A high-flow humidograph for testing the water uptake by ambient aerosol

Tenbrink, H; Khlystov, A.; Kos, G.P.A.; Tuch, T.; Roth, Ch.; Kreyling, W. C.

doi:10.1016/s1352-2310(00)00197-7

Cited by 28 publications

(8 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A sample volumetric flow rate of 30 actual lpm required for impactor size cuts and to limit sample residence time combined with the desire to measure supermicrometer D p particles necessitated the use of heating for aerosol drying. However, an important improvement from past measurements was better accounting for instrumental heating effects on sample RH and an effort to keep the sample temperature below 40°C to limit losses of semivolatile species [ ten Brink et al , 2000]. Maximum dry bulb temperatures were detected downstream of the preheater drier and downstream of the humidifier with average T = 39.7 ± 2.4°C and 39.3 ± 3.0°C, respectively.…”

Section: Experimental Methodsmentioning

confidence: 99%

Mixtures of pollution, dust, sea salt, and volcanic aerosol during ACE‐Asia: Radiative properties as a function of relative humidity

et al. 2003

View full text Add to dashboard Cite

[1] The Ron Brown cruise during ACE-Asia (March-April 2001) encountered complex aerosol that at times was dominated by marine, polluted, volcanic, and dust aerosols. Average total light scattering coefficients (s sp for D p < 10 mm, relative humidity (RH) = 19%, and l = 550 nm) ranged from 23 (marine) to 181 Mm À1 (dust). Aerosol hygroscopicity ranged from deliquescent with hysteresis (marine frequently and polluted variably) to hygroscopic without hysteresis (volcanic) to nearly hygrophobic (dustdominated). Average deliquescence and crystallization RH were 77 ± 2% and 42 ± 3%, respectively. The ambient aerosol was typically on the upper branch of the hysteresis loop for marine and polluted air masses and the lower branch for dust-dominated aerosols. Average f (RH = ambient), defined as s sp (RH = ambient)/s sp (RH = 19%), ranged from 1.25 (dust) to 2.88 (volcanic). Average h(RH $60%), defined as f (RH) upper branch / f (RH) lower branch , were 1.6, 1.3, 1, and 1.25 for marine, polluted, volcanic, and dust, demonstrating an importance of hysteresis to optical properties. Hemispheric backscatter fraction (b) at ambient RH ranged from 0.077 (marine) to 0.111 (dust), while single scattering albedo (w) at ambient RH ranged from 0.94 (dust and polluted) to 0.99 (marine).

show abstract

Section: Experimental Methodsmentioning

confidence: 99%

Mixtures of pollution, dust, sea salt, and volcanic aerosol during ACE‐Asia: Radiative properties as a function of relative humidity

et al. 2003

View full text Add to dashboard Cite

show abstract

“…Heating of the walls surrounding the sensing volume by the scanning‐RH nephelometers' lamps caused the RH that was measured immediately upstream of the RH‐scanning nephelometers to be greater than the nephelometers' internally measured “sensing volume RH” values. The temperature of the TSI scanning RH nephelometer's sensing volume was at 33.3 ± 1.9°C to minimize instrumental heating effects on sample RH, and to limit losses of semivolatile species [ ten Brink et al , 2000]. The protocols that were used to calculate “sensing volume RH” from the measured T and RH values that are reported here are described by Carrico et al [2003].…”

Section: Methodsmentioning

confidence: 99%

Aerosol optical properties along the northeast coast of North America during the New England Air Quality Study–Intercontinental Transport and Chemical Transformation 2004 campaign and the influence of aerosol composition

