Development and testing of a desert dust module in a regional climate model

International audienceWe develop a desert dust module and implement it within a regional climate model (RegCM). The dust module includes emission, transport, gravitational settling, wet and dry removal and calculations of dust optical properties. The coupled RegCM-dust model is applied to the simulation of two dust episodes over the Sahara region (a northeastern Africa dust outbreak, and a west Africa-Atlantic dust outbreak observed during the SHADE "Saharan Dust Experiment") as well as a three month simulation over an extended domain covering the Africa-Europe sector. Comparison with satellite and insitu (for SHADE) measurements shows that the model captures the main spatial (both horizontal and vertical) and temporal features of the dust distribution. The main model deficiency occurred in the SHADE case, when the model failed to accurately simulate the development of a mesoscale low associated with an easterly wave that contributed to the generation of the dust outbreak. The model appears suitable to conduct long term simulations of the effects of Saharan dust on African and European climate

Simulation of dust aerosol and its regional feedbacks over East Asia using a regional climate model

International audienceThe ICTP regional climate model (RegCM3) coupled with a desert dust model is used to simulate the radiative forcing and related climate effects of dust aerosols over East Asia. Two sets of experiments encompassing the main dust producing months, February to May, for 10 years (1997?2006) are conducted and inter-compared, one without (Exp. 1) and one with (Exp. 2) the radiative effects of dust aerosols. The simulation results are evaluated against ground station and satellite data. The model captures the basic observed climatology over the area of interest. The spatial and temporal variations of near surface concentration, mass load, and emission of dust aerosols from the main source regions are reproduced by model, with the main model deficiency being an overestimate of dust amount over the source regions and underestimate downwind of these source areas. Both the top-of-the-atmosphere (TOA) and surface radiative fluxes are decreased by dust and this causes a surface cooling locally up to ?1°C. The inclusion of dust radiative forcing leads to a reduction of dust emission in the East Asia source regions, which is mainly caused by an increase in local stability and a corresponding decrease in dust lifting. Our results indicate that dust effects should be included in the assessment of climate change over East Asia

Implementation and testing of a desert dust module in a regional climate model

International audienceIn an effort to improve our understanding of aerosol impacts on climate, we implement a desert dust module within a regional climate model (RegCM). The dust module includes emission, transport, gravitational settling, wet and dry removal and calculations of dust optical properties. The coupled RegCM-dust model is used to simulate two dust episodes observed over the Sahara region (a northeastern Africa dust outbreak, and a west Africa-Atlantic dust outbreak observed during the SHADE "Saharan Dust Experiment"), as well as a three month simulation over an extended domain covering the Africa-Europe sector. Comparisons with satellite and local aerosol optical depth measurements shows that the model captures the main spatial (both horizontal and vertical) and temporal features of the dust distribution. The main model deficiency occurs in the representation of certain dynamical patterns observed during the SHADE case which is associated with an active easterly wave that contributed to the generation of the dust outbreak. The model appears suitable to conduct long term simulations of the effects of Saharan dust on African and European climate

Performances assessment of the first grid-connected photovoltaic micro power in Africa: The PVGIS approach

In this paper, a novel trimeric chain approach to organometallic ferrimagnetics is proposed. The inter and intratrimer exchange interaction has been determined to be antiferromagnetic from a theoretical model magnetic susceptibility.The Curie law observed at very low temperature (q = 5.764 K l0) contrasts with significant ferromagnetic behaviour. The magnetic data were fitted with the IDC model. The compounds interestingly exhibit ferrimagnetic interactions with gCu1 =1.81, gCu2 =2.04 and gCu3 =2.43; J1 =-89.93K and J2 = -2.68 KIn this paper, a novel trimeric chain approach to organometallic ferrimagnetics is proposed. The inter and intratrimer exchange interaction has been determined to be antiferromagnetic from a theoretical model magnetic susceptibility.The Curie law observed at very low temperature (q = 5.764 K l0) contrasts with significant ferromagnetic behaviour. The magnetic data were fitted with the IDC model. The compounds interestingly exhibit ferrimagnetic interactions with gCu1 =1.81, gCu2 =2.04 and gCu3 =2.43; J1 =-89.93K and J2 = -2.68

Development of a fluorine-thiol reaction platform for post-translational modification analysis and stapled peptide synthesis

