scholarly journals High-Resolution Climate Simulations Using GFDL HiRAM with a Stretched Global Grid

2016 ◽  
Vol 29 (11) ◽  
pp. 4293-4314 ◽  
Author(s):  
Lucas M. Harris ◽  
Shian-Jiann Lin ◽  
ChiaYing Tu
Keyword(s):  
High Resolution ◽  
Warm Season ◽  
Warm Pool ◽  
Climate Simulation ◽  
Enhanced Resolution ◽  
Pacific Warm Pool ◽  
Climate Simulations ◽  
Mean Climate ◽  
The Tropics ◽  
The Western Pacific

Abstract An analytic Schmidt transformation is used to create locally refined global model grids capable of efficient climate simulation with gridcell widths as small as 10 km in the GFDL High-Resolution Atmosphere Model (HiRAM). This method of grid stretching produces a grid that varies very gradually into the region of enhanced resolution without changing the topology of the model grid and does not require radical changes to the solver. AMIP integrations were carried out with two grids stretched to 10-km minimum gridcell width: one centered over East Asia and the western Pacific warm pool, and the other over the continental United States. Robust improvements to orographic precipitation, the diurnal cycle of warm-season continental precipitation, and tropical cyclone maximum intensity were found in the region of enhanced resolution, compared to 25-km uniform-resolution HiRAM. The variations in grid size were not found to create apparent grid artifacts, and in some measures the global-mean climate improved in the stretched-grid simulations. In the enhanced-resolution regions, the number of tropical cyclones was reduced, but the fraction of storms reaching hurricane intensity increased, compared to a uniform-resolution simulation. This behavior was also found in a stretched-grid perpetual-September aquaplanet simulation with 12-km resolution over a part of the tropics. Furthermore, the stretched-grid aquaplanet simulation was also largely free of grid artifacts except for an artificial Walker-type circulation, and simulated an ITCZ in its unrefined region more resembling that of higher-resolution aquaplanet simulations, implying that the unrefined region may also be improved in stretched-grid simulations. The improvements due to stretching are attributable to improved resolution as these stretched-grid simulations were sparingly tuned.

scholarly journals High-Resolution Climate Simulations in the Tropics with Complex Terrain Employing the CESM/WRF Model

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Tomi Afrizal ◽  
Chinnawat Surussavadee
Keyword(s):  
High Resolution ◽  
Complex Terrain ◽  
Global Climate ◽  
Global Climate Model ◽  
Simulation System ◽  
Climate Simulation ◽  
Climate Projections ◽  
Temperature And Precipitation ◽  
Climate Simulations ◽  
The Tropics

This study evaluates the high-resolution climate simulation system CESM/WRF composed of the global climate model, Community Earth System Model (CESM) version 1, and the mesoscale model, Weather Research and Forecasting Model (WRF), for simulating high-resolution climatological temperature and precipitation in the tropics with complex terrain where temperature and precipitation are strongly inhomogeneous. The CESM/WRF climatological annual and seasonal precipitation and temperature simulations for years 1980–1999 at 10 km resolution for Sumatra and nearby regions are evaluated using observations and the global climate reanalysis ERA-Interim (ERA). CESM/WRF simulations at 10 km resolution are also compared with the downscaled reanalysis ERA/WRF at 10 km resolution. Results show that while temperature and precipitation patterns of the original CESM are very different from observations, those for CESM/WRF agree well with observations. Resolution and accuracies of simulations are significantly improved by dynamically downscaling CESM using WRF. CESM/WRF can simulate locations of very cold temperature at mountain peaks well. The high-resolution climate simulation system CESM/WRF can provide useful climate simulations at high resolution for Sumatra and nearby regions. CESM/WRF-simulated climatological temperature and precipitation at 10 km resolution agree well with ERA/WRF. This suggests the use of CESM/WRF for climate projections at high resolution for Sumatra and nearby regions.

scholarly journals Response of Climate Simulation to a New Convective Parameterization in the National Center for Atmospheric Research Community Climate Model (CCM3)*

1998 ◽  
Vol 11 (8) ◽  
pp. 2097-2115 ◽  
Author(s):  
Guang J. Zhang ◽  
Jeffrey T. Kiehl ◽  
Philip J. Rasch
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Warm Pool ◽  
Climate Simulation ◽  
Quasi Equilibrium ◽  
Atmospheric Research ◽  
Surface Evaporation ◽  
Pacific Warm Pool ◽  
Convection Schemes ◽  
The Western Pacific

