Top PDF Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray

Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray

Wind speed dependent size-resolved parameterization for the organic enrichment of sea spray

tion (OC ss ) has been developed and used to calculate marine primary organic aerosol emissions in different parts of the global oceans. Our analysis predicts the highest en- richments of marine aerosol with organics during calm winds, when large amounts of organic material accumulate at the sea-surface often forming visible slicks. An increase in wind speed (above 3–4 m s −1 ) will initiate Langmuir circulations causing a breakup

28 Ler mais

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

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

chard, 1964; Gershey, 1983a; Hoffman and Duce, 1974, 1976; Oppo et al., 1999; Keene et al., 2007; Facchini et al., 2008; Russell et al., 2010). The exact mechanism for such large organic mass fraction (and roughly by 2 to 3 or- ders of magnitude organic enrichment relative to subsurface waters) of submicron SSA is not well defined. It is thought that when ocean bubbles generated by the entrainment of air due to wave action rise to the surface, the surface active ma- terial in the bulk water aggregates to the walls of the bub- bles. When these bubbles reach the water surface after hav- ing been enriched in organics relative to the bulk sea wa- ter, they burst and eject the organics absorbed on their sur- face into the atmosphere along with dissolved inorganic con- stituents of seawater (Blanchard, 1964). The amount of or- ganics absorbed on the bubble surface is thought to be mainly controlled by the abundance of dissolved and particulate or- ganic matter of the subsurface water (broadly characterized as lipids, amino and fatty acids, mono- and poly-saccharides, humic substances, and phytoplankton cell fragments) (Ben- ner et al., 1992; Millero, 2006). However, not all the organic material brought to the surface gets aerosolized. A signifi- cant amount of biogenic organic matter can accumulate at the air-sea interface, forming an organic film (thesea surface microlayer”, SML) (Blanchard, 1964; Gershey et al., 1983b; Liss and Duce, 1997). Bubble-mediated processes also are not the only mechanism for forming SML. Transparent ex- opolymer particles (TEP) formed from dissolved exudates re- leased by phytoplankton and bacteria are positively buoyant and able to ascend the water column (Alldredge et al., 1993; Azetsu-Scott and Passow, 2004). These gel-like clumps are mostly polysaccharide, negatively charged, very sticky parti- cles ranging in size from ∼2 to ∼200 µm and present in high concentrations in most sea and freshwaters (Azetsu-Scott and Passow, 2004). The ascending TEP can initiate the forma- tion of natural biofilms on surfaces even under calm condi- tions. Overall, a number of water column processes (convec- tion, mobile biota, biota attached to buoyant particles, burst- ing bubbles, buoyant TEPs, diffusion and wave motion) can regulate the accumulation and reduction of material in SML (Wurl and Obbard, 2004; Cunliffe et al., 2011). Past stud- ies have shown that the SML can have a strong influence on the bubble-bursting process at the air-sea interface and sub- micron marine aerosol production and chemical composition (e.g., Ellison et al., 1999; O’Dowd et al., 2004).
Mostrar mais

14 Ler mais

A sea-state based source function for size- and composition-resolved marine aerosol production

A sea-state based source function for size- and composition-resolved marine aerosol production

Despite their global significance, the size-resolved phys- ical (mass and number) and chemical (organic and inor- ganic) characteristics and production fluxes of primary ma- rine aerosols are not adequately parameterized in compre- hensive Earth system models as functions of major drivers (wind velocity and the chemical composition of surface sea- water). Some parameterizations are based on measurements in ambient air, which are advantageous in that they directly relate variability in production rates inferred from ambient concentrations to the corresponding environmental drivers (e.g. wind speed). These include parameterizations inferred from measured number size distributions in near-surface ma- rine air (Gong et al., 2002; Gong, 2003), vertical gradients in number size distributions measured immediately down wind of coastal surf (Clarke et al., 2006), eddy covariance mea- surements of sub-µm number concentrations during onshore flow (Geever et al., 2005), and associated measurements of ambient aerosol composition (O’Dowd et al., 2008). How- ever, these and other measurement techniques cannot quan- tify, at high temporal resolution, the size-resolved composi- tion of primary marine aerosol produced by bursting bubbles over the full relevant size range (10-nm to 30-µm ambient diameter). In addition, the initial composition of nascent ma- rine aerosol changes rapidly (seconds to minutes) via expo- sure to light and reactive trace gases (Chameides and Stel- son, 1992; Erickson et al., 1999; Zhou et al., 2008). Conse- quently, it is extremely difficult to reliably deconvolute the characteristics of fresh versus processed aerosols based on ambient-air measurements.
Mostrar mais

14 Ler mais

Towards space based verification of CO<sub>2</sub> emissions from strong localized sources: fossil fuel power plant emissions as seen by a CarbonSat constellation

