scholarly journals Temperature influence on the natural aerosol budget over boreal forests

2014 ◽  
Vol 14 (16) ◽  
pp. 8295-8308 ◽  
Author(s):  
L. Liao ◽  
V.-M. Kerminen ◽  
M. Boy ◽  
M. Kulmala ◽  
M. Dal Maso
Keyword(s):  
Boreal Forests ◽  
Cloud Condensation Nuclei ◽  
Field Measurements ◽  
Back Trajectories ◽  
Aerosol Mass ◽  
Clean Air ◽  
A Minor ◽  
Natural Aerosol ◽  
Term Field

Abstract. We investigated the natural aerosol evolution of biogenic monoterpene emissions over the northern boreal forest area as a function of temperature using long-term field measurements of aerosol size distributions and back trajectories at two SMEAR (Station for Measuring Ecosystem–Atmosphere Relations) stations, SMEAR I and SMEAR II, in Finland. Similar to earlier studies, we found that new particles were formed via nucleation when originally clean air from the ocean entered the land, after which these particles continuously grew to larger sizes during the air mass transport. Both the travelling hour over land and temperature influenced the evolution of the particle number size distribution and aerosol mass yield from biogenic emissions. Average concentrations of nucleation mode particles were higher at lower temperatures, whereas the opposite was true for accumulation mode particles. Thus, more cloud condensation nuclei (CCN) may be formed at higher temperatures. The overall apparent aerosol yield, derived from the aerosol masses against accumulated monoterpene emissions, ranges from 13 to 37% with a minor, yet complicating, temperature dependence.

scholarly journals Temperature influence on the natural aerosol budget over boreal forests

2013 ◽  
Vol 13 (12) ◽  
pp. 33311-33342
Author(s):  
L. Liao ◽  
V.-M. Kerminen ◽  
M. Boy ◽  
M. Kulmala ◽  
M. Dal Maso
Keyword(s):  
Boreal Forests ◽  
Particle Number ◽  
Field Measurements ◽  
Back Trajectories ◽  
Aerosol Mass ◽  
Higher Temperature ◽  
A Minor ◽  
Natural Aerosol ◽  
Term Field

Abstract. We investigated the natural aerosol evolution from biogenic monoterpene emissions among northern boreal forest area as function of temperature, using long-term field measurements of aerosol size distributions and back trajectories at two stations SMEAR I and SMEAR II in Finland. Particles were formed via nucleation through the clean ocean to land transition of air parcels, and continuously grew to larger sizes during air mass transport. Both the travelling hour over land and temperature influences the evolution of the particle number size distribution and the average aerosol mass yield from BVOC emissions. Average concentrations of nucleation mode particles were higher at lower temperatures, whereas the opposite was true for accumulation mode particles, thus more CCN may be formed at higher temperature. The overall apparent aerosol yield derived from the aerosol masses against accumulated monoterpene emissions ranges 13–37% with a minor yet complicating temperature dependence.

scholarly journals Comment on ''Observing desert dust devils with a pressure logger" by Lorenz (2012) – insights on measured pressure fluctuations from large-eddy simulations

2012 ◽  
Vol 1 (2) ◽  
pp. 151-154 ◽  
Author(s):  
A. Spiga
Keyword(s):  
Pressure Fluctuations ◽  
Field Measurements ◽  
Large Eddy Simulations ◽  
Pressure Measurements ◽  
Dust Devils ◽  
Pressure Drops ◽  
Large Eddy ◽  
Measured Pressure ◽  
Term Field

Abstract. Lorenz et al. (2012) proposes to use pressure loggers for long-term field measurements in terrestrial deserts. The dataset obtained through this method features both pressure drops (reminiscent of dust devils) and periodic convective signatures. Here we use large-eddy simulations to provide an explanation for those periodic convective signatures and to argue that pressure measurements in deserts have broader applications than monitoring dust devils.

scholarly journals Simulating secondary organic aerosol from missing diesel-related intermediate-volatility organic compound emissions during the Clean Air for London (ClearfLo) campaign

2016 ◽  
Author(s):  
R. Ots ◽  
D. E. Young ◽  
M. Vieno ◽  
L. Xu ◽  
R. E. Dunmore ◽  
...  
Keyword(s):  
Organic Compound ◽  
Atmospheric Chemistry ◽  
Secondary Organic Aerosol ◽  
Transport Model ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Total Particulate Matter ◽  
Aerosol Mass ◽  
Clean Air ◽  
The Uk

