Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences
Identifieur interne : 000E40 ( Istex/Corpus ); précédent : 000E39; suivant : 000E41Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences
Auteurs : S. Halldin ; S-E. Gryning ; L. Gottschalk ; A. Jochum ; L-C. Lundin ; A. A. Van De GriendSource :
- Agricultural and Forest Meteorology [ 0168-1923 ] ; 1999.
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- KwdEn :
Abstract
The role of the land surface in controlling climate is still underestimated and access to information from the boreal-forest zone is instrumental to improve this situation. This motivated the organisation of NOPEX (Northern hemisphere climate-Processes land-surface Experiment) in the southern part of the European boreal zone. This paper summarises results from NOPEX in its first phase, dealing with spring- and summertime conditions. Two concentrated field efforts (CFE1 on 27 May–23 June 1994, CFE2 on 18 April–14 July 1995) were carried out with coordinated measurements of energy, water, and CO2 budgets at 13 ground-based sites and at various airborne platforms. Flux aggregation was a central issue in the heterogeneous, patchy NOPEX landscape. It is shown that simple land-use-weighted averaging of fluxes from fields/forests/lakes agree well with regional fluxes. Momentum fluxes can be parameterised over the whole area with a roughness length of approximately 1.5m, whereas fluxes of sensible heat and other scalars depend on the averaging scale. Local measurements of soil moisture can be classified and meaningful averages can be deduced with a 1km resolution. Lakes play an important role and differs in both diurnal and annual cycles compared to the forests and fields. Multiannual data from an agricultural and a forest site has allowed quantification and modelling of seldom occuring phenomena. One unexpected result was that the Norunda Common forest acted as a source and not a sink of CO2. The successful completion of CFE1–2 and a pilot winter campaign (CFE3) will lead NOPEX into its final phase, devoted to wintertime processes. Measurements and model results reside in SINOP, the System for Information in NOPEX, open for NOPEX participants. Data from CFE1 and CFE2 are released on CD as an integrated part of this Special Issue.
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DOI: 10.1016/S0168-1923(99)00148-3
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Halldin</name><affiliation><mods:affiliation>E-mail: sven.halldin@hyd.uu.se</mods:affiliation></affiliation><affiliation><mods:affiliation>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</mods:affiliation></affiliation></author><author><name sortKey="Gryning, S E" sort="Gryning, S E" uniqKey="Gryning S" first="S-E." last="Gryning">S-E. Gryning</name><affiliation><mods:affiliation>Wind Energy and Atmospheric Physics Department, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark</mods:affiliation></affiliation></author><author><name sortKey="Gottschalk, L" sort="Gottschalk, L" uniqKey="Gottschalk L" first="L." last="Gottschalk">L. Gottschalk</name><affiliation><mods:affiliation>Department of Geophysics, University of Oslo, P.O. Box 1022, Blindern, NO-0315 Oslo, Norway</mods:affiliation></affiliation></author><author><name sortKey="Jochum, A" sort="Jochum, A" uniqKey="Jochum A" first="A." last="Jochum">A. Jochum</name><affiliation><mods:affiliation>Meteorology and Air Quality Group, Department of Environmental Sciences, Wageningen Agricultural University, Duivendaal 2, NL-6701 AP Wageningen, The Netherlands</mods:affiliation></affiliation></author><author><name sortKey="Lundin, L C" sort="Lundin, L C" uniqKey="Lundin L" first="L-C." last="Lundin">L-C. Lundin</name><affiliation><mods:affiliation>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</mods:affiliation></affiliation></author><author><name sortKey="Van De Griend, A A" sort="Van De Griend, A A" uniqKey="Van De Griend A" first="A. A." last="Van De Griend">A. A. 