Sea spray are aerosol particles formed from the ocean, mostly by ejection into Earth's atmosphere by bursting bubbles at the air-sea interface. [1] Sea spray contains both organic matter and inorganic salts that form sea salt aerosol (SSA). [2] SSA has the ability to form cloud condensation nuclei (CCN) and remove anthropogenic aerosol pollutants from the atmosphere. [3] Coarse sea spray has also been found to inhibit the development of lightning in storm clouds. [4]
Sea spray is directly (and indirectly, through SSA) responsible for a significant degree of the heat and moisture fluxes between the atmosphere and the ocean, [5] [6] affecting global climate patterns and tropical storm intensity. [7] Sea spray also influences plant growth and species distribution in coastal ecosystems [8] and increases corrosion of building materials in coastal areas. [9]
When wind, whitecaps, and breaking waves mix air into the sea surface, the air regroups to form bubbles, floats to the surface, and bursts at the air-sea interface. [10] When they burst, they release up to a thousand particles of sea spray, [10] [11] which range in size from nanometers to micrometers and can be expelled up to 20 cm from the sea surface. [10] Film droplets make up the majority of the smaller particles created by the initial burst, while jet droplets are generated by a collapse of the bubble cavity and are ejected from the sea surface in the form of a vertical jet. [12] [11] In windy conditions, water droplets are mechanically torn off from crests of breaking waves. Sea spray droplets generated via such a mechanism are called spume droplets [11] and are typically larger in size and have less residence time in air. Impingement of plunging waves on sea surface also generates sea spray in the form of splash droplets [11] [13] . The composition of the sea spray depends primarily on the composition of the water from which it is produced, but broadly speaking is a mixture of salts and organic matter. Several factors determine the production flux of sea spray, especially wind speed, swell height, swell period, humidity, and temperature differential between the atmosphere and the surface water. [14] Production and size distribution rate of SSAs are thus sensitive to the mixing state. [15] A lesser studied area of sea spray generation is the formation of sea spray as a result of rain drop impact on the sea surface . [11]
In addition to the local conditions that influence sea spray formation, there are also consistent spatial patterns in sea spray production and composition. Because sea spray is generated when air is mixed into the ocean, formation gradients are established by turbulence of the surface water. [14] Wave action along coastal shorelines is generally where turbulence is greatest, so this is where sea spray production is the highest. Particles generated in turbulent coastal areas can travel horizontally up to 25 km within the planetary boundary layer. [14] As distance from shore decreases, sea spray production declines to a level sustained almost exclusively by whitecaps. [14] The proportion of the ocean surface area that is turbulent enough to produce significant sea spray is called the whitecap fraction. [10] The only other production mechanism of sea spray in the open ocean is through direct wind action, where strong winds actually break the surface tension of the water and lift particles into the air. [10] However, particles of seawater generated in this way are often too heavy to remain suspended in the atmosphere and usually are deposited back to the sea within a few dozen meters of transport. [10]
During winter months, the ocean typically experiences stormy, windy conditions that generate more air inundation into the sea and therefore more sea spray. [16] Calmer summer months result in lower overall production of sea spray. [16] During peak primary productivity in the summer, increased organic matter in the surface ocean drives subsequent increases in sea spray. Given that sea spray retains the properties of the water from which it was produced, the composition of sea spray experiences extreme seasonal variation. During the summer, dissolved organic carbon (DOC) can constitute 60-90% of sea spray mass. [16] Even though much more sea spray is produced during the stormy winter season, the composition is nearly all salt because of the low primary production. [16]
The organic matter in sea spray consists of dissolved organic carbon [17] (DOC) and even microbes themselves, like bacteria and viruses. [18] The amount of organic matter in sea spray depends on microbiological processes, [19] though the total effect of these processes is still unknown. [20] [21] Chlorophyll-a is often used as a proxy for primary production and organic matter content in sea spray, but its reliability for estimating dissolved organic carbon concentrations is controversial. [21] Biomass often enters sea spray through the death and lysis of algal cells, often caused by viral infections. [20] Cells are broken apart into the dissolved organic carbon that is propelled into the atmosphere when surface bubbles pop. When primary productivity peaks during the summer, algal blooms can generate an enormous amount of organic matter that is eventually incorporated into sea spray. [16] [20] In the right conditions, aggregation of the dissolved organic carbon can also form surfactant or sea foam.
