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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ftdoajarticles:oai:doaj.org/article:bb89ad265fca40bc94851cbb3ed8b85e 2023-05-15T17:35:30+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 2020-08-01T00:00:00Z https://doi.org/10.3390/rs12172723 https://doaj.org/article/bb89ad265fca40bc94851cbb3ed8b85e EN eng MDPI AG https://www.mdpi.com/2072-4292/12/17/2723 https://doaj.org/toc/2072-4292 doi:10.3390/rs12172723 2072-4292 https://doaj.org/article/bb89ad265fca40bc94851cbb3ed8b85e Remote Sensing, Vol 12, Iss 2723, p 2723 (2020) Sahel precipitation vegetation sea surface temperature greening wetting Science Q article 2020 ftdoajarticles https://doi.org/10.3390/rs12172723 2022-12-31T13:00:58Z 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. Article in Journal/Newspaper North Atlantic Directory of Open Access Journals: DOAJ Articles Remote Sensing 12 17 2723 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
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language |
English |
topic |
Sahel precipitation vegetation sea surface temperature greening wetting Science Q |
spellingShingle |
Sahel precipitation vegetation sea surface temperature greening wetting Science Q 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 Science Q |
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 |
Article in Journal/Newspaper |
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 |
MDPI AG |
publishDate |
2020 |
url |
https://doi.org/10.3390/rs12172723 https://doaj.org/article/bb89ad265fca40bc94851cbb3ed8b85e |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Remote Sensing, Vol 12, Iss 2723, p 2723 (2020) |
op_relation |
https://www.mdpi.com/2072-4292/12/17/2723 https://doaj.org/toc/2072-4292 doi:10.3390/rs12172723 2072-4292 https://doaj.org/article/bb89ad265fca40bc94851cbb3ed8b85e |
op_doi |
https://doi.org/10.3390/rs12172723 |
container_title |
Remote Sensing |
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12 |
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17 |
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2723 |
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1766134679587520512 |