Examining Interior Grid Nudging Techniques Using Two-Way Nesting in the WRF Model for Regional Climate Modeling

Abstract This study evaluates interior nudging techniques using the Weather Research and Forecasting (WRF) model for regional climate modeling over the conterminous United States (CONUS) using a two-way nested configuration. NCEP–Department of Energy Atmospheric Model Intercomparison Project (AMIP-II) Reanalysis (R-2) data are downscaled to 36 km × 36 km by nudging only at the lateral boundaries, using gridpoint (i.e., analysis) nudging and using spectral nudging. Seven annual simulations are conducted and evaluated for 1988 by comparing 2-m temperature, precipitation, 500-hPa geopotential height, and 850-hPa meridional wind to the 32-km North American Regional Reanalysis (NARR). Using interior nudging reduces the mean biases for those fields throughout the CONUS compared to the simulation without interior nudging. The predictions of 2-m temperature and fields aloft behave similarly when either analysis or spectral nudging is used. For precipitation, however, analysis nudging generates monthly precipitation totals, and intensity and frequency of precipitation that are closer to observed fields than spectral nudging. The spectrum of 250-hPa zonal winds simulated by the WRF model is also compared to that of the R-2 and NARR. The spatial variability in the WRF model is reduced by using either form of interior nudging, and analysis nudging suppresses that variability more strongly than spectral nudging. Reducing the nudging strengths on the inner domain increases the variability but generates larger biases. The results support the use of interior nudging on both domains of a two-way nest to reduce error when the inner nest is not otherwise dominated by the lateral boundary forcing. Nevertheless, additional research is required to optimize the balance between accuracy and variability in choosing a nudging strategy.

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Impact of Soil Moisture Initialization on Temperature Extreme Detection in the context of Regional Climate Modeling

10.5194/egusphere-egu2020-17121 ◽

2020 ◽

Author(s):

Matilde García-Valdecasas Ojeda ◽

Juan José Rosa-Cánovas ◽

Emilio Romero-Jiménez ◽

Patricio Yeste ◽

Sonia R. Gámiz-Fortis ◽

...

Keyword(s):

Soil Moisture ◽

Initial Conditions ◽

Climate Modeling ◽

Regional Climate ◽

Wrf Model ◽

Regional Climate Modeling ◽

Weather Research And Forecasting ◽

Temperature Extremes ◽

Temperature Extreme ◽

The Impact

Land surface-related processes play an essential role in the climate conditions at a regional scale. In this study, the impact of soil moisture (SM) initialization on regional climate modeling has been explored by using a dynamical downscaling experiment. To this end, the Weather Research and Forecasting (WRF) model was used to generate a set of high-resolution climate simulations driven by the ERA-Interim reanalysis for a period from 1989 to 2009. As the spatial configuration, two one-way nested domains were used, with the finer domain being centered over the Iberian Peninsula (IP) at a spatial resolution of about 10 km, and nested over a coarser domain that covers the Euro-CORDEX region at 50 km of spatial resolution.The sensitivity experiment consisted of two control runs (CTRL) performed using as SM initial conditions those provided by ERA-Interim, and initialized for two different dates times (January and June). Additionally, another set of runs was completed driven by the same climate data but using as initial conditions prescribed SM under wet and dry scenarios.The study is based on assessing the WRF performance by comparing the CTRL simulations with those performed with the different prescribed SM, and also, comparing them with the observations from the Spanish Temperature At Daily scale (STEAD) dataset. In this sense, we used two temperature extreme indices within the framework of decadal predictions: the warm spell index (WSDI) and the daily temperature range (DTR).These results provide valuable information about the impact of the SM initial conditions on the ability of the WRF model to detect temperature extremes, and how long these affect the regional climate in this region. Additionally, these results may provide a source of knowledge about the mechanisms involved in the occurrence of extreme events such as heatwaves, which are expected to increase in frequency, duration, and magnitude under the context of climate change.Keywords: soil moisture initial conditions, temperature extremes, regional climate, Weather Research and Forecasting modelAcknowledgments: This work has been financed by the project CGL2017-89836-R (MINECO-Spain, FEDER). The WRF simulations were performed in the Picasso Supercomputer at the University of M&#225;laga, a member of the Spanish Supercomputing Network.

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Modeling the Influence of Upstream Land-atmosphere Coupling on the 2017 Persistent Drought over Northeast China

Journal of Climate ◽

10.1175/jcli-d-20-0650.1 ◽

2021 ◽

pp. 1-62

Author(s):

Dingwen Zeng ◽

Xing Yuan

Keyword(s):

Land Surface ◽

Northeast China ◽

Large Scale ◽

Climate Modeