North African vegetation–precipitation feedback in early and mid-Holocene climate simulations with CCSM3-DGVM

Rachmayani, Rima; Prange, Matthias; Schulz, Michael

doi:10.5194/cp-11-175-2015

Cited by 73 publications

(66 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence, in these simulations, and in line with previous studies (e.g. Rachmayani et al, 2015), it is a local hydrological climate-vegetation feedback which leads to multiple equilibria over the Sahel region in the pre-industrial climate.…”

Section: Discussionsupporting

confidence: 73%

“…12). Stronger AEJ over the moister or greener Sahel region is in line with earlier simulations by Cook (1999) and Rachmayani et al (2015). The stronger AEJ is accompanied by a stronger horizontal moisture flux convergence (Fig.…”

Section: Bistable Sahel In the Pre-industrial Climatesupporting

confidence: 78%

“…For example, the intransitivity of the climatevegetation system over northern Africa vanishes, or becomes much less pronounced, for the mid-Holocene climate in the simulations by Claussen and Gayler (1997) and Rachmayani et al (2015). Likewise, Bathiany et al (2012) showed that the pattern of bistability over northern Africa changes at different times in different locations during the transition from mid-to late Holocene.…”

Section: Introductionmentioning

confidence: 91%

“…In our study, albedo differences are assumed to be small. Hence, a hydrological feedback causes multiple states, as is the case in the simulations by Rachmayani et al (2015).…”

Section: Bistable Sahel In the Pre-industrial Climatementioning

confidence: 99%

“…Multiple equilibrium states have been detected in various model simulations when initialized with different vegetation covers. Claussen (1994), Claussen and Gayler (1997), Claussen (1998), Kubatzki and Claussen (1998), Wang and Eltahir (2000), Zeng and Neelin (2000), and Rachmayani et al (2015) found multiple states in northern Africa; Oyama and Nobre (2003) found these in the Amazon region, Claussen (1998) in central Asia, and Dekker et al (2010) found them in the northern high latitudes. In all cases, simulations with initially more extended vegetation cover lead to a moister climate and smaller deserts than simulations initialized with sparse vegetation coverage.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Transitivity of the climate–vegetation system in a warm climate

Port

Claußen

2015

Clim. Past

View full text Add to dashboard Cite

Abstract. To date, the transitivity of the global system has been analysed for late Quaternary (glacial, interglacial, and present-day) climate. Here, we extend this analysis to a warm, almost ice-free climate with a different configuration of continents. We use the Earth system model of the Max Planck Institute for Meteorology to analyse the stability of the climate system under early Eocene and pre-industrial conditions. We initialize the simulations by prescribing either dense forests or bare deserts on all continents. Starting with desert continents, an extended desert remains in central Asia in the early Eocene climate. Starting with dense forest coverage, the Asian desert is much smaller, while coastal deserts develop in the Americas which appear to be larger than in the simulations with initially bare continents. These differences can be attributed to differences in the large-scale tropical circulation. With initially forested continents, a stronger dipole in the 200 hPa velocity potential develops than in the simulation with initially bare continents. This difference prevails when vegetation is allowed to adjust to and interact with climate. Further simulations with initial surface conditions that differ in the region of the Asian desert only indicate that local feedback processes are less important in the development of multiple states. In the interglacial, pre-industrial climate, multiple states develop only in the Sahel region. There, local climate-vegetation interaction seems to dominate.

show abstract

Section: Discussionsupporting

confidence: 73%

Section: Bistable Sahel In the Pre-industrial Climatesupporting

confidence: 78%

Section: Introductionmentioning

confidence: 91%

“…In our study, albedo differences are assumed to be small. Hence, a hydrological feedback causes multiple states, as is the case in the simulations by Rachmayani et al (2015).…”

Section: Bistable Sahel In the Pre-industrial Climatementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Transitivity of the climate–vegetation system in a warm climate

Port

Claußen

2015

Clim. Past

View full text Add to dashboard Cite

show abstract

The role of fall season tropical plumes in enhancing Saharan rainfall during the African Humid Period

Skinner

Poulsen

2016

Geophysical Research Letters

View full text Add to dashboard Cite

The early Holocene to mid‐Holocene African Humid Period (AHP) is marked by widespread rainfall throughout the present‐day arid Sahara. Here we simulate early Holocene and mid‐Holocene climate with the Community Atmosphere Model version 5 to explore the role of fall season dynamics in driving Saharan rainfall during the AHP. An enhanced summer monsoon during the AHP results in abundant fall season moisture throughout tropical Africa, particularly during the mid‐Holocene. During the fall, extratropical troughs advect tropical moisture toward the Sahara in the form of concentrated plumes of water vapor and extend the Saharan rainy season into October. Fall season tropical plumes contribute up to 30% of annual Saharan rainfall during the mid‐Holocene. Our results suggest that tropical plumes serve as an important mechanism for enhancing Saharan rainfall during the late AHP and that further understanding of changes in tropical plumes through time may provide valuable insights into past African hydroclimate change.

show abstract

Multi vegetation model evaluation of the Green Sahara climate regime

Hopcroft

Valdes

Harper

et al. 2017

Geophysical Research Letters

View full text Add to dashboard Cite

During the Quaternary, the Sahara desert was periodically colonized by vegetation, likely because of orbitally induced rainfall increases. However, the estimated hydrological change is not reproduced in climate model simulations, undermining confidence in projections of future rainfall. We evaluated the relationship between the qualitative information on past vegetation coverage and climate for the mid‐Holocene using three different dynamic vegetation models. Compared with two available vegetation reconstructions, the models require 500–800 mm of rainfall over 20°–25°N, which is significantly larger than inferred from pollen but largely in agreement with more recent leaf wax biomarker reconstructions. The magnitude of the response also suggests that required rainfall regime of the early to middle Holocene is far from being correctly represented in general circulation models. However, intermodel differences related to moisture stress parameterizations, biases in simulated present‐day vegetation, and uncertainties about paleosoil distributions introduce uncertainties, and these are also relevant to Earth system model simulations of African humid periods.

show abstract

North African vegetation–precipitation feedback in early and mid-Holocene climate simulations with CCSM3-DGVM

Cited by 73 publications

References 85 publications

Transitivity of the climate–vegetation system in a warm climate

Transitivity of the climate–vegetation system in a warm climate

The role of fall season tropical plumes in enhancing Saharan rainfall during the African Humid Period

Multi vegetation model evaluation of the Green Sahara climate regime

Contact Info

Product

Resources

About