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Relationships between Atmospheric Circulation and Wind Erosion in Southern Sweden and Australia

Ekström, Marie LU (2002)
Abstract (Swedish)
Popular Abstract in Swedish

Områden som är kontinuerligt utsatta för vinderosion löper stor risk för att erhålla en försämrad jordkvalitet eftersom vinderosion innebär en utsållning av fina fraktioner och humus från jordmånen. För att vinderosion ska inträffa krävs en kombination av vissa väder- och markförhållanden. Flera av dessa är direkt relaterade till klimatet, t ex vindhastighet och jordfuktighet. Få studier inom fältet för vinderosionsforskning fokuserar på förhållandet mellan vinderosion och klimat/klimatförändringar. I föreliggande avhandling undersöks förhållandet mellan vinderosion och atmosfärisk cirkulation i Skåne (södra Sverige) och Australien. Estimerad markvind från 1900-talet används för att studera... (More)
Popular Abstract in Swedish

Områden som är kontinuerligt utsatta för vinderosion löper stor risk för att erhålla en försämrad jordkvalitet eftersom vinderosion innebär en utsållning av fina fraktioner och humus från jordmånen. För att vinderosion ska inträffa krävs en kombination av vissa väder- och markförhållanden. Flera av dessa är direkt relaterade till klimatet, t ex vindhastighet och jordfuktighet. Få studier inom fältet för vinderosionsforskning fokuserar på förhållandet mellan vinderosion och klimat/klimatförändringar. I föreliggande avhandling undersöks förhållandet mellan vinderosion och atmosfärisk cirkulation i Skåne (södra Sverige) och Australien. Estimerad markvind från 1900-talet används för att studera lågfrekvent variabilitet i den atmosfäriska cirkulationen över Skåne. Analys av förhållandet mellan vinderosion och atmosfärisk cirkulation utförs med hjälp av marklufttrycksmönster som beskriver de huvudsakliga cirkulationstyperna för respektive område. I den skånska studien relaterades dessa mönster till vinderosionsdata baserat på vinderosionsskadad areal inom sockerbruksdistriktet Jordberga (1973-1991) och i den australiensiska studien relaterades de till meteorologiska observationer av stoft-/ sandstorm data från hela Australien (1960-1999). Förhållandet mellan stoft-/ sandstormar och den atmosfäriska cirkulationen undersöktes yttligare med hjälp av atmosfäriska flödesindex (1960-1999). För Skåne visade analysen av marklufttrycksmönster att huvuddelen (74 %) av de vinderosions relaterade skadorna på sockerbetorna sker under ett östligt flöde över Skåne följt av ett västligt flöde (5 %). Väderförhållandena under det förstnämnda karakteriseras av relativt torra förhållanden samt medelstarka till starka vindar, och det västliga flödet karakteriseras av korta perioder med höga vindhastigheter. Studien av markvind i Skåne visade på stor variation i vindriktning under 1900-talet, speciellt under våren. Väsliga vindar dominerar generellt under hela århundradet med undantag av perioden 1930-1960, då ostliga vindar hade ett ökat inflytande på vindklimatet. I Australien fanns åtminstone två regioner där stoft-/ sandstormar begränsades av olika faktorer. Inom huvuddelen av de kustnära områdena var stoft-/ sandstormar vanligast under sommaren, då markytan var som torrast. Inom den kontinentala regionen var stoft-/ sandstormar vanligast under våren och den tidiga sommaren, den period när nederbördsfria kall fronter är vanligast förekommande. I tidsserier av stoft-/ sandstormar från de båda regionerna sågs perioder av förhöjd stoft-/sandstorms aktivitet. I den kontinentala regionen inträffade dessa under 1960-talet och det tidiga 1990-talet och i den kustnära regionen under 1990-talet. Det är sannorlikt att förhöjningen av stoft/sand stormar under 1960-talet kan relateras till en högre frekvens av en cirkulation som tillät en mer nordlig passage av kallfronter över kontinenten i kombination med ett större antal lågtryck. Ökningen under 1990-talet var troligen associerad med den starka El Niño cirkulation (vanligtvis sammankopplad med lägre nederbörd än normalt) som rådde under den tidsperioden. (Less)
Abstract
Wind erosion is a serious threat to soil resources as it causes depletion of the fine fractions that may result in a less fertile soil. Wind erosion encompasses several processes of which many are related to climate variables. To date, there is little work performed on how wind erosion relates to climate and climate change. In this thesis, atmospheric circulation and wind erosion were analysed to improve the understanding of these relationship in Scania (southern Sweden) and Australia. Low-frequency variability of the atmospheric circulation in Scania was examined using surface wind from the 20th century. Analysis of the relationship between wind erosion and atmospheric circulation was based on de-seasonalized mean-sea-level pressure... (More)
Wind erosion is a serious threat to soil resources as it causes depletion of the fine fractions that may result in a less fertile soil. Wind erosion encompasses several processes of which many are related to climate variables. To date, there is little work performed on how wind erosion relates to climate and climate change. In this thesis, atmospheric circulation and wind erosion were analysed to improve the understanding of these relationship in Scania (southern Sweden) and Australia. Low-frequency variability of the atmospheric circulation in Scania was examined using surface wind from the 20th century. Analysis of the relationship between wind erosion and atmospheric circulation was based on de-seasonalized mean-sea-level pressure patterns (PPs), describing the main modes of atmospheric circulation. For Scania, the PPs were related to wind erosion inferred from area damage in the sugar beet district Jordberga (1973-1991). For Australia, the PPs were related to dust storm data from meteorological stations (1960-1999). Relationships between dust storms and the atmospheric circulation were further analysed using atmospheric