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Title: Comparison of simulated and reconstructed variations in East African hydroclimate over the last millennium

Journal Article · · Climate of the Past (Online)
 [1];  [1];  [2];  [3]
  1. Univ. catholique de Louvaine (UCL) (Belgium)
  2. Hydrologic Research Center, San Diego, CA (United States)
  3. Ghent Univ. (Belgium)
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The multi-decadal to centennial hydroclimate changes in East Africa over the last millennium are studied by comparing the results of forced transient simulations by six general circulation models (GCMs) with published hydroclimate reconstructions from four lakes: Challa and Naivasha in equatorial East Africa, and Masoko and Malawi in southeastern inter-tropical Africa. All GCMs simulate fairly well the unimodal seasonal cycle of precipitation in the Masoko–Malawi region, while the bimodal seasonal cycle characterizing the Challa–Naivasha region is generally less well captured by most models. Model results and lake-based hydroclimate reconstructions display very different temporal patterns over the last millennium. Additionally, there is no common signal among the model time series, at least until 1850. This suggests that simulated hydroclimate fluctuations are mostly driven by internal variability rather than by common external forcing. After 1850, half of the models simulate a relatively clear response to forcing, but this response is different between the models. Overall, the link between precipitation and tropical sea surface temperatures (SSTs) over the pre-industrial portion of the last millennium is stronger and more robust for the Challa–Naivasha region than for the Masoko–Malawi region. At the inter-annual timescale, last-millennium Challa–Naivasha precipitation is positively (negatively) correlated with western (eastern) Indian Ocean SST, while the influence of the Pacific Ocean appears weak and unclear. Although most often not significant, the same pattern of correlations between East African rainfall and the Indian Ocean SST is still visible when using the last-millennium time series smoothed to highlight centennial variability, but only in fixed-forcing simulations. Furthermore, this means that, at the centennial timescale, the effect of (natural) climate forcing can mask the imprint of internal climate variability in large-scale teleconnections.

Research Organization:
Univ. catholique de Louvain (UCL) (Belgium). Georges Lemaître Centre for Earth and Climate Research (TECLIM), Earth and Life Institute
Sponsoring Organization:
USDOE
OSTI ID:
1375428
Journal Information:
Climate of the Past (Online), Vol. 12, Issue 7; ISSN 1814-9332
Publisher:
European Geophysical Union - CopernicusCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 16 works
Citation information provided by
Web of Science

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Projected changes in mean rainfall and temperature over East Africa based on CMIP5 models: CLIMATE PROJECTION OVER EAST AFRICA journal October 2017
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Modelling Climate Suitability for Rainfed Maize Cultivation in Kenya Using a Maximum Entropy (MaxENT) Approach journal November 2019
Testing the consistency between changes in simulated climate and Alpine glacier length over the past millennium journal January 2018
Assessing the robustness of Antarctic temperature reconstructions over the past 2 millennia using pseudoproxy and data assimilation experiments journal January 2019
Testing the consistency between changes in simulated climate and Alpine glacier length over the past millennium journal May 2018
Niche change analysis as a tool to inform management of two invasive species in Eastern Africa text January 2020
Assessing the robustness of Antarctic temperature reconstructions over the past 2 millennia using pseudoproxy and data assimilation experiments text January 2019

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