At high winds the droplet evaporation layer (DEL) influences the surface energy heat exchange of the ocean. [22] The latent heat flux of sea spray generated at the droplet evaporation layer has been cited as an important addition to climate modeling efforts, particularly in simulations assessing air/sea heat balance as related to hurricanes and cyclones formed during high wind events. [6] During the formation of whitecaps, sea spray droplets exhibit the same properties as the ocean surface, but rapidly adapt to surrounding air. Some sea spray droplets immediately reabsorb into the sea while others evaporate entirely and contribute salt particles like dimethyl sulfide (DMS) to the atmosphere where they can be transported via turbulence to cloud layers and serve as cloud condensation nuclei. [15] The formation of these cloud condensation nuclei like dimethyl sulfide have climate implications as well, due to their influence on cloud formation and interaction with solar radiation. [15] Additionally, the contribution of sea spray DMS to the atmosphere is linked to the global sulfur cycle. [23] Understanding total forcing from natural sources like sea spray can illuminate critical constraints posed by anthropogenic influence and can be coupled with ocean chemistry, biology and physics to predict future ocean and atmospheric variability. [15]
The proportion of organic matter in sea spray can impact reflectance, determine the overall cooling effect of SSAs, [20] and slightly alter the capacity for SSAs to form cloud condensation nuclei (17). Even small changes in SSA levels can affect the global radiation budget leading to implications for global climate. [20] SSA has a low albedo, but its presence overlaid on the darker ocean surface affects absorption and reflectance of incoming solar radiation. [20]
The influence of sea spray on the surface heat and moisture exchange peaks during times of greatest difference between air and sea temperatures. [22] When air temperature is low, sea spray sensible heat flux can be nearly as great as the spray latent heat flux at high latitudes. [6] In addition, sea spray enhances the air/sea enthalpy flux during high winds as a result of temperature and humidity redistribution in the marine boundary layer. [7] Sea spray droplets injected into the air thermally equilibrate ~1% of their mass. This leads to the addition of sensible heat prior to ocean reentry, enhancing their potential for significant enthalpy input. [7]
The effects of sea spray transport in the atmospheric boundary layer is not yet completely understood. [11] Sea spray droplets alter the air-sea momentum fluxes by being accelerated and decelerated by the winds. [11] In hurricane-force winds, it is observed that there is some reduction in the air/sea momentum flux. [10] This reduction in momentum flux manifests as saturation of air/sea drag coefficient. Some studies have identified spray effects as one of the potential reasons for the air/sea drag coefficient saturation. [24] [25] [26] It has been shown through several numerical and theoretical studies that sea spray, if present in significant amounts in the atmospheric boundary layer, leads to saturation of air-sea drag coefficients. [27] [28]
Salt deposition from sea spray is the primary factor influencing distribution of plant communities in coastal ecosystems. [29] Ion concentrations of sea spray deposited on land generally mirror their concentrations in the ocean, except that potassium is often higher in sea spray. [8] Deposition of salts on land generally decreases with distance from the ocean but increases with increasing wind speed. [8] Salt deposition from sea spray is correlated with a decrease in plant height and significant scarring, shoot reduction, stem height decrease, and tissue death on the windward side of shrubs and trees. [30] [31] Variation in salt deposition also influences competition between plants and establishes gradients of salt tolerance. [30]
While the salts within sea spray can severely inhibit plant growth in coastal ecosystems, selecting for salt-tolerant species, sea spray can also bring vital nutrients to these habitats. For example, one study showed that sea spray in Wales, UK delivers roughly 32 kg of potassium per hectare to coastal sand dunes each year. [10] Because dune soils leach nutrients very quickly, sea spray fertilization could be very influential to dune ecosystems, especially for plants that are less competitive in nutrient-limited environments.