Towards space based verification of CO<sub>2</sub> emissions from strong localized sources: fossil fuel power plant emissions as seen by a CarbonSat constellation

Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D., Haywood, J., Lean, J., Lowe, D., Myhre, G., Nganga, J., Prinn, R., Raga, G. M. S., and Dorland, R. V.: Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the In- tergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, United

36 Ler mais

Estimation of ETo with Hargreaves-Samani and FAO-PM temperature methods for a wide range of climates in Iran

Estimation of ETo with Hargreaves-Samani and FAO-PM temperature methods for a wide range of climates in Iran

selected stations have the longest and nearly complete data records for the period 1971–2005, particularly considering sunshine, rela- tive humidity and wind speed data. The selected stations are first order synoptic stations that passed careful quality control by the Iranian meteorological organization and are quite regularly dis- tributed through the country (Fig. 1a). However, the time series of the considered variables were further investigated for possible non-homogeneities by comparing the time series of a given station with those of neighbouring stations. The result proved that all the variables were homogeneous, with the exception of wind speed records at Tabass, Bam, Semnan, Kashan, Khoramabad, Dezful and Chabahar stations, which exhibited extreme step changes and non- homogeneity. Therefore, the wind datasets at these 7 stations were corrected through establishing linear regression between the con- sidered station data and those of neighbouring stations as proposed by Allen et al. (1998).
Mostrar mais

18 Ler mais

A multi-model assessment of the efficacy of sea spray geoengineering

A multi-model assessment of the efficacy of sea spray geoengineering

ance and the skewness of the distribution varies. Vertical velocity is typically smaller at cloud base but increases with height until reaching a maximum around (or above) the centre of the cloud (Lu and Seinfeld, 2005, 2006; Hill et al., 2009). The velocity in the lower levels of the cloud is of most interest for this work as it is mainly these values that control the cloud droplet number concentration: activation starts close to cloud base

42 Ler mais

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

Application of the Aventech AIMMS20AQ airborne probe for turbulence measurements during the Convective Storm Initiation Project

help farmers meet regulations on pesticide application in the United States. In conse- quence, economies of scale ensure the probe is robust, reliable, relatively low cost and easy to install and calibrate. Whilst the Cessna uses the standard probe casing, the sensor head can also be supplied to fit a PMS pod to make it simple to fit on research aircraft which are already modified for this widely used type of canister.

37 Ler mais

Modeling dissolved oxygen dynamics and coastal hypoxia: a review

Modeling dissolved oxygen dynamics and coastal hypoxia: a review

events in the Baltic Sea, which occur at irregular intervals of one to ten years and renew the bottom waters of the central Baltic. They find that the extent of hypoxia and suitable habitat volume of calanoid copepods and optimal volume for the reproduction of cod could not be calculated with confidence because they all vary considerably in response to different meteorological data used to force the model. Karim et al. (2002)

62 Ler mais

Wind profiler observations of a monsoon low-level jet over a tropical Indian station

Wind profiler observations of a monsoon low-level jet over a tropical Indian station

Figures 4, 5, and 6 clearly show a mutual influence be- tween the LLJ and boundary layer. It can be understood from the figures that the LLJ features have been diluted and some- times even eroded completely during noontime. Further, high LLJ intensities of the order of greater than 20 m s −1 can persist throughout the day without much dilution by the pre- vailing convective mixing associated with CBL. The strong convective activity associated with CBL during the monsoon season might have been forcing the LLJ core to higher levels and diluting the immediate lower flange of the LLJ, causing reduced LLJ thickness. This apparent shifting or dilution of the jet feature depends on the relative strength of the LLJ and the convective activity associated with the boundary layer. If the LLJ strength is strong enough, the convective activity of CBL can only shift the LLJ structure to higher heights by modifying from beneath. Otherwise, strong mixing associ- ated with the CBL is able to dilute the jet feature, causing homogeneous winds in the CBL. Thus, the mutual strengths
Mostrar mais

13 Ler mais

Lidar observations of atmospheric internal waves in the boundary layer of
the atmosphere on the coast of Lake Baikal

Lidar observations of atmospheric internal waves in the boundary layer of the atmosphere on the coast of Lake Baikal

Sun, J., Nappo, C. J., Mahrt, L., Beluši´c, D., Grisogono, B., Stauf- fer, D. R., Pulido, M., Staquet, C., Jiang, Q., Pouquet, A., Yagüe, C., Galperin, B., Smith, R. B., Finnigan, J. J., Mayor, S. D., Svensson, G., Grachev, A. A., and Neff, W. D.: Review of wave- turbulence interactions in the stable atmospheric boundary layer, Rev. Geophys., 53, 956–993, doi:10.1002/2015RG000487, 2015. Vakkari, V., O’Connor, E. J., Nisantzi, A., Mamouri, R. E., and Had- jimitsis, D. G.: Low-level mixing height detection in coastal lo- cations with a scanning Doppler lidar, Atmos. Meas. Tech., 8, 1875–1885, doi:10.5194/amt-8-1875-2015, 2015.
Mostrar mais

