Congo Basin precipitation: Assessing seasonality, regional interactions, and sources of moisture

Dyer, Ellen; Jones, Dylan B. A.; Nusbaumer, Jesse; Li, Harry; Collins, Owen; Vettoretti, G.; Noone, David

doi:10.1002/2016jd026240

Cited by 108 publications

(116 citation statements)

References 38 publications

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“…This diagnostic hydrologic cycle experiences all the same changes and processes that the regular water cycle does, but has no influence on any other underlying simulation of the predicted state of the model. The simulated water isotopes are represented as numerical “water tracers”; they track water through space and time, through the different phases of water, and the different components of the hydrologic cycle (e.g., Bosilovich, ; Dyer et al, ; Noone & Simmonds, ; Risi et al, ; Singh et al, ). This secondary water tracer cycle has been implemented in all components of CESM, except land ice, along with the necessary fractionation physics routines.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Water tagging has been implemented in the atmospheric component of CESM with new infrastructure within CAM and CLM to facilitate a variety of applications. For instance, the scheme has already been used to examine global (Singh et al, ) and regional (Dyer et al, ) variations in moisture source, as well as to determine the average moisture sources for specific weather phenomena (Nusbaumer & Noone, ). This water tagging can be applied to water isotopologues as well, allowing one to determine the impact of moisture source and pathway changes on the isotope ratios for a particular region (Tabor et al, ; Zhu et al, ).…”

Section: Model Descriptionmentioning

confidence: 99%

“…water through space and time, through the different phases of water, and the different components of the hydrologic cycle (e.g., Bosilovich, 2002;Dyer et al, 2017;Noone & Simmonds, 2002;Risi et al, 2010;. This secondary water tracer cycle has been implemented in all components of CESM, except land ice, along with the necessary fractionation physics routines.…”

Section: Model Descriptionmentioning

confidence: 99%

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The Connected Isotopic Water Cycle in the Community Earth System Model Version 1

Brady

Stevenson

Bailey

et al. 2019

J Adv Model Earth Syst

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172

213

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Because of the pervasive role of water in the Earth system, the relative abundances of stable isotopologues of water are valuable for understanding atmospheric, oceanic, and biospheric processes, and for interpreting paleoclimate proxy reconstructions. Isotopologues are transported by both large‐scale and turbulent flows, and the ratio of heavy to light isotopologues changes due to fractionation that can accompany condensation and evaporation processes. Correctly predicting the isotopic distributions requires resolving the relationships between large‐scale ocean and atmospheric circulation and smaller‐scale hydrological processes, which can be accomplished within a coupled climate modeling framework. Here we present the water isotope‐enabled version of the Community Earth System Model version 1 (iCESM1), which simulates global variations in water isotopic ratios in the atmosphere, land, ocean, and sea ice. In a transient Last Millennium simulation covering the 850–2005 period, iCESM1 correctly captures the late‐twentieth‐century structure of δ18O and δD over the global oceans, with more limited accuracy over land. The relationship between salinity and seawater δ18O is also well represented over the observational period, including interbasin variations. We illustrate the utility of coupled, isotope‐enabled simulations using both Last Millennium simulations and freshwater hosing experiments with iCESM1. Closing the isotopic mass balance between all components of the coupled model provides new confidence in the underlying depiction of the water cycle in CESM, while also highlighting areas where the underlying hydrologic balance can be improved. The iCESM1 is poised to be a vital community resource for ongoing model development with both modern and paleoclimate applications.