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This motivated the organisation of NOPEX (Northern hemisphere climate-Processes land-surface Experiment) in the southern part of the European boreal zone. This paper summarises results from NOPEX in its first phase, dealing with spring- and summertime conditions. Two concentrated field efforts (CFE1 on 27 May–23 June 1994, CFE2 on 18 April–14 July 1995) were carried out with coordinated measurements of energy, water, and CO2 budgets at 13 ground-based sites and at various airborne platforms. Flux aggregation was a central issue in the heterogeneous, patchy NOPEX landscape. It is shown that simple land-use-weighted averaging of fluxes from fields/forests/lakes agree well with regional fluxes. Momentum fluxes can be parameterised over the whole area with a roughness length of approximately 1.5m, whereas fluxes of sensible heat and other scalars depend on the averaging scale. Local measurements of soil moisture can be classified and meaningful averages can be deduced with a 1km resolution. Lakes play an important role and differs in both diurnal and annual cycles compared to the forests and fields. Multiannual data from an agricultural and a forest site has allowed quantification and modelling of seldom occuring phenomena. One unexpected result was that the Norunda Common forest acted as a source and not a sink of CO2. The successful completion of CFE1–2 and a pilot winter campaign (CFE3) will lead NOPEX into its final phase, devoted to wintertime processes. Measurements and model results reside in SINOP, the System for Information in NOPEX, open for NOPEX participants. Data from CFE1 and CFE2 are released on CD as an integrated part of this Special Issue.</div></front></TEI><istex><corpusName>elsevier</corpusName><author><json:item><name>S. Halldin</name><affiliations><json:string>E-mail: sven.halldin@hyd.uu.se</json:string><json:string>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</json:string></affiliations></json:item><json:item><name>S-E. Gryning</name><affiliations><json:string>Wind Energy and Atmospheric Physics Department, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark</json:string></affiliations></json:item><json:item><name>L. Gottschalk</name><affiliations><json:string>Department of Geophysics, University of Oslo, P.O. Box 1022, Blindern, NO-0315 Oslo, Norway</json:string></affiliations></json:item><json:item><name>A. Jochum</name><affiliations><json:string>Meteorology and Air Quality Group, Department of Environmental Sciences, Wageningen Agricultural University, Duivendaal 2, NL-6701 AP Wageningen, The Netherlands</json:string></affiliations></json:item><json:item><name>L-C. 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This motivated the organisation of NOPEX (Northern hemisphere climate-Processes land-surface Experiment) in the southern part of the European boreal zone. This paper summarises results from NOPEX in its first phase, dealing with spring- and summertime conditions. Two concentrated field efforts (CFE1 on 27 May–23 June 1994, CFE2 on 18 April–14 July 1995) were carried out with coordinated measurements of energy, water, and CO2 budgets at 13 ground-based sites and at various airborne platforms. Flux aggregation was a central issue in the heterogeneous, patchy NOPEX landscape. It is shown that simple land-use-weighted averaging of fluxes from fields/forests/lakes agree well with regional fluxes. Momentum fluxes can be parameterised over the whole area with a roughness length of approximately 1.5m, whereas fluxes of sensible heat and other scalars depend on the averaging scale. Local measurements of soil moisture can be classified and meaningful averages can be deduced with a 1km resolution. Lakes play an important role and differs in both diurnal and annual cycles compared to the forests and fields. Multiannual data from an agricultural and a forest site has allowed quantification and modelling of seldom occuring phenomena. One unexpected result was that the Norunda Common forest acted as a source and not a sink of CO2. The successful completion of CFE1–2 and a pilot winter campaign (CFE3) will lead NOPEX into its final phase, devoted to wintertime processes. Measurements and model results reside in SINOP, the System for Information in NOPEX, open for NOPEX participants. Data from CFE1 and CFE2 are released on CD as an integrated part of this Special Issue.