Determination of the concentration of chemical main and trace elements (chemical matrix) in the aerosol from 1972 to 1982 at a North-alpine pure air station at 1780 m a.s.l.

Summary Aerosol particles have been separated by filter at a mountain station at 1780 m a.s.l. continuously since 1972. The station (a WMO-BAPMoN station with extended program) is freely exposed to all sides and in no way influenced by local aerosol sources. In the cold seasons it lies almost exclusively above the convection layer (very often over inversions) so that real background data can be acquired in these cases. By means of analytical methods the chemical components are determined on the exposed filters. This includes (apart from crust elements) also cations and anions from man-made and maritime sources as well as some important trace elements (in all, 15 components). Filters are exposed over 1–4 days. Filter exchange is determined by the respective weather situation with due regard to all changes so that the requirements for a reasonable correlation of the measured values with the meteorological conditions are met. Additionally, all meteorological parameters are determined, as well as intensity of the vertical exchange, number density of Aitken nuclei, concentration of natural radioactivity (RaB), and other variables. In the present paper the components of the aerosol chemical matrix are related to the behavior of the parameters below and the results are discussed in detail: Dependence of the individual components on total aerosol mass per volume, type of air mass; representation of two single cases of long-range transport of crust elements (source areas: Sahara, Colorado); vertical exchange coefficient, concentration of natural radioactivity, temperature gradient between valley and mountain station, temperature at the sampling site, relative humidity, precipitation rate, wind direction. occurrence of fog.Zusammenfassung An einer allseitig frei exponierten Bergstation in 1780 m NN werden seit 1982 die Aerosolpartikel auf Filtern gesammelt. Die Station (eine WMO-BAPMoN-Station mit erweitertem Programm) wird nicht durch lokale Aerosolquellen in irgendeiner Weise beeinflußt. Sie liegt in den kalten Jahreszeiten fast ausschließlich über der Konvektionsschicht (sehr oft oberhalb von Inversionen), so daß in diesen Fällen echte Background-Daten erfaßt werden. Mittels analytischer Verfahren werden an den exponierten Filtern alle chemischen Hauptkomponenten (von den Krustenelementen abgesehen auch die Kationen und Anionen sowohl anthropogenen als auch maritimen Ursprungs), sowie einige gewichtige Spurenelemente (insgesamt 15 Komponenten) bestimmt. Die Filter werden 1–4 Tage lang exponiert. Der Filterwechsel wird durch den jeweiligen Wetterzustand bzw. seiner Veränderung gesteuert, so daß eine gute Voraussetzung für eine Zuordnung der Meßwerte zu den meteorologischen Bedingungen gegeben ist. Zusätzlich werden alle meteorologischen Parameter, sowie die Intensität des Vertikalaustausches, Zahl der Aitken-Kerne, Konzentration der natürlichen Radioaktivität (RaB) und andere Größen bestimmt. In der vorliegenden Arbeit werden die Komponenten der chemischen Aerosolmatrix zum Verhalten der folgenden Parameter in Beziehung gesetzt und die Ergebnisse eingehend diskutiert:Abhängigkeit der Einzelkomponenten von: Gesamt-Aerosohnasse pro Volumen; Typ der Luftmasse und Darstellung von zwei Einzelfällen eines Ferntransportes von Krustenelementen (Quellgebiete: Sahara, Colorado); vertikaler Austauschkoeffizient; Konzentration der natürlichen Radioaktivität; Temperaturgradient zwischen Tal- und Bergstation; Temperatur an der Probennahmestelle; relative Feuchte; Niederschlagsintensität; Windrichtung; Auftreten von Nebel.

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Bestimmung der Konzentration chemischer Haupt- und Spurenstoffe (chemische Matrix) im Aerosol von 1972 bis 1982 an einer nordalpinen Reinluftstation in 1780 m NN.Teil II: Parametrische Korrelationsanalyse der chemischen Matrix mit Berücksichtigung meteorologischer Größen

     

Determination of the concentration of chemical main and trace elements (chemical matrix) in the aerosol from 1972 to 1982 at a North-alpine pure air station at 1780 m a.s.l.

Theoretical and Applied Climatology - Aerosol particles have been separated by filter at a mountain station at 1780 m a.s.l. continuously since 1972. The station (a WMO-BAPMoN station with extended...     