Post-translational modifications (PTMs) allot versatility to the biological functions of highly conserved proteins. Recently, modifications to non-histone proteins such as methylation, acetylation, phosphorylation, glycosylation, ubiquitination, and many more have been linked to the regulation of pivotal pathways related to cellular response and stability. Due to the broad spectrum of pathways PTMs are associated with, their dysregulation is often linked to oncogenesis and various autoimmune diseases. Proteins involved in the incorporation (writers), removal (erasers) and recognition (readers) of PTMs, and substrate proteins, are regarded as important biomarkers and potential therapeutic targets as a result of their role in detrimental pathways. Current methodologies to monitor PTM substrates rely on alkyne/azide-based chemical proteomics, which are inefficient due to their bulky nature. This steric hindrance has been shown to limit the metabolic incorporation of alkyne/azide tags via PTM writers on to substrate proteins and has limited the use of these chemical reporters to enzymes containing large active sites. One portion of this dissertation will focus on the development of a steric-free biorthogonal chemical tagging platform utilizing a fluorine-thiol displacement reaction. Fluorinated PTM cofactors/precursors are steric free and could be easily recognized and metabolized by PTM enzymes. Reaction development identified thiophenols as a suitable partner for the displacement reaction to convert fluorine to other useful functionalities, allowing for the labeling and enrichment of multiple acetylation substrates in cell lysates. Another goal of this dissertation was the synthesis of novel stapled peptide therapeutics with this FTDR platform. A library of unprotected peptides were cyclized with this methodology, and were found to promote sufficient levels of alpha helical stability. Biological evaluation of FTDR-based stapled peptides showed that this methodology produced compounds with enhanced stabilities, which were a significant upgrade to ring-closing metathesis-based peptides in regard to solubility and cell permeability. The final goal of this dissertation focuses on the synthesis of a novel PET imaging probe. Immuno-PET imaging is a rising field in cancer prognosis and therapy, yet current probes utilize full-length IgGs and random conjugation methods, that lead to conjugates with random stabilities and activities. In conjunction with biologist in our lab, a 64Cu chelating NOTA linker, tethered to a BCN moiety was site-specifically conjugated to Fab fragments. The smaller unnatural amino acid containing Fab fragments, specifically mutated with p-azidophenylalanine (pAzF), boasted improved pharmacokinetic profiles and allowed for site-specific conjugation via strain-promoted cycloaddition.Chemistr

Perkaitan polisi populis 1Malaysia dengan sokongan rakyat terhadap Barisan Nasional dalam Pilihan Raya Umum 2018

Barisan Nasional (BN) tewas kepada Pakatan Harapan (PH) dalam PRU-14 walaupun telah melaksanakan polisi 1Malaysia. Sehubungan itu, kajian ini bertujuan untuk meneliti corak polisi populis 1Malaysia dan pola pengundian penyandang masyarakat bandar pelbagai etnik di Malaysia. Kajian ini juga berhasrat menentukan perkaitan polisi populis tersebut dengan pengundian penyandang dalam kalangan penerima dan bukan penerima polisi, menggunakan pilihan rasional sebagai landasan teori. Bagi tujuan tersebut, kajian ini telah dijalankan di Lembah Klang melibatkan seramai 400 orang responden tiga etnik utama iaitu Melayu, Cina dan India yang berumur dua puluh satu tahun dan ke atas. Pendekatan yang digunakan dalam kajian ini adalah pendekatan kuantitatif melalui teknik tinjauan borang soal selidik bersemuka. Data kajian yang diperoleh dianalisis secara deskriptif menggunakan program IBM SPSS Statistic Version 20 (SPSS 20.0) dan analisis inferensi menerusi teknik Partial Least Squares Structural Equation Modeling (PLS-SEM) dengan perisian SmartPLS 3.0. Analisis statistik deskriptif digunakan dalam menentukan corak polisi populis dan pola pengundian penyandang melibatkan perbandingan antara etnik dan antara penerima dengan bukan penerima manfaat polisi populis. Manakala analisis statistik inferensi digunakan dalam menentukan perkaitan di antara polisi populis dengan pengundian penyandang dan faktor yang mempengaruhi kecenderungan pengundian penyandang serta polisi populis dalam kalangan masyarakat bandar yang dikaji. Justeru kajian ini mencadangkan model persamaan struktur perkaitan polisi populis dengan pengundian penyandang masyarakat bandar Malaysia. Hasil kajian menunjukkan terdapat hubungan signifikan yang positif di antara polisi populis dengan pengundian penyandang. Kajian juga mendapati faktor pilihan rasional menentukan pengaruh yang diterima daripada polisi populis dan turut berpengaruh terhadap kecenderungan pengundian penyandang. Analisis menunjukkan terdapat corak polisi populis yang ketara dalam 1Malaysia dan pola pengundian penyandang juga wujud dengan kukuh dalam masyarakat yang dikaji. Berdasarkan hasil kajian ini, terbina model persamaan struktur polisi populis dan pengundian penyandang penerima dan bukan penerima manfaat. Model persamaan struktur yang merangkumi ideologi dan strategi politik populis tersebut juga melibatkan pilihan rasional dalam konteks hubungannya dengan pengundian penyandang. Justeru, polisi populis dan pengundian penyandang telah memberi sumbangan kepada perkembangan teori pilihan rasional khususnya dalam penelitian tingkah laku politik pengundian di Malaysia

Effect of the aerosol type selection for the retrieval of shortwave ground net radiation: case study using landsat 8 data

