scholarly journals Condensation and coagulation sinks and formation of nucleation mode particles in coastal and boreal forest boundary layers

2002 ◽  
Vol 107 (D19) ◽  
Author(s):  
M. Dal Maso
Keyword(s):  
Boreal Forest ◽  
Boundary Layers ◽  
Nucleation Mode ◽  
Forest Boundary

Nitrogen isotope pattern in Mongolian larch stands at the southern Eurasian boreal forest boundary

2018 ◽  
Vol 54 (6) ◽  
pp. 608-621 ◽  
Author(s):  
Mika Hayashi ◽  
Maximo Larry Lopez Caceres ◽  
Yoshihiro Nobori ◽  
Byambasuren Mijidsuren ◽  
Jens Boy
Keyword(s):  
Boreal Forest ◽  
Nitrogen Isotope ◽  
Isotope Pattern ◽  
Forest Boundary

scholarly journals Analysis of the growth of nucleation mode particles observed in Boreal forest

Tellus B ◽  
1998 ◽  
Vol 50 (5) ◽  
pp. 449-462 ◽  
Author(s):  
Markku Kulmala ◽  
Anne Toivonen ◽  
Jyrki M. Mäkelä ◽  
Ari Laaksonen
Keyword(s):  
Boreal Forest ◽  
Nucleation Mode

The late-Quaternary vegetational history of the Western Interior of Canada

1976 ◽  
Vol 54 (15) ◽  
pp. 1793-1818 ◽  
Author(s):  
J. C. Ritchie
Keyword(s):  
Boreal Forest ◽  
Vegetation History ◽  
Deciduous Forest ◽  
Late Quaternary ◽  
The South ◽  
Southern Limit ◽  
Growing Seasons ◽  
Pollen Stratigraphy ◽  
Late Wisconsinan ◽  
Forest Boundary

The late-Wisconsinan pollen stratigraphy of the Western Interior of Canada is assembled and 16 representative sites provide a basis for establishing trends of vegetation history. Sites in the southern, prairie region show an early Picea–Artemisia assemblage (12 × 103 to 10 × 103) replaced by a zone dominated by herb pollen. Similarly, sites in the Aspen Parkland and Transitional zones all have the Picea–Artemisia zone from as early as 13.9 × 103 to 10 × 103, followed by a herb zone. It is replaced by an arboreal pollen zone at 4.5 × 103 to 3 × 103 B.P. While there is a broad trend common to all sites in the modern boreal forest, from an early spruce-dominated assemblage to a late postglacial spruce–pine–birch assemblage identical with modern spectra, there are differences in the details of stratigraphy. Two sites in central Alberta have a poplar zone preceding the early spruce zone. Sites near the modern southern forest boundary show a late development (3 × 103 B.P.) of the mixed boreal forest from prairie and hardwood deciduous forest communities. One site, at Flin Flon, Saskatchewan, provides clear evidence for a treeless episode (Artemisia–grass–sedge) preceding the spruce zone.As the late-Wisconsinan glacial ended, an early version of the boreal forest, dominated by spruce and lacking pine, spread from adjacent U.S. on to deglaciated surfaces and till over stagnant ice. It persisted in the southern part of the area until about 10 × 103 and until 6 × 103 in the northernmost portions. In the south the spruce forest was replaced directly by prairie, spreading from the southwest and extending farther north than its modern limit between 7.5 × 103 and 6 × 103. All remnants of ice sheets and glacial lakes had disappeared by about 7 × 103 and the northern part of the area was occupied by a boreal forest undergoing rapid changes in composition from the early spruce-dominated version to the mixed spruce–pine–birch–poplar mosaic prevalent today. Pine probably spread from western réfugia, at least into areas north and west of L. Winnipeg. At about 3 × 103 the southern limit of the forest extended to the south, apparently in response to a climate with cooler and (or) wetter growing seasons. The rapid replacement of the spruce-dominated boreal forest by grasslands in the early postglacial was probably a response to warmer and drier growing seasons.

scholarly journals Airborne measurements of nucleation mode particles II: boreal forest nucleation events

2008 ◽  
Vol 8 (1) ◽  
pp. 2821-2848 ◽  
Author(s):  
C. D. O'Dowd ◽  
Y. J. Yoon ◽  
W. Junkerman ◽  
P. Aalto ◽  
M. Kulmala ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Forest Canopy ◽  
Particle Production ◽  
Spatial Scales ◽  
Source Region ◽  
Free Troposphere ◽  
Airborne Measurements ◽  
Nucleation Mode ◽  
Gulf Of Bothnia ◽  
Nocturnal Inversion

Abstract. Airborne measurements of nucleation mode aerosol concentrations during nucleation events over the boreal forest of southern Finland are reported. Three case studies are analysis in an attempt to characterise the spatial scales over which these events occur and to identify the source region for particle production. For the cases presented, there is no evidence of nucleation mode particles in the Free Troposphere. Nucleation mode particles are first detected in the surface layer as the nocturnal inversion breaks up and develops into the current-day's new boundary layer. In terms of spatial variability, significant variability in the concentration of nucleation mode particles was observed and was attributed to changes in the topography which comprised a mix of forest canopy and frozen lakes. Measurements over the Gulf of Bothnia indicated no nucleation mode over the sea and confirm that the scale of the events is associated with the boreal forest scale and that the new particles are produced directly above the forest canopy.

scholarly journals Holocene Eolian Activity in South-central Saskatchewan and the Southern Canadian Prairies*