Marked changes in the aerosol chemical matrix recently observed at 1780 m a.s.l. (BAPMoN mountain station) and results of first comparisons with samples obtained simultaneously at 740 m a.s.l

Summary Recently we reported on results concerning the structure of the aerosol chemical matrix in samples collected from 1972 to 1982 at a mountain observatory at 1780 m a.s.l. in a clean air region (BAPMoN-station). Trend analyses and parameterizations have been made using the meteorological environmental conditions. Sampling and measurements were continued and show in the recent past for components of mostly anthropogenic origin significant reductions. Moreover, we give for the first time results of synchronous aerosol sampling at the mountain observatory and in the neighboring valley floor at 740 m a.s.l., the horizontal distance being only 6 km. The results are analyzed statistically.

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In jüngster Zeit beobachtete starke Änderungen in der Aerosolchemischen Matrix in 1780 m NN (BAPMoN-Bergstation) und Ergebnisse erster Vergleiche mit simultanen Proben aus 740 m NN

Zusammenfassung Kürzlich wurde über Ergebnisse der Struktur der chemischen Aerosol-Matrix berichtet, welche von 1972 bis 1982 auf einem Bergobservatorium in 1780 m NN in einer Reinluftzone(BAPMoN-Station)gesammelt wurden. Trend-Analysen und Parameterisierungen mit Hilfe der meteorologischen Umweltbedingungen wurden durchgeführt. Die Probenahmen und Messungen wurden fortgesetzt und zeigen im Hinblick auf Komponenten hauptsächlich anthropogenen Ursprungs in jüngster Zeit signifikante Reduzierungen, die dargestellt werden. Außerdem werden erstmals Ergebnisse mitgeteilt aus synchronen Aerosol-Probenahmen am Bergobservatorium in 740 m NN bei nur 6 km horizontaler Distanz. Die Ergebnisse werden statistisch analysiert.

     

Case study of cloud physical and chemical processes in low clouds at Mt. Brocken

Frequency distributions of cloud base height and cloud type of low clouds observed between May and October 1998 at Mt. Brocken (Germany) have been derived from ceilometer measurements and synoptic observations. The summit at 1142 m a.s.l. was about 50% of that time in cloud. During daytime, Stratus clouds were the dominant cloud type (65%), whereas Cumulus clouds amounted to 27% and Stratocumulus clouds to 8%. Evidence was found that the increase of the cloud base height observed at Mt. Brocken continues since the end of the 1980s. An example for a clear anticorrelation between the liquid water content (LWC) of the cloud and the height above cloud base is shown. Other results of this detailed case study of a cloud event on October 8, 1998 concerning phase partitioning of water-soluble inorganic compounds, black carbon (BC) and organic carbon (OC) between the liquid and the interstitial phase will also be presented. The observed ion-specific increase in the solute mass per cubic meter of air with decrease of the distance between sampling position and cloud base was caused mainly by entrainment of air from the below-cloud layer. As expected, for sulfate, ammonia and nitrate, high scavenging coefficients (>0.8) were found. OC exhibits a high scavenging fraction of between 0.4 and 0.7; the value for black carbon (0.2–0.4) implies that soot was possibly to some extent internally mixed in the cloud condensation nuclei (CCN). Simultaneous measurements during a cloud event of HNO₂ and HNO₃ in the gas phase and N(III) and N(V) in the liquid phase were made for the first time.     

Spatial variability in the chemical composition of the snowcover at high alpine sites

Summary For a comparison of snow chemistry data from different glaciers or snow fields it is important to have informations about the spatial representativeness of the data from each of the individual sites. In order to assess the representativeness of concentration data of major ions (volume weighted means of the winter accumulation) from glacier fields we investigated the variability in the average concentration of major ions from parallel samples within one snow pit and from different pits within one glacier field. The variabilities in the average concentrations of NO ₃ ^- , SO ₄ ^2- and NH ₄ ⁺ for three parallel profiles within one snow pit at Goldbergkees (Austria) were 1.2, 3.3 and 2.0% (coefficient of variation). Cl^– and Na⁺ showed larger variations (6.6 and 56.6%) possibly originating from contaminations. The variability of average concentration data from different snow pits within one glacier field was studied at La Grave (France) and at Goldbergkees (Austria). At La Grave 3 pits and at Goldbergkees 4 pits at distance of several hundred meters were sampled. Variabilities for SO ₄ ^2- and NO ₃ ^- were quite similar for the two sites (17% for both ions at La Grave, 12% and 15% at Goldbergkees). Whereas variabilities for Na⁺, NH ₄ ⁺ , Mg²⁺, Ca²⁺ and Cl^– were quite low at La Grave ( 12% and 27% for Cl^–), higher values were obtained at Goldbergkees for these ions (17–56%). Likely reasons for the higher variability observed at Goldbergkees are a) higher spatial variability of crustal aerosol species (Mg²⁺, Ca²⁺), b) problems with the detection limit of the analytical method (Ca²⁺), c) contaminations (Na⁺, Cl^–).With 4 Figures     

