scholarly journals Relationship between the NO<sub>2</sub> photolysis frequency and the solar global irradiance

2009 ◽  
Vol 2 (4) ◽  
pp. 1537-1573 ◽  
Author(s):  
I. Trebs ◽  
B. Bohn ◽  
C. Ammann ◽  
U. Rummel ◽  
M. Blumthaler ◽  
...  
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Field Experiments ◽  
Global Radiation ◽  
Ground Level ◽  
Field Studies ◽  
Atmospheric Conditions ◽  
Global Irradiance ◽  
Tropical Environments ◽  
Photolysis Frequency

Abstract. Representative values of the atmospheric NO2 photolysis frequency, (j(NO2)), are required for the adequate calculation and interpretation of NO and NO2 concentrations and exchange fluxes near the surface. Direct measurements of j(NO2) at ground level are often not available in field studies. In most cases, modeling approaches involving complex radiative transfer calculations are used to estimate j(NO2) and other photolysis frequencies for air chemistry studies. However, important input parameters for accurate modeling are often missing, most importantly with regard to the radiative effects of clouds. On the other hand, solar global irradiance ("global radiation", G) is nowadays measured as a standard parameter in most field experiments and in many meteorological observation networks around the world. A linear relationship between j(NO2) and G was reported in previous studies and has been used to estimate j(NO2) from G in the past 30 years. We have measured j(NO2) using spectro- or filter radiometers and G using pyranometers side-by-side at several field sites. Our results cover a solar zenith angle range of 0–90°, and are based on nine field campaigns in temperate, subtropical and tropical environments during the period 1994–2008. We show that a second-order polynomial function (intercept=0): j(NO2)=(1+α)×(B1×G+B2×G2), with α defined as the site-dependent UV-A surface albedo and the polynomial coefficients (including uncertainty ranges): B1=(1.47±0.03)×10−5 W−1 m2 s−1 and B2=(−4.84±0.31)×10−9 W−2 m4 s−1 can be used to estimate ground-level j(NO2) directly from G, independent of solar zenith angle under all atmospheric conditions. The absolute j(NO2)↓ residual of the empirical function is ±6×10−4 s−1 (95.45% confidence level). The relationship is valid for sites below 800 m a.s.l. and under low background albedo conditions. It is not valid in alpine regions, above snow or ice and sandy or dry soil surfaces. Our function can be applied to estimate chemical life times of the NO2 molecule with respect to photolysis, and is useful for surface-atmosphere exchange and photochemistry studies close to the ground, e.g., above fields with short vegetation and above forest canopies.

scholarly journals Relationship between the NO<sub>2</sub> photolysis frequency and the solar global irradiance

2009 ◽  
Vol 2 (2) ◽  
pp. 725-739 ◽  
Author(s):  
I. Trebs ◽  
B. Bohn ◽  
C. Ammann ◽  
U. Rummel ◽  
M. Blumthaler ◽  
...  
Keyword(s):  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Surface Albedo ◽  
Field Experiments ◽  
Global Radiation ◽  
Ground Level ◽  
Field Studies ◽  
Atmospheric Conditions ◽  
Global Irradiance ◽  
Photolysis Frequency

Abstract. Representative values of the atmospheric NO2 photolysis frequency j(NO2) are required for the adequate calculation and interpretation of NO and NO2 concentrations and exchange fluxes near the surface. Direct measurements of j(NO2) at ground level are often not available in field studies. In most cases, modeling approaches involving complex radiative transfer calculations are used to estimate j(NO2) and other photolysis frequencies for air chemistry studies. However, important input parameters for accurate modeling are often missing, most importantly with regard to the radiative effects of clouds. On the other hand, solar global irradiance ("global radiation", G) is nowadays measured as a standard parameter in most field experiments and in many meteorological observation networks around the world. Previous studies mainly reported linear relationships between j(NO2) and G. We have measured j(NO2) using spectro- or filter radiometers and G using pyranometers side-by-side at several field sites. Our results cover a solar zenith angle range of 0–90°, and are based on nine field campaigns in temperate, subtropical and tropical environments during the period 1994–2008. We show that a second-order polynomial function (intercept = 0): j(NO2)=(1+α)× (B1×G+B2×G2), with α defined as the site-dependent UV-A surface albedo and the polynomial coefficients: B1=(1.47± 0.03)×10-5 W−1 m2 s−1 and B2=(-4.84±0.31)×10-9 W−2 m4 s−1 can be used to estimate ground-level j(NO2) directly from G, independent of solar zenith angle under all atmospheric conditions. The absolute j(NO2) residual of the empirical function is ±6×10-4 s−1(2σ). The relationship is valid for sites below 800 m a.s.l. and with low surface albedo (α<0.2). It is not valid in high mountains, above snow or ice and sandy or dry soil surfaces.