et al. 2007

View full text Add to dashboard Cite

[1] Optical and hygroscopic properties of submicrometer diameter aerosol particles were measured on board the NOAA R/V Ronald H. Brown as part of the NEAQS-ITCT field campaign. The campaign occurred along the northeast coast of North America during the summer of 2004. A scanning relative humidity (RH) nephelometry system (humidograph) measured total light scattering and backscattering coefficients (s sp and s bsp , respectively) at three wavelengths (ls) and RH = 26% and while RH was scanned between 40% and 85%. These measurements were combined with aerosol light absorption and composition measurements to describe s sp , s bsp , single scattering albedo (w), Å ngström exponent (å), and hemispheric backscatter fraction (b) at a low reference RH of 26 ± 4% and the aerosol's hygroscopic properties based on its optical response up to 85% RH. Humidogram curve structure was dominated by hygroscopic growth without hysteresis (76% frequency). Dependence of the aerosol's s sp values with changes in RH, f ssp (RH, 26), was observed to decrease with increasing mass fraction of particulate organic matter (POM, F O ). Statistical analyses indicated that increasing F O resulted in a less hygroscopic aerosol, while increasing molar equivalence ratio (ER) resulted in lower hysteresis factors based on the aerosols' optical responses at a 0.95 confidence level. w showed little RH dependence while å and b decreased with increasing RH values. Values for å(l 1 , l 2 ), b, and f ssp (82, 26) increased with increasing l values. Sensitivities of top of the atmosphere aerosol radiative forcing to changes in w, b, and s sp with RH were also estimated.

show abstract

“…The aerosol single scattering albedo is defined as the fraction of extinction that is caused by scattering. The effect of water vapor on the scattering properties of aerosols is taken into account in the single scattering albedo using a radiosonde water vapor profile together with the relative‐humidity dependence of the light‐scattering as measured with a humidograph [ Ten Brink et al , 2001]. The asymmetry parameter of aerosols is not measured on site.…”

Section: Experimental Approachmentioning

confidence: 99%

Effect of aerosols on the downward shortwave irradiances at the surface: Measurements versus calculations with MODTRAN4.1

et al. 2004

View full text Add to dashboard Cite

[1] A detailed analysis of measurements and model calculations of clear-sky shortwave irradiances at the surface is presented for a set of 18 cases collected during 3 cloudless days in the Netherlands in 2000. The analysis is focused on the influence of the optical and physical properties of aerosols on simulations of direct and diffuse downward solar irradiance at the surface. The properties of aerosols in the boundary layer are derived from surface measurements, under the assumption that all aerosol is confined to a well-mixed atmospheric boundary layer. The simulations of the irradiances are performed with the radiative transfer model MODTRAN 4, version 1.1. The analysis reveals no discernable differences between model and measurement for the direct irradiance, but several significant differences for the diffuse irradiance. The model always overestimates the diffuse irradiance measurements by 7 to 44 Wm À2 (average: 25 Wm À2). On the basis of an estimated uncertainty in the differences of 18 Wm À2 , it appears that for 13 out of 18 cases the model significantly overestimates the measurements. This number decreases if instrumental errors (e.g., pyranometer zero-offset) and assumptions on the model input (e.g., wavelength-independent surface albedo) are considered. Nevertheless, the analysis presented here points to a persistent and significant positive model-measurement difference for the diffuse irradiance, which typically amounts to 1-4% of the top-ofatmosphere irradiance, and does not depend on the solar zenith angle. The reason for the discrepancy may be found in the presence of ultrafine absorbing aerosol particles that were not detected by the surface instrument for measuring aerosol absorption. It is also possible that these particles are not present near the surface, due to dry deposition, but do contribute to the total extinction if they are situated higher up in the boundary layer.

show abstract

A high-flow humidograph for testing the water uptake by ambient aerosol

Cited by 28 publications

References 17 publications

Mixtures of pollution, dust, sea salt, and volcanic aerosol during ACE‐Asia: Radiative properties as a function of relative humidity

Mixtures of pollution, dust, sea salt, and volcanic aerosol during ACE‐Asia: Radiative properties as a function of relative humidity

Aerosol optical properties along the northeast coast of North America during the New England Air Quality Study–Intercontinental Transport and Chemical Transformation 2004 campaign and the influence of aerosol composition

Effect of aerosols on the downward shortwave irradiances at the surface: Measurements versus calculations with MODTRAN4.1

Contact Info

Product

Resources

About