Influence of regional pollution and sandstorms on the chemical composition of cloud/fog at the summit of Mt. Taishan in northern China

Cloud/fog samples were collected during spring of 2007 in the highly polluted North China Plain in order to examine the impact of pollution and dust particles on cloud water chemistry. The volume weighted mean pH of cloud water was 3.68. The cloud acidity was shown to be associated with air mass origins. Cloud water with its air mass trajectories originating from the southern part of China was more acidic than those from northern China. Anthropogenic source and dust had obvious impact on cloud water composition as indicated by the very high mean concentrations of SO₄^2? (1331.65 μeq L^? 1), NO₃^? (772.44 μeq L^? 1), NH₄⁺ (1375.92 μeq L^? 1) and Ca²⁺ (625.81 μeq L^? 1) in the observation periods. During sandstorm days, cloud pH values were relatively high, and the concentrations of all the ions in cloud water reached unusual high levels. Significant decreases in the mass concentrations of PM_2.5 and PM₁₀ were observed during cloud events. The average scavenging ratio for PM_2.5 and PM₁₀ was 52.0% and 55.7%, respectively. Among the soluble ions in fine particles, NO₃^?, K⁺ and NH₄⁺ tend to be more easily scavenged than Ca²⁺ and Na⁺.     

Air masses and aerosols chemical components in the free troposphere at the subtropical northeast atlantic region

The dynamics and the aerosol chemistry of the air masses reaching the free troposphere of the subtropical Northeast Atlantic region during the period 1995–98 have been studied. Seven days backward trajectories were calculated daily with HYSPLIT-4 model for Izaña Global Atmospheric Watch (GAW) Observatory (28.3^°N 16.5^°W, 2367 m a.s.l.). These back-trajectories were classified by means of a k-means clustering strategy. The daily air masses have been coded using 16 variables to detect the aerosol load of each one of them. Four clusters were found: Cluster 1, representative of Atlantic oceanic middle troposphere air masses, (OMT), has an average frequency of occurrence of 50.6%. Cluster 2, which includes air masses originated in the African continent (AfD), has been recorded in a 19.8% of time. Cluster 3 represents a mixture at least of two of the next sources: Europe, Africa and Ocean, (EAM), with a frequency of 12.7%. Finally, Cluster 4 includes air masses with a high load of maritime aerosols, (MaA), and it has been detected in a 16.9%. An analysis of four aerosol components: NO₃ ^?, NH₄ ⁺, non-sea-salt-SO₄ ^2?, and mineral dust and its relation with the origin and transport of the air masses have been done. The highest quantities of mineral dust and nss-SO₄ ^2? are linked with African air masses with a mean value of 86.5 and 1.9 μg/m³ respectively. Whereas the highest levels of NO₃ ^?, 1.0 μg/m³, and NH₄ ⁺, 0.4 μg/m³, were obtained for AfD and EAM. The lowest levels were associated with OMT and MaA air masses types: 12.7, 0.6, 0.2, and 0.5 μg/m³ for dust, NO₃ ^?, NH₄ ⁺, and nss-SO₄ ^2? in average for the four studied years. However, it is remarkable that the values of the median for dust are 2.2 and 3.5 μg/m³ in clusters MaA and OMT respectively. Using non-parametric statistical tests the distributions of concentrations in each cluster by year have been compared in order to detect similarities. The results show that the aerosol loads of OMT and MaA air masses are quite similar and the same occurs for AfD and EAM air masses. However, the correlation analysis between the levels of anions and ammonium evidenced important differences among the air mass types. In AfD air masses is clear a low correlation between levels of nss-SO₄ ^2? and NH₄ ⁺ (r ² = 0.08) suggesting that the sulfate speciation was dominated by sulfate species others than ammonium sulfate, such as calcium sulfate. CaSO₄ ?2H₂O (gypsum) is mainly present in the coarse mode, where the radiative effects of sulfate are less important that in the accumulative mode. For OMT air masses is noticeable an important increasing on the correlation between the levels of anions and those of NH₄ ⁺ for the two last years of the study period (1997–1998, r ² = 0.61 –0.85%) with respect to the first ones (1995–1996, r ² = 0.25–0.49%), coinciding with the second strongest ENSO (El Niño Southern Oscillation) event recorded. This behavior indicates a change in the speciation of the aerosol component.     