10 Ler mais

Measurements of size-resolved hygroscopicity in the California coastal zone

Measurements of size-resolved hygroscopicity in the California coastal zone

i.e., in-shore southerly flow extending up the California coast and advecting pollution from the urbanized Los Angeles basin. Furthermore, a very large and long-lived forest fire (the second largest in California history) took place during the study period and on a number of occasions the fire smoke haze was advected into our operational area. Mean DHGF spectra for clearly pollution and clearly biomass fire smoke cases (based

30 Ler mais

Performance of different methods for reference evapotranspiration estimation in Jaíba, Brazil

Performance of different methods for reference evapotranspiration estimation in Jaíba, Brazil

FAO-Penman-Monteith (FAO-PM) is considered the standard method for the estimation of reference evapotranspiration (ET 0 ) but requires various meteorological data, which are often not available. The objective of this work was to evaluate the performance of the FAO-PM method with limited meteorological data and other methods as alternatives to estimate ET 0 in Jaíba-MG. The study used daily meteorological data from 2007 to 2016 of the National Institute of Meteorology’s station. Daily ET 0 values were randomized, and 70% of these were used to determine the calibration parameters of the ET 0 for the equations of each method under study. The remaining data were used to test the calibration against the standard method. Performance evaluation was based on Willmott’s index of agreement, confidence coefficient and root-mean-square error. When one meteorological variable was missing, either solar radiation, relative air humidity or wind speed, or in the simultaneous absence of wind speed and relative air humidity, the FAO-PM method showed the best performances and, therefore, was recommended for Jaíba. The FAO-PM method with two missing variables, one of them being solar radiation, showed intermediate performance. Methods that used only air temperature data are not recommended for the region.
Mostrar mais

7 Ler mais

Braz. j. oceanogr.  vol.59 número4

Braz. j. oceanogr. vol.59 número4

In 1962, Clovis Teixeira started an in-depth study of phytoplankton ecology, biogeochemical cycles, physical and chemica1 factors and climatology in the Lagunar Region of Cananéia with a group of 6 people. This group, along with some students, produced several papers for the series Plankton studies in a mangrove environment. These papers have citations in the international literature, until today.

1 Ler mais

Wind-wave amplification mechanisms: possible models for steep   wave events in finite depth

Wind-wave amplification mechanisms: possible models for steep wave events in finite depth

Very recently, Tian and Choi (2013) investigated experimen- tally and numerically the evolution of deep-water waves in- teracting with wind, with breaking effects. They discussed the relative importance of Miles’ and Jeffreys’ models and showed that Miles’ model may be used for waves of mod- erate wave steepness under weak to moderate wind forc- ing, whereas for steep waves under strong wind forcing both mechanisms may have to be considered. In this section we desire to measure the relative importance of Miles’ mecha- nism versus Jeffreys’ mechanism in finite depth. To do that, we follow the idea in Touboul and Kharif (2006). Taking the derived growth rates from Sects. 3.1 and 3.2, one can establish the ratio between them. It reads, with only non- dimensional parameters,
Mostrar mais

9 Ler mais

Sea surface wind perturbations over the Kashevarov Bank of the Okhotsk Sea: a satellite study

Sea surface wind perturbations over the Kashevarov Bank of the Okhotsk Sea: a satellite study

of temperature dependence of air and water viscosity are not considered in the empirical ratio, connecting a scatterometer signal and sea surface wind (Brown, 2000; Park et al., 2006). Thirdly, errors in wind estimations can be a result of as- sumption about the neutral stratification of a surface atmo- sphere layer in empirical relationships of the scatterometer signal and wind (Brown, 2000). The stratification of a sur- face atmosphere layer defined in basic water-air temperature difference is not considered. It is practically impossible to measure this difference neither by radiometers nor by scat- terometers. In our case it is possible to assume strong stabil- ity of sea surface air over a cold spot with a difference be- tween water and air temperatures to −10.5 ◦ C (if it needs to
Mostrar mais

7 Ler mais

The origin of summer monsoon rainfall at New Delhi by deuterium excess

The origin of summer monsoon rainfall at New Delhi by deuterium excess

To smooth other factors controlling d-excess variation, (wind speed, sea surface temperature over the source area and the re-evaporation of raindrops), the mean d-excess value from June to September was used in the analysis. Compared with other IAEA/WMO stations in the monsoon regions, at New Delhi the stable isotopic data record (d 18 O