scholarly journals NO<sub>2</sub> and HCHO photolysis frequencies from irradiance measurements in Thessaloniki, Greece

2005 ◽  
Vol 5 (6) ◽  
pp. 1645-1653 ◽  
Author(s):  
C. Topaloglou ◽  
S. Kazadzis ◽  
A. F. Bais ◽  
M. Blumthaler ◽  
B. Schallhart ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Nitrogen Dioxide ◽  
Atmospheric Conditions ◽  
Actinic Flux ◽  
Lower Upper ◽  
Global Irradiance ◽  
Photolysis Frequencies ◽  
Photolysis Frequency ◽  
Flux Measurements

Abstract. An empirical approach for the retrieval of nitrogen dioxide (NO2) and formaldehyde (HCHO) photolysis frequencies from measurements of global irradiance is presented in this work. Four months of synchronous measurements of actinic flux and global irradiance performed in Thessaloniki, Greece by a Bentham spectroradiometer were used to extract polynomials for the conversion of global irradiance to photolysis frequencies [J(NO2) and J(HCHO)]. The comparison of these photolysis frequency values to the corresponding values calculated by spectral actinic flux measurements, showed a ratio very close to unity for all J's with a standard deviation of 12% (2σ) for J(NO2) and 6% (2σ) for J(HCHO). Additional sets of polynomials were also extracted to allow determination of J(NO2) by spectroradiometers with lower upper wavelength limits such as single and double Brewer spectroradiometers within acceptable uncertainty (corresponding ratio was 1 and standard deviation was 12% (2σ) for the method that can be used with double Brewers and 20% for the method that can be used for single Brewers). The validity of the method under different atmospheric conditions was also examined by applying the polynomials to another set of actinic flux and global irradiance measurements performed in May 2004, in Buchhofen, Germany. In this case, comparing J values extracted from the polynomials to those calculated from actinic flux, showed equivalent results, demonstrating that the method can also be applied to other measurement sites.

scholarly journals Project Sagebrush: Revisiting the Value of the Horizontal Plume Spread Parameter σy

2016 ◽  
Vol 55 (6) ◽  
pp. 1305-1322 ◽  
Author(s):  
D. Finn ◽  
K. L. Clawson ◽  
R. M. Eckman ◽  
H. Liu ◽  
E. S. Russell ◽  
...  
Keyword(s):  
Field Experiments ◽  
National Laboratory ◽  
Field Studies ◽  
Tracer Experiment ◽  
Horizontal Wind ◽  
Plume Dispersion ◽  
Atmospheric Conditions ◽  
Stability Class ◽  
Wind Speeds ◽  
Range Of Values

AbstractThe first phase of an atmospheric tracer experiment program, designated Project Sagebrush, was conducted at the Idaho National Laboratory in October 2013. The purpose was to reevaluate the results of classical field experiments in short-range plume dispersion (e.g., Project Prairie Grass) using the newer technologies that are available for measuring both turbulence levels and tracer concentrations. All releases were conducted during the daytime with atmospheric conditions ranging from neutral to unstable. The key finding was that the values of the horizontal plume spread parameter σy tended to be larger, by up to a factor of ~2, than those measured in many previous field studies. The discrepancies tended to increase with downwind distance. The values of the ratio σy/σθ, where σθ is the standard deviation of the horizontal wind direction, also trend near the upper limit or above the range of values determined in earlier studies. There was also evidence to suggest that the value of σy began to be independent of σθ for σθ greater than 18°. It was also found that the commonly accepted range of values for σθ in different stability conditions might be limiting, at best, and might possibly be unrealistically low, especially at night in low wind speeds. The results raise questions about the commonly accepted magnitudes of σy derived from older studies. These values are used in the parameterization and validation of both older stability-class dispersion models as well as newer models that are based on Taylor’s equation and modern PBL theory.

scholarly journals Analysis of relationships between ultraviolet radiation (295–385 nm) and aerosols as well as shortwave radiation in North China Plain

2008 ◽  
Vol 26 (7) ◽  
pp. 2043-2052 ◽  
Author(s):  
X. Xia ◽  
Z. Li ◽  
P. Wang ◽  
M. Cribb ◽  
H. Chen ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Precipitable Water ◽  
Ground Level ◽  
Weather Conditions ◽  
Northern China ◽  
Shortwave Radiation ◽  
Relevant Variables