Source identification and variation in the chemical composition of rainwater at coastal and industrial areas of India

Studies on precipitation chemistry were carried out to understand the nature and sources of rainwater at Rameswaram and NTPC Dadri, India representing coastal and industrial region during 2010. The rainwater samples, collected at these locations, were analyzed for major ions and pH. The data were assessed for its quality. The pH of rainwater at two locations varied from 5.53 to 6.73 and 5.1–6.6, indicating alkaline nature except a few acidic events. The dominance of Cl− and Na+ were observed in coastal environment whereas dominance of Ca2+ was seen in industrial environment. The nss-SO42- (37.9%) at Rameswaram is less influenced by anthropogenic activities whereas nss-SO42- (72.5%) at NTPC Dadri is influenced by pollutants emitted by anthropogenic sources. The ratio of H+/(NO3- + SO42-) was observed as 0.04 and 0.008 for Rameswaram and NTPC Dadri which is close to zero, indicate 99.99% of acidity was neutralized in precipitation. Ca2+, NH4+ and Mg2+ play an important role in neutralization of acidic ions in rainwater. For source identification, correlation matrix analysis was established, which showed that in general, at both sites; correlation between the acidic ions SO42- and NO3- indicating their origin from similar sources, because of the similarity in their behavior in precipitation and the co-emissions of their precursors SO2 and NOX. The correlation coefficient of (SO42- + NO3-) vs (Ca2+) at Rameswaram and NTPC Dadri were 0.77 and 0.87 indicates that CaCO3 is the major neutralizing agent for both the region. Overall, the influence of marine, terrestrial and anthropogenic sources was observed in the rain events.     

Physical,mineralogical and chemical properties of harmattan dust at Ile-Ife,Nigeria

Summary Meteorological conditions associated with the transport and deposition of harmattan dust particles in West Africa are discussed as well as particle-size distribution analyses of Saharan aeolian dust monitored at Ile-Ife (7.29 N, 4.34 E) nearly 2,000 km South-West of its predominant source region, the Chad Basin.Mineralogical analysis of the dust indicated that it is predominantly composed of quartz (> 70%) followed by microcline, kaolinite and traces of mica and halloysite. Chemical analyses indicated a predominance of SiO₂ (> 60%) followed by Al₂O₃ (17.4%), Na₂O (10.1%), Fe₂0₃ (5.6%), TiO₂ (3.33%), K₂O (1.88%), MgO (0.56%), and CaO (0.37%). The following trace elements were identified: Zn (931 ppm), Mn (834 ppm), Ni (113 ppm), Cr (103 ppm), Cu (106 ppm), Co (77 ppm) V (65 ppm) and Li (25 ppm).The effect of the poor visibility caused by the harmattan dust on aviation operation and safety as well as the health hazards posed on the respiratory system by the air-borne toxic elements should be of concern to relevant decision makers and should be further investigated.

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Zusammenfassung Vorliegende Studie behandelt meteorologische Bedingungen in Zusammenhang mit dem Transport und der Ablagerung von Harmattan-Staubpartikeln in Westafrika, als auch Partikelgrößenverteilungen, die in Ile-Ife (7.29N, 4.34E) aufgezeichnet wurden, beinahe 2000 km südwestlich von ihrer wichtigsten Ursprungsregion, dem Tschad-Becken.Die mineralogische Analyse des Staubes hat gezeigt, daß er im wesentlichen aus Quartz (> 70%) besteht. Chemische Analysen des Staubes wiesen hauptsächlich SiO₂ (> 60%), sowie Al₂O₃ (17,4%), Na₂O (10,1%), Fe₂O₃ (5,6%) TiO₂ (3,33%), K₂O (1,88%), MgO (0,56%) und CaO (0.37%) aus; an Spurenelementen wurden Zn (931 ppm), Mn (834 ppm), Ni (113 ppm), Cr (103 ppm), Cu (106 ppm), Co (77 ppm), V (65 ppm) und Li (25 ppm) nachgewiesen.Die Auswirkungen der durch den Harmattan-Staub stark geminderten Sichtweite auf den Flugverkehr und dessen Sicherheit sowie die gesundheitliche Beeinträchtigung der Atemwege durch giftige Aerosole sollten Gegenstand der Sorge staatstragender Kräfte als auch weiterer Forschungsbemühungen sein!

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Annual and decadal variation in chemical composition of rain water at all the ten GAW stations in India

Spatial variation of long term annual precipitation volume weighted concentrations of major chemical constituents (SO₄ ^?2, NO₃ ^?, Cl^?, NH₄ ⁺, Ca⁺², Mg⁺², Na⁺ and K⁺ ) at all the ten Global Atmospheric Watch (GAW) stations in India for the period from 1981 to 2012 is studied in this paper. Ionic abundance and balance is studied as well. The range of long term annual mean pH at ten stations was 5.25?±?0.82 to 6.91?±?0.76, lowest at Mohanbari and highest at Jodhpur. The long term annual mean pH for the period 1981–2012 showed decreasing trend at all the stations (significant at 5 % level). Decadal mean pH among ten stations for 1981–1990, 1991–2000 and 2001–2012 ranged between 7.31 to 5.76, 7.45 to 4.92 and 6.16 to 4.77 respectively and showed decreasing trend at all the stations during 1981–1990 to 2001–12. The percentage occurrence of acidic pH (<5.65) at ten stations ranged from 3 to 72 %, lowest at Jodhpur and highest at Mohanbari and it increased from 1981–1990 to 2001–2012 almost at all the stations. Temporal variation of annual mean values of nssSO₄ ^?2, NO₃ ^?, Ca⁺² and pH for the study period were attempted. Variation of nss K (non sea salt Potassium) at all the stations was studied to assess the biomass burning contribution in different regions. Non-marine (terrestrial) contribution dominated for majority of ionic constituents at most of the stations. However marine contribution was found to be dominant for Mg at Port Blair and Minicoy. Also sea salt fraction of SO₄ was higher than terrestrial at Minicoy. Sources of measured ionic constituents in rain water are assessed through correlation analysis. The concentrations of all the ionic species were lowest at Kodaikanal, a high altitude hill top station and the total ionic mass was 136.0 μeq/l. Jodhpur, an arid station not only had highest concentrations of Ca⁺², SO₄ ^?2 and K⁺ but also had highest total ionic content (1051.8 μeq/l) among all the stations. At Srinagar, Jodhpur, Allahabad, Nagpur and Pune stations Ca⁺² was the dominant cation while dominant anion was NO₃ ^? for Srinagar, Allahabad, and Nagpur and Cl^? for Jodhpur and Pune; at Mohanbari NO₃ ^? and Ca⁺²; at Visakhapatnam, Port Blair and Minicoy Na⁺ and Cl^? were abundant. Temporal variation had shown an increasing trend for nssSO₄ ^?2 and NO₃ ^? and obviously decreasing trend for pH at all the stations. However, Ca⁺² showed a decreasing trend at all the stations except at Port Blair. With the exception of Pune and Jodhpur stations, nssK showed a decreasing trend at all the stations revealing decreasing influence of soil/biomass burning over Indian GAW stations. Negative correlation of pH with SO₄ ^?2 was found to be weak compared to NO₃ ^–.     