Abstract This study examines the response of the climate simulation by the National Center for Atmospheric Research Community Climate Model (CCM3) to the introduction of the Zhang and McFarlane convective parameterization in the model. It is shown that in the CCM3 the simulated surface climate in the tropical convective regimes, especially in the western Pacific warm pool, is markedly improved, yielding a much better agreement with the recent observations. The systematic bias in the surface evaporation, surface wind stress over the tropical Pacific Ocean in previous model simulations is significantly reduced, owing to the better simulation of the surface flow. Experiments using identical initial and boundary conditions, but different convection schemes, are performed to isolate the role of the convection schemes and to understand the interaction between convection and the large-scale circulation in a convecting atmosphere. The comparison of the results from these experiments in the western Pacific warm pool suggests that use of the Zhang and McFarlane scheme makes a significant contribution to the improved climate simulation in CCM3. The simulated atmosphere using the Zhang and McFarlane scheme exhibits a quasi-equilibrium between convection and the large-scale processes. When this scheme is removed from the CCM3, such a quasi-equilibrium is no longer observed. In addition, the simulated thermodynamic structures, the surface evaporation, and surface winds in the Pacific warm pool become very similar to those in the CCM2 climate. Examination of the temporal evolution of the various fields demonstrates that the stabilization of the atmosphere using the new convection scheme takes place during the transition from nonequilibrium to quasi equilibrium at the beginning of the time integration. After quasi equilibrium is reached, the atmosphere is warmer and more stable compared to the run without the new scheme. Associated with the more stable stratification, the atmospheric circulation becomes weaker, thus the surface winds and evaporation are weaker because of the coupling between thermodynamics and dynamics in the tropical troposphere.

Sea-Surface Temperature Estimates for the Tropical Western Pacific during the Last Glaciation and Their Implications for the Pacific Warm Pool

1994 ◽  
Vol 41 (3) ◽  
pp. 255-264 ◽  
Author(s):  
Robert Thunell ◽  
David Anderson ◽  
Debrorah Gellar ◽  
Qingmin Miao
Keyword(s):  
Last Glacial Maximum ◽  
Warm Pool ◽  
Glacial Maximum ◽  
Western Pacific ◽  
Last Glacial ◽  
Pacific Warm Pool ◽  
The Tropics ◽  
The Last Glacial Maximum ◽  
The Western Pacific ◽  
The Last Glacial

AbstractTwenty deep-sea sediment cores from the western Pacific between 30°N and 30°S provide evidence of sea-surface temperature (SST) changes throughout the tropics and subtropics. Glacial SSTs were estimated using the modern analog technique (MAT) applied to planktonic foraminifers and planktonic foraminiferal δ18O changes. We used δ18O to identify the last glacial maximum. The MAT method differs from the traditional transfer function approach in that it utilizes a global coretop database, and estimates paleotemperature by finding analogs from the modern coretop samples. In addition, the MAT approach appears to be less susceptible than the transfer function technique to biases introduced by carbonate dissolution. Our results indicate that tropical SSTs differed by less than 2°C from present; away from the tropics (30°N and 30°S) SSTs were at least 3°C cooler. Our results differ from those of previous studies in the western Pacific by using a set of well-preserved, high-sedimentation rate cores from shallow regions. The results of this study clearly indicate that a western Pacific warm pool existed during the last glacial maximum (LGM), providing a heat and moisture source for a Walker Circulation cell similar to that of today. We propose that a steeper lapse rate existed during the last glacial maximum and that this can explain at least part of the discrepancy between marine and terrestrial temperature estimates adjacent to New Guinea for the LGM.

Just aFAD? Ecosystem impacts of tuna purse‐seine fishing associated with fish aggregating devices in the western Pacific Warm Pool Province

2018 ◽  
Vol 28 (1) ◽  
pp. 94-112 ◽  
Author(s):  
Shane P. Griffiths ◽  
Valerie Allain ◽  
Simon D. Hoyle ◽  
Tim A. Lawson ◽  
Simon J. Nicol
Keyword(s):  
Warm Pool ◽  
Western Pacific ◽  
Purse Seine ◽  
Western Pacific Warm Pool ◽  
Ecosystem Impacts ◽  
Pacific Warm Pool ◽  
Fish Aggregating Devices ◽  
The Western Pacific

scholarly journals Model evaluation of high-resolution urban climate simulations: using the WRF/Noah LSM/SLUCM model (Version 3.7.1) as a case study

2019 ◽  
Vol 12 (11) ◽  
pp. 4571-4584 ◽  
Author(s):  
Zhiqiang Li ◽  
Yulun Zhou ◽  
Bingcheng Wan ◽  
Hopun Chung ◽  
Bo Huang ◽  
...  
Keyword(s):  
High Resolution ◽  
Model Evaluation ◽  
Urban Climate ◽  
Simulation Models ◽  
Climate Simulation ◽  
Model Uncertainties ◽  
Temporal Dimension ◽  
Climate Simulations ◽  
Hong Kong Sar

