Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations
<p>Satellite observations have been widely used to examine afforestation effects on local surface temperature at large spatial scales. Different approaches, which potentially lead to differing definitions of the afforestation effect, have been used in previous studies. Despite their large diff...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-01-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/20/75/2023/bg-20-75-2023.pdf |
| _version_ | 1797959978672193536 |
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| author | H. Wang C. Yue C. Yue S. Luyssaert |
| author_facet | H. Wang C. Yue C. Yue S. Luyssaert |
| author_sort | H. Wang |
| collection | DOAJ |
| description | <p>Satellite observations have been widely used to examine
afforestation effects on local surface temperature at large spatial scales.
Different approaches, which potentially lead to differing definitions of the
afforestation effect, have been used in previous studies. Despite their
large differences, the results of these studies have been used in climate
model validation and cited in climate synthesis reports. Such differences
have been simply treated as observational uncertainty, which can be an order
of magnitude bigger than the signal itself. Although the fraction of the
satellite pixel actually afforested has been noted to influence the
magnitude of the afforestation effect, it remains unknown whether it is a key
factor which can reconcile the different approaches. Here, we provide a
synthesis of three influential approaches (one estimates the actual effect
and the other two the potential effect) and use large-scale afforestation
over China as a test case to examine whether the different approaches can be
reconciled. We found that the actual effect (<span class="inline-formula">Δ<i>T</i><sub>a</sub></span>) often relates
to incomplete afforestation over a medium-resolution satellite pixel (1 km).
<span class="inline-formula">Δ<i>T</i><sub>a</sub></span> increased with the afforestation fraction, which explained
89 % of its variation. One potential effect approach quantifies the impact
of quasi-full afforestation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">1</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="677674539f8953bf7ed40a5ef371bc26"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-75-2023-ie00001.svg" width="23pt" height="14pt" src="bg-20-75-2023-ie00001.png"/></svg:svg></span></span>), whereas the other
quantifies the potential impact of full afforestation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="33a2cfde4256c46d16268d4c12d8be0d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-75-2023-ie00002.svg" width="23pt" height="14pt" src="bg-20-75-2023-ie00002.png"/></svg:svg></span></span>) by
assuming a shift from 100 % openland to 100 % forest coverage. An
initial paired-sample <span class="inline-formula"><i>t</i></span> test shows that <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mi mathvariant="normal">a</mi></msub><mo><</mo><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">1</mn></msub></mrow></msub><mo><</mo><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="89pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="319cffb63d16bfc1870b46170bda3bae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-75-2023-ie00003.svg" width="89pt" height="14pt" src="bg-20-75-2023-ie00003.png"/></svg:svg></span></span> for the cooling effect of
afforestation ranging from 0.07 to 1.16 K. But when all three methods are
normalized for full afforestation, the observed range in surface cooling
becomes much smaller (0.79 to 1.16 K). Potential cooling effects have a
value in academic studies where they can be used to establish an envelope of
effects, but their realization at large scales is challenging given its
nature of scale dependency. The reconciliation of the different approaches
demonstrated in this study highlights the fact that the afforestation
fraction should be accounted for in order to bridge different estimates of
surface cooling effects in policy evaluation.</p> |
| first_indexed | 2024-04-11T00:39:27Z |
| format | Article |
| id | doaj.art-aaf61e583900426396d15f3bf776f7e1 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-11T00:39:27Z |
| publishDate | 2023-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-aaf61e583900426396d15f3bf776f7e12023-01-06T10:39:06ZengCopernicus PublicationsBiogeosciences1726-41701726-41892023-01-0120759210.5194/bg-20-75-2023Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observationsH. Wang0C. Yue1C. Yue2S. Luyssaert3College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, P.R. ChinaState Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, P.R. ChinaCollege of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, P.R. ChinaDepartment of Ecological Sciences, Faculty of Sciences, Vrije Universiteit Amsterdam, Amsterdam 1081 HV, the Netherlands<p>Satellite observations have been widely used to examine afforestation effects on local surface temperature at large spatial scales. Different approaches, which potentially lead to differing definitions of the afforestation effect, have been used in previous studies. Despite their large differences, the results of these studies have been used in climate model validation and cited in climate synthesis reports. Such differences have been simply treated as observational uncertainty, which can be an order of magnitude bigger than the signal itself. Although the fraction of the satellite pixel actually afforested has been noted to influence the magnitude of the afforestation effect, it remains unknown whether it is a key factor which can reconcile the different approaches. Here, we provide a synthesis of three influential approaches (one estimates the actual effect and the other two the potential effect) and use large-scale afforestation over China as a test case to examine whether the different approaches can be reconciled. We found that the actual effect (<span class="inline-formula">Δ<i>T</i><sub>a</sub></span>) often relates to incomplete afforestation over a medium-resolution satellite pixel (1 km). <span class="inline-formula">Δ<i>T</i><sub>a</sub></span> increased with the afforestation fraction, which explained 89 % of its variation. One potential effect approach quantifies the impact of quasi-full afforestation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">1</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="677674539f8953bf7ed40a5ef371bc26"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-75-2023-ie00001.svg" width="23pt" height="14pt" src="bg-20-75-2023-ie00001.png"/></svg:svg></span></span>), whereas the other quantifies the potential impact of full afforestation (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="23pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="33a2cfde4256c46d16268d4c12d8be0d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-75-2023-ie00002.svg" width="23pt" height="14pt" src="bg-20-75-2023-ie00002.png"/></svg:svg></span></span>) by assuming a shift from 100 % openland to 100 % forest coverage. An initial paired-sample <span class="inline-formula"><i>t</i></span> test shows that <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mi mathvariant="normal">a</mi></msub><mo><</mo><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">1</mn></msub></mrow></msub><mo><</mo><mi mathvariant="normal">Δ</mi><msub><mi>T</mi><mrow><msub><mi mathvariant="normal">p</mi><mn mathvariant="normal">2</mn></msub></mrow></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="89pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="319cffb63d16bfc1870b46170bda3bae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="bg-20-75-2023-ie00003.svg" width="89pt" height="14pt" src="bg-20-75-2023-ie00003.png"/></svg:svg></span></span> for the cooling effect of afforestation ranging from 0.07 to 1.16 K. But when all three methods are normalized for full afforestation, the observed range in surface cooling becomes much smaller (0.79 to 1.16 K). Potential cooling effects have a value in academic studies where they can be used to establish an envelope of effects, but their realization at large scales is challenging given its nature of scale dependency. The reconciliation of the different approaches demonstrated in this study highlights the fact that the afforestation fraction should be accounted for in order to bridge different estimates of surface cooling effects in policy evaluation.</p>https://bg.copernicus.org/articles/20/75/2023/bg-20-75-2023.pdf |
| spellingShingle | H. Wang C. Yue C. Yue S. Luyssaert Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations Biogeosciences |
| title | Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations |
| title_full | Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations |
| title_fullStr | Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations |
| title_full_unstemmed | Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations |
| title_short | Reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations |
| title_sort | reconciling different approaches to quantifying land surface temperature impacts of afforestation using satellite observations |
| url | https://bg.copernicus.org/articles/20/75/2023/bg-20-75-2023.pdf |
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