Size-resolved aerosol chemical concentrations at rural and urban sites in Central California,USA

Aerosol size distributions were measured with Micro Orifice Uniform Deposit Impactor (MOUDI) cascade impactors at the rural Angiola and urban Fresno Supersites in California's San Joaquin Valley during the California Regional PM₁₀/PM_2.5 Air Quality Study (CRPAQS) winter campaign from December 15, 2000 to February 3, 2001. PM_2.5 filter samples were collected concurrently at both sites with Sequential Filter Samplers (SFS). MOUDI nitrate (NO₃⁻) concentrations reached 66 μg/m³ on January 6, 2001 during the 1000–1600 PST (GMT-8) period. Pair-wise comparisons between PM_2.5 MOUDI and SFS concentrations revealed high correlations at the Angiola site (r > 0.93) but more variability (r < 0.85) at the Fresno site for NO₃⁻, sulfate (SO₄⁼), and ammonium (NH₄⁺). Correlations were higher at Fresno (r > 0.87) than at Angiola (r < 0.7) for organic carbon (OC), elemental carbon (EC), and total carbon (TC). NO₃⁻ and SO₄⁼ size distributions in Fresno were multi-modal and wider than the uni-modal distributions observed at Angiola. Geometric mean diameters (GMD) were smaller for OC and EC than for NO₃⁻ and SO₄⁼ at both sites. OC and EC were more concentrated on the lowest MOUDI stage (0.056 µm) at Angiola than at Fresno. The NO₃⁻ GMD increased from 0.97 to 1.02 µm as the NO₃⁻ concentration at Angiola increased from 43 to 66 µg m^− 3 during a PM_2.5 episode from January 4–7, 2001. There was a direct relationship between GMD and NO₃⁻ and SO₄⁼ concentrations at Angiola but no such relationships for OC or EC. This demonstrates that secondary aerosol formation increases both concentration and particle size for the rural California environment.     

Size-resolved aerosol chemical concentrations at rural and urban sites in Central California, USA

Aerosol size distributions were measured with Micro Orifice Uniform Deposit Impactor (MOUDI) cascade impactors at the rural Angiola and urban Fresno Supersites in California's San Joaquin Valley during the California Regional PM₁₀/PM_2.5 Air Quality Study (CRPAQS) winter campaign from December 15, 2000 to February 3, 2001. PM_2.5 filter samples were collected concurrently at both sites with Sequential Filter Samplers (SFS). MOUDI nitrate (NO₃⁻) concentrations reached 66 μg/m³ on January 6, 2001 during the 1000–1600 PST (GMT-8) period. Pair-wise comparisons between PM_2.5 MOUDI and SFS concentrations revealed high correlations at the Angiola site (r > 0.93) but more variability (r < 0.85) at the Fresno site for NO₃⁻, sulfate (SO₄⁼), and ammonium (NH₄⁺). Correlations were higher at Fresno (r > 0.87) than at Angiola (r < 0.7) for organic carbon (OC), elemental carbon (EC), and total carbon (TC). NO₃⁻ and SO₄⁼ size distributions in Fresno were multi-modal and wider than the uni-modal distributions observed at Angiola. Geometric mean diameters (GMD) were smaller for OC and EC than for NO₃⁻ and SO₄⁼ at both sites. OC and EC were more concentrated on the lowest MOUDI stage (0.056 µm) at Angiola than at Fresno. The NO₃⁻ GMD increased from 0.97 to 1.02 µm as the NO₃⁻ concentration at Angiola increased from 43 to 66 µg m^− 3 during a PM_2.5 episode from January 4–7, 2001. There was a direct relationship between GMD and NO₃⁻ and SO₄⁼ concentrations at Angiola but no such relationships for OC or EC. This demonstrates that secondary aerosol formation increases both concentration and particle size for the rural California environment.     

Nocturnal Surface-Layer Characteristics at the Bottom of a Valley

Nighttime data collected at the bottom of a valley locatedin southern Brazil are studied. The analyzed quantities includemomentum and sensible heat fluxes, turbulence statistics andintermittency factors, and their relationship to the stability parameter.The proper interval for averaging and flux calculations is foundto be 20 min, based on the comparison of the fluxes and therandom error associated in their determination. Each data seriesis classified as calm or windy, according to the mean windspeed. A much better dependency of the variables in terms of thestability parameter is found under windy conditions. Analysis ofthe wind direction and topographic scales indicates that distortioneffects under calm conditions affect the flow, while the flow is inlocal equilibrium for windy conditions. In this case, the sensible heatflux shows a minimum for a value of z/L=0.08, while the momentumflux and the normalized scales of the wind components andtemperature decrease monotonically as the stability increases. Anintermittency factor is proposed and shown to be larger (moreintermittency) for more stable conditions.