Viruses, bacteria, and plankton are ubiquitous in sea water, and this biodiversity is reflected in the composition of sea spray. [14] Generally speaking, sea spray has slightly lower concentrations of microbes than the water it is produced from. However, the microbial community in sea spray is often distinct from nearby water and sandy beaches, suggesting that some species are more biased towards SSA transportation than others. Sea spray from one beach can contain thousands of operational taxonomic units (OTUs). [14] Nearly 10,000 different OTUs have been discovered in sea spray just between San Francisco, CA and Monterey, CA, with only 11% of them found ubiquitously. [14] This suggests that sea spray in every coastal region likely has its own unique assemblage of microbial diversity, with thousands of new OTUs yet to be discovered. Many of the more common OTUs have been identified to the following taxa: Cryptophyta (order), Stramenopiles (order) and OM60 (family). [14] Many have even been identified to genus: Persicirhabdus, Fluviicola, Synecococcus, Vibrio, and Enterococcus. [14]
Scientists have conjectured a stream of airborne microorganisms circles the planet above weather systems but below commercial air lanes. [32] Some of these peripatetic microorganisms are swept up from terrestrial dust storms, but most originate from the marine microorganisms in sea spray. In 2018 a team of scientists reported that hundreds of millions of viruses and tens of millions of bacteria are deposited daily on every square meter around the planet. [33] [34]
Sea spray is largely responsible for corrosion of metallic objects near the coastline, as the salts accelerate the corrosion process in the presence of abundant atmospheric oxygen and moisture. [9] Salts do not dissolve in air directly, but are suspended as fine particulates, or dissolved in microscopic airborne water droplets. [35]
The salt spray test is a measure of material endurance or resistance to corrosion, particularly if the material will be used outdoors and must perform in a mechanical load bearing or otherwise critical role. These results are often of great interest to marine industries, whose products may suffer extreme acceleration of corrosion and subsequent failure due to salt water exposure. [36]
Cloud condensation nuclei (CCNs), also known as cloud seeds, are small particles typically 0.2 μm, or one hundredth the size of a cloud droplet. CCNs are a unique subset of aerosols in the atmosphere on which water vapour condenses. This can affect the radiative properties of clouds and the overall atmosphere. Water vapour requires a non-gaseous surface to make the transition to a liquid; this process is called condensation.
The oceanic or limnological mixed layer is a layer in which active turbulence has homogenized some range of depths. The surface mixed layer is a layer where this turbulence is generated by winds, surface heat fluxes, or processes such as evaporation or sea ice formation which result in an increase in salinity. The atmospheric mixed layer is a zone having nearly constant potential temperature and specific humidity with height. The depth of the atmospheric mixed layer is known as the mixing height. Turbulence typically plays a role in the formation of fluid mixed layers.
The Saharan air layer (SAL) is an extremely hot, dry, and sometimes dust-laden layer of the atmosphere that often overlies the cooler, more humid surface air of the Atlantic Ocean. It carries upwards of 60 million tons of dust annually over the ocean and the Americas. This annual phenomenon sometimes cools the ocean and suppresses Atlantic tropical cyclogenesis.
The sea surface microlayer (SML) is the boundary interface between the atmosphere and ocean, covering about 70% of Earth's surface. With an operationally defined thickness between 1 and 1,000 μm (1.0 mm), the SML has physicochemical and biological properties that are measurably distinct from underlying waters. Recent studies now indicate that the SML covers the ocean to a significant extent, and evidence shows that it is an aggregate-enriched biofilm environment with distinct microbial communities. Because of its unique position at the air-sea interface, the SML is central to a range of global marine biogeochemical and climate-related processes.
Tropospheric ozone depletion events are phenomena that reduce the concentration of ozone in the earth's troposphere. Ozone (O3) is a trace gas which has been of concern because of its unique dual role in different layers of the lower atmosphere. Apart from absorbing UV-B radiation and converting solar energy into heat in the stratosphere, ozone in the troposphere provides greenhouse effect and controls the oxidation capacity of the atmosphere.
Marine cloud brightening also known as marine cloud seeding and marine cloud engineering is a proposed solar radiation management climate engineering technique that would make clouds brighter, reflecting a small fraction of incoming sunlight back into space in order to offset anthropogenic global warming. Along with stratospheric aerosol injection, it is one of the two solar radiation management methods that may most feasibly have a substantial climate impact. The intention is that increasing the Earth's albedo, in combination with greenhouse gas emissions reduction, carbon dioxide removal, and adaptation, would reduce climate change and its risks to people and the environment. If implemented, the cooling effect is expected to be felt rapidly and to be reversible on fairly short time scales. However, technical barriers remain to large-scale marine cloud brightening. There are also risks with such modification of complex climate systems.
Iberulites are a particular type of microspherulites that develop in the atmosphere (troposphere), finally falling to the Earth's surface. The name comes from the Iberian Peninsula where they were discovered.
Frost flowers are ice crystals commonly found growing on young sea ice and thin lake ice in cold, calm conditions. The ice crystals are similar to hoar frost, and are commonly seen to grow in patches around 3–4 cm in diameter. Frost flowers growing on sea ice have extremely high salinities and concentrations of other sea water chemicals and, because of their high surface area, are efficient releasers of these chemicals into the atmosphere.
