Impact of cloud-borne aerosol representation on aerosol direct and indirect effects

International audienceAerosol particles attached to cloud droplets are much more likely to be removed from the atmosphere and are much less efficient at scattering sunlight than if unattached. Models used to estimate direct and indirect effects of aerosols employ a variety of representations of such cloud-borne particles. Here we use a global aerosol model with a relatively complete treatment of cloud-borne particles to estimate the sensitivity of simulated aerosol, cloud and radiation fields to various approximations to the representation of cloud-borne particles. We find that neglecting transport of cloud-borne particles introduces little error, but that diagnosing cloud-borne particles produces global mean biases of 20% and local errors of up to 40% for aerosol, droplet number, and direct and indirect radiative forcing. Aerosol number, aerosol optical depth and droplet number are significantly underestimated in regions and seasons where and when wet removal is primarily by stratiform rather than convective clouds (polar regions during winter), but direct and indirect effects are less biased because of the limited sunlight there and then. A treatment that predicts the total mass concentration of cloud-borne particles for each mode yields smaller errors and runs 20% faster than the complete treatment. The errors are much smaller than current estimates of uncertainty in direct and indirect effects of aerosols, which suggests that the treatment of cloud-borne aerosol is not a significant source of uncertainty in estimates of direct and indirect effects

Numerical modelling of liquid droplet dynamics in microgravity

Microgravity provides ideal experimental conditions for studying highly reactive and under-cooled materials where there is no contact between the sample and the other experimental apparatus. The non-contact conditions allow material properties to be measured from the oscillating liquid droplet response to perturbations. This work investigates the impact of a strong magnetic field on these measurement processes for weakly viscous, electrically conducting droplets. We present numerical results using an axisymmetric model that employs the pseudo-spectral collocation method and a recently developed 3D model. Both numerical models have been developed to solve the equations describing the coupled electromagnetic and fluid flow processes. The models represent the changing surface shape that results from the interaction between forces inside the droplet and the surface tension imposed boundary conditions. The models are used to examine the liquid droplet dynamics in a strong DC magnetic field. In each case the surface shape is decomposed into a superposition of spherical harmonic modes. The oscillation of the individual mode coefficients is then analysed to determine the oscillation frequencies and damping rates that are then compared to the low amplitude solutions predicted by the published analytical asymptotic theory

STUDI EKOLOGI OSEANOGRAFI TELUK MANADO UNTUK PENENTUAN STRUKTUR ARTIFICIAL CORAL GARDEN DAN AREA MANGROVE SEBAGAI DESTINASI WISATA BARU

The purpose of this study is to investigate the ecological conditions of mangrove ecosystems in the Manado Bay and analyze the suitability of the mangrove ecosystems as a new tourist destination, examine the oceanographic conditions in the Manado Bay area, study the data on the development of coral reef ecosystems to be able to produce artificial coral reefs and produce mangrove areas and coral reefs artificial as a new tourist destination. This research was conducted in April - September 2019 with the location of Manado Bay and the location of the Manado Bay coral reef ecosystem survey set at 3 sample points, equipped with 3 points in front of the BOBOCA Malalayang monument, in front of the Malalayang gas station and ANTRA Sario. Retrieval of coral reef data is by using the Line Intercept Transect (LIT) method. LIT observations were carried out with SCUBA diving at a depth of 6m. Observations were made by recording coral lifeforms found along the transect line, and calculating the percentage of the selection. The data taken is the percentage of dead coral cover, live coral, and type of life form, diversity index taken at 3 sample points. From field observations found on Site 2 (Front of Malalayang gas station) the condition of coral reefs is included in the good category, with the percentage of live coral cover (Hard Coral) of 55%. At this station found various types of coral growth, but the highest at this station is a form of growth of Coral Masive (CM) of 19.2%, while the least found were corals in the form of Coral Mushrooms (Mushroom Coral) with a percentage of 0.4 %. Then Site 3, namely in ANTRA Sario obtained from coral reefs is included in the bad category, with the percentage of live coral cover (Hard Coral) only 7.1%. Coral Diversity in the three survey stations is different. Of the three stations determined above the Tugu Boboca Malalayang site with an index value of 2.54, followed at site 2 namely the Malalayang gas station with an index value of 2.36 and the lowest at site 3 at ANTRA Sario with an index value of 1.33. Furthermore, oceanographic conditions in the Gulf of Manado region are seen in the receding period, most of the air moves westward at the beginning of the period, then moves northeastward in the next period. While in the tide period the water moves northward, starting the period and then it is seen moving northeast and at the end of the period, the east direction.Key words : Coral reef, Oceanographic conditio

Indirect radiative forcing by ion-mediated nucleation of aerosol

A clear understanding of particle formation mechanisms is critical for assessing aerosol indirect radiative forcing and associated climate feedback processes. Recent studies reveal the importance of ion-mediated nucleation (IMN) in generating new particles and cloud condensation nuclei (CCN) in the atmosphere. Here we implement the IMN scheme into the Community Atmosphere Model version 5 (CAM5). Our simulations show that, compared to globally averaged results based on H<sub>2</sub>SO<sub>4</sub>-H<sub>2</sub>O binary homogeneous nucleation (BHN), the presence of ionization (i.e., IMN) halves H<sub>2</sub>SO<sub>4</sub> column burden, but increases the column integrated nucleation rate by around one order of magnitude, total particle number burden by a factor of ~3, CCN burden by ~10% (at 0.2% supersaturation) to 65% (at 1.0% supersaturation), and cloud droplet number burden by ~18%. Compared to BHN, IMN increases cloud liquid water path by 7.5%, decreases precipitation by 1.1%, and increases total cloud cover by 1.9%. This leads to an increase of total shortwave cloud radiative forcing (SWCF) by 3.67 W m<sup>−2</sup> (more negative) and longwave cloud forcing by 1.78 W m<sup>−2</sup> (more positive), with large spatial variations. The effect of ionization on SWCF derived from this study (3.67 W m<sup>−2</sup>) is a factor of ~3 higher that of a previous study (1.15 W m<sup>−2</sup>) based on a different ion nucleation scheme and climate model. Based on the present CAM5 simulation, the 5-yr mean impacts of solar cycle induced changes in ionization rates on CCN and cloud forcing are small (~−0.02 W m<sup>−2</sup>) but have larger inter-annual (from −0.18 to 0.17 W m<sup>−2</sup>) and spatial variations

Global distribution and climate forcing of marine organic aerosol: 1. Model improvements and evaluation

Marine organic aerosol emissions have been implemented and evaluated within the National Center of Atmospheric Research (NCAR)'s Community Atmosphere Model (CAM5) with the Pacific Northwest National Laboratory's 7-mode Modal Aerosol Module (MAM-7). Emissions of marine primary organic aerosols (POA), phytoplankton-produced isoprene- and monoterpenes-derived secondary organic aerosols (SOA) and methane sulfonate (MS<sup>−</sup>) are shown to affect surface concentrations of organic aerosols in remote marine regions. Global emissions of submicron marine POA is estimated to be 7.9 and 9.4 Tg yr<sup>−1</sup>, for the Gantt et al. (2011) and Vignati et al. (2010) emission parameterizations, respectively. Marine sources of SOA and particulate MS<sup>−</sup> (containing both sulfur and carbon atoms) contribute an additional 0.2 and 5.1 Tg yr<sup>−1</sup>, respectively. Widespread areas over productive waters of the Northern Atlantic, Northern Pacific, and the Southern Ocean show marine-source submicron organic aerosol surface concentrations of 100 ng m<sup>−3</sup>, with values up to 400 ng m<sup>−3</sup> over biologically productive areas. Comparison of long-term surface observations of water insoluble organic matter (WIOM) with POA concentrations from the two emission parameterizations shows that despite revealed discrepancies (often more than a factor of 2), both Gantt et al. (2011) and Vignati et al. (2010) formulations are able to capture the magnitude of marine organic aerosol concentrations, with the Gantt et al. (2011) parameterization attaining better seasonality. Model simulations show that the mixing state of the marine POA can impact the surface number concentration of cloud condensation nuclei (CCN). The largest increases (up to 20%) in CCN (at a supersaturation (<i>S</i>) of 0.2%) number concentration are obtained over biologically productive ocean waters when marine organic aerosol is assumed to be externally mixed with sea-salt. Assuming marine organics are internally-mixed with sea-salt provides diverse results with increases and decreases in the concentration of CCN over different parts of the ocean. The sign of the CCN change due to the addition of marine organics to sea-salt aerosol is determined by the relative significance of the increase in mean modal diameter due to addition of mass, and the decrease in particle hygroscopicity due to compositional changes in marine aerosol. Based on emerging evidence for increased CCN concentration over biologically active surface ocean areas/periods, our study suggests that treatment of sea spray in global climate models (GCMs) as an internal mixture of marine organic aerosols and sea-salt will likely lead to an underestimation in CCN number concentration