2004 ◽  
Vol 56 (2-3) ◽  
pp. 215-227 ◽  
Author(s):  
Stephen A. Wolfe ◽  
Jeff Ollerhead ◽  
Olav B. Lian**
Keyword(s):  
Boreal Forest ◽  
Late Holocene ◽  
Sand Dunes ◽  
Canadian Prairies ◽  
South Central ◽  
South Saskatchewan River ◽  
Dune Stability ◽  
Eolian Deposits ◽  
Forest Boundary ◽  
Dune Activity

Abstract The chronology and stratigraphy of eolian deposits at two sites in south-central Saskatchewan were studied in order to extend the spatial and temporal record of dune activity on the Canadian prairies. Optical ages document the timing of valley-infilling by sand dunes in the Qu’Appelle River area, and of cliff-top eolian deposition along the South Saskatchewan River. These ages, along with published radiocarbon and optical ages, are used to develop a chronology of eolian activity for south-central Saskatchewan. Optical ages of eolian sands ranging from 5.7 to 0.14 ka (before AD 2000), with intervening paleosols, indicate alternating periods of eolian activity and dune stability during the late Holocene, supported by published radiocarbon ages. Other published radiocarbon ages ranging from 11.3 to 8.4 cal ka BP indicate early Holocene eolian activity. Mid-Holocene ages are predominantly absent from the chronology and this is interpreted as being due to extensive eolian reworking during at least the latter part of the mid-Holocene. The chronology in south-central Saskatchewan is similar to other parts of the southern Canadian prairies. It is likely that preserved mid-Holocene eolian deposits occur within depositional basins in the southern Canadian prairies, and at sites near the southern boreal forest boundary with the prairie ecozone.

scholarly journals Mode resolved density of atmospheric aerosol particles

2008 ◽  
Vol 8 (2) ◽  
pp. 7263-7288 ◽  
Author(s):  
J. Kannosto ◽  
M. Lemmetty ◽  
A. Virtanen ◽  
J. M. Mäkelä ◽  
J. Keskinen ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Growth Process ◽  
Particle Density ◽  
Particle Growth ◽  
Forest Environment ◽  
Accumulation Mode ◽  
Nucleation Mode ◽  
Density Values ◽  
Forest Measurement ◽  
Aitken Mode

Abstract. In this study, we investigate the mode resolved density of ultrafine atmospheric particles measured in boreal forest environment. The method used here enables us to find the distinct density information for each mode in atmospheric fine particle population: the density values for nucleation, Aitken, and accumulation mode particles are presented. The experimental data was gained during 2 May 2005–19 May 2005 at the boreal forest measurement station "SMEAR II" in Hyytiälä, southern Finland. The density values for accumulation mode varied from 1.1 to 2 g/cm3 (average 1.5 g/cm3) and for Aitken mode from 0.4 to 2 g/cm3 (average 0.97 g/cm3. As an overall trend during the two weeks campaign, the density value of Aitken mode was seen to gradually increase. With the present method, the time dependent behaviour of the particle density can be investigated in time scale of 10 min. This allows us the follow the density evolution of the nucleation mode particles during the particle growth process following the nucleation burst. The density of nucleation mode particles decreased during the growth process. The density values for 15 nm particles were 1.2–1.5 g/cm3 and for grown 30 nm particles 0.5–1 g/cm3. These values are consistent with the present knowledge that the condensing species are semi volatile organics, emitted from the Boreal forest.

Analysis of the growth of nucleation mode particles observed in Boreal forest

Tellus B ◽  
1998 ◽  
Vol 50 (5) ◽  
pp. 449-462 ◽  
Author(s):  
MARKKU KULMALA ◽  
ANNE TOIVONEN ◽  
JYRKI M. MAKELA ◽  
ARI LAAKSONEN
Keyword(s):  
Boreal Forest ◽  
Nucleation Mode

scholarly journals Mode resolved density of atmospheric aerosol particles

2008 ◽  
Vol 8 (17) ◽  
pp. 5327-5337 ◽  
Author(s):  
J. Kannosto ◽  
A. Virtanen ◽  
M. Lemmetty ◽  
J. M. Mäkelä ◽  
J. Keskinen ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Growth Process ◽  
Particle Density ◽  
Particle Growth ◽  
Forest Environment ◽  
Accumulation Mode ◽  
Nucleation Mode ◽  
Density Values ◽  
Forest Measurement ◽  
Aitken Mode

Abstract. In this study, we investigate the mode resolved density of ultrafine atmospheric particles measured in boreal forest environment. The method used here enables us to find the distinct density information for each mode in atmospheric fine particle population: the density values for nucleation, Aitken, and accumulation mode particles are presented. The experimental data was gained during 2 May 2005–19 May 2005 at the boreal forest measurement station "SMEAR II" in Hyytiälä, Southern Finland. The density values for accumulation mode varied from 1.1 to 2 g/cm3 (average 1.5 g/cm3) and for Aitken mode from 0.4 to 2 g/cm3 (average 0.97 g/cm3). As an overall trend during the two weeks campaign, the density value of Aitken mode was seen to gradually increase. With the present method, the time dependent behaviour of the particle density can be investigated in the time scale of 10 min. This allows us to follow the density evolution of the nucleation mode particles during the particle growth process following the nucleation burst. The density of nucleation mode particles decreased during the growth process. The density values for 15 nm particles were 1.2–1.5 g/cm3 and for grown 30 nm particles 0.5–1 g/cm3. These values are consistent with the present knowledge that the condensing species are semi-volatile organics, emitted from the boreal forest.

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