In fluid dynamics, wave setup is the increase in mean water level due to the presence of breaking waves. Similarly, wave setdown is a wave-induced decrease of the mean water level before the waves break. For short, the whole phenomenon is often denoted as wave setup, including both increase and decrease of mean elevation. This setup is primarily present in and near the coastal surf zone. Besides a spatial variation in the (mean) wave setup, also a variation in time may be present – known as surf beat – causing infragravity wave radiation.
Sea salt aerosol, which originally comes from sea spray, is one of the most widely distributed natural aerosols. Sea salt aerosols are characterized as non-light-absorbing, highly hygroscopic, and having coarse particle size. Some sea salt dominated aerosols could have a single scattering albedo as large as ~0.97. Due to the hygroscopy, a sea salt particle can serve as a very efficient cloud condensation nuclei (CCN), altering cloud reflectivity, lifetime, and precipitation process. According to the IPCC report, the total sea salt flux from ocean to atmosphere is ~3300 teragrams (Tg) per year.
Regional Ocean Modeling System (ROMS) is a free-surface, terrain-following, primitive equations ocean model widely used by the scientific community for a diverse range of applications. The model is developed and supported by researchers at the Rutgers University, University of California Los Angeles and contributors worldwide.
Sreedharan Krishnakumari Satheesh is an Indian meteorologist and a professor at the Centre for Atmospheric and Oceanic Sciences of the Indian Institute of Science (IISc). He holds the chair of the Divecha Centre for Climate Change, a centre under the umbrella of the IISc for researches on climate variability, climate change and their impact on the environment. He is known for his studies on atmospheric aerosols and is an elected fellow of all the three major Indian science academies viz. Indian Academy of Sciences Indian National Science Academy and the National Academy of Sciences, India as well as The World Academy of Sciences. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards for his contributions to Earth, Atmosphere, Ocean and Planetary Sciences in 2009. He received the TWAS Prize of The World Academy of Sciences in 2011. In 2018, he received the Infosys Prize, one of the highest monetary awards in India that recognize excellence in science and research, for his work in the field of climate change.
Anne Mee Thompson is an American scientist, who specializes in atmospheric chemistry and climate change. Her work focuses on how human activities have changed the chemistry of the atmosphere, climate forcing, and the Earth's oxidizing capacity. Thompson is an elected fellow of the American Meteorological Society, American Geophysical Union, and AAAS.
The North Atlantic Aerosols and Marine Ecosystems Study (NAAMES) was a five-year scientific research program that investigated aspects of phytoplankton dynamics in ocean ecosystems, and how such dynamics influence atmospheric aerosols, clouds, and climate. The study focused on the sub-arctic region of the North Atlantic Ocean, which is the site of one of Earth's largest recurring phytoplankton blooms. The long history of research in this location, as well as relative ease of accessibility, made the North Atlantic an ideal location to test prevailing scientific hypotheses in an effort to better understand the role of phytoplankton aerosol emissions on Earth's energy budget.
Saharan dust is an aeolian mineral dust from the Sahara, the largest hot desert in the world. The desert spans just over 9 million square kilometers, from the Atlantic Ocean to the Red Sea, from the Mediterranean Sea to the Niger River valley and the Sudan region in the south.
The boron cycle is the biogeochemical cycle of boron through the atmosphere, lithosphere, biosphere, and hydrosphere.
Patricia K. Quinn is an atmospheric chemist working at the National Oceanic and Atmospheric Agency's Pacific Marine Environmental Lab. She is known for her work on the impact of atmospheric aerosol particles on air quality and climate.
The sea surface skin temperature (SSTskin), or ocean skin temperature, is the temperature of the sea surface as determined through its infrared spectrum (3.7–12 μm) and represents the temperature of the sublayer of water at a depth of 10–20 μm. High-resolution data of skin temperature gained by satellites in passive infrared measurements is a crucial constituent in determining the sea surface temperature (SST).
Patricia Ana Matrai is a marine scientist known for her work on the cycling of sulfur. She is a senior research scientist at Bigelow Laboratory for Ocean Sciences.
Randall V. Martin is a scientist, engineer, academic and author. He is the Raymond R. Tucker Distinguished Professor in the Department of Energy, Environmental, and Chemical Engineering, with a courtesy appointment in Computer Science and Engineering at Washington University in St. Louis, McKelvey School of Engineering.
{{cite journal}}
: Cite journal requires |journal=
(help){{cite book}}
: CS1 maint: multiple names: authors list (link)