scholarly journals Parameterization of oceanic whitecap fraction based on satellite observations

2016 ◽  
Vol 16 (21) ◽  
pp. 13725-13751 ◽  
Author(s):  
Monique F. M. A. Albert ◽  
Magdalena D. Anguelova ◽  
Astrid M. M. Manders ◽  
Martijn Schaap ◽  
Gerrit de Leeuw
Keyword(s):  
Wind Speed ◽  
Regional Scale ◽  
Global Scale ◽  
Sea Spray ◽  
Emission Rates ◽  
Data Set ◽  
Starting Point ◽  
Different Seasons ◽  
Sea Spray Aerosol ◽  
Intrinsic Correlation

Abstract. In this study, the utility of satellite-based whitecap fraction (W) data for the prediction of sea spray aerosol (SSA) emission rates is explored. More specifically, the study aims at evaluating how an account for natural variability of whitecaps in the W parameterization would affect SSA mass flux predictions when using a sea spray source function (SSSF) based on the discrete whitecap method. The starting point is a data set containing W data for 2006 together with matching wind speed U10 and sea surface temperature (SST) T. Whitecap fraction W was estimated from observations of the ocean surface brightness temperature TB by satellite-borne radiometers at two frequencies (10 and 37 GHz). A global-scale assessment of the data set yielded approximately quadratic correlation between W and U10. A new global W(U10) parameterization was developed and used to evaluate an intrinsic correlation between W and U10 that could have been introduced while estimating W from TB. A regional-scale analysis over different seasons indicated significant differences of the coefficients of regional W(U10) relationships. The effect of SST on W is explicitly accounted for in a new W(U10, T) parameterization. The analysis of W values obtained with the new W(U10) and W(U10, T) parameterizations indicates that the influence of secondary factors on W is for the largest part embedded in the exponent of the wind speed dependence. In addition, the W(U10, T) parameterization is able to partially model the spread (or variability) of the satellite-based W data. The satellite-based parameterization W(U10, T) was applied in an SSSF to estimate the global SSA emission rate. The thus obtained SSA production rate for 2006 of 4.4  ×  1012 kg year−1 is within previously reported estimates, however with distinctly different spatial distribution.

scholarly journals Parameterization of oceanic whitecap fraction based on satellite observations

2015 ◽  
Vol 15 (15) ◽  
pp. 21219-21269 ◽  
Author(s):  
M. F. M. A. Albert ◽  
M. D. Anguelova ◽  
A. M. M. Manders ◽  
M. Schaap ◽  
G. de Leeuw
Keyword(s):  
Wind Speed ◽  
Regional Scale ◽  
Regional Analysis ◽  
Global Scale ◽  
Sea Spray ◽  
Emission Rates ◽  
Data Set ◽  
Scale Assessment ◽  
Starting Point ◽  
Speed Dependence

Abstract. In this study the utility of satellite-based whitecap fraction (W) values for the prediction of sea spray aerosol (SSA) emission rates is explored. More specifically, the study is aimed at improving the accuracy of the sea spray source function (SSSF) derived by using the whitecap method through the reduction of the uncertainties in the parameterization of W by better accounting for its natural variability. The starting point is a dataset containing W data, together with matching environmental and statistical data, for 2006. Whitecap fraction W was estimated from observations of the ocean surface brightness temperature TB by satellite-borne radiometers at two frequencies (10 and 37 GHz). A global scale assessment of the data set to evaluate the wind speed dependence of W revealed a quadratic correlation between W and U10, as well as a relatively larger spread in the 37 GHz data set. The latter could be attributed to secondary factors affecting W in addition to U10. To better visualize these secondary factors, a regional scale assessment over different seasons was performed. This assessment indicates that the influence of secondary factors on W is for the largest part imbedded in the exponent of the wind speed dependence. Hence no further improvement can be expected by looking at effects of other factors on the variation in W explicitly. From the regional analysis, a new globally applicable quadratic W(U10) parameterization was derived. An intrinsic correlation between W and U10 that could have been introduced while estimating W from TB was determined, evaluated and presumed to lie within the error margins of the newly derived W(U10) parameterization. The satellite-based parameterization was compared to parameterizations from other studies and was applied in a SSSF to estimate the global SSA emission rate. The thus obtained SSA production for 2006 of 4.1 × 1012 kg is within previously reported estimates. While recent studies that account for parameters other than U10 explicitly could be suitable to improve predictions of SSA emissions, we promote our new W(U10) parameterization as an alternative approach that implicitly accounts for these different parameters and helps to improve SSA emission estimates equally well.

