Dynamical downscaling with the fifth-generation Canadian regional climate model (CRCM5) over the CORDEX Arctic domain: effect of large-scale spectral nudging and of empirical correction of sea-surface temperature

Abstract. Instrumental records of the North Atlantic sea surface temperature reveal a large-scale low frequency mode of variability that has become known as the Atlantic Multidecadal Oscillation (AMO). Proxy and modelling studies have demonstrated the important consequences of the AMO on other components of the climate system both within and outside the Atlantic region. Over longer time scales, the past behavior of the AMO is predominantly constrained by terrestrial proxies and only a limited number of records are available from the marine realm itself. Here we use an Earth System-Climate Model of intermediate complexity to simulate AMO-type behavior in the Atlantic with a specific focus placed on the ability of ocean paleothermometers to capture the associated surface and subsurface temperature variability. Given their lower prediction errors and annual resolution, coral-based proxies of sea surface temperature appear to be capable of reconstructing the temperature variations associated with the past AMO with an adequate signal-to-noise ratio. In contrast, the relatively high prediction error and low temporal resolution of sediment-based proxies, such as the composition of foraminiferal calcite, limits their ability to produce interpretable records of past temperature anomalies corresponding to AMO activity. Whilst the presented results will inevitably be model-dependent to some degree, the statistical framework is model-independent and can be applied to a wide variety of scenarios.

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Can oceanic paleothermometers reconstruct the Atlantic Multidecadal Oscillation?

Climate of the Past Discussions ◽

10.5194/cpd-6-2177-2010 ◽

2010 ◽

Vol 6 (5) ◽

pp. 2177-2197 ◽

Cited By ~ 1

Author(s):

D. Heslop ◽

A. Paul

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Large Scale ◽

Climate Model ◽

Low Frequency ◽

Atlantic Multidecadal Oscillation ◽

Sea Surface ◽

Prediction Errors ◽

The Past ◽

Instrumental Records

Abstract. Instrumental records of North Atlantic sea surface temperature reveal a large-scale low frequency mode of variability that has become known as the Atlantic Multidecadal Oscillation (AMO). Proxy and modelling studies have demonstrated the important consequences of the AMO on other components of the climate system both within and outside the Atlantic region. Over longer time scales the past behavior of the AMO is predominantly constrained by terrestrial proxies and only a limited number of records are available from the marine realm itself. Here we use an Earth System-Climate Model of intermediate complexity to simulate AMO-type behavior in the Atlantic with a specific focus placed on the ability of ocean paleothermometers to capture the associated surface and subsurface temperature variability. Given their lower prediction errors and annual resolution, coral-based proxies of sea surface temperature appear to be capable of reconstructing the temperature variations associated with the past AMO with an adequate signal-to-noise ratio. Contrastingly, the relatively high prediction error and low temporal resolution of sediment-based proxies, such as the composition of foraminiferal calcite, limits their ability to produce interpretable records of past temperature anomalies corresponding to AMO activity.

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A Hybrid Downscaling Approach for Future Temperature and Precipitation Change

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-20-0013.1 ◽

2020 ◽

Vol 59 (11) ◽

pp. 1793-1807 ◽

Cited By ~ 1

Author(s):

Helene Birkelund Erlandsen ◽

Kajsa M. Parding ◽

Rasmus Benestad ◽

Abdelkader Mezghani ◽

Marie Pontoppidan

Keyword(s):

Regional Climate Model ◽

Statistical Models ◽

Large Scale ◽

Climate Model ◽

Dynamical Downscaling ◽

Global Climate ◽

Global Climate Model ◽

Regional Climate ◽

Small Scale ◽

Regional Climate Model Output

AbstractWe used empirical–statistical downscaling in a pseudoreality context, in which both large-scale predictors and small-scale predictands were based on climate model results. The large-scale conditions were taken from a global climate model, and the small-scale conditions were taken from dynamical downscaling of the same global model with a convection-permitting regional climate model covering southern Norway. This hybrid downscaling approach, a “perfect model”–type experiment, provided 120 years of data under the CMIP5 high-emission scenario. Ample calibration samples made rigorous testing possible, enabling us to evaluate the effect of empirical–statistical model configurations and predictor choices and to assess the stationarity of the statistical models by investigating their sensitivity to different calibration intervals. The skill of the statistical models was evaluated in terms of their ability to reproduce the interannual correlation and long-term trends in seasonal 2-m temperature T2m, wet-day frequency fw, and wet-day mean precipitation μ. We found that different 30-yr calibration intervals often resulted in differing statistical models, depending on the specific choice of years. The hybrid downscaling approach allowed us to emulate seasonal mean regional climate model output with a high spatial resolution (0.05° latitude and 0.1° longitude grid) for up to 100 GCM runs while circumventing the issue of short calibration time, and it provides a robust set of empirically downscaled GCM runs.

