North American Climate in CMIP5 Experiments. Part I: Evaluation of Historical Simulations of Continental and Regional Climatology

This is the first part of a three-part paper on North American climate in phase 5 of the Coupled Model Intercomparison Project (CMIP5) that evaluates the historical simulations of continental and regional climatology with a focus on a core set of 17 models. The authors evaluate the models for a set of basic surface climate and hydrological variables and their extremes for the continent. This is supplemented by evaluations for selected regional climate processes relevant to North American climate, including cool season western Atlantic cyclones, the North American monsoon, the U.S. Great Plains low-level jet, and Arctic sea ice. In general, the multimodel ensemble mean represents the observed spatial patterns of basic climate and hydrological variables but with large variability across models and regions in the magnitude and sign of errors. No single model stands out as being particularly better or worse across all analyses, although some models consistently outperform the others for certain variables across most regions and seasons and higher-resolution models tend to perform better for regional processes. The CMIP5 multimodel ensemble shows a slight improvement relative to CMIP3 models in representing basic climate variables, in terms of the mean and spread, although performance has decreased for some models. Improvements in CMIP5 model performance are noticeable for some regional climate processes analyzed, such as the timing of the North American monsoon. The results of this paper have implications for the robustness of future projections of climate and its associated impacts, which are examined in the third part of the paper.

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Toward Assessing NARCCAP Regional Climate Model Credibility for the North American Monsoon: Future Climate Simulations*

Journal of Climate ◽

10.1175/jcli-d-14-00695.1 ◽

2015 ◽

Vol 28 (17) ◽

pp. 6707-6728 ◽

Cited By ~ 16

Author(s):

Melissa S. Bukovsky ◽

Carlos M. Carrillo ◽

David J. Gochis ◽

Dorit M. Hammerling ◽

Rachel R. McCrary ◽

...

Keyword(s):

Climate Change ◽

North American ◽

Southern Oscillation ◽

Monsoon Season ◽

Regional Climate ◽

Global Climate Models ◽

North American Monsoon ◽

The North ◽

Climate Simulations ◽

Projected Changes

Abstract This study presents climate change results from the North American Regional Climate Change Assessment Program (NARCCAP) suite of dynamically downscaled simulations for the North American monsoon system in the southwestern United States and northwestern Mexico. The focus is on changes in precipitation and the processes driving the projected changes from the regional climate simulations and their driving coupled atmosphere–ocean global climate models. The effect of known biases on the projections is also examined. Overall, there is strong ensemble agreement for a large decrease in precipitation during the monsoon season; however, this agreement and the magnitude of the ensemble-mean change is likely deceiving, as the greatest decreases are produced by the simulations that are the most biased in the baseline/current climate. Furthermore, some of the greatest decreases in precipitation are being driven by changes in processes/phenomena that are less credible (e.g., changes in El Niño–Southern Oscillation, when it is initially not simulated well). In other simulations, the processes driving the precipitation change may be plausible, but other biases (e.g., biases in low-level moisture or precipitation intensity) appear to be affecting the magnitude of the projected changes. The most and least credible simulations are clearly identified, while the other simulations are mixed in their abilities to produce projections of value.

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Long-Term Changes in the Climatology of Transient Inverted Troughs over the North American Monsoon Region and Their Effects on Precipitation

Journal of Climate ◽

10.1175/jcli-d-15-0726.1 ◽

2016 ◽

Vol 29 (17) ◽

pp. 6037-6064 ◽

Cited By ~ 18

Author(s):

Timothy M. Lahmers ◽

Christopher L. Castro ◽

David K. Adams ◽

Yolande L. Serra ◽

John J. Brost ◽

...