scholarly journals HTAP_v2.2: a mosaic of regional and global emission grid maps for 2008 and 2010 to study hemispheric transport of air pollution

2015 ◽  
Vol 15 (19) ◽  
pp. 11411-11432 ◽  
Author(s):  
G. Janssens-Maenhout ◽  
M. Crippa ◽  
D. Guizzardi ◽  
F. Dentener ◽  
M. Muntean ◽  
...  
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Low Income ◽  
Regional Scale ◽  
Global Scale ◽  
Air Pollutant ◽  
Pollutant Emissions ◽  
Pollution Transport ◽  
Data Set ◽  
Per Capita

Abstract. The mandate of the Task Force Hemispheric Transport of Air Pollution (TF HTAP) under the Convention on Long-Range Transboundary Air Pollution (CLRTAP) is to improve the scientific understanding of the intercontinental air pollution transport, to quantify impacts on human health, vegetation and climate, to identify emission mitigation options across the regions of the Northern Hemisphere, and to guide future policies on these aspects. The harmonization and improvement of regional emission inventories is imperative to obtain consolidated estimates on the formation of global-scale air pollution. An emissions data set has been constructed using regional emission grid maps (annual and monthly) for SO2, NOx, CO, NMVOC, NH3, PM10, PM2.5, BC and OC for the years 2008 and 2010, with the purpose of providing consistent information to global and regional scale modelling efforts. This compilation of different regional gridded inventories – including that of the Environmental Protection Agency (EPA) for USA, the EPA and Environment Canada (for Canada), the European Monitoring and Evaluation Programme (EMEP) and Netherlands Organisation for Applied Scientific Research (TNO) for Europe, and the Model Inter-comparison Study for Asia (MICS-Asia III) for China, India and other Asian countries – was gap-filled with the emission grid maps of the Emissions Database for Global Atmospheric Research (EDGARv4.3) for the rest of the world (mainly South America, Africa, Russia and Oceania). Emissions from seven main categories of human activities (power, industry, residential, agriculture, ground transport, aviation and shipping) were estimated and spatially distributed on a common grid of 0.1° × 0.1° longitude-latitude, to yield monthly, global, sector-specific grid maps for each substance and year. The HTAP_v2.2 air pollutant grid maps are considered to combine latest available regional information within a complete global data set. The disaggregation by sectors, high spatial and temporal resolution and detailed information on the data sources and references used will provide the user the required transparency. Because HTAP_v2.2 contains primarily official and/or widely used regional emission grid maps, it can be recommended as a global baseline emission inventory, which is regionally accepted as a reference and from which different scenarios assessing emission reduction policies at a global scale could start. An analysis of country-specific implied emission factors shows a large difference between industrialised countries and developing countries for acidifying gaseous air pollutant emissions (SO2 and NOx) from the energy and industry sectors. This is not observed for the particulate matter emissions (PM10, PM2.5), which show large differences between countries in the residential sector instead. The per capita emissions of all world countries, classified from low to high income, reveal an increase in level and in variation for gaseous acidifying pollutants, but not for aerosols. For aerosols, an opposite trend is apparent with higher per capita emissions of particulate matter for low income countries.

scholarly journals Factors driving the seasonal and hourly variability of sea-spray aerosol number in the North Atlantic

