick atmospheric boundary layer, preventing precipitation in shallow convection so that the fraction of recycled rainfall appears to be low.

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