Abstract. We present high-resolution atmospheric chemistry transport model (ACTM) simulations of secondary organic aerosol (SOA) formation over the UK for 2012. Our simulations include additional diesel-related intermediate volatility organic compound (IVOC) emissions derived directly from comprehensive field measurements at an urban background site in London during the 2012 Clean Air for London (ClearfLo) campaign. Our IVOC emissions are added proportionally to VOC emissions, as opposed to proportionally to primary organic aerosol (POA) as has been done by previous ACTM studies seeking to simulate the effects of these missing emissions. Modelled concentrations are evaluated against hourly and daily measurements of organic aerosol (OA) components derived from aerosol mass spectrometer (AMS) measurements also made during the ClearfLo campaign at three sites in the London area. Good hourly performance in comparison to the measurements was shown, giving confidence in the SOA prediction skill of the ACTM system used. According to the model simulations, diesel-related IVOCs can explain on average ~30% of the annual SOA in and around London. Furthermore, the 90-th percentile of modelled daily SOA concentrations for the whole year is 3.8 μg m−3 (more than 40% of which is produced from the missing diesel precursors), constituting a notable addition to total particulate matter. More measurements of these precursors (currently not included in official emissions inventories) is recommended. During the period of concurrent measurements, SOA concentrations at the Detling rural background location east of London were greater than at the central London location. The model shows that this was caused by an intense pollution plume with a strong gradient of imported SOA passing over the rural location. This demonstrates the value of modelling for supporting the interpretation of measurements taken at different sites or for short durations.

A long-term field study (1951-2003) of ventifacts formed by katabatic winds at Paulatuk, western Arctic coast, Canada

2005 ◽  
Vol 42 (9) ◽  
pp. 1615-1635 ◽  
Author(s):  
J Ross Mackay ◽  
C R Burn
Keyword(s):  
Field Measurements ◽  
Katabatic Winds ◽  
Abrasion Rate ◽  
Western Arctic ◽  
Arctic Coast ◽  
Optical Examination ◽  
East West ◽  
Coastal Settlement ◽  
Term Field

Field measurements have been made since 1951 on hundreds of ventifacts abraded by strong, southerly, katabatic winds that blow in winter and summer past Paulatuk, a small western Arctic coastal settlement. Sand is commonly entrained by the strongest winds in winter. The ventifacts, all glacial erratics deposited prior to 12 ka BP, have been gradually rotated by the southerly winds until the long axes of most ventifacts now trend approximately east–west, normal to the katabatic winds. In contrast, pebbles have a slightly preferred north–south orientation, parallel to the katabatic winds. The facets on sandstone and diabase ventifacts are almost planar, but are rounded on granites and hackled on limestones, reflecting the influence of both solution and abrasion. Abrasion is evident on the built structures in Paulatuk, but despite the over 50 years of observation, abrasion of the ventifacts has been virtually undetectable. The extremely slow abrasion rate has been estimated from: observations on two ventifacts from 1951 to 2003; photographic comparisons and observations of 60 ventifacts from 1968 to 2003; optical examination of 14 granite slabs, polished and unpolished, exposed to abrasion from 1967 to 1976; and comparisons of the windward and leeward sides of six large rock caches built with ventifacts probably long before 1900. If the present rates of abrasion are representative of Holocene conditions, ventifact formation has probably taken much of postglacial time. The increase in vegetation cover around many rocks between 1968 and 2003 suggests that the climate has changed in the last three decades.

scholarly journals A GROSS LONGSHORE TRANSPORT RATE FORMULA

1972 ◽  
Vol 1 (13) ◽  
pp. 47 ◽  
Author(s):  
Cyril J. Galvin
Keyword(s):  
Current Velocity ◽  
Empirical Relation ◽  
Field Measurements ◽  
Transport Rate ◽  
Longshore Current ◽  
Physical Explanation ◽  
Littoral Drift ◽  
Longshore Transport ◽  
Term Field

Gross longshore transport rates for 11 long-term field measurements are predicted reasonably well by the empirical relation, Q=2H2, where Q is longshore transport rate in 100,000 yd3/yr, and H is a mean breaker height in feet. A physical explanation of this empirical relation assumes: (1) most littoral drift is transported in suspension; (2) longshore current velocity is predicted by V-gmTsin28j,; (3) the empirical relation is an equation for conservation of suspended sediment in the longshore current.

scholarly journals Comment on "Observing desert dust devils with a pressure logger" by Lorenz (2012)

2012 ◽  
Vol 2 (2) ◽  
pp. 593-601 ◽  
Author(s):  
A. Spiga
Keyword(s):  
Field Measurements ◽  
Large Eddy Simulations ◽  
Pressure Measurements ◽  
Dust Devils ◽  
Pressure Drops ◽  
Desert Dust ◽  
Large Eddy ◽  
Term Field

Abstract. Lorenz (2012) proposes to use pressure loggers for long-term field measurements in terrestrial deserts. The dataset obtained through this method features both pressure drops (reminiscent of dust devils) and periodic convective signatures. Here we use Large-Eddy Simulations to provide an explanation for those periodic convective signatures and to argue that pressure measurements in deserts have broader applications than monitoring dust devils.

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