2019 ◽  
Vol 116 (41) ◽  
pp. 20309-20314 ◽  
Author(s):  
Georges Saliba ◽  
Chia-Li Chen ◽  
Savannah Lewis ◽  
Lynn M. Russell ◽  
Laura-Helena Rivellini ◽  
...  
Keyword(s):  
Wind Speed ◽  
North Atlantic ◽  
Climate Models ◽  
Marine Boundary Layer ◽  
Phytoplankton Bloom ◽  
Cloud Condensation Nuclei ◽  
Sea Spray ◽  
Wind Speeds ◽  
The North ◽  
Sea Spray Aerosol

Four North Atlantic Aerosol and Marine Ecosystems Study (NAAMES) field campaigns from winter 2015 through spring 2018 sampled an extensive set of oceanographic and atmospheric parameters during the annual phytoplankton bloom cycle. This unique dataset provides four seasons of open-ocean observations of wind speed, sea surface temperature (SST), seawater particle attenuation at 660 nm (cp,660, a measure of ocean particulate organic carbon), bacterial production rates, and sea-spray aerosol size distributions and number concentrations (NSSA). The NAAMES measurements show moderate to strong correlations (0.56 < R < 0.70) between NSSA and local wind speeds in the marine boundary layer on hourly timescales, but this relationship weakens in the campaign averages that represent each season, in part because of the reduction in range of wind speed by multiday averaging. NSSA correlates weakly with seawater cp,660 (R = 0.36, P << 0.01), but the correlation with cp,660, is improved (R = 0.51, P < 0.05) for periods of low wind speeds. In addition, NAAMES measurements provide observational dependence of SSA mode diameter (dm) on SST, with dm increasing to larger sizes at higher SST (R = 0.60, P << 0.01) on hourly timescales. These results imply that climate models using bimodal SSA parameterizations to wind speed rather than a single SSA mode that varies with SST may overestimate SSA number concentrations (hence cloud condensation nuclei) by a factor of 4 to 7 and may underestimate SSA scattering (hence direct radiative effects) by a factor of 2 to 5, in addition to overpredicting variability in SSA scattering from wind speed by a factor of 5.

scholarly journals What is the P value of Siberian soils? Soil phosphorus status in south-western Siberia and comparison with a global data set

2016 ◽  
Vol 13 (8) ◽  
pp. 2493-2509 ◽  
Author(s):  
Félix Brédoire ◽  
Mark R. Bakker ◽  
Laurent Augusto ◽  
Pavel A. Barsukov ◽  
Delphine Derrien ◽  
...  
Keyword(s):  
Agricultural Development ◽  
Western Siberia ◽  
Regional Scale ◽  
Global Scale ◽  
Available P ◽  
Northern Eurasia ◽  
Data Set ◽  
Slow Kinetics ◽  
Wide Range ◽  
Plant Available P

Abstract. Climate change is particularly strong in northern Eurasia and substantial ecological changes are expected in this extensive region. The reshaping and migration northwards of bioclimatic zones may offer opportunities for agricultural development in western and central Siberia. However, the bioclimatic vegetation models currently employed for projections still do not consider soil fertility, in spite of this being highly critical for plant growth. In the present study, we surveyed the phosphorus (P) status in the south-west of Siberia where soils have developed on loess parent material. We selected six sites differing in pedoclimatic conditions and the soil was sampled at different depths down to 1 m in aspen (Populus tremula L.) forest as well as in grassland areas. The P status was assessed by conventional methods and by isotope dilution kinetics. We found that P concentrations and stocks, as well as their distribution through the soil profile, were fairly homogeneous on the regional scale studied, although there were some differences between sites (particularly in organic P). The young age of the soils, together with slow kinetics of soil formation processes have probably not yet resulted in a sufficiently wide range of soil physico-chemical conditions to observe a more diverging P status. The comparison of our data set with similar vegetation contexts on the global scale revealed that the soils of south-western Siberia, and more generally of northern Eurasia, often have (very) high levels of total, organic and inorganic P. The amount of plant-available P in topsoils, estimated by the isotopically exchangeable phosphate ions, was not particularly high but was intermediate on the global scale. However, large stocks of plant-available P are stored in subsurface layers which currently have low fine-root exploration intensities. These results suggest that the P resource is unlikely to constrain vegetation growth and agricultural development under the present conditions or in the near future.