</abstract><qualityIndicators><score>8</score><pdfVersion>1.2</pdfVersion><pdfPageSize>522 x 745 pts</pdfPageSize><refBibsNative>true</refBibsNative><keywordCount>5</keywordCount><abstractCharCount>1854</abstractCharCount><pdfWordCount>13539</pdfWordCount><pdfCharCount>87053</pdfCharCount><pdfPageCount>25</pdfPageCount><abstractWordCount>286</abstractWordCount></qualityIndicators><title>Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences</title><pii><json:string>S0168-1923(99)00148-3</json:string></pii><genre><json:string>research-article</json:string></genre><host><volume>98–99</volume><pii><json:string>S0168-1923(00)X0066-4</json:string></pii><pages><last>29</last><first>5</first></pages><issn><json:string>0168-1923</json:string></issn><genre><json:string>journal</json:string></genre><language><json:string>unknown</json:string></language><title>Agricultural and Forest Meteorology</title><publicationDate>1999</publicationDate></host><categories><wos><json:string>science</json:string><json:string>meteorology & atmospheric sciences</json:string><json:string>forestry</json:string><json:string>agronomy</json:string></wos><scienceMetrix><json:string>natural sciences</json:string><json:string>earth & environmental sciences</json:string><json:string>meteorology & atmospheric sciences</json:string></scienceMetrix></categories><publicationDate>1999</publicationDate><copyrightDate>1999</copyrightDate><doi><json:string>10.1016/S0168-1923(99)00148-3</json:string></doi><id>C63D641E6DC1754B57AFAD3A24BF627059A5EED5</id><score>0.038424186</score><fulltext><json:item><extension>pdf</extension><original>true</original><mimetype>application/pdf</mimetype><uri>https://api.istex.fr/document/C63D641E6DC1754B57AFAD3A24BF627059A5EED5/fulltext/pdf</uri></json:item><json:item><extension>zip</extension><original>false</original><mimetype>application/zip</mimetype><uri>https://api.istex.fr/document/C63D641E6DC1754B57AFAD3A24BF627059A5EED5/fulltext/zip</uri></json:item><istex:fulltextTEI uri="https://api.istex.fr/document/C63D641E6DC1754B57AFAD3A24BF627059A5EED5/fulltext/tei"><teiHeader><fileDesc><titleStmt><title level="a" type="main" xml:lang="en">Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences</title></titleStmt><publicationStmt><authority>ISTEX</authority><publisher>ELSEVIER</publisher><availability><p>©1999 Elsevier Science B.V.</p></availability><date>1999</date></publicationStmt><notesStmt><note type="content">Fig. 1: Outline of the NOPEX region. Dotted lines are flight legs coordinated with the sites located in forests (57% of the surface) and bogs (7% light grey), agricultural land (27% white), and lakes (4% dark grey). The three dashed areas are EMISAR targets. Drawing by Hans Nilsson.</note><note type="content">Fig. 2: Typical variability of albedo, sensible (H) and latent (LE) heat fluxes, radiative surface temperature (Tr), air temperature (Ta), and wind speed (u) along an agricultural-forest-agricultural-lake flight leg. Data averaged from four legs flown on 14 June 1994 (from Frech and Jochum, 1999).</note><note type="content">Fig. 3: Regional fluxes (Wm−2) calculated with different methods against land-use-weighted mast measurements. The 24h periods represent full diurnal cycles on 13–14, 21 June 1994 and 2–4, 8 May, 20, 26 June 1995, starting at midnight. The flight periods represent approximately 2h periods around noon the same days (modified from Gottschalk et al., 1999a).</note><note type="content">Fig. 4: Daytime course of sensible heat fluxes (Wm−2) on 14 June 1994. Left panel shows measurements over two forest sites, central panel measurements over two agricultural sites, and right panel calculations with the mixed-layer-evolution method (MLEM) and the land-use-weighted-average method (LUWA) (modified from Gryning and Batchvarova, 1999).