Impact of the Sunda Shelf on the Climate of the Maritime Continent

Sarr, Anta‐Clarisse; Sepulchre, Pierre; Husson, Laurent

doi:10.1029/2018jd029971

Cited by 23 publications

(19 citation statements)

References 59 publications

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“…region (up to +5 mm.d −1 during the humid season). This bias has been described earlier with LMDZ pre-industrial simulations run either in atmospheric-only or fully-coupled mode (Toh et al, 2018;Sarr et al, 2019) and it was shown that LMDZ systematically overestimates rainfall over both land and sea surfaces of the Maritime Continent, together with western Indian Ocean and Bengal Bay. Given the complexity of the Indonesian region, with a myriad of islands that the model spatial resolution cannot capture, it is no surprise that rainfall are misrepresented in this model (Qian, 2008).…”

Section: °Csupporting

confidence: 74%

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

Sepulchre¹,

Caubel²,

Ladant³

et al. 2019

Preprint

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Abstract. Based on the CMIP5-generation previous IPSL earth system model, we designed a new version, IPSL-CM5A2, aiming at running multi-millennial simulations typical of deep-time paleoclimates studies. Three priorities were followed during the set-up of the model: (1) improving the overall model computing performance, (2) overcoming a persistent cold bias depicted in the previous model generation, and (3) making the model able to handle the specific continental configurations of the geological past. Technical developments have been performed on separate components and on the coupling system to speed up the whole coupled model. These developments include the integration of hybrid parallelization MPI-OpenMP in LMDz atmospheric component, the use of a new library to perform parallel asynchronous input/output by using computing cores as “IO servers”, the use of a parallel coupling library between the ocean and the atmospheric components. The model can now simulate ~100 years per day, opening new possibilities towards the production of multi-millennial simulations with a full earth system model. The tuning strategy employed to overcome a persistent cold bias is detailed. The confrontation of an historical simulation to climatological observations shows overall improved ocean meridional overturning circulation, marine productivity and latitudinal position of zonal wind patterns. We also present the numerous steps required to run the IPSL-CM5A2 for deep-time paleoclimates through a preliminary case-study for the Cretaceous. Namely, a specific work on the ocean model grid was required to run the model for specific continental configurations in which continents are relocated according to past paleogeographic reconstructions. By briefly discussing the spin-up of such a simulation, we elaborate on the requirements and challenges awaiting paleoclimate modelling in the next years, namely finding the best trade-off between the level of description of the processes and the computing cost on supercomputers.

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Section: °Csupporting

confidence: 74%

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

Sepulchre¹,

Caubel²,

Ladant³

et al. 2019

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although at the first order, the seasonal cycle of precipitation is correctly represented over the "Maritime Continent", IPSL-CM5A2 depicts a strong humid bias over the region (up to +5 mm d −1 during the humid season). This bias has been described earlier with LMDZ preindustrial simulations run either in atmospheric-only or fully coupled mode (Toh et al, 2018;Sarr et al, 2019) and it was shown that LMDZ systematically overestimates rainfall over both land and sea surfaces of the Maritime Continent, to- gether with western Indian Ocean and Bay of Bengal. Given the complexity of the Indonesian region, with a myriad of islands that the model spatial resolution cannot capture, it is no surprise that rainfall is misrepresented in this model (Qian, 2008).…”

Section: Tropical Precipitationsupporting

confidence: 73%

IPSL-CM5A2 – an Earth system model designed for multi-millennial climate simulations