scholarly journals Wind speed dependent size-resolved parameterization for the organic mass fraction of sea spray aerosol

2011 ◽  
Vol 11 (16) ◽  
pp. 8777-8790 ◽  
Author(s):  
B. Gantt ◽  
N. Meskhidze ◽  
M. C. Facchini ◽  
M. Rinaldi ◽  
D. Ceburnis ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Wind Speed ◽  
Organic Carbon ◽  
Mass Fraction ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Sea Spray ◽  
Organic Mass ◽  
Chl A ◽  
Sea Spray Aerosol

Abstract. For oceans to be a significant source of primary organic aerosol (POA), sea spray aerosol (SSA) must be highly enriched with organics relative to the bulk seawater. We propose that organic enrichment at the air-sea interface, chemical composition of seawater, and the aerosol size are three main parameters controlling the organic mass fraction of sea spray aerosol (OMSSA). To test this hypothesis, we developed a new marine POA emission function based on a conceptual relationship between the organic enrichment at the air-sea interface and surface wind speed. The resulting parameterization is explored using aerosol chemical composition and surface wind speed from Atlantic and Pacific coastal stations, and satellite-derived ocean concentrations of chlorophyll-a, dissolved organic carbon, and particulate organic carbon. Of all the parameters examined, a multi-variable logistic regression revealed that the combination of 10 m wind speed and surface chlorophyll-a concentration ([Chl-a]) are the most consistent predictors of OMSSA. This relationship, combined with the published aerosol size dependence of OMSSA, resulted in a new parameterization for the organic mass fraction of SSA. Global emissions of marine POA are investigated here by applying this newly-developed relationship to existing sea spray emission functions, satellite-derived [Chl-a], and modeled 10 m winds. Analysis of model simulations shows that global annual submicron marine organic emission associated with sea spray is estimated to be from 2.8 to 5.6 Tg C yr−1. This study provides additional evidence that marine primary organic aerosols are a globally significant source of organics in the atmosphere.

Global scale emission and distribution of sea-spray aerosol: Sea-salt and organic enrichment

2010 ◽  
Vol 44 (5) ◽  
pp. 670-677 ◽  
Author(s):  
E. Vignati ◽  
M.C. Facchini ◽  
M. Rinaldi ◽  
C. Scannell ◽  
D. Ceburnis ◽  
...  
Keyword(s):  
Global Scale ◽  
Sea Salt ◽  
Organic Enrichment ◽  
Sea Spray ◽  
Sea Spray Aerosol

The sensitivity of Southern Ocean aerosol concentrations to sea spray and DMS emissions in the HadGEM3-GA7.1 chemistry–climate model

2020 ◽  
Author(s):  
Laura Revell ◽  
Stefanie Kremser ◽  
Sean Hartery ◽  
Mike Harvey ◽  
Jane Mulcahy ◽  
...  
Keyword(s):  
Wind Speed ◽  
Southern Ocean ◽  
Source Function ◽  
Climate Model ◽  
Cloud Condensation Nuclei ◽  
Number Concentration ◽  
Sea Spray ◽  
Condensation Nuclei ◽  
Sea Spray Aerosol ◽  
Aerosol Source