</note><note type="content">Fig. 5: Average volumetric water content in the upper 15cm of till soils versus the averaging area. Data from 8 May 1996 (from Beldring et al., 1999a).</note><note type="content">Fig. 6: Stand reflectance expressed as digital numbers (DN) of Landsat TM and SPOT images in green (TM2, XS1), red (TM3, XS2), near infrared (TM4, XS3), and middle infrared (TM5) wavelength bands versus ground-truth values of needle-area index (from Nilson et al., 1999a).</note><note type="content">Fig. 7: Measured carbon-dioxide fluxes from fields of barley, wheat, and bare soil at Tisby on 3 July 1995. Calculated bare-soil emissions is given as dotted line (from Soegaard, 1999).</note><note type="content">Fig. 8: Monthly-average diurnal latent heat fluxes from lakes (Råksjön, Tämnaren) and a forest (Norunda) during the 1995 growth season (from Venäläinen et al., 1999).</note><note type="content">Fig. 9: Sap-flow measurements of transpiration from pine and spruce in the Norunda Common forest 1994–97. Transpiration is expressed as 3-day-average fluxes corresponding to mono-specific stands with the same basal area as the actual mixed stand (from Cienciala, 1999a).</note></notesStmt><sourceDesc><biblStruct type="inbook"><analytic><title level="a" type="main" xml:lang="en">Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences</title><author xml:id="author-1"><persName><forename type="first">S.</forename><surname>Halldin</surname></persName><email>sven.halldin@hyd.uu.se</email><note type="correspondence"><p>Corresponding author. Tel.: +46-018-471-22-62; fax: +46-018-55-11-24</p></note><affiliation>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</affiliation></author><author xml:id="author-2"><persName><forename type="first">S-E.</forename><surname>Gryning</surname></persName><affiliation>Wind Energy and Atmospheric Physics Department, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark</affiliation></author><author xml:id="author-3"><persName><forename type="first">L.</forename><surname>Gottschalk</surname></persName><affiliation>Department of Geophysics, University of Oslo, P.O. Box 1022, Blindern, NO-0315 Oslo, Norway</affiliation></author><author xml:id="author-4"><persName><forename type="first">A.</forename><surname>Jochum</surname></persName><affiliation>Meteorology and Air Quality Group, Department of Environmental Sciences, Wageningen Agricultural University, Duivendaal 2, NL-6701 AP Wageningen, The Netherlands</affiliation></author><author xml:id="author-5"><persName><forename type="first">L-C.</forename><surname>Lundin</surname></persName><affiliation>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</affiliation></author><author xml:id="author-6"><persName><forename type="first">A.A.</forename><surname>Van de Griend</surname></persName><affiliation>Faculty of Earth Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands</affiliation></author></analytic><monogr><title level="j">Agricultural and Forest Meteorology</title><title level="j" type="abbrev">AGMET</title><idno type="pISSN">0168-1923</idno><idno type="PII">S0168-1923(00)X0066-4</idno><imprint><publisher>ELSEVIER</publisher><date type="published" when="1999"></date><biblScope unit="volume">98–99</biblScope><biblScope unit="supplement">C</biblScope><biblScope unit="page" from="5">5</biblScope><biblScope unit="page" to="29">29</biblScope></imprint></monogr><idno type="istex">C63D641E6DC1754B57AFAD3A24BF627059A5EED5</idno><idno type="DOI">10.1016/S0168-1923(99)00148-3</idno><idno type="PII">S0168-1923(99)00148-3</idno></biblStruct></sourceDesc></fileDesc><profileDesc><creation><date>1999</date></creation><langUsage><language ident="en">en</language></langUsage><abstract xml:lang="en"><p>The role of the land surface in controlling climate is still underestimated and access to information from the boreal-forest zone is instrumental to improve this situation. This motivated the organisation of NOPEX (Northern hemisphere climate-Processes land-surface Experiment) in the southern part of the European boreal zone. This paper summarises results from NOPEX in its first phase, dealing