The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST
The Sahel, a semi-arid climatic zone with highly seasonal and erratic rainfall, experienced severe droughts in the 1970s and 1980s. Based on remote sensing vegetation indices since early 1980, a clear greening trend is found, which can be attributed to the recovery of contemporaneous precipitation....
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ftmdpi:oai:mdpi.com:/2072-4292/12/17/2723/ 2023-08-20T04:08:29+02:00 The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST Tiexi Chen Shengjie Zhou Chuanzhuang Liang Daniel Fiifi Tawia Hagan Ning Zeng Jun Wang Tingting Shi Xin Chen A.J. Dolman agris 2020-08-23 application/pdf https://doi.org/10.3390/rs12172723 EN eng Multidisciplinary Digital Publishing Institute https://dx.doi.org/10.3390/rs12172723 https://creativecommons.org/licenses/by/4.0/ Remote Sensing; Volume 12; Issue 17; Pages: 2723 Sahel precipitation vegetation sea surface temperature greening wetting Text 2020 ftmdpi https://doi.org/10.3390/rs12172723 2023-07-31T23:58:19Z The Sahel, a semi-arid climatic zone with highly seasonal and erratic rainfall, experienced severe droughts in the 1970s and 1980s. Based on remote sensing vegetation indices since early 1980, a clear greening trend is found, which can be attributed to the recovery of contemporaneous precipitation. Here, we present an analysis using long-term leaf area index (LAI), precipitation, and sea surface temperature (SST) records to investigate their trends and relationships. LAI and precipitation show a significant positive trend between 1982 and 2016, at 1.72 × 10 −3 yr −1 (p < 0.01) and 4.63 mm yr−1 (p < 0.01), respectively. However, a piecewise linear regression approach indicates that the trends in both LAI and precipitation are not continuous throughout the 35 year period. In fact, both the greening and wetting of the Sahel have been leveled off (pause of rapid growth) since about 1999. The trends of LAI and precipitation between 1982 and 1999 and 1999–2016 are 4.25 × 10 − 3 yr −1 to − 0.27 × 10 −3 yr −1, and 9.72 mm yr −1 to 2.17 mm yr −1, respectively. These declines in trends are further investigated using an SST index, which is composed of the SSTs of the Mediterranean Sea, the subtropical North Atlantic, and the global tropical oceans. Causality analysis based on information flow theory affirms this precipitation stabilization between 2003 and 2014. Our results highlight that both the greening and the wetting of the Sahel have been leveled off, a feature that was previously hidden in the apparent long-lasting greening and wetting records since the extreme low values in the 1980s. Text North Atlantic MDPI Open Access Publishing Remote Sensing 12 17 2723 |
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Open Polar |
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MDPI Open Access Publishing |
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ftmdpi |
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English |
topic |
Sahel precipitation vegetation sea surface temperature greening wetting |
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Sahel precipitation vegetation sea surface temperature greening wetting Tiexi Chen Shengjie Zhou Chuanzhuang Liang Daniel Fiifi Tawia Hagan Ning Zeng Jun Wang Tingting Shi Xin Chen A.J. Dolman The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST |
topic_facet |
Sahel precipitation vegetation sea surface temperature greening wetting |
description |
The Sahel, a semi-arid climatic zone with highly seasonal and erratic rainfall, experienced severe droughts in the 1970s and 1980s. Based on remote sensing vegetation indices since early 1980, a clear greening trend is found, which can be attributed to the recovery of contemporaneous precipitation. Here, we present an analysis using long-term leaf area index (LAI), precipitation, and sea surface temperature (SST) records to investigate their trends and relationships. LAI and precipitation show a significant positive trend between 1982 and 2016, at 1.72 × 10 −3 yr −1 (p < 0.01) and 4.63 mm yr−1 (p < 0.01), respectively. However, a piecewise linear regression approach indicates that the trends in both LAI and precipitation are not continuous throughout the 35 year period. In fact, both the greening and wetting of the Sahel have been leveled off (pause of rapid growth) since about 1999. The trends of LAI and precipitation between 1982 and 1999 and 1999–2016 are 4.25 × 10 − 3 yr −1 to − 0.27 × 10 −3 yr −1, and 9.72 mm yr −1 to 2.17 mm yr −1, respectively. These declines in trends are further investigated using an SST index, which is composed of the SSTs of the Mediterranean Sea, the subtropical North Atlantic, and the global tropical oceans. Causality analysis based on information flow theory affirms this precipitation stabilization between 2003 and 2014. Our results highlight that both the greening and the wetting of the Sahel have been leveled off, a feature that was previously hidden in the apparent long-lasting greening and wetting records since the extreme low values in the 1980s. |
format |
Text |
author |
Tiexi Chen Shengjie Zhou Chuanzhuang Liang Daniel Fiifi Tawia Hagan Ning Zeng Jun Wang Tingting Shi Xin Chen A.J. Dolman |
author_facet |
Tiexi Chen Shengjie Zhou Chuanzhuang Liang Daniel Fiifi Tawia Hagan Ning Zeng Jun Wang Tingting Shi Xin Chen A.J. Dolman |
author_sort |
Tiexi Chen |
title |
The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST |
title_short |
The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST |
title_full |
The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST |
title_fullStr |
The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST |
title_full_unstemmed |
The Greening and Wetting of the Sahel Have Leveled off since about 1999 in Relation to SST |
title_sort |
greening and wetting of the sahel have leveled off since about 1999 in relation to sst |
publisher |
Multidisciplinary Digital Publishing Institute |
publishDate |
2020 |
url |
https://doi.org/10.3390/rs12172723 |
op_coverage |
agris |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Remote Sensing; Volume 12; Issue 17; Pages: 2723 |
op_relation |
https://dx.doi.org/10.3390/rs12172723 |
op_rights |
https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.3390/rs12172723 |
container_title |
Remote Sensing |
container_volume |
12 |
container_issue |
17 |
container_start_page |
2723 |
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1774720760059789312 |