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Section: Model Descriptionmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

Section: Model Descriptionmentioning

confidence: 99%

See 1 more Smart Citation

The Connected Isotopic Water Cycle in the Community Earth System Model Version 1

Brady

Stevenson

Bailey

et al. 2019

J Adv Model Earth Syst

Self Cite

172

213

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“…The tagged water vapor can be advected and goes through phase changes until it leaves the atmosphere as precipitation. There are already several studies using this water‐tagging technique to track moisture and water isotopes (Dyer et al, ; Nusbaumer & Noone, ; Singh et al, ; Tabor et al, ).…”

Section: Experimental Designmentioning

confidence: 99%

Deciphering Oxygen Isotope Records From Chinese Speleothems With an Isotope‐Enabled Climate Model

Emile‐Geay

Tabor

et al. 2019

Paleoceanog and Paleoclimatol

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Speleothem 18 O is widely used to reconstruct past hydroclimate variability, particularly over Asia. However, the interpretation of this proxy is still in debate. While this proxy is originally interpreted as regional rainfall amount of the Asian monsoon, other studies have interpreted it as upstream monsoon rainfall or atmospheric circulation changes. To better understand the signal preserved in speleothems over various time scales, this study employs a state-of-the-art isotope-enabled climate model to quantify contributions to the oxygen isotope composition of precipitation ( 18 O P ) over China. Results suggest that orbital-scale speleothem 18 O variations at Chinese sites mainly record the meridional migration of the Asian monsoon circulation, accompanied by an early northward movement of the East Asian rain belt. At interannual scales, Chinese speleothem 18 O is also tied to the intensity of monsoonal circulation, via a change in moisture source locations: Enhanced moisture delivery from remote source regions leads to more negative 18 O P , particularly in late summer and early autumn. Our results have implications for the hydroclimatic interpretation of speleothem 18 O from Chinese caves and suggest that this interpretation is time scale dependent.

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“…In addition, we might be able to suggest whether certain schemes should be used in more models to improve evaporation during the wet seasons specifically. As the Congo Basin is believed to be a hot spot of moisture recycling during the wet seasons (Dyer et al, 2017), this might help to constrain the model spread in rainfall evident during the two wet seasons. Table 1 shows that models with realistic evaporation (CNRM-CM5 and GISS-E2-R) use subgrid rainfall schemes in their land surface components.…”

Section: Journal Of Geophysical Research: Atmospheresmentioning

confidence: 99%

Evaluation of Evaporation Climatology for the Congo Basin Wet Seasons in 11 Global Climate Models

2020

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Across the Congo, there is a wide spread in rainfall in the two wet seasons in Coupled Model Intercomparison Project 5 global climate models (GCMs). As the Congo is believed to be a moisture recycling hot spot, the evaporation of excess water from the land surface in some models could be amplifying the model spread in rainfall. This study performs an exploratory process‐based evaluation of Congo Basin evaporation in 11 Coupled Model Intercomparison Project 5 GCMs that took part in the Atmospheric Model Intercomparison Project. Our aims are to improve scientific understanding about Congo evaporation, and to determine whether there are opportunities to improve how models produce Congo evaporation. Climatologically, we find that models with “realistic” rainfall simulate higher rainfall in November, the peak of the second wet season, than March, the peak of the first. However, models with “realistic” evaporation simulate lower evaporation in November than March, because these models suppress the transpiration component of the evaporation in November relative to March. In both wet seasons, subgrid rainfall schemes make these models simulate a credible ratio of transpiration to canopy evaporation, and cause them to generate evaporation in a more realistic manner. We therefore trust how these models produce evaporation in the wet seasons, and argue that lower transpiration is likely to explain why evaporation is lower in November than March in reality. We also suggest that using subgrid rainfall schemes in all GCMs could improve how models produce Congo evaporation during the wet seasons. This might reduce the model spread in Congo rainfall.

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Congo Basin precipitation: Assessing seasonality, regional interactions, and sources of moisture

Cited by 108 publications

References 38 publications

The Connected Isotopic Water Cycle in the Community Earth System Model Version 1

The Connected Isotopic Water Cycle in the Community Earth System Model Version 1

Deciphering Oxygen Isotope Records From Chinese Speleothems With an Isotope‐Enabled Climate Model

Evaluation of Evaporation Climatology for the Congo Basin Wet Seasons in 11 Global Climate Models

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