with spring- and summertime conditions. Two concentrated field efforts (CFE1 on 27 May–23 June 1994, CFE2 on 18 April–14 July 1995) were carried out with coordinated measurements of energy, water, and CO2 budgets at 13 ground-based sites and at various airborne platforms. Flux aggregation was a central issue in the heterogeneous, patchy NOPEX landscape. It is shown that simple land-use-weighted averaging of fluxes from fields/forests/lakes agree well with regional fluxes. Momentum fluxes can be parameterised over the whole area with a roughness length of approximately 1.5m, whereas fluxes of sensible heat and other scalars depend on the averaging scale. Local measurements of soil moisture can be classified and meaningful averages can be deduced with a 1km resolution. Lakes play an important role and differs in both diurnal and annual cycles compared to the forests and fields. Multiannual data from an agricultural and a forest site has allowed quantification and modelling of seldom occuring phenomena. One unexpected result was that the Norunda Common forest acted as a source and not a sink of CO2. The successful completion of CFE1–2 and a pilot winter campaign (CFE3) will lead NOPEX into its final phase, devoted to wintertime processes. Measurements and model results reside in SINOP, the System for Information in NOPEX, open for NOPEX participants. Data from CFE1 and CFE2 are released on CD as an integrated part of this Special Issue.</p></abstract><textClass xml:lang="en"><keywords scheme="keyword"><list><head>Keywords</head><item><term>Boreal-forest</term></item><item><term>Eddy-correlation</term></item><item><term>Pine trees</term></item><item><term>Spruce trees</term></item><item><term>NOPEX</term></item></list></keywords></textClass></profileDesc><revisionDesc><change when="1999">Published</change></revisionDesc></teiHeader></istex:fulltextTEI><json:item><extension>txt</extension><original>false</original><mimetype>text/plain</mimetype><uri>https://api.istex.fr/document/C63D641E6DC1754B57AFAD3A24BF627059A5EED5/fulltext/txt</uri></json:item></fulltext><metadata><istex:metadataXml wicri:clean="Elsevier, elements deleted: ce:floats; body; tail"><istex:xmlDeclaration>version="1.0" encoding="utf-8"</istex:xmlDeclaration><istex:docType PUBLIC="-//ES//DTD journal article DTD version 4.5.2//EN//XML" URI="art452.dtd" name="istex:docType"><istex:entity SYSTEM="gr1" NDATA="IMAGE" name="gr1"></istex:entity><istex:entity SYSTEM="gr2" NDATA="IMAGE" name="gr2"></istex:entity><istex:entity SYSTEM="gr3" NDATA="IMAGE" name="gr3"></istex:entity><istex:entity SYSTEM="gr4" NDATA="IMAGE" name="gr4"></istex:entity><istex:entity SYSTEM="gr5" NDATA="IMAGE" name="gr5"></istex:entity><istex:entity SYSTEM="gr6" NDATA="IMAGE" name="gr6"></istex:entity><istex:entity SYSTEM="gr7" NDATA="IMAGE" name="gr7"></istex:entity><istex:entity SYSTEM="gr8" NDATA="IMAGE" name="gr8"></istex:entity><istex:entity SYSTEM="gr9" NDATA="IMAGE" name="gr9"></istex:entity></istex:docType><istex:document><converted-article version="4.5.2" docsubtype="fla" xml:lang="en"><item-info><jid>AGMET</jid><aid>2749</aid><ce:pii>S0168-1923(99)00148-3</ce:pii><ce:doi>10.1016/S0168-1923(99)00148-3</ce:doi><ce:copyright type="full-transfer" year="1999">Elsevier Science B.V.</ce:copyright></item-info><head><ce:title>Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences</ce:title><ce:author-group><ce:author><ce:given-name>S.</ce:given-name><ce:surname>Halldin</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref><ce:cross-ref refid="CORR1">*</ce:cross-ref><ce:e-address>sven.halldin@hyd.uu.se</ce:e-address></ce:author><ce:author><ce:given-name>S-E.</ce:given-name><ce:surname>Gryning</ce:surname><ce:cross-ref refid="AFF2"><ce:sup>b</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>L.</ce:given-name><ce:surname>Gottschalk</ce:surname><ce:cross-ref refid="AFF3"><ce:sup>c</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>A.</ce:given-name><ce:surname>Jochum</ce:surname><ce:cross-ref refid="AFF4"><ce:sup>d</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>L-C.