Dust Module Research Articles

Modeling the interstellar dust detections by DESTINY[formula omitted] I: Instrumental constraints and detectability of organic compounds

The DESTINY+ spacecraft will be launched to the active asteroid (3200) Phaethon in 2025. The spacecraft will be equipped with the DESTINY+ Dust Analyzer (DDA) which will be a time-of-flight impact ionization mass spectrometer. In addition to the composition of impacting dust particles, the instrument will measure the particle mass, velocity vector, and surface charge. Here, we study the detection conditions of DDA for interstellar dust during the DESTINY+ mission. We use the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX Sterken et al., 2013; Strub et al., 2019) to simulate the flow of interstellar dust through the Solar System. Extending earlier work by Krüger et al. (2019b) we consider the entire DESTINY+ mission, i.e. the Earth-orbiting phase of the spacecraft during the initial approximately 1.5 years after launch, the nominal interplanetary mission phase up to the Phaethon flyby, and a four-years mission extension beyond the Phaethon flyby. The latter may include additional asteroid flybys. For predicting dust fluxes and fluences we take into account a technical constraint for DDA not to point closer than 90° towards the Sun direction for health and safety reasons of the instrument and in order to avoid electrical noise generated by photoelectrons. For the Earth orbiting phase after launch of DESTINY+ our simulations predict that up to 28 interstellar particles will be detectable with DDA in 2026. In the following years the interplanetary magnetic field changes to a focussing configuration for small (≲0.1μm) interstellar dust particles. This increases the total number of detectable particles to 50 during the interplanetary mission of DESTINY+ in 2027. In 2028 and 2029/30 approximately 160 and 190 particles will be detectable, respectively, followed by about 500 in 2030/31. We also make predictions for the detectability of organic compounds contained in the interstellar particles which is a strong function of the particle impact speed onto the detector. While organic compounds will be measurable only in a negligible number of particles during the Earth orbiting and the nominal interplanetary mission phases, a few 10s of interstellar particle detections with measurable organic compounds are predicted for the extended mission from 2028 to 2031.

Dynamics of a severe summer Shamal wind and its induced dust storm in the Middle East: A diagnostic study based on numerical simulation

This study investigates the formation and dynamics of the Summer Shamal Wind (SSW) and its associated dust storms over the Middle East. A regional climate model, RegCM4, coupled with a dust module, is employed to simulate a severe dust storm event on June 12, 2006. To gain deeper insights, a novel dynamical mechanism is proposed. This mechanism highlights the crucial role of both mechanical and thermal forcing in shaping the regional atmospheric circulation. The vertical heat advection from the Zagros Mountains (ZAG), combined with the mechanical forcing from a shallow incident flow originating from the Turkmenistan anticyclone, triggers upward motion over the ZAG. This synergistic effect leads to the development of a mid-tropospheric anticyclone over the ZAG, which, in turn, induces a westward-propagating Rossby wave. The downward motion and descending air associated with this wave over Mesopotamia establish a terrain-induced local circulation. Consequently, the SSW emerges within a shallow layer at the null-vorticity zone of a coupling-pressure pattern formed by the Arabian anticyclone and the Zagros trough, which is itself a product of the terrain-induced circulation. The study concludes that the intensification and southward movement of the Turkmenistan anticyclone play a pivotal role in the formation of severe SSWs and subsequent dust storms over the Middle East.

Investigation of Dust‐Induced Direct Radiative Forcing Over the Arabian Peninsula Based on High‐Resolution WRF‐Chem Simulations

