A study on air–sea interaction on the simulated seasonal climate in an ocean–atmosphere coupled model

Ham, Suryun; Hong, Song‐You; Park, Suhee

doi:10.1007/s00382-013-1847-0

Cited by 14 publications

(9 citation statements)

References 69 publications

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“…In JJA, the precipitation biases over the EIO, MC islands, and eastern China are improved in CPD ( Fig. 1h), indicating the importance of air-sea coupling for the simulation of the precipitation climatology over these regions (e.g., Hendon et al 2012;Zhu and Shukla 2013;Ham et al 2014). However, coupling clearly does not eliminate the biases in the atmospheric model simulations; for example, there is no improvement in the lack of monsoonal precipitation over the Indian subcontinent (Figs.…”

Section: Metum-goml1 Climatologymentioning

confidence: 97%

Attribution of Forced Decadal Climate Change in Coupled and Uncoupled Ocean–Atmosphere Model Experiments

et al. 2017

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There is still no consensus about the best methodology for attributing observed changes in climate or climate events. One widely used approach relies on experiments in which the time periods of interest are simulated using an atmospheric general circulation model (AGCM) forced by prescribed sea surface temperatures (SSTs), with and without estimated anthropogenic influences. A potential limitation of such experiments is the lack of explicit atmosphere–ocean coupling; therefore a key question is whether the attribution statements derived from such studies are in fact robust. In this research the authors have carried out climate model experiments to test attribution conclusions in a situation where the answer is known—a so-called perfect model approach. The study involves comparing attribution conclusions for decadal changes derived from experiments with a coupled climate model (specifically an AGCM coupled to an ocean mixed-layer model) with conclusions derived from parallel experiments with the same AGCM forced by SSTs derived from the coupled model simulations. Results indicate that attribution conclusions for surface air temperature changes derived from AGCM experiments are generally robust and not sensitive to air–sea coupling. However, changes in seasonal mean and extreme precipitations, and circulation in some regions, show large sensitivity to air–sea coupling, notably in the summer monsoons over East Asia and Australia. Comparison with observed changes indicates that the coupled simulations generally agree better with observations. These results demonstrate that the AGCM-based attribution method has limitations and may lead to erroneous attribution conclusions in some regions for local circulation and mean and extreme precipitation. The coupled mixed-layer model used in this study offers an alternative and, in some respects, superior tool for attribution studies.

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Section: Metum-goml1 Climatologymentioning

confidence: 97%

Attribution of Forced Decadal Climate Change in Coupled and Uncoupled Ocean–Atmosphere Model Experiments

et al. 2017

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“…In this section, the skills of the coupled ENSEMBLES and DEMETER MMEs are compared with that of the uncoupled HFP2 MME, in predicting the WNP‐EASM variability and the underlying SST conditions. While there are many studies targeting on comparing the prediction performances of coupled and uncoupled models for outside the WNP‐EASM region [e.g., Graham et al , ; Guérémy et al , ; Kumar et al , ; Stefanova et al , ; Landman et al , ; Misra et al , ; Li and Misra , ; Tang et al , ], most of the previous comparison studies for the WNP‐EASM region have been mainly focused on the monsoon simulation, rather than on the monsoon prediction [e.g., Fu et al , ; Aldrian et al , ; Hu et al , ; Huang et al , ; Fang et al , ; Ham et al , ; Zou and Zhou , ; Song and Zhou , ; Cha et al , ]. Here we present an assessment about the practical advantages of the current one‐tier over two‐tier operational MME systems in predicting the WNP‐EASM.…”

Section: Skills Of Coupled Versus Uncoupled Mmesmentioning

confidence: 99%

Probabilistic versus deterministic skill in predicting the western North Pacific‐East Asian summer monsoon variability with multimodel ensembles