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Impacts of SST Anomalies in the Agulhas Current System on the Regional Climate Variability

Journal of Climate ◽

10.1175/jcli-d-11-00088.1 ◽

2012 ◽

Vol 25 (4) ◽

pp. 1213-1229 ◽

Cited By ~ 16

Author(s):

Mototaka Nakamura

Keyword(s):

Surface Temperature ◽

Sea Surface Temperature ◽

Large Scale ◽

Current System ◽

Regional Climate ◽

Sea Surface ◽

Near Surface ◽

Agulhas Current ◽

Sea Surface Temperature Anomalies ◽

Potential Impact

Abstract The potential impact of the variability in the Agulhas Current system on the large-scale atmospheric state in the Southern Hemisphere is examined, using the monthly near-surface baroclinicity as the key parameter, for the period between September 1980 and August 2002. Dominant patterns of anomalous near-surface baroclinicity found from empirical orthogonal function (EOF) analyses in the region that includes most of the Agulhas Current system show a wide variety of anomaly patterns: some of which indicate spatial shifts in the position of the Agulhas Retroflection and/or Agulhas Return Current. Composited anomalies in various atmospheric fields, sea surface temperature, and the net surface heat flux at the air–sea boundary based on the signals in the EOFs suggest that sea surface temperature anomalies in the Agulhas Current system thermally force the atmosphere on the synoptic scale via modification of the near-surface baroclinicity in March and April and possibly in January and February as well.

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Impact of Indian Ocean sea-surface temperature anomaly on Indian summer monsoon precipitation using a regional climate model

International Journal of Climatology ◽

10.1002/joc.1485 ◽

2007 ◽

Vol 27 (11) ◽

pp. 1455-1465 ◽

Cited By ~ 28

Author(s):

G. P. Singh ◽

Jai-Ho Oh

Keyword(s):

Indian Ocean ◽

Surface Temperature ◽

Regional Climate Model ◽

Indian Summer Monsoon ◽

Climate Model ◽

Temperature Anomaly ◽

Regional Climate ◽

Sea Surface ◽

Monsoon Precipitation ◽

Sea Surface Temperature Anomaly

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A Comparison between One-Step and Two-Step Nesting Strategy in the Dynamical Downscaling of Regional Climate Model COSMO-CLM at 2.2 km Driven by ERA5 Reanalysis

Atmosphere ◽

10.3390/atmos12020260 ◽

2021 ◽

Vol 12 (2) ◽

pp. 260

Author(s):

Mario Raffa ◽

Alfredo Reder ◽

Marianna Adinolfi ◽

Paola Mercogliano

Keyword(s):

Regional Climate Model ◽

Climate Model ◽

Dynamical Downscaling ◽

Spatial Scales ◽

Regional Climate ◽

Weather Forecast ◽

Medium Range Weather Forecast ◽

Spatial And Temporal Scales ◽

Starting Point ◽

One Step

Recently, the European Centre for Medium Range Weather Forecast (ECMWF) has released a new generation of reanalysis, acknowledged as ERA5, representing at the present the most plausible picture for the current climate. Although ERA5 enhancements, in some cases, its coarse spatial resolution (~31 km) could still discourage a direct use of precipitation fields. Such a gap could be faced dynamically downscaling ERA5 at convection permitting scale (resolution < 4 km). On this regard, the selection of the most appropriate nesting strategy (direct one-step against nested two-step) represents a pivotal issue for saving time and computational resources. Two questions may be raised within this context: (i) may the dynamical downscaling of ERA5 accurately represents past precipitation patterns? and (ii) at what extent may the direct nesting strategy performances be adequately for this scope? This work addresses these questions evaluating two ERA5-driven experiments at ~2.2 km grid spacing over part of the central Europe, run using the regional climate model COSMO-CLM with different nesting strategies, for the period 2007–2011. Precipitation data are analysed at different temporal and spatial scales with respect to gridded observational datasets (i.e., E-OBS and RADKLIM-RW) and existing reanalysis products (i.e., ERA5-Land and UERRA). The present work demonstrates that the one-step experiment tendentially outperforms the two-step one when there is no spectral nudging, providing results at different spatial and temporal scales in line with the other existing reanalysis products. However, the results can be highly model and event dependent as some different aspects might need to be considered (i.e., the nesting strategies) during the configuration phase of the climate experiments. For this reason, a clear and consolidated recommendation on this topic cannot be stated. Such a level of confidence could be achieved in future works by increasing the number of cities and events analysed. Nevertheless, these promising results represent a starting point for the optimal experimental configuration assessment, in the frame of future climate studies.

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