</ce:given-name><ce:surname>Lundin</ce:surname><ce:cross-ref refid="AFF1"><ce:sup>a</ce:sup></ce:cross-ref></ce:author><ce:author><ce:given-name>A.A.</ce:given-name><ce:surname>Van de Griend</ce:surname><ce:cross-ref refid="AFF5"><ce:sup>e</ce:sup></ce:cross-ref></ce:author><ce:affiliation id="AFF1"><ce:label>a</ce:label><ce:textfn>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</ce:textfn></ce:affiliation><ce:affiliation id="AFF2"><ce:label>b</ce:label><ce:textfn>Wind Energy and Atmospheric Physics Department, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark</ce:textfn></ce:affiliation><ce:affiliation id="AFF3"><ce:label>c</ce:label><ce:textfn>Department of Geophysics, University of Oslo, P.O. Box 1022, Blindern, NO-0315 Oslo, Norway</ce:textfn></ce:affiliation><ce:affiliation id="AFF4"><ce:label>d</ce:label><ce:textfn>Meteorology and Air Quality Group, Department of Environmental Sciences, Wageningen Agricultural University, Duivendaal 2, NL-6701 AP Wageningen, The Netherlands</ce:textfn></ce:affiliation><ce:affiliation id="AFF5"><ce:label>e</ce:label><ce:textfn>Faculty of Earth Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands</ce:textfn></ce:affiliation><ce:correspondence id="CORR1"><ce:label>*</ce:label><ce:text>Corresponding author. Tel.: +46-018-471-22-62; fax: +46-018-55-11-24</ce:text></ce:correspondence></ce:author-group><ce:abstract><ce:section-title>Abstract</ce:section-title><ce:abstract-sec><ce:simple-para>The role of the land surface in controlling climate is still underestimated and access to information from the boreal-forest zone is instrumental to improve this situation. This motivated the organisation of NOPEX (Northern hemisphere climate-Processes land-surface Experiment) in the southern part of the European boreal zone. This paper summarises results from NOPEX in its first phase, dealing with spring- and summertime conditions. Two concentrated field efforts (CFE1 on 27 May–23 June 1994, CFE2 on 18 April–14 July 1995) were carried out with coordinated measurements of energy, water, and CO<ce:inf>2</ce:inf> budgets at 13 ground-based sites and at various airborne platforms. Flux aggregation was a central issue in the heterogeneous, patchy NOPEX landscape. It is shown that simple land-use-weighted averaging of fluxes from fields/forests/lakes agree well with regional fluxes. Momentum fluxes can be parameterised over the whole area with a roughness length of approximately 1.5<ce:hsp sp="0.25"></ce:hsp>m, whereas fluxes of sensible heat and other scalars depend on the averaging scale. Local measurements of soil moisture can be classified and meaningful averages can be deduced with a 1<ce:hsp sp="0.25"></ce:hsp>km resolution. Lakes play an important role and differs in both diurnal and annual cycles compared to the forests and fields. Multiannual data from an agricultural and a forest site has allowed quantification and modelling of seldom occuring phenomena. One unexpected result was that the Norunda Common forest acted as a source and not a sink of CO<ce:inf>2</ce:inf>. The successful completion of CFE1–2 and a pilot winter campaign (CFE3) will lead NOPEX into its final phase, devoted to wintertime processes. Measurements and model results reside in SINOP, the System for Information in NOPEX, open for NOPEX participants. Data from CFE1 and CFE2 are released on CD as an integrated part of this Special Issue.</ce:simple-para></ce:abstract-sec></ce:abstract><ce:keywords class="keyword" xml:lang="en"><ce:section-title>Keywords</ce:section-title><ce:keyword><ce:text>Boreal-forest</ce:text></ce:keyword><ce:keyword><ce:text>Eddy-correlation</ce:text></ce:keyword><ce:keyword><ce:text>Pine trees</ce:text></ce:keyword><ce:keyword><ce:text>Spruce trees</ce:text></ce:keyword><ce:keyword><ce:text>NOPEX</ce:text></ce:keyword></ce:keywords></head></converted-article></istex:document></istex:metadataXml><mods version="3.6"><titleInfo lang="en"><title>Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences</title></titleInfo><titleInfo type="alternative" lang="en" contentType="CDATA"><title>Energy, water and carbon exchange in a boreal forest landscape — NOPEX experiences</title></titleInfo><name type="personal"><namePart type="given">S.