4 Ler mais

The Current State of Neoadjuvant Chemotherapy for Muscle-Invasive Bladder Cancer

The Current State of Neoadjuvant Chemotherapy for Muscle-Invasive Bladder Cancer

and surgical outcomes of patients (N=317) treated with radical cystectomy and NAC (combination group) were compared with radical cystectomy alone (cystectomy group). They found that planned radical cystectomy was performed in 82% and 81% of the patients in the combination and cystectomy groups, respectively. There were no signiicant diferences between the two groups in the rate of Grade 2 or 3 post-surgical complications, or deaths. Although there were no signiicant diferences between the two groups in the rates of surgical mortality and morbidity, the median survival of the combination group (77 months) was longer than the cystectomy group (46 months). The percentage of surviving patients at Year 5 was 57% and 43% in the combination and cystectomy groups, respectively. Similarly, the data of the combined Nordic trial (N=620) showed that NAC did not have a signiicant efect on the rate of performable radical cystectomy. The cystectomy frequencies of the experimental and control groups were 86% and 87%, respectively. 3
Mostrar mais

6 Ler mais

What Negative Impact does Wind have on the Deadline of a Construction Project? Mathematical Modeling for the Measurement and Optimization of Wind Effects

What Negative Impact does Wind have on the Deadline of a Construction Project? Mathematical Modeling for the Measurement and Optimization of Wind Effects

Abstract— In regard to economic phenomena such as the expansion of trade, the interactions between markets encouraging companies to cross borders, the research for market in new areas should be accompanied by sufficient knowledge of their own environment and especially the weather conditions. Indeed, the objectives of a construction project (cost, deadline and quality) are affected by a multitude of events, of internal and external origin, such as climate changes when they are severe and abrupt. Certainly, each region is characterized by a specific climate. For some regions, it is rather the wind that remains the most characterizing climate factor. Wind is widely felt in areas exposed to currents such as (trade wind, North wind, Nordet, Harmattan etc…), in other places we underestimate, see, ignore the effects of wind, particularly on a construction site. Yet, the consequences of ignoring this risk factor can be heavy on a construction company (in terms of late penalty law for example); In fact, if bad weather affects particularly on the initial works: earthworks, foundations, slab; wind effects may proclaim during all the duration of the construction site. The wind affect all project’s aspects, quality, cost, safety as well as deadline. Nevertheless there are few studies that were interested in studying relation construction‘s deadline and wind. Tangier, the city located on the Strait of Gibraltar, where the study was conducted, is exposed to wind whose origin is the Anti cyclone of the Azores, in addition to the local winds that are due to the presence of the two seas and imposing mountains, with a wind that might exceed 220km/h. The equation introduced by this study will allow evaluating (measuring) the impact of wind on the deadline (expressed Δ), it shall encompass all aspects:
Mostrar mais

10 Ler mais

J. Aerosp. Technol. Manag.  vol.2 número2

J. Aerosp. Technol. Manag. vol.2 número2

However, this study developed an initial procedure to understand the atmospheric low at ASC using wind tunnel, presenting important behaviors such as the displacement, the formation of circulation bubble and the reattachment of the low on the tunnel surface. With the PIV technique it was possible to get a general view of the low based on streamlines and vorticity. A modiication of the low when reaching the step (coastal cliff) was veriied, as well as the formation of the recirculation region. During the second tests, measurements had been conducted with the simulation of the MTI existing in the ASC, where the rockets are positioned for the launching. An alteration of the low was observed by the streamlines in the place, forming a von Karman street vortex. The vorticity in the localization of the MTI resulted in the same one that was occurred during the passage of the low by the coastal cliff. Comparing the results of velocity low map and mean vorticity obtained with PIV and turbulence intensity values obtained with HWA, it was observed that the highest values of turbulence intensity occurs in the identiied low separation regions and that the lowest turbulence intensity was observed in the free stream regions, as expected.
Mostrar mais

10 Ler mais

The Impact of the Expansion of the Bolsa Familia Program on the Time Allocation of Youths And Their Parents Lia Chitolina Miguel Nathan Foguel Naercio Menezes-Filho

The Impact of the Expansion of the Bolsa Familia Program on the Time Allocation of Youths And Their Parents Lia Chitolina Miguel Nathan Foguel Naercio Menezes-Filho

The transfer of the two main variable benefits of the program is conditioned on health and education requirements. Health conditions require children younger than 7 years old to have their growth monitored and vaccinations up-to-date and pregnant and nursing women to visit regularly health centers for prenatal and postnatal care. Education conditions are that all children aged 6 to 15 must be enrolled in school and attend at least 85% of school days. Enrollment in school is also required for youths aged 16 and 17 and the minimum attendance rate for them is 75 per cent. Variable benefits are paid until December of the year when the child becomes 15 years old or when the youth completes 17 years old. After its inception in 2007, when a child becomes 16 the family is entitled to receive the higher benefit of the BVJ.
Mostrar mais

39 Ler mais

Show all 10000 documents...

temas relacionados