Keyword(s):

North American ◽

Climate Model ◽

Regional Climate ◽

Track Density ◽

North American Monsoon ◽

Northwest Mexico ◽

The North ◽

Simulated Precipitation ◽

Precipitation Estimates ◽

Resolution Model

Abstract Transient inverted troughs (IVs) are a trigger for severe weather during the North American monsoon (NAM) in the southwest contiguous United States (CONUS) and northwest Mexico. These upper-tropospheric disturbances enhance the synoptic-scale and mesoscale environment for organized convection, increasing the chances for microbursts, straight-line winds, blowing dust, and flash flooding. This work considers changes in the track density climatology of IVs between 1951 and 2010. IVs are tracked as potential vorticity (PV) anomalies on the 250-hPa surface from a regional climate model that dynamically downscales the NCEP–NCAR Reanalysis 1. Late in the NAM season, a significant increase in IV track density over the 60-yr period is observed over Southern California and western Arizona, coupled with a slight decrease over northwest Mexico. Changes in precipitation are evaluated on days when an IV is observed and days without an IV, using high-resolution model-simulated precipitation estimates and CPC gridded precipitation observations. Because of changes in the spatial distribution of IVs during the 1951–2010 analysis period, which are associated with a strengthening of the monsoon ridge, it is suggested that IVs have played a lesser role in the initiation and organization of monsoon convection in the southwest CONUS during recent warm seasons.

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Towards Assessing NARCCAP Regional Climate Model Credibility for the North American Monsoon: Current Climate Simulations*

Journal of Climate ◽

10.1175/jcli-d-12-00538.1 ◽

2013 ◽

Vol 26 (22) ◽

pp. 8802-8826 ◽

Cited By ~ 49

Author(s):

Melissa S. Bukovsky ◽

David J. Gochis ◽

Linda O. Mearns

Keyword(s):

North American ◽

Climate Models ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Regional Climate ◽

North American Monsoon ◽

The North ◽

Current Climate ◽

Depth Analysis

Abstract The authors examine 17 dynamically downscaled simulations produced as part of the North American Regional Climate Change Assessment Program (NARCCAP) for their skill in reproducing the North American monsoon system. The focus is on precipitation and the drivers behind the precipitation biases seen in the simulations of the current climate. Thus, a process-based approach to the question of model fidelity is taken in order to help assess confidence in this suite of simulations. The results show that the regional climate models (RCMs) forced with a reanalysis product and atmosphere-only global climate model (AGCM) time-slice simulations perform reasonably well over the core Mexican and southwest United States regions. Some of the dynamically downscaled simulations do, however, have strong dry biases in Arizona that are related to their inability to develop credible monsoon flow structure over the Gulf of California. When forced with different atmosphere–ocean coupled global climate models (AOGCMs) for the current period, the skill of the RCMs subdivides largely by the skill of the forcing or “parent” AOGCM. How the inherited biases affect the RCM simulations is investigated. While it is clear that the AOGCMs have a large influence on the RCMs, the authors also demonstrate where the regional models add value to the simulations and discuss the differential credibility of the six RCMs (17 total simulations), two AGCM time slices, and four AOGCMs examined herein. It is found that in-depth analysis of parent GCM and RCM scenarios can identify a meaningful subset of models that can produce credible simulations of the North American monsoon precipitation.

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Bias correction of the CCSM4 for improved regional climate modeling of the North American monsoon

Climate Dynamics ◽

10.1007/s00382-015-2744-5 ◽

2015 ◽

Vol 46 (9-10) ◽

pp. 2961-2976 ◽

Cited By ~ 8

Author(s):

Jonathan D. D. Meyer ◽

Jiming Jin

Keyword(s):

North American ◽

Bias Correction ◽

Climate Modeling ◽

Regional Climate ◽

Regional Climate Modeling ◽

North American Monsoon ◽

The North

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Skill of Seasonal Arctic Sea Ice Extent Predictions Using the North American Multimodel Ensemble

Journal of Climate ◽

10.1175/jcli-d-17-0766.1 ◽

2019 ◽

Vol 32 (2) ◽

pp. 623-638 ◽

Cited By ~ 1

Author(s):

K. J. Harnos ◽

M. L’Heureux ◽

Q. Ding ◽

Q. Zhang

Keyword(s):