&lt;p&gt;With low concentrations of tropospheric aerosol, the Southern Ocean offers a &quot;natural laboratory&quot; for studies of aerosol&amp;#8211;cloud interactions. Aerosols over the Southern Ocean are produced from biogenic activity in the ocean, which generates sulfate aerosol via dimethylsulfide (DMS) oxidation, and from strong winds and waves that lead to bubble bursting and sea spray emission. Here, we evaluate the representation of Southern Ocean aerosols in the Hadley Centre Global Environmental Model version 3, Global Atmosphere 7.1 (HadGEM3-GA7.1) chemistry&amp;#8211;climate model. Compared with aerosol optical depth (AOD) observations from two satellite instruments (the Moderate Resolution Imaging Spectroradiometer, MODIS-Aqua c6.1, and the Multi-angle Imaging Spectroradiometer, MISR), the model simulates too-high AOD during winter and too-low AOD during summer. By switching off DMS emission in the model, we show that sea spray aerosol is the dominant contributor to AOD during winter. In turn, the simulated sea spray aerosol flux depends on near-surface wind speed. By examining MODIS AOD as a function of wind speed from the ERA-Interim reanalysis and comparing it with the model, we show that the sea spray aerosol source function in HadGEM3-GA7.1 overestimates the wind speed dependency. We test a recently developed sea spray aerosol source function derived from measurements made on a Southern Ocean research voyage in 2018. In this source function, the wind speed dependency of the sea spray aerosol flux is less than in the formulation currently implemented in HadGEM3-GA7.1. The new source function leads to good agreement between simulated and observed wintertime AODs over the Southern Ocean; however, it reveals partially compensating errors in DMS-derived AOD. While previous work has tested assumptions regarding the seawater climatology or sea&amp;#8211;air flux of DMS, we test the sensitivity of simulated AOD, cloud condensation nuclei and cloud droplet number concentration to three atmospheric sulfate chemistry schemes. The first scheme adds DMS oxidation by halogens and the other two test a recently developed sulfate chemistry scheme for the marine troposphere; one tests gas-phase chemistry only, while the second adds extra aqueous-phase sulfate reactions. We show how simulated sulfur dioxide and sulfuric acid profiles over the Southern Ocean change as a result and how the number concentration and particle size of the soluble Aitken, accumulation and coarse aerosol modes are affected. The new DMS chemistry scheme leads to a 20% increase in the number concentration of cloud condensation nuclei and cloud droplets, which improves agreement with observations. Our results highlight the importance of atmospheric chemistry for simulating aerosols and clouds accurately over the Southern Ocean.&lt;/p&gt;

scholarly journals A Dynamic Link between Ice Nucleating Particles Released in Nascent Sea Spray Aerosol and Oceanic Biological Activity during Two Mesocosm Experiments

2017 ◽  
Vol 74 (1) ◽  
pp. 151-166 ◽  
Author(s):  
Christina S. McCluskey ◽  
Thomas C. J. Hill ◽  
Francesca Malfatti ◽  
Camille M. Sultana ◽  
Christopher Lee ◽  
...  
Keyword(s):  
Biological Activity ◽  
Heterotrophic Bacteria ◽  
Phytoplankton Bloom ◽  
Sea Spray ◽  
Emission Rates ◽  
Phytoplankton Blooms ◽  
Aerosol Composition ◽  
Chl A ◽  
Mesocosm Experiments ◽  
Sea Spray Aerosol

Abstract Emission rates and properties of ice nucleating particles (INPs) are required for proper representation of aerosol–cloud interactions in atmospheric models. Few investigations have quantified marine INP emissions, a potentially important INP source for remote oceanic regions. Previous studies have suggested INPs in sea spray aerosol (SSA) are linked to oceanic biological activity. This proposed link was explored in this study by measuring INP emissions from nascent SSA during phytoplankton blooms during two mesocosm experiments. In a Marine Aerosol Reference Tank (MART) experiment, a phytoplankton bloom was produced with chlorophyll-a (Chl a) concentrations reaching 39 μg L−1, while Chl a concentrations more representative of natural ocean conditions were obtained during the Investigation into Marine Particle Chemistry and Transfer Science (IMPACTS; peak Chl a of 5 μg L−1) campaign, conducted in the University of California, San Diego, wave flume. Dynamic trends in INP emissions occurred for INPs active at temperatures &gt; −30°C. Increases in INPs active between −25° and −15°C lagged the peak in Chl a in both studies, suggesting a consistent population of INPs associated with the collapse of phytoplankton blooms. Trends in INP emissions were also compared to aerosol composition, abundances of microbes, and enzyme activity. In general, increases in INP concentrations corresponded to increases in organic species in SSA and the emissions of heterotrophic bacteria, suggesting that both microbes and biomolecules contribute to marine INP populations. INP trends were not directly correlated with a single biological marker in either study. Direct measurements of INP chemistry are needed to accurately identify particles types contributing to marine INP populations.

scholarly journals An empirically derived inorganic sea spray source function incorporating sea surface temperature

