Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan Africa
Fire can induce long-lived changes to land-surface albedo, an important aspect of the Earth’s energy budget, but the temporal evolution of these anomalies is poorly understood. Due to the widespread presence of fire in Africa, this represents uncertainty in the continental energy budget, w...
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doaj-51bc44a1bea24b6ea35b3e8e6d8ac25d2020-11-25T00:48:17ZengMDPI AGRemote Sensing2072-42922019-05-01119109010.3390/rs11091090rs11091090Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan AfricaMichael V. Saha0Paolo D’Odorico1Todd M. Scanlon2Department of Environmental Science, Clark Hall, University of Virginia, Charlottesville, VA 22904, USADepartment of Environmental Science, Policy, and Management, Mulford Hall, The University of California at Berkeley, Berkeley, CA 94720, USADepartment of Environmental Science, Clark Hall, University of Virginia, Charlottesville, VA 22904, USAFire can induce long-lived changes to land-surface albedo, an important aspect of the Earth’s energy budget, but the temporal evolution of these anomalies is poorly understood. Due to the widespread presence of fire in Africa, this represents uncertainty in the continental energy budget, which has important implications for regional climate and hydrologic cycling. In this study, we present the first object-based accounting of albedo anomalies induced by larger (>1 km<sup>2</sup>) individual wildfires in sub-Saharan Africa. We group spatially contiguous wildfire pixels into fire objects and track the albedo anomaly for five years after the burn. We find that albedo anomalies all have the same general temporal signature: An immediate, brief period of darkening followed by persistent brightening. The strongest brightening is found in the Kalahari region while more intense and long-lived initial darkening is found in the Sahel region. The average southern hemisphere albedo anomaly is +1.50 × 10<sup>−3</sup> in the year following wildfire, representing a statistically significant negative surface energy balance forcing on a continental scale. This study challenges an existing paradigm surrounding the physical effects of fire on the landscape. Our results suggest that models of albedo that assume a darkening and recovery to baseline are overly simplistic in almost all circumstances. Furthermore, the presumption that immediate darkening is the only meaningful effect on albedo is incorrect for the majority of the African continent.https://www.mdpi.com/2072-4292/11/9/1090firealbedobrighteningland-atmosphere interactionsAfrica |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Michael V. Saha Paolo D’Odorico Todd M. Scanlon |
spellingShingle |
Michael V. Saha Paolo D’Odorico Todd M. Scanlon Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan Africa Remote Sensing fire albedo brightening land-atmosphere interactions Africa |
author_facet |
Michael V. Saha Paolo D’Odorico Todd M. Scanlon |
author_sort |
Michael V. Saha |
title |
Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan Africa |
title_short |
Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan Africa |
title_full |
Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan Africa |
title_fullStr |
Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan Africa |
title_full_unstemmed |
Kalahari Wildfires Drive Continental Post-Fire Brightening in Sub-Saharan Africa |
title_sort |
kalahari wildfires drive continental post-fire brightening in sub-saharan africa |
publisher |
MDPI AG |
series |
Remote Sensing |
issn |
2072-4292 |
publishDate |
2019-05-01 |
description |
Fire can induce long-lived changes to land-surface albedo, an important aspect of the Earth’s energy budget, but the temporal evolution of these anomalies is poorly understood. Due to the widespread presence of fire in Africa, this represents uncertainty in the continental energy budget, which has important implications for regional climate and hydrologic cycling. In this study, we present the first object-based accounting of albedo anomalies induced by larger (>1 km<sup>2</sup>) individual wildfires in sub-Saharan Africa. We group spatially contiguous wildfire pixels into fire objects and track the albedo anomaly for five years after the burn. We find that albedo anomalies all have the same general temporal signature: An immediate, brief period of darkening followed by persistent brightening. The strongest brightening is found in the Kalahari region while more intense and long-lived initial darkening is found in the Sahel region. The average southern hemisphere albedo anomaly is +1.50 × 10<sup>−3</sup> in the year following wildfire, representing a statistically significant negative surface energy balance forcing on a continental scale. This study challenges an existing paradigm surrounding the physical effects of fire on the landscape. Our results suggest that models of albedo that assume a darkening and recovery to baseline are overly simplistic in almost all circumstances. Furthermore, the presumption that immediate darkening is the only meaningful effect on albedo is incorrect for the majority of the African continent. |
topic |
fire albedo brightening land-atmosphere interactions Africa |
url |
https://www.mdpi.com/2072-4292/11/9/1090 |
work_keys_str_mv |
AT michaelvsaha kalahariwildfiresdrivecontinentalpostfirebrighteninginsubsaharanafrica AT paolododorico kalahariwildfiresdrivecontinentalpostfirebrighteninginsubsaharanafrica AT toddmscanlon kalahariwildfiresdrivecontinentalpostfirebrighteninginsubsaharanafrica |
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