AbstractThis study investigates the impact of dust on radiation over the Arabian Peninsula (AP) during the reported high, low, and normal dust seasons (March–August) of 2012, 2014, and 2015, respectively. Simulations were performed using the Weather Research and Forecasting model coupled to a Chemistry module (WRF‐Chem). The simulated seasonal horizontal and vertical dust concentrations, and their interannual distinctions, match well with those from two ground‐based AERONET observations, and measurements from MODIS and CALIOP satellites. The maximum dust concentrations over the dust‐source regions in the southern AP reach vertically upto 700 hPa during the high dust season, but only upto 900–950 hPa during the low/normal dust seasons. Stronger incoming low‐level winds along the southern Red Sea and those from Iraq bring in higher‐than‐normal dust during the high dust summers. We conducted a sensitivity experiment by switching‐off the dust module to assess the radiative perturbations due to dust. The results suggest that active dust‐module improved the fidelity of simulated radiation fluxes distributions at the surface and top of the atmosphere vis‐à‐vis Clouds and the Earth's Radiant Energy System (CERES) measurements. Dust results in a 26 Wm−2 short‐wave (SW) radiative forcing in the tropospheric‐column over the AP. The SW radiative forcing increases by another 6–8 Wm−2 during the high dust season due to the increased number of extreme dust days, which also amplifies atmospheric heating. During extreme dust days, the heating rate exhibits a dipolar structure, with cooling over the Iraq region and warming of 40%–60% over the southern‐AP.

FARGOCPT: 2D Multiphysics code for simulating disk interactions with stars, planets, and particles

Context. Planet-disk interactions play a crucial role in the understanding of planet formation and disk evolution. There are multiple numerical tools available to simulate these interactions, including the commonly used FARGO code and its variants. Many of the codes have been extended over time to include additional physical processes, with a focus on their accurate modeling. Aims. We introduce FARGOCPT, an updated version of FARGO that incorporates other previous enhancements to the code, to provide a simulation environment tailored to studies of the interactions between stars, planets, and disks. It is meant to ensure an accurate representation of planet systems, hydrodynamics, and dust dynamics, with a focus on usability. Methods. The radiation-hydrodynamics part of FARGOCPT uses a second-order upwind scheme in 2D polar coordinates, supporting multiple equations of state, radiation transport, heating and cooling, and self-gravity. Shocks are considered using artificial viscosity. The integration of the N-body system is achieved by leveraging the REBOUND code. The dust module utilizes massless tracer particles, adapted to drag laws for the Stokes and Epstein regimes. Moreover, FARGOCPT provides mechanisms to simulate accretion onto stars and planets. Results. The code has been tested in practice in the context of multiple studies. Additionally, it comes with an automated test suite for checking the physics modules. It is available online. Conclusions. FARGOCPT offers a unique set of simulation capabilities within the current landscape of publicly available planet-disk interaction simulation tools. Its structured interface and underlying technical updates are intended to assist researchers in ongoing explorations of planet formation.

Performance evaluation of solar panels under different dust accumulation conditions using thermography: focusing on PV temperature variation

Degradation performance of photovoltaic modules (SPV) by real conditions has become increasingly problematic. In dusty areas, dust accumulation is one of the main concerns that may cause a significant determination of SPV efficiency. In the current study, the effect of four dust-accumulated densities of 6, 12, 18, and 24 g/m2 have been investigated in outdoor conditions in Cairo, Egypt. The performance evaluation of SPV modules in the form of front and backside temperatures of the SPV module has been evaluated in addition to current, voltage, power, and efficiency of the SPV modules. The results showed that, as compared with a clean SPV module, with increasing dust density from 6 to 24 g/m2 the frontside temperature of SPV modules were lower by 6–8 ℃. While their backside temperatures were found to be higher by 2–6 ℃. In addition, the difference between the backside and frontside temperatures of the SPV module ranged from 5 to 14 ℃ for dust modules as compared with 3 ℃ for the clean SPV module. The output power and efficiency of dusty SPV modules were found to be lower by 6–45% and 13–38%, respectively as compared with clean SPV module. The results clearly showed the importance of properly maintaining and servicing the SPV modules to avoid their degradation by dust accumulated.