2015 ◽  
Vol 15 (9) ◽  
pp. 13783-13826 ◽  
Author(s):  
M. E. Salter ◽  
P. Zieger ◽  
J. C. Acosta Navarro ◽  
H. Grythe ◽  
A. Kirkevåg ◽  
...  
Keyword(s):  
Wind Speed ◽  
Source Function ◽  
Particle Production ◽  
Seawater Temperature ◽  
Air Entrainment ◽  
Scale Model ◽  
Sea Spray ◽  
Laboratory Measurements ◽  
Wide Range ◽  
Sea Spray Aerosol

Abstract. We have developed an inorganic sea spray source function that is based upon state-of-the-art measurements of sea spray aerosol production using a temperature-controlled plunging jet sea spray aerosol chamber. The size-resolved particle production was measured between 0.01 and 10 μm dry diameter. Particle production decreased non-linearly with increasing seawater temperature (between −1 and 30 °C) similar to previous findings. In addition, we observed that the particle effective radius as well as the particle-surface, -volume and -mass, increased with increasing seawater temperature due to increased production of super-micron particles. By combining these measurements with the volume of air entrained by the plunging jet we have determined the size-resolved particle flux as a function of air entrainment. Through the use of existing parameterisations of air entrainment as a function of wind speed we were subsequently able to scale our laboratory measurements of particle production to wind speed. By scaling in this way we avoid the difficulties associated with defining the "white-area" of the laboratory whitecap – a contentious issue when relating laboratory measurements of particle production to oceanic whitecaps using the more frequently applied whitecap method. The here-derived inorganic sea spray sea spray source function was implemented in a Lagrangian particle dispersion model (FLEXPART). An estimated annual global flux of inorganic sea spray aerosol of 5.9 ± 0.2 Pg yr−1 was derived that is close to the median of estimates from the same model using a wide range of existing sea spray source functions. When using the source function derived here, the model also showed good skill in predicting measurements of Na+ concentration at a number of field sites further underlining the validity of our source function. In a final step, the sensitivity of a large-scale model (NorESM) to our new source function was tested. Compared to the previously implemented parameterisation, a clear decrease of sea spray aerosol number flux and increase in aerosol residence time was observed, especially over the Southern Ocean. At the same time an increase in aerosol optical depth due to an increase in the number of particles with optically relevant sizes was found. That there were noticeable regional differences may have important implications for aerosol optical properties and number concentrations, subsequently also affecting the indirect radiative forcing by non-sea spray anthropogenic aerosols.

scholarly journals Diel cycle of sea spray aerosol concentration over vast areas of the tropical Pacific Ocean and the Caribbean Sea

2020 ◽  
Author(s):  
J. Michel Flores ◽  
Guillaume Bourdin ◽  
Alexander Kostinski ◽  
Orit Altaratz ◽  
Guy Dagan ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Caribbean Sea ◽  
Global Scale ◽  
Number Concentration ◽  
Sea Spray ◽  
Near Surface ◽  
The Pacific ◽  
Sea Spray Aerosol ◽  
The Pacific Ocean ◽  
Size Of Particles

Abstract Ocean-atmosphere interactions such as sea spray aerosol (SSA) formation have a major role in the climate system, but a global-scale assessment of this micro-scale process is highly challenging. We measured high-resolution temporal patterns of SSA number concentration over the Atlantic Ocean, Caribbean Sea, and the Pacific Ocean covering 42,000 km of open ocean waters. We discovered a ubiquitous 24-hour rhythm to the number concentration, clearly seen for particle diameters > ~ 0.58 µm, with spikes at dawn and drops at dusk throughout the Pacific Ocean and Caribbean Sea, showing more than doubling of the SSA number concentration during the day than at night. No correlation with surface winds, atmospheric radiation, pollution nor oceanic physical properties were found. Instead, parallel diel patterns in particle sizes detected in near-surface waters, attributed to variations in the size of particles smaller than ~ 1 µm, point to microbial day-to-night modulation of bubble-bursting dynamics as the cause of the SSA cycle.

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