Abstract. The veracity of urban climate simulation models should be systematically evaluated to demonstrate the trustworthiness of these models against possible model uncertainties. However, existing studies paid insufficient attention to model evaluation; most studies only provided some simple comparison lines between modelled variables and their corresponding observed ones on the temporal dimension. Challenges remain since such simple comparisons cannot concretely prove that the simulation of urban climate behaviours is reliable. Studies without systematic model evaluations, being ambiguous or arbitrary to some extent, may lead to some seemingly new but scientifically misleading findings. To tackle these challenges, this article proposes a methodological framework for the model evaluation of high-resolution urban climate simulations and demonstrates its effectiveness with a case study in the area of Shenzhen and Hong Kong SAR, China. It is intended to (again) remind urban climate modellers of the necessity of conducting systematic model evaluations with urban-scale climatology modelling and reduce these ambiguous or arbitrary modelling practices.

scholarly journals Multidecadal Evaluation of WRF Downscaling Capabilities over Western Australia in Simulating Rainfall and Temperature Extremes

2015 ◽  
Vol 54 (2) ◽  
pp. 370-394 ◽  
Author(s):  
Julia Andrys ◽  
Thomas J. Lyons ◽  
Jatin Kala
Keyword(s):  
High Resolution ◽  
Western Australia ◽  
General Circulation ◽  
Regional Climate ◽  
Wrf Model ◽  
Climate Extremes ◽  
Convective Precipitation ◽  
Climate Simulation ◽  
Climate Indices ◽  
Climate Simulations

AbstractThe authors evaluate a 30-yr (1981–2010) Weather Research and Forecast (WRF) Model regional climate simulation over the southwest of Western Australia (SWWA), a region with a Mediterranean climate, using ERA-Interim boundary conditions. The analysis assesses the spatial and temporal characteristics of climate extremes, using a selection of climate indices, with an emphasis on metrics that are relevant for forestry and agricultural applications. Two nested domains at 10- and 5-km resolution are examined, with the higher-resolution simulation resolving convection explicitly. Simulation results are compared with a high-resolution, gridded observational dataset that provides daily rainfall, minimum temperatures, and maximum temperatures. Results show that, at both resolutions, the model is able to simulate the daily, seasonal, and annual variation of temperature and precipitation well, including extreme events. The higher-resolution domain displayed significant performance gains in simulating dry-season convective precipitation, rainfall around complex terrain, and the spatial distribution of frost conditions. The high-resolution domain was, however, influenced by grid-edge effects in the southwestern margin, which reduced the ability of the domain to represent frontal rainfall along the coastal region. On the basis of these results, the authors feel confident in using the WRF Model for regional climate simulations for the SWWA, including studies that focus on the spatial and temporal representation of climate extremes. This study provides a baseline climatological description at a high resolution that can be used for impact studies and will also provide a benchmark for climate simulations driven by general circulation models.

Role of Abnormally Enhanced MJO over the Western Pacific in the Formation and Subseasonal Predictability of the Record-Breaking Northeast Asian Heatwave in the Summer of 2018

2020 ◽  
Vol 33 (8) ◽  
pp. 3333-3349 ◽  
Author(s):  
Pang-Chi Hsu ◽  
Yitian Qian ◽  
Yu Liu ◽  
Hiroyuki Murakami ◽  
Yingxia Gao
Keyword(s):  
Real Time ◽  
Time Scale ◽  
Wave Train ◽  
Northeast Asia ◽  
Warm Pool ◽  
Western Pacific ◽  
Western Pacific Warm Pool ◽  
Pacific Warm Pool ◽  
Northeast Asian ◽  
The Western Pacific

AbstractIn the summer of 2018, Northeast Asia experienced a heatwave event that broke the existing high-temperature records in several locations in Japan, the Korean Peninsula, and northeastern China. At the same time, an unusually strong Madden–Julian oscillation (MJO) was observed to stay over the western Pacific warm pool. Based on reanalysis diagnosis, numerical experiments, and assessments of real-time forecast data from two subseasonal-to-seasonal (S2S) models, we discovered the importance of the western Pacific MJO in the generation of this heatwave event, as well as its predictability at the subseasonal time scale. During the prolonged extreme heat period (11 July–14 August), a high pressure anomaly with variability at the intraseasonal (30–90 days) time scale appeared over Northeast Asia, causing persistent adiabatic heating and clear skies in this region. As shown in the composites of MJO-related convection and circulation anomalies, the occurrence of this 30–90-day high anomaly over Northeast Asia was linked with an anomalous wave train induced by tropical heating associated with the western tropical Pacific MJO. The impact of the MJO on the heatwave was further confirmed by sensitivity experiments with a coupled GCM. As the western Pacific MJO-related components were removed by nudging prognostic variables over the tropics toward their annual cycle and longer time scales (>90 days) in the coupled GCM, the anomalous wave train along the East Asian coast disappeared and the surface air temperature in Northeast Asia lowered. The MJO over the western Pacific warm pool also influenced the predictability of the extratropical heatwave. Our assessments of two S2S models’ real-time forecasts suggest that the extremity of this Northeast Asian heatwave can be better predicted 1–4 weeks in advance if the enhancement of MJO convection over the western Pacific warm pool is predicted well.

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