</namePart><namePart type="family">Halldin</namePart><affiliation>E-mail: sven.halldin@hyd.uu.se</affiliation><affiliation>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</affiliation><description>Corresponding author. Tel.: +46-018-471-22-62; fax: +46-018-55-11-24</description><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">S-E.</namePart><namePart type="family">Gryning</namePart><affiliation>Wind Energy and Atmospheric Physics Department, Risø National Laboratory, P.O. Box 49, DK-4000 Roskilde, Denmark</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">L.</namePart><namePart type="family">Gottschalk</namePart><affiliation>Department of Geophysics, University of Oslo, P.O. Box 1022, Blindern, NO-0315 Oslo, Norway</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">A.</namePart><namePart type="family">Jochum</namePart><affiliation>Meteorology and Air Quality Group, Department of Environmental Sciences, Wageningen Agricultural University, Duivendaal 2, NL-6701 AP Wageningen, The Netherlands</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">L-C.</namePart><namePart type="family">Lundin</namePart><affiliation>Department of Earth Sciences/Hydrology, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden</affiliation><role><roleTerm type="text">author</roleTerm></role></name><name type="personal"><namePart type="given">A.A.</namePart><namePart type="family">Van de Griend</namePart><affiliation>Faculty of Earth Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands</affiliation><role><roleTerm type="text">author</roleTerm></role></name><typeOfResource>text</typeOfResource><genre type="research-article" displayLabel="Full-length article"></genre><originInfo><publisher>ELSEVIER</publisher><dateIssued encoding="w3cdtf">1999</dateIssued><copyrightDate encoding="w3cdtf">1999</copyrightDate></originInfo><language><languageTerm type="code" authority="iso639-2b">eng</languageTerm><languageTerm type="code" authority="rfc3066">en</languageTerm></language><physicalDescription><internetMediaType>text/html</internetMediaType></physicalDescription><abstract lang="en">The role of the land surface in controlling climate is still underestimated and access to information from the boreal-forest zone is instrumental to improve this situation. This motivated the organisation of NOPEX (Northern hemisphere climate-Processes land-surface Experiment) in the southern part of the European boreal zone. This paper summarises results from NOPEX in its first phase, dealing with spring- and summertime conditions. Two concentrated field efforts (CFE1 on 27 May–23 June 1994, CFE2 on 18 April–14 July 1995) were carried out with coordinated measurements of energy, water, and CO2 budgets at 13 ground-based sites and at various airborne platforms. Flux aggregation was a central issue in the heterogeneous, patchy NOPEX landscape. It is shown that simple land-use-weighted averaging of fluxes from fields/forests/lakes agree well with regional fluxes. Momentum fluxes can be parameterised over the whole area with a roughness length of approximately 1.5m, whereas fluxes of sensible heat and other scalars depend on the averaging scale. Local measurements of soil moisture can be classified and meaningful averages can be deduced with a 1km resolution. Lakes play an important role and differs in both diurnal and annual cycles compared to the forests and fields. Multiannual data from an agricultural and a forest site has allowed quantification and modelling of seldom occuring phenomena. One unexpected result was that the Norunda Common forest acted as a source and not a sink of CO2. The successful completion of CFE1–2 and a pilot winter campaign (CFE3) will lead NOPEX into its final phase, devoted to wintertime processes. Measurements and model results reside in SINOP, the System for Information in NOPEX, open for NOPEX participants. Data from CFE1 and CFE2 are released on CD as an integrated part of this Special Issue.