DAYA TARIK Dugong dugon SEBAGAI POTENSI WISATA DI KAWASAN PERAIRAN DESA ARAKAN KABUPATEN MINAHASA SELATAN

Arakan village has great potential and opportunities in the field of tourism and as a touristattraction, so it is necessary to follow up with the management of the Dugong tourist attraction in thewaters of Arakan village. The problem formulated in this study is how to develop dugong tourismpotential inthe watersof Arakanvillage. This studyuseddescriptivemethod. Dataretrieval carriedoutinthis study was to directly visit the research site in Arakanvillage and in Arakan waters to makeobservations about the attraction of Dugong as tourism potential in Arakan village. Dugong orcommonly known by the locals as duyung is one of 35 species of marine mammals found in Indonesianwaters, especially in seagrass habitats. In this study, it was found that the attraction of Dugong as atourism potential in the waters of the Arakan village, the South Minahasa regency, North Sulawesiprovince, although it is only of particular interest to Dugong lovers. From observations made throughthis study, twodugongs were found in the Kolam Dugong area in the waters of Arakan village in aseagrasshabitat of 176.25 ha.Keywords: Dugong, Arakan Village ABSTRAKDesa Arakan memiliki potensi dan peluang yang besar dalam bidang pariwisata dan sebagaisalah satudayatarik wisata makaperluditindaklanjutidenganpengelolaan dayatarikwisata Dugong dikawasan perairan desa Arakan dan masalah yang dirumuskan dalam penelitianini adalahbagaimanamengembangkan potensi wisata dugong di kawasan perairandesa Arakan. dengan menggunakanmetode deskriptif. Pengambilan data yang dilakukan dalam penelitian ini adalah dengan mengunjungilangsung tempat penelitian di desa Arakandan di perairan Arakan serta melakukan pengamatantentang daya tarik Dugong sebagai potensi wisata di desa Arakan. Dugong atau biasa dikenal dengannama duyung merupakan satu dari 35 jenis mamalia laut yang dijumpai yang tersebar di perairanindonesia, khususnyadi habitat padang lamun. Pada peneltian ini didapati daya tarik Dugong sebagaipotensi wisata di peraiaran desa Arakan kecamatan Tatapan kabupaten minahasa selatan provinsisulawesi utara, walaupun hanya diminati secara khusus oleh pencinta Dugong. Dari pengamatan yangdilakukan malalui penelitian ini di jumpai 2 hewan Dugong di area kolamDugong perairan desa Arakanpada habitat lamun seluas 176,25 ha. Kata Kunci: Dugong, Desa Araka

Growth of the adult goldfish eye--I: Optics

We have measured the optical and retinal fields of goldfish eyes; the animals ranged from 6 to 20 cm in body length. Both fields are spherically symmetric, invariant with the size of the eye, and equal (retinal FIELD = 185.3[deg] +/- 4.1[deg], optical FIELD = 183.6[deg] +/- 2.7[deg], means +/- S.D.). They are tilted with respect to one another by a few (< 10) degrees. We have also measured the retinal magnification factor, the number of [mu]m per degree on the retinal surface. It is 20.5 x lens diameter, where lens diameter is expressed in mm.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23062/1/0000634.pd

Global volcanic aerosol properties derived from emissions, 1990-2014, using CESM1(WACCM)

Accurate representation of global stratospheric aerosols from volcanic and non-volcanic sulfur emissions is key to understanding the cooling effects and ozone-losses that may be linked to volcanic activity. Attribution of climate variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the rate of global average temperature increases. We have compiled a database of volcanic SO2 emissions and plume altitudes for eruptions from 1990 to 2014, and developed a new prognostic capability for simulating stratospheric sulfate aerosols in the Community Earth System Model (CESM). We used these combined with other non-volcanic emissions of sulfur sources to reconstruct global aerosol properties from 1990 to 2014. Our calculations show remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD), and with in situ measurements of stratospheric aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD calculations represent a clear improvement over available satellite-based analyses, which generally ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at mid- and high-latitudes. Our SAD calculations greatly improve on that provided for the Chemistry-Climate Model Initiative, which misses about 60% of the SAD measured in situ on average during both volcanically active and volcanically quiescent periods