et al. 2020

Self Cite

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Abstract. Based on the fifth phase of the Coupled Model Intercomparison Project (CMIP5)-generation previous Institut Pierre Simon Laplace (IPSL) Earth system model, we designed a new version, IPSL-CM5A2, aiming at running multi-millennial simulations typical of deep-time paleoclimate studies. Three priorities were followed during the setup of the model: (1) improving the overall model computing performance, (2) overcoming a persistent cold bias depicted in the previous model generation and (3) making the model able to handle the specific continental configurations of the geological past. These developments include the integration of hybrid parallelization Message Passing Interface – Open Multi-Processing (MPI-OpenMP) in the atmospheric model of the Laboratoire de Météorologie Dynamique (LMDZ), the use of a new library to perform parallel asynchronous input/output by using computing cores as “I/O servers” and the use of a parallel coupling library between the ocean and the atmospheric components. The model, which runs with an atmospheric resolution of 3.75∘×1.875∘ and 2 to 0.5∘ in the ocean, can now simulate ∼100 years per day, opening new possibilities towards the production of multi-millennial simulations with a full Earth system model. The tuning strategy employed to overcome a persistent cold bias is detailed. The confrontation of a historical simulation to climatological observations shows overall improved ocean meridional overturning circulation, marine productivity and latitudinal position of zonal wind patterns. We also present the numerous steps required to run IPSL-CM5A2 for deep-time paleoclimates through a preliminary case study for the Cretaceous. Namely, specific work on the ocean model grid was required to run the model for specific continental configurations in which continents are relocated according to past paleogeographic reconstructions. By briefly discussing the spin-up of such a simulation, we elaborate on the requirements and challenges awaiting paleoclimate modeling in the next years, namely finding the best trade-off between the level of description of the processes and the computing cost on supercomputers.

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“…Jet position and AMOC have been improved, together with the sea-ice cover. IPSL-CM5A2 also benefits from higher parallelization (namely MPI-OpenMP in the atmosphere), which improves the model scalability and allows the model to reach ∼ 100 yr d −1 simulated on the JOLIOT-CURIE French supercomputer (Sarr et al, 2019;Sepulchre et al, 2019). We nonetheless first provide a validation of the model on modern climatic conditions for the Asian monsoon regions.…”

Section: Model Description and Validationmentioning

confidence: 99%

The origin of Asian monsoons: a modelling perspective

et al. 2020

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Abstract. The Cenozoic inception and development of the Asian monsoons remain unclear and have generated much debate, as several hypotheses regarding circulation patterns at work in Asia during the Eocene have been proposed in the few last decades. These include (a) the existence of modern-like monsoons since the early Eocene; (b) that of a weak South Asian monsoon (SAM) and little to no East Asian monsoon (EAM); or (c) a prevalence of the Intertropical Convergence Zone (ITCZ) migrations, also referred to as Indonesian–Australian monsoon (I-AM). As SAM and EAM are supposed to have been triggered or enhanced primarily by Asian palaeogeographic changes, their possible inception in the very dynamic Eocene palaeogeographic context remains an open question, both in the modelling and field-based communities. We investigate here Eocene Asian climate conditions using the IPSL-CM5A2 (Sepulchre et al., 2019) earth system model and revised palaeogeographies. Our Eocene climate simulation yields atmospheric circulation patterns in Asia substantially different from modern conditions. A large high-pressure area is simulated over the Tethys ocean, which generates intense low tropospheric winds blowing southward along the western flank of the proto-Himalayan–Tibetan plateau (HTP) system. This low-level wind system blocks, to latitudes lower than 10∘ N, the migration of humid and warm air masses coming from the Indian Ocean. This strongly contrasts with the modern SAM, during which equatorial air masses reach a latitude of 20–25∘ N over India and southeastern China. Another specific feature of our Eocene simulation is the widespread subsidence taking place over northern India in the midtroposphere (around 5000 m), preventing deep convective updraught that would transport water vapour up to the condensation level. Both processes lead to the onset of a broad arid region located over northern India and over the HTP. More humid regions of high seasonality in precipitation encircle this arid area, due to the prevalence of the Intertropical Convergence Zone (ITCZ) migrations (or Indonesian–Australian monsoon, I-AM) rather than monsoons. Although the existence of this central arid region may partly result from the specifics of our simulation (model dependence and palaeogeographic uncertainties) and has yet to be confirmed by proxy records, most of the observational evidence for Eocene monsoons are located in the highly seasonal transition zone between the arid area and the more humid surroundings. We thus suggest that a zonal arid climate prevailed over Asia before the initiation of monsoons that most likely occurred following Eocene palaeogeographic changes. Our results also show that precipitation seasonality should be used with caution to infer the presence of a monsoonal circulation and that the collection of new data in this arid area is of paramount importance to allow the debate to move forward.

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Impact of the Sunda Shelf on the Climate of the Maritime Continent

Cited by 23 publications

References 59 publications

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

IPSL-CM5A2. An Earth System Model designed for multi-millennial climate simulations

IPSL-CM5A2 – an Earth system model designed for multi-millennial climate simulations

The origin of Asian monsoons: a modelling perspective

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