Abstract. The fraction of ultraviolet (UV) radiation to broadband shortwave (SW) radiation (FUV=UV/SW) and the influences of aerosol, precipitable water vapor content (PWV) and snow on FUV were examined using two year's worth of ground-based measurements of relevant variables in northern China. The annual mean FUV was 3.85%. Larger monthly values occurred in summer and minimum appeared in winter. Under cloudless condition, FUV decreased linearly with τ500 nm and the resulting regression indicated a reduction of about 26% in daily FUV per unit τ500 nm, implying that aerosol is an efficient agent in lowering the ground-level UV radiation, especially when the sun is high. Given that the annual mean τ500 nm is 0.82, aerosol induced reduction in surface UV radiation was from 24% to 74% when the solar zenith angle (θ) changed from 20° to 80°. One cm of PWV led to an increase of about 17% in daily FUV. One case study of snow influence on surface irradiance showed that UV and SW radiation increased simultaneously when the ground was covered with snow, but SW radiation increased much less than UV radiation. Accordingly, FUV increased by 20% for this case. Models were developed to describe the dependence of instantaneous UV radiation on aerosol optical depth, the cosine of the solar zenith angle (μ), and clearness index (Kt) under both clear and all-weather conditions.

scholarly journals Large Contributions from Biogenic Monoterpenes and Sesquiterpenes to Organic Aerosol in the Southeastern United States

2018 ◽  
Author(s):  
Lu Xu ◽  
Havala O. T. Pye ◽  
Jia He ◽  
Yunle Chen ◽  
Benjamin N. Murphy ◽  
...  
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Organic Aerosol ◽  
Atmospheric Model ◽  
Average Concentration ◽  
Mass Spectrometry Data ◽  
World Health ◽  
Atmospheric Conditions ◽  
Considerable Uncertainty ◽  
Health Organization

Abstract. Atmospheric organic aerosol (OA) has important impacts on climate and human health but its sources remain poorly understood. Biogenic monoterpenes and sesquiterpenes are critical precursors of OA. The OA generation from these precursors predicted by models has considerable uncertainty owing to a lack of appropriate observations as constraints. Here, we perform novel lab-in-the-field experiments, which allow us to study OA formation under realistic atmospheric conditions and offer a connection between laboratory and field studies. Based on the lab-in-the-field experimental approach and positive matrix factorization analysis on aerosol mass spectrometry data, we provide a measure of OA from monoterpenes and sesquiterpenes in the southeastern U.S. Further, we use an upgraded atmospheric model and reproduce the measured OA concentration from monoterpenes and sesquiterpenes at multiple sites in the southeastern U.S., building confidence in the observed attribution of monoterpene SOA. We show that the annual average concentration of OA from monoterpenes and sesquiterpenes in the southeastern U.S. is ~ 2.1 µg m−3. This amount is substantially higher than represented in current regional models and accounts for 21 % of World Health Organization PM2.5 standard, indicating a significant contributor of environmental risk to the 77 million habitants in the southeastern U.S.

scholarly journals NO<sub>2</sub> and HCHO photolysis frequencies from irradiance measurements in Thessaloniki, Greece

2005 ◽  
Vol 5 (2) ◽  
pp. 1619-1646
Author(s):  
C. Topaloglou ◽  
S. Kazadzis ◽  
A. F. Bais ◽  
M. Blumthaler ◽  
B. Schallhart ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Nitrogen Dioxide ◽  
Atmospheric Conditions ◽  
Actinic Flux ◽  
Lower Upper ◽  
Global Irradiance ◽  
Photolysis Frequencies ◽  
Photolysis Frequency ◽  
Flux Measurements

Abstract. An empirical approach for the retrieval of nitrogen dioxide (NO2) and formaldehyde (HCHO) photolysis frequencies from measurements of global irradiance is presented in this work. Four months of synchronous measurements of actinic flux and global irradiance performed in Thessaloniki, Greece by a Bentham spectroradiometer were used to extract polynomials for the conversion of global irradiance to photolysis frequencies [(NO2) and J(HCHO)]. The comparison of these photolysis frequency values to the corresponding values calculated by spectral actinic flux measurements, showed a ratio very close to unity for all J's with a standard deviation of 6% for J(NO2) and 3% for J(HCHO). Additional sets of polynomials were also extracted to allow determination of J(NO2) by spectroradiometers with lower upper wavelength limits such as single and double Brewer spectroradiometers within acceptable uncertainty (corresponding ratio was 1 and standard deviation was 6% for double and 10% for single Brewers). The validity of the method under different atmospheric conditions was also examined by applying the polynomials to another set of actinic flux and global irradiance measurements performed in May 2004, in Buchhofen, Germany. In this case, comparing J values extracted from the polynomials to those calculated from actinic flux, showed equivalent results, demonstrating that the method can also be applied to other measurement sites.

scholarly journals An Upper Threshold of Enhanced Global Shortwave Irradiance in the Troposphere Derived from Field Measurements in Tropical Mountains