Yang

Xie

et al. 2016

JGR Atmospheres

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Based on historical forecasts of three quasi-operational multimodel ensemble (MME) systems, this study assesses the superiority of coupled MME over contributing single-model ensembles (SMEs) and over uncoupled atmospheric MME in predicting the Western North Pacific-East Asian summer monsoon variability. The probabilistic and deterministic forecast skills are measured by Brier skill score (BSS) and anomaly correlation (AC), respectively. A forecast-format-dependent MME superiority over SMEs is found. The probabilistic forecast skill of the MME is always significantly better than that of each SME, while the deterministic forecast skill of the MME can be lower than that of some SMEs. The MME superiority arises from both the model diversity and the ensemble size increase in the tropics, and primarily from the ensemble size increase in the subtropics. The BSS is composed of reliability and resolution, two attributes characterizing probabilistic forecast skill. The probabilistic skill increase of the MME is dominated by the dramatic improvement in reliability, while resolution is not always improved, similar to AC. A monotonic resolution-AC relationship is further found and qualitatively explained, whereas little relationship can be identified between reliability and AC. It is argued that the MME's success in improving the reliability arises from an effective reduction of the overconfidence in forecast distributions. Moreover, it is examined that the seasonal predictions with coupled MME are more skillful than those with the uncoupled atmospheric MME forced by persisting sea surface temperature (SST) anomalies, since the coupled MME has better predicted the SST anomaly evolution in three key regions.

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“…The cold bias in the eastern tropical Pacific is reduced (Misra et al 2008). For the variability on intra-seasonal and inter annual scales, including the diurnal cycle in the SST strongly influences the onset and intensity of MJO convection (Seo et al 2014) and leads to a distinct improvement of the simulated intra-seasonal oscillation signal (Ham et al 2014). The simulated MJO is stronger and more coherent (Bernie et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Air–sea fluxes in a climate model using hourly coupling between the atmospheric and the oceanic components

2016

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We analyse the changes in the air–sea fluxes of momentum, heat and fresh water flux caused by increasing the ocean–atmosphere coupling frequency from once per day to once per hour in the Max Planck Institute Earth System Model. We diagnose the relative influences of daily averaging and high-frequency feedbacks on the basic statistics of the air–sea fluxes at grid point level and quantify feedback modes responsible for large scale changes in fluxes over the Southern Ocean and the Equatorial Pacific. Coupling once per hour instead of once per day reduces the mean of the momentum-flux magnitude by up to 7 % in the tropics and increases it by up to 10 % in the Southern Ocean. These changes result solely from feedbacks between atmosphere and ocean occurring on time scales shorter than 1 day. The variance and extremes of all the fluxes are increased in most parts of the oceans. Exceptions are found for the momentum and fresh water fluxes in the tropics. The increases result mainly from the daily averaging, while the decreases in the tropics are caused by the high-frequency feedbacks. The variance increases are substantial, reaching up to 50 % for the momentum flux, 100 % for the fresh water flux, and a factor of 15 for the net heat flux. These diurnal and intra-diurnal variations account for up to 50–90 % of the total variances and exhibit distinct seasonality. The high-frequency coupling can influence the large-scale feedback modes that lead to large-scale changes in the magnitude of wind stress over the Southern Ocean and Equatorial Pacific. In the Southern Ocean, the dependence of the SST-wind-stress feedback on the mean state of SST, which is colder in the experiment with hourly coupling than in the experiment with daily coupling, leads to an increase of westerlies. In the Equatorial Pacific, Bjerknes feedback in the hourly coupled experiment reveals a diurnal cycle during the El Niño events, with the feedback being stronger in the nighttime than in the daytime and no clear diurnal cycle during the La Niña events. This asymmetry might lead to the decrease of wind stress in the Equatorial Pacific in the hourly coupled experiment. © 2016 The Author(s

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A study on air–sea interaction on the simulated seasonal climate in an ocean–atmosphere coupled model

Cited by 14 publications

References 69 publications

Attribution of Forced Decadal Climate Change in Coupled and Uncoupled Ocean–Atmosphere Model Experiments

Attribution of Forced Decadal Climate Change in Coupled and Uncoupled Ocean–Atmosphere Model Experiments

Probabilistic versus deterministic skill in predicting the western North Pacific‐East Asian summer monsoon variability with multimodel ensembles

Air–sea fluxes in a climate model using hourly coupling between the atmospheric and the oceanic components

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