flow indices (1960-1999). In Scania, the analysis of the PPs showed that the majority (74 %) of crop damage due to wind erosion was associated with an easterly and then a westerly flow pattern (5 %). The former was associated with relatively dry conditions and moderate wind speeds whilst the westerly flow PP characterised short episodes of high wind speeds. Analysis of the wind series showed large shifts in wind conditions during the 20th century, particularly during the spring. The westerly winds dominated throughout the century, although the period 1930-1960 showed increased frequencies of easterly winds. In Australia, at least two regions existed where dust storms were limited by different factors. In much of the coastal region dust storms were most common in summer when the region was at its driest. In the continental region dust storms were most common during late spring to early summer when the non-precipitation cold front was most frequent. Increased dust storm activity was found during the 1960s and early 1990s for the continental interior region and during the 1990s for the coastal region. It was suggested that increased dust storm activity during the 1960s was due to higher frequencies of a circulation that allowed for a further northward pathway of the fronts over the continent in combination with larger numbers of mid-latitude cyclones. The increase during the 1990s was most likely linked to the pronounced El Niño conditions, associated with less than average rainfall in much of Australia, during these years. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Dr. Palutikof, Jean, Climatic Research Unit, University of East Anglia
organization
publishing date
type
Thesis
publication status
published
subject
keywords
pedology, cartography, climatology, Fysisk geografi, geomorfologi, marklära, kartografi, klimatologi, Physical geography, geomorphology, Geologi, fysisk geografi, physical geography, Geology, sea level pressure, atmospheric circulation, erosivity, wind erosion, wind climatology, Scania, Australia
pages
206 pages
publisher
Marie Ekström, Dept. of Phys. Geog. and Ecos. Anal., V-huset John Ericssons väg 1, 2nd floor,
defense location
Geografiska institutionernas föreläsningssal 3:e våningen Sölvegatan 13, Lund
defense date
2002-04-05 10:15
ISSN
0346-6787
ISBN
91-973857-4-3
language
English
LU publication?
yes
id
ae6761dc-a6e8-41ac-9839-fff4848cbb14 (old id 464467)
date added to LUP
2007-09-04 11:04:55
date last changed
2016-09-19 08:44:57
@phdthesis{ae6761dc-a6e8-41ac-9839-fff4848cbb14,
  abstract     = {Wind erosion is a serious threat to soil resources as it causes depletion of the fine fractions that may result in a less fertile soil. Wind erosion encompasses several processes of which many are related to climate variables. To date, there is little work performed on how wind erosion relates to climate and climate change. In this thesis, atmospheric circulation and wind erosion were analysed to improve the understanding of these relationship in Scania (southern Sweden) and Australia. Low-frequency variability of the atmospheric circulation in Scania was examined using surface wind from the 20th century. Analysis of the relationship between wind erosion and atmospheric circulation was based on de-seasonalized mean-sea-level pressure patterns (PPs), describing the main modes of atmospheric circulation. For Scania, the PPs were related to wind erosion inferred from area damage in the sugar beet district Jordberga (1973-1991). For Australia, the PPs were related to dust storm data from meteorological stations (1960-1999). Relationships between dust storms and the atmospheric circulation were further analysed using atmospheric flow indices (1960-1999). In Scania, the analysis of the PPs showed that the majority (74 %) of crop damage due to wind erosion was associated with an easterly and then a westerly flow pattern (5 %). The former was associated with relatively dry conditions and moderate wind speeds whilst the westerly flow PP characterised short episodes of high wind speeds. Analysis of the wind series showed large shifts in wind conditions during the 20th century, particularly during the spring. The westerly winds dominated throughout the century, although the period 1930-1960 showed increased frequencies of easterly winds. In Australia, at least two regions existed where dust storms were limited by different factors. In much of the coastal region dust storms were most common in summer when the region was at its driest. In the continental region dust storms were most common during late spring to early summer when the non-precipitation cold front was most frequent. Increased dust storm activity was found during the 1960s and early 1990s for the continental interior region and during the 1990s for the coastal region. It was suggested that increased dust storm activity during the 1960s was due to higher frequencies of a circulation that allowed for a further northward pathway of the fronts over the continent in combination with larger numbers of mid-latitude cyclones. The increase during the 1990s was most likely linked to the pronounced El Niño conditions, associated with less than average rainfall in much of Australia, during these years.},
  author       = {Ekström, Marie},
  isbn         = {91-973857-4-3},
  issn         = {0346-6787},
  keyword      = {pedology,cartography,climatology,Fysisk geografi,geomorfologi,marklära,kartografi,klimatologi,Physical geography,geomorphology,Geologi,fysisk geografi,physical geography,Geology,sea level pressure,atmospheric circulation,erosivity,wind erosion,wind climatology,Scania,Australia},
  language     = {eng},
  pages        = {206},
  publisher    = {Marie Ekström, Dept. of Phys. Geog. and Ecos. Anal., V-huset John Ericssons väg 1, 2nd floor,},
  school       = {Lund University},
  title        = {Relationships between Atmospheric Circulation and Wind Erosion in Southern Sweden and Australia},
  year         = {2002},
}