2008 ◽  
Vol 47 (11) ◽  
pp. 2828-2845 ◽  
Author(s):  
P. Emck ◽  
M. Richter
Keyword(s):  
Global Radiation ◽  
Field Measurements ◽  
Absolute Maximum ◽  
Atmospheric Conditions ◽  
Maximum Enhancement ◽  
General Validity ◽  
Tropical Mountains ◽  
Clear Sky ◽  
Global Irradiance ◽  
Diffuse Cloud

Abstract Extraordinarily high values of global irradiance (up to 1832 W m−2) incident upon a horizontal surface were observed during a 4-yr meteorological field campaign in the southern Ecuadorian Andes Mountains (4°S). The unexpected magnitude gave rise to a thorough revision of the instrumentation and an assessment of the radiation database. Infrastructure at the sites and software were critically examined, and the sensor and datalogger manufacturers were contacted. The observed enhanced irradiance was quantified with a simple clear-sky model for global radiation. The efforts showed that atmospheric conditions and not artifacts had produced the high values. Cloud radiative effects could be singled out as the exclusive source of the “superirradiance.” Mean (bihourly) maximum enhancement was 119.6% of the potential (clear sky) irradiance; absolute maximum enhancement occasionally reached to over 170%. Thereby, under ideal conditions, the upper threshold of global irradiance is apparently ∼200% of the potential (clear sky) direct radiation [i.e., at the point of observation, downwelling diffuse cloud radiation can (almost) equal the magnitude of its apparent “source”]. The observations were made between altitudes of 1500 and 3400 m MSL in different climates ranging from perhumid to semiarid (i.e., in very cloudy climates and in less cloudy climates). The conditions that were found to explain the magnitude of the extremely enhanced irradiance are not confined to tropical or mountainous environments only, but rather they can occur at any spot in the troposphere where clouds exist. Therefore, the findings appear to be of general validity.

Effect of solar zenith angle on satellite cloud retrievals based on O2–O2 absorption band

2021 ◽  
Vol 42 (11) ◽  
pp. 4224-4240
Author(s):  
Gyuyeon Kim ◽  
Yong-Sang Choi ◽  
Sang Seo Park ◽  
Jhoon Kim
Keyword(s):  
Absorption Band ◽  
Zenith Angle ◽  
Solar Zenith Angle

Sun-induced production of vitamin D3 throughout 1 year in tropical and subtropical regions: relationship with latitude, cloudiness, UV-B exposure and solar zenith angle

2021 ◽  
Vol 20 (2) ◽  
pp. 265-274
Author(s):  
Angela C. G. B. Leal ◽  
Marcelo P. Corrêa ◽  
Michael F. Holick ◽  
Enaldo V. Melo ◽  
Marise Lazaretti-Castro
Keyword(s):  
Zenith Angle ◽  
Vitamin D3 ◽  
Solar Zenith Angle

scholarly journals Evaluating the Impact of Two Generalist Predators on the Leafhopper Erasmoneura vulnerata Population Density

Insects ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 321
Author(s):  
Stefan Cristian Prazaru ◽  
Giulia Zanettin ◽  
Alberto Pozzebon ◽  
Paola Tirello ◽  
Francesco Toffoletto ◽  
...  
Keyword(s):  
Field Experiments ◽  
Field Studies ◽  
Generalist Predators ◽  
Predator Species ◽  
Potted Plants ◽  
Naturally Occurring ◽  
Orius Majusculus ◽  
Limited Effectiveness ◽  
Pest Outbreaks ◽  
The Impact

Outbreaks of the Nearctic leafhopper Erasmoneura vulnerata represent a threat to vinegrowers in Southern Europe, in particular in North-eastern Italy. The pest outbreaks are frequent in organic vineyards because insecticides labeled for organic viticulture show limited effectiveness towards leafhoppers. On the other hand, the naturally occurring predators and parasitoids of E. vulnerata in vineyards are often not able to keep leafhopper densities at acceptable levels for vine-growers. In this study, we evaluated the potential of two generalist, commercially available predators, Chrysoperla carnea and Orius majusculus, in suppressing E. vulnerata. Laboratory and semi-field experiments were carried out to evaluate both species’ predation capacity on E. vulnerata nymphs. The experiments were conducted on grapevine leaves inside Petri dishes (laboratory) and on potted and caged grapevines (semi-field); in both experiments, the leaves or potted plants were infested with E. vulnerata nymphs prior to predator releases. Both predator species exhibited a remarkable voracity and significantly reduced leafhopper densities in laboratory and semi-field experiments. Therefore, field studies were carried out over two growing seasons in two vineyards. We released 4 O. majusculus adults and 30 C. carnea larvae per m2 of canopy. Predator releases in vineyards reduced leafhopper densities by about 30% compared to the control plots. Results obtained in this study showed that the two predators have a potential to suppress the pest density, but more research is required to define appropriate predator–prey release ratios and release timing. Studies on intraguild interactions and competition with naturally occurring predators are also suggested.

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