</abstract><note type="content">Fig. 1: Outline of the NOPEX region. Dotted lines are flight legs coordinated with the sites located in forests (57% of the surface) and bogs (7% light grey), agricultural land (27% white), and lakes (4% dark grey). The three dashed areas are EMISAR targets. Drawing by Hans Nilsson.</note><note type="content">Fig. 2: Typical variability of albedo, sensible (H) and latent (LE) heat fluxes, radiative surface temperature (Tr), air temperature (Ta), and wind speed (u) along an agricultural-forest-agricultural-lake flight leg. Data averaged from four legs flown on 14 June 1994 (from Frech and Jochum, 1999).</note><note type="content">Fig. 3: Regional fluxes (Wm−2) calculated with different methods against land-use-weighted mast measurements. The 24h periods represent full diurnal cycles on 13–14, 21 June 1994 and 2–4, 8 May, 20, 26 June 1995, starting at midnight. The flight periods represent approximately 2h periods around noon the same days (modified from Gottschalk et al., 1999a).</note><note type="content">Fig. 4: Daytime course of sensible heat fluxes (Wm−2) on 14 June 1994. Left panel shows measurements over two forest sites, central panel measurements over two agricultural sites, and right panel calculations with the mixed-layer-evolution method (MLEM) and the land-use-weighted-average method (LUWA) (modified from Gryning and Batchvarova, 1999).</note><note type="content">Fig. 5: Average volumetric water content in the upper 15cm of till soils versus the averaging area. Data from 8 May 1996 (from Beldring et al., 1999a).</note><note type="content">Fig. 6: Stand reflectance expressed as digital numbers (DN) of Landsat TM and SPOT images in green (TM2, XS1), red (TM3, XS2), near infrared (TM4, XS3), and middle infrared (TM5) wavelength bands versus ground-truth values of needle-area index (from Nilson et al., 1999a).</note><note type="content">Fig. 7: Measured carbon-dioxide fluxes from fields of barley, wheat, and bare soil at Tisby on 3 July 1995. Calculated bare-soil emissions is given as dotted line (from Soegaard, 1999).</note><note type="content">Fig. 8: Monthly-average diurnal latent heat fluxes from lakes (Råksjön, Tämnaren) and a forest (Norunda) during the 1995 growth season (from Venäläinen et al., 1999).</note><note type="content">Fig. 9: Sap-flow measurements of transpiration from pine and spruce in the Norunda Common forest 1994–97. Transpiration is expressed as 3-day-average fluxes corresponding to mono-specific stands with the same basal area as the actual mixed stand (from Cienciala, 1999a).</note><subject lang="en"><genre>Keywords</genre><topic>Boreal-forest</topic><topic>Eddy-correlation</topic><topic>Pine trees</topic><topic>Spruce trees</topic><topic>NOPEX</topic></subject><relatedItem type="host"><titleInfo><title>Agricultural and Forest Meteorology</title></titleInfo><titleInfo type="abbreviated"><title>AGMET</title></titleInfo><genre type="journal">journal</genre><originInfo><dateIssued encoding="w3cdtf">19991231</dateIssued></originInfo><identifier type="ISSN">0168-1923</identifier><identifier type="PII">S0168-1923(00)X0066-4</identifier><part><date>19991231</date><detail type="volume"><number>98–99</number><caption>vol.</caption></detail><detail type="supplement"><number>C</number><caption>Suppl.</caption></detail><extent unit="issue pages"><start>1</start><end>702</end></extent><extent unit="pages"><start>5</start><end>29</end></extent></part></relatedItem><identifier type="istex">C63D641E6DC1754B57AFAD3A24BF627059A5EED5</identifier><identifier type="DOI">10.1016/S0168-1923(99)00148-3</identifier><identifier type="PII">S0168-1923(99)00148-3</identifier><accessCondition type="use and reproduction" contentType="copyright">©1999 Elsevier Science B.V.</accessCondition><recordInfo><recordContentSource>ELSEVIER</recordContentSource><recordOrigin>Elsevier Science B.V., ©1999</recordOrigin></recordInfo></mods></metadata><serie></serie></istex></record>Pour manipuler ce document sous Unix (Dilib)
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