The Development of METAL-WRF Regional Model for the Description of Dust Mineralogy in the Atmosphere

The mineralogical composition of airborne dust particles is an important but often neglected parameter for several physiochemical processes, such as atmospheric radiative transfer and ocean biochemistry. We present the development of the METAL-WRF module for the simulation of the composition of desert dust minerals in atmospheric aerosols. The new development is based on the GOCART-AFWA dust module of WRF-Chem. A new wet deposition scheme has been implemented in the dust module alongside the existing dry deposition scheme. The new model includes separate prognostic fields for nine (9) minerals: illite, kaolinite, smectite, calcite, quartz, feldspar, hematite, gypsum, and phosphorus, derived from the GMINER30 database and also iron derived from the FERRUM30 database. Two regional model sensitivity studies are presented for dust events that occurred in August and December 2017, which include a comparison of the model versus elemental dust composition measurements performed in the North Atlantic (at Izaña Observatory, Tenerife Island) and in the eastern Mediterranean (at Agia Marina Xyliatos station, Cyprus Island). The results indicate the important role of dust minerals, as dominant aerosols, for the greater region of North Africa, South Europe, the North Atlantic, and the Middle East, including the dry and wet depositions away from desert sources. Overall, METAL-WRF was found to be capable of reproducing the relative abundances of the different dust minerals in the atmosphere. In particular, the concentration of iron (Fe), which is an important element for ocean biochemistry and solar absorption, was modeled in good agreement with the corresponding measurements at Izaña Observatory (22% overestimation) and at Agia Marina Xyliatos site (4% overestimation). Further model developments, including the implementation of newer surface mineralogical datasets, e.g., from the NASA-EMIT satellite mission, can be implemented in the model to improve its accuracy.

Application of a satellite-retrieved sheltering parameterization (v1.0) for dust event simulation with WRF-Chem v4.1

Abstract. Roughness features (e.g., rocks, vegetation, furrows) that shelter or attenuate wind flow over the soil surface can considerably affect the magnitude and spatial distribution of sediment transport in active aeolian environments. Existing dust and sediment transport models often rely on vegetation attributes derived from static land use datasets or remotely sensed greenness indicators to incorporate sheltering effects on simulated particle mobilization. However, these overly simplistic approaches do not represent the three-dimensional nature or spatiotemporal changes of roughness element sheltering. They also ignore the sheltering contribution of non-vegetation roughness features and photosynthetically inactive (i.e., brown) vegetation common to dryland environments. Here, we explore the use of a novel albedo-based sheltering parameterization in a dust transport modeling application of the Weather Research and Forecasting model with Chemistry (WRF-Chem). The albedo method estimates sheltering effects on surface wind friction speeds and dust entrainment from the shadows cast by subgrid-scale roughness elements. For this study, we applied the albedo-derived drag partition to the Air Force Weather Agency (AFWA) dust emission module and conducted a sensitivity study on simulated PM10 concentrations using the Georgia Institute of Technology–Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model as implemented in WRF-Chem v4.1. Our analysis focused on a convective dust event case study from 3–4 July 2014 for the southwestern United States desert region discussed by other published works. Previous studies have found that WRF-Chem simulations grossly overestimated the dust transport associated with this event. Our results show that removing the default erodibility map and adding the drag parameterization to the AFWA dust module markedly improved the overall magnitude and spatial pattern of simulated dust conditions for this event. Simulated PM10 values near the leading edge of the storm substantially decreased in magnitude (e.g., maximum PM10 values were reduced from 17 151 to 8539 µg m−3), bringing the simulated results into alignment with the observed PM10 measurements. Furthermore, the addition of the drag partition restricted the erroneous widespread dust emission of the original model configuration. We also show that similar model improvements can be achieved by replacing the wind friction speed parameter in the original dust emission module with globally scaled surface wind speeds, suggesting that a well-tuned constant could be used as a substitute for the albedo-based product for short-duration simulations in which surface roughness is not expected to change and for landscapes wherein roughness is constant over years to months. Though this alternative scaling method requires less processing, knowing how to best tune the model winds a priori could be a considerable challenge. Overall, our results demonstrate how dust transport simulation and forecasting with the AFWA dust module can be improved in vegetated drylands by calculating the dust emission flux with surface wind friction speed from a drag partition treatment.