This paper discusses the aerosol radiative effects involved in the accuracy of shortwave net radiation, Rn.sw, with sw 2 (400–900) nm, retrieved by the Operational Land Imager (OLI), the new generation sensor of the Landsat mission. Net radiation is a key parameter for the energy exchange between the land and atmosphere; thus, Rn.sw retrieval from space is under investigation by exploiting the increased spatial resolution of the visible and near-infrared OLI data. We adopted the latest version of the Second Simulation of a Satellite Signal in the Solar Spectrum (6SV) atmospheric radiative transfer model implemented in the atmospheric correction algorithm (OLI Atmospherically-Corrected Reflectance Imagery (OLI@CRI)) developed specifically for OLI data. The values of Rn.sw were obtained by varying the microphysical properties of the aerosol during the OLI@CRI retrieval of both the OLI surface reflectance, roli pxl , and the incoming solar irradiance at the surface. The analysis of the aerosol effects on the Rn.sw was carried out on a spectrally-homogeneous desert area located in the southwestern Nile Delta. The results reveal that the Rn.sw available for energy exchange between the land and atmosphere reduces the accuracy (NRMSE ' 14%) when the local aerosol microphysical properties are not considered during the processing of space data. Consequently, these findings suggest that the aerosol type should be considered for variables retrieved by satellite observations concerning the energy exchange in the natural ecosystems, such as Photosynthetically-Active Radiation (PAR). This will also improve the accuracy of land monitoring and of solar energy for power generation when space data are used

effects of climate changes on dust aerosol over east asia from regcm3

Abstract In order to understand impacts of global warming on dust aerosol over East Asia, a regional climate model (RegCM3) coupled with a dust model is employed to simulate the present (1991–2000, following the observed concentration of the greenhouse gases) and future (2091–2100, following the A1B scenario) dust aerosol. Three experiments are performed over East Asia at a horizontal resolution of 50 km, driven by the outputs from a global model of the Model for Interdisciplinary Research on Climate (MIROC3.2_hires), two without (Exp.1 for the present and Exp.2 for the future) and one with (Exp.3 for the future) the radiative effects of dust aerosols. Effects of climate changes on dust aerosols and the feedback of radiative effects in the future are investigated by comparing differences of Exp.2 and Exp.1, Exp.3 and Exp.2, respectively. Results show that global warming will lead to the increases of dust emissions and column burden by 2% and 14% over East Asia, characterized by the increase in December–January–February–March (DJFM) and the decrease in April–May (AM). Similar variations are also seen in the projected frequencies of high dust emission events, showing an advanced active season of dust in the future. The net top-of-atmosphere (TOA) radiative forcing is positive over the desert source regions and negative over downwind regions, while the surface radiative forcing is negative over the domain, which will lead to a reduction of dust emissions and column burden

Downscaling system for modeling of atmospheric composition on regional, urban and street scales

In this study, the downscaling modeling chain for prediction of weather and atmospheric composition is described and evaluated against observations. The chain consists of interfacing models for forecasting at different spatiotemporal scales that run in a semi-operational mode. The forecasts were performed for European (EU) regional and Danish (DK) subregional-urban scales by the offline coupled numerical weather prediction HIRLAM and atmospheric chemical transport CAMx models, and for Copenhagen citystreet scale by the online coupled computational fluid dynamics M2UE model. The results showed elevated NOx and lowered O-3 concentrations over major urban, industrial, and transport land and water routes in both the EU and DK domain forecasts. The O-3 diurnal cycle predictions in both these domains were equally good, although O-3 values were closer to observations for Denmark. At the same time, the DK forecast of NOx and NO2 levels was more biased (with a better prediction score of the diurnal cycle) than the EU forecast, indicating a necessity to adjust emission rates. Further downscaling to the street level (Copenhagen) indicated that the NOx pollution was 2-fold higher on weekends and more than 5 times higher during the working day with high pollution episodes. Despite high uncertainty in road traffic emissions, the street-scale model effectively captured the NOx and NO2 diurnal cycles and the onset of elevated pollution episodes. The demonstrated downscaling system could be used in future online integrated meteorology and air quality research and operational forecasting, as well as for impact assessents on environment, population, and decision making for emergency preparedness and safety measures planning.Peer reviewe

An exploration of the aerosol indirect effects in East Asia using a regional climate model

In this study, the aerosol direct, semi-direct and indirect effects on the East Asia climate are investigated using the International Center for Theoretical Physics Regional Climate Model v. 4 (RegCM4.1.1), by focusing on the East Asian Summer Monsoon temperature and precipitation. The externally mixed aerosols, including sulfate (SO42–), black carbon and organic carbon, reduced the solar flux reaching the surface directly by scattering solar radiation, and indirectly by increasing the cloud droplet concentration and cloud liquid water path over East China. The combined aerosol effects (direct and indirect) decreased the temperature on the continent and increased it over the oceans, leading to the reduction of rainfall in the central regions of China and an enhancement of rainfall in the adjacent ocean regions