Sea Ice ◽

North American ◽

Arctic Sea Ice ◽

Multiple Model ◽

Multimodel Ensemble ◽

Sea Ice Extent ◽

The North ◽

Arctic Sea ◽

North American Multimodel Ensemble ◽

Arctic Sea Ice Extent

AbstractPrevious studies have outlined benefits of using multiple model platforms to make seasonal climate predictions. Here, reforecasts from five models included in the North American Multimodel Ensemble (NMME) project are utilized to determine skill in predicting Arctic sea ice extent (SIE) during 1982–2010. Overall, relative to the individual models, the multimodel average results in generally smaller biases and better correlations for predictions of total SIE and year-to-year (Y2Y), linearly, and quadratically detrended variability. Also notable is the increase in error for NMME predictions of total September SIE during the mid-1990s through 2000s. After 2000, observed September SIE is characterized by more significant negative trends and increased Y2Y variance, which suggests that recent sea ice loss is resulting in larger prediction errors. While this tendency is concerning, due to the possibility of models not accurately representing the changing trends in sea ice, the multimodel approach still shows promise in providing more skillful predictions of Arctic SIE over any individual model.

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Review for "Geochemistry of last glacial lacustrine sediments in core region of the North American Monsoon, northwest Mexico: Source of biomass, hydrological balance and chemical weathering"

10.1002/gj.3827/v1/review1 ◽

2020 ◽

Author(s):

NURIA VALLE

Keyword(s):

North American ◽

Chemical Weathering ◽

Lacustrine Sediments ◽

Core Region ◽

North American Monsoon ◽

Hydrological Balance ◽

Last Glacial ◽

Northwest Mexico ◽

The North

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Decision letter for "Geochemistry of last glacial lacustrine sediments in core region of the North American Monsoon, northwest Mexico: Source of biomass, hydrological balance and chemical weathering"

10.1002/gj.3827/v1/decision1 ◽

2020 ◽

Keyword(s):

North American ◽

Chemical Weathering ◽

Lacustrine Sediments ◽

Core Region ◽

North American Monsoon ◽

Hydrological Balance ◽

Last Glacial ◽

Northwest Mexico ◽

The North

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Spurious Grid-Scale Precipitation in the North American Regional Reanalysis

Monthly Weather Review ◽

10.1175/mwr3375.1 ◽

2007 ◽

Vol 135 (6) ◽

pp. 2168-2184 ◽

Cited By ~ 33

Author(s):

Gregory L. West ◽

W. James Steenburgh ◽

William Y. Y. Cheng

Keyword(s):

North American ◽

Prediction Models ◽

Weather Prediction ◽

Regional Climate ◽

Potential Temperature ◽

Climate Data ◽

The North ◽

North American Regional Reanalysis ◽

Upper Level ◽

Regional Reanalysis

Abstract Spurious grid-scale precipitation (SGSP) occurs in many mesoscale numerical weather prediction models when the simulated atmosphere becomes convectively unstable and the convective parameterization fails to relieve the instability. Case studies presented in this paper illustrate that SGSP events are also found in the North American Regional Reanalysis (NARR) and are accompanied by excessive maxima in grid-scale precipitation, vertical velocity, moisture variables (e.g., relative humidity and precipitable water), mid- and upper-level equivalent potential temperature, and mid- and upper-level absolute vorticity. SGSP events in environments favorable for high-based convection can also feature low-level cold pools and sea level pressure maxima. Prior to 2003, retrospectively generated NARR analyses feature an average of approximately 370 SGSP events annually. Beginning in 2003, however, NARR analyses are generated in near–real time by the Regional Climate Data Assimilation System (R-CDAS), which is identical to the retrospective NARR analysis system except for the input precipitation and ice cover datasets. Analyses produced by the R-CDAS feature a substantially larger number of SGSP events with more than 4000 occurring in the original 2003 analyses. An oceanic precipitation data processing error, which resulted in a reprocessing of NARR analyses from 2003 to 2005, only partially explains this increase since the reprocessed analyses still produce approximately 2000 SGSP events annually. These results suggest that many NARR SGSP events are not produced by shortcomings in the underlying Eta Model, but by the specification of anomalous latent heating when there is a strong mismatch between modeled and assimilated precipitation. NARR users should ensure that they are using the reprocessed NARR analyses from 2003 to 2005 and consider the possible influence of SGSP on their findings, particularly after the transition to the R-CDAS.

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