The role of dust aerosols in forming the regional climate of Georgia

The scope of this work is to study some aspects of the formation of the regional climate of the Caucasus (with a specific focus on Georgia) against the background of the impact of mineral aerosols using modelling (the RegCM interactively coupled with a dust module, WRF-Chem, and HYSPLIT models) and satellite data (MODIS, CALIPSO). The annual mean, as well as the error in summer and winter temperatures, standard deviation and correlation coefficient compared to the CRU data were calculated for 8 sub-regions with different orographic and climate properties. The calculation results showed that dust aerosol is an active player in the climatic system of the Caucasus (Georgia). Numerical results showed that the inclusion of dust radiative forcing in the RegCM numerical model brought the simulated summer temperature closer to the observed temperature values. The mean annual temperature increased throughout Georgia in simulations that took into account the direct impact of dust. Calculations using the WRF-Chem and HYSPLIT models revealed that during the study period, aeolian dust was brought into the territory of the South Caucasus (Georgia) equally not only from Africa and the Middle East, but also from Central (Western) Asia deserts, which was not noted earlier.

Development of Digital Device Using ZigBee for Environmental Monitoring in Underground Mines

In underground mines, various mining activities may generate dust or vibrations, affecting workers’ health and safety. Therefore, for worker safety, we must monitor the environment and identify possible risks. However, it is difficult to install multiple sensors and acquire data simultaneously because of the difficulties of connecting to an external network in underground mines. This study developed a digital device to share acquired data by combining ZigBee communication technology with an accelerometer and dust sensor. In total, 29 vibration modules, 14 dust modules, and 2 coordinator modules were installed at Taeyoung EMC’s Samdo Mine in Samcheok, Republic of Korea. Because of its application, we could detect changes in vibration and dust before and after blasting. The dust density of the devices close to the blasting point increases rapidly up to about 230 µg/m3 and then decreases to about 180 µg/m3, and the dust density of the devices further increases over time. The dust density was usually maintained at a value of about 100 to 150 µg/m3 before blasting. The spatial distribution of the dust density of multiple devices was visualized using ArcGIS Pro. Although the wireless sensor network is well-established, some modules were temporarily disconnected from the network. In order to solve the problem of unstable network connection in some modules, change of network settings and line of sight analysis are required. Improvements in the technology developed in this study may help prevent potential hazards in underground mines.

Application and testing of a windblown dust module for a bare riverbed

To accurately predict the occurrence of riverbed dust events, a high-grid resolution (1 km2) riverbed dust module was constructed for this study. Although the module used the built-in CMAQ (Community Multiscale Air Quality model) dust module, the critical parameter values in the module were adjusted according to the experimental data for Taiwan. The results showed that the riverbed dust module can accurately predict the occurrence time of riverbed dust and thus improve the prediction of CMAQ's for the PM10 concentrations of downwind riverbed dust. The mean fractional bias and mean fractional error improved from −77 and 84% to −5 and 57%, respectively. Seven sensitivity-case simulations were performed to understand which parameters and formulas were important. The results are summarized as follows. (1) Selecting an appropriate horizontal sand flux estimation formula/vertical-to-horizontal dust flux ratio estimation formula/surface roughness length value is important because it can significantly affect dust emissions estimation. A local experimental value for the surface roughness length value is preferred. (2) For bare river land, it was acceptable to use the default value (= 1) for the surface roughness correction factor value. (3) In environments with high soil moisture, special attention should be paid to setting the threshold soil moisture value. (4) Different river locations may require different parameter values to be set within the module, and the ideal threshold friction velocity is an important parameter. (5) The estimation and use of gusts can improve the prediction of intense dust emissions; however, the prediction of hourly gusts must be improved.

Importance of different parameterization changes for the updated dust cycle modeling in the Community Atmosphere Model (version 6.1)

Abstract. The Community Atmosphere Model (CAM6.1), the atmospheric component of the Community Earth System Model (CESM; version 2.1), simulates the life cycle (emission, transport, and deposition) of mineral dust and its interactions with physio-chemical components to quantify the impacts of dust on climate and the Earth system. The accuracy of such quantifications relies on how well dust-related processes are represented in the model. Here we update the parameterizations for the dust module, including those on the dust emission scheme, the aerosol dry deposition scheme, the size distribution of transported dust, and the treatment of dust particle shape. Multiple simulations were undertaken to evaluate the model performance against diverse observations, and to understand how each update alters the modeled dust cycle and the simulated dust direct radiative effect. The model–observation comparisons suggest that substantially improved model representations of the dust cycle are achieved primarily through the new more physically-based dust emission scheme. In comparison, the other modifications induced small changes to the modeled dust cycle and model–observation comparisons, except the size distribution of dust in the coarse mode, which can be even more influential than that of replacing the dust emission scheme. We highlight which changes introduced here are important for which regions, shedding light on further dust model developments required for more accurately estimating interactions between dust and climate.

A Multifluid Dust Module in Athena++: Algorithms and Numerical Tests

We describe the algorithm, implementation, and numerical tests of a multifluid dust module in the Athena++ magnetohydrodynamic code. The module can accommodate an arbitrary number of dust species interacting with the gas via aerodynamic drag (characterized by the stopping time), with a number of numerical solvers. In particular, we describe two second-order accurate, two-stage, fully implicit solvers that are stable in stiff regimes, including short stopping times and high dust mass loading, and they are paired with the second-order explicit van Leer and Runge–Kutta gas dynamics solvers in Athena++, respectively. Moreover, we formulate a consistent treatment of dust concentration diffusion with dust back-reaction, which incorporates momentum diffusion and ensures Galilean invariance. The new formulation and stiff drag solvers are implemented to be compatible with most of the existing features of Athena++, including different coordinate systems, mesh refinement, and shearing box and orbital advection. We present a large suite of test problems, including the streaming instability in linear and nonlinear regimes, as well as local and global settings, which demonstrate that the code achieves the desired performance. This module will be particularly useful for studies of dust dynamics and planet formation in protoplanetary disks.

Climatology and the dynamic mechanism of the Levar wind and dust events in eastern Iran

AbstractDust storms in eastern Iran have a wide range of socioeconomic impacts, yet long‐term numerical model analysis of the mechanism of strong winds and dust events in this region is limited. The regional climate model version 4 (RegCM4) coupled with a dust module is used to understand the climatology, climatic change, and the dynamic mechanism of the Levar wind and dust events in eastern Iran for the period 1991–2017. It is found that the strong Levar wind is the main driver of dust events in eastern Iran, particularly from June to September. Both model simulation and observations indicate that the Levar wind is strongest on the border between South Khorasan Province in Iran and Afghanistan. Our analysis indicates that the Levar wind is caused by the development of anomalous surface high pressure in Central Asia extending toward northeastern Iran and anomalous surface low pressure on the border between western Afghanistan and Pakistan. The strong pressure gradient force associated with these anomalous high‐ and low‐pressure systems is responsible for the strong northerly Levar wind on the border between Iran and Afghanistan. Dust activity in eastern Iran exhibits a distinct seasonality. The highest dust emission occurs on the border between eastern South Khorasan Province in Iran and western Afghanistan from June to September, where near‐surface winds are also the strongest. Relatively less dust emission occurs in dry beds of Jazmourian from June to September, south of Saravan in May, and Rig‐e Yalan in June. The removal of dust particles from the atmosphere is mainly by dry deposition in eastern Iran. The main sink of dust is located in the western parts of the Sistan Basin. Dust emission and burden in the main source of dust in eastern Iran have significantly decreased during the period 1991–2017, while near‐surface wind speed has remained nearly unchanged.

Development of a Dust Source Map for WRF-Chem Model Based on MODIS NDVI

We present the development of a physically-based dust source map for the GOCART-AFWA dust module in WRF-Chem model. The new parameterization is based on MODIS-NDVI and an updated emission strength map is computed every 15 days from the latest satellite observations. Modeling simulations for the period April–May 2017 over the Mediterranean, north Africa, and the Middle East are compared with observations of AOD at 31 AERONET stations. The new module is capable of reproducing the dust sources at finer detail. The overall performance of the model is improved, especially for stronger dust episodes with AOD > 0.25. For this threshold the model BIAS decreases from −0.20 to −0.02, the RMSE from 0.38 to 0.30, the Correlation Coefficient improves from 0.21 to 0.47, the fractional gross error (FGE) from 0.62 to 0.40, and the mean fractional bias (MFB) from −0.49 to −0.08. Similar improvement is also found for the lower AOD thresholds (>0.0 and >0.1), especially for the stations in Europe, the Mediterranean, Sahel, the Middle East, and Arabian Peninsula, which are mostly affected by dust transport during the experimental period. An overprediction of AOD, compared to the original dust-source scheme, is found for some stations in the Sahara desert, the Atlantic Ocean, and the Iberian Peninsula. In total, 124 out of the 170 statistical scores that are calculated indicate improvement of model performance.

Annual and early summer variability in WRF-CHEM simulated West African PM10 during 1960–2016

We examine annual PM10 concentrations across the Sahara and Sahel using the Weather, Research and Forecast (WRF) model with the GOCART dust module during 1960–2016 driven at the lateral boundaries with the NCEP reanalysis. We show that there is a simulated annual downward trend in surface PM10 concentrations in Senegal and Cabo Verde after the 1980s, which is similar to earlier findings. The analysis of simulated PM10 concentrations over the period of 1960–2016 during May, June and July (MJJ) suggests that there has been an increase in the vertical transport of dust over the Western Sahara which is then horizontally transported downstream at approximately 700 hPa for Cabo Verde. This suggests that dust transport to the Eastern Atlantic, which could be further transported downstream towards the Caribbean and United States, may have increased during the early 21st century.

Mineral dust cycle in the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model (MONARCH) Version 2.0

Abstract. We present the dust module in the Multiscale Online Non-hydrostatic AtmospheRe CHemistry model (MONARCH) version 2.0, a chemical weather prediction system that can be used for regional and global modeling at a range of resolutions. The representations of dust processes in MONARCH were upgraded with a focus on dust emission (emission parameterizations, entrainment thresholds, considerations of soil moisture and surface cover), lower boundary conditions (roughness, potential dust sources), and dust–radiation interactions. MONARCH now allows modeling of global and regional mineral dust cycles using fundamentally different paradigms, ranging from strongly simplified to physics-based parameterizations. We present a detailed description of these updates along with four global benchmark simulations, which use conceptually different dust emission parameterizations, and we evaluate the simulations against observations of dust optical depth. We determine key dust parameters, such as global annual emission/deposition flux, dust loading, dust optical depth, mass-extinction efficiency, single-scattering albedo, and direct radiative effects. For dust-particle diameters up to 20 µm, the total annual dust emission and deposition fluxes obtained with our four experiments range between about 3500 and 6000 Tg, which largely depend upon differences in the emitted size distribution. Considering ellipsoidal particle shapes and dust refractive indices that account for size-resolved mineralogy, we estimate the global total (longwave and shortwave) dust direct radiative effect (DRE) at the surface to range between about −0.90 and −0.63 W m−2 and at the top of the atmosphere between −0.20 and −0.28 W m−2. Our evaluation demonstrates that MONARCH is able to reproduce key features of the spatiotemporal variability of the global dust cycle with important and insightful differences between the different configurations.

Flexible multijunction solar cells embedded inside smart dust modules for outdoor applications to Smart Grids

The functioning of self-sustaining smart dust modules plays a vital role in the development of the smart electric grid. In this work, we first devise a flexible triple-junction III-V solar cell embedded inside a smart dust module suitable for outdoor applications. These flexible solar cells are demonstrated to have a bending radius of over 5 cm and exhibit a conversion efficiency of around 25% under air mass 1.5G (1 sun) conditions. Under normal incidence of sunlight at the same conditions, our cell with its small active area of 0.4 cm2 can generate around 10.1 mW of electrical power. This is sufficient to meet the direct current power consumption (∼5.4 mW) requirements of our dust module, which includes a temperature/moisture sensor, a 3-axis linear accelerometer, and a Bluetooth chip. In comparison to a silicon-based flexible solar cell, our demonstrated III-V solar cell is smaller, requiring approximately 40% of the area to produce the same electrical power output. Our dust module is controlled using a self-developed Android application installed on a smartphone and can sustain continuous-wave operation for data collection and wireless transmission even when the incident angle of the sunlight reaches 75°. Pulse-mode operation is still possible even in the case of nearly 90° illuminations (for example, at sunset). Overall, the measurement results for this flexible solar cell are promising, allowing for further reduction in the size of a self-sustaining smart dust module with improved reliability. These advantages could facilitate development of the next generation of energy saving smart electric grids.

A kind of new “dust-free” rice thresher

The project was designed based on air curtain dust control of novel small rice threshing apparatus, mainly involves dust reduction in the working process of agricultural machinery, specifically belongs to the field of agricultural machinery emission reduction. The apparatus is designed feeding modules, threshing modules, dust module, the control module total four modules, means by using a vertical multi-feeding port semi-feeding type of structure, in the while maintaining efficiency reduction rolling straw produced powder dust and realizes dust removal from the source. By adopting the air curtain dust control technology, the dust produced is restrained within the specified range at the first time of diffusion, and further dust control is realized.

Potential Dust Induced Changes on the Seasonal Variability of Temperature Extremes Over the Sahel: A Regional Climate Modeling Study

The aim of this study is to simulate the impact of mineral dust emissions from the Sahel–Saharan zone on temperature extremes over the Sahel. To achieve this goal, we performed two numerical simulations: one with the standard version of the regional climate model RegCM4 (no dust run) and another one with the same version of this model incorporating a dust module (dust run). The difference between both versions of the model allowed to isolate the impacts of mineral dust emissions on temperature extremes. The results show that the accumulation of mineral dust into the atmosphere leads to a decrease of the frequency of warm days, very warm days, and warm nights over the Sahel. This decrease is higher during the MAM (March-April-May) and JJA (June-July-August) periods especially in the northern and western parts of the Sahel. The impact of the mineral dust emissions is also manifested by a decrease of the frequency of tropical nights especially during MAM in the northern Sahel. When considering the warm spells, mineral particles tend to weaken them especially in MAM and JJA in the northern Sahel. To estimate the potential impacts of the mineral dust accumulation on heat stress, the heat index and the humidex are used. The analysis of the heat index shows that the dust impact is to reduce the health risks particularly in the northern Sahel during the MAM period, in the western Sahel during JJA, and in the southern and the northeastern parts of the Sahel during the SON (September-October-November) period. As for the humidex, it is characterized by a decrease especially in the northern Sahel for all seasons. This reduction of the occurrence of thermal extremes may have a positive effect on the energy demand for cooling and on global health. However, the accumulation of dust particles in the atmosphere may also increase the meningitis incidence and prevalence.

Modelling DESTINY+ interplanetary and interstellar dust measurements en route to the active asteroid (3200) Phaethon

The JAXA/ISAS spacecraft DESTINY+ will be launched to the active asteroid (3200) Phaethon in 2022. Among the proposed core payload is the DESTINY+ Dust Analyzer (DDA) which is an upgrade of the Cosmic Dust Analyzer flown on the Cassini spacecraft to Saturn (Srama et al., 2011). We use two up-to-date computer models, the ESA Interplanetary Meteoroid Engineering Model (IMEM, Dikarev et al., 2005a, c), and the interstellar dust module of the Interplanetary Meteoroid environment for EXploration model (IMEX;Sterken et al. 2013; Strub et al., 2019) to study the detection conditions and fluences of interplanetary and interstellar dust with DDA. Our results show that a statistically significant number of interplanetary and interstellar dust particles will be detectable with DDA during the 4-years interplanetary cruise of DESTINY+. The particle impact direction and speed can be used to descriminate between interstellar and interplanetary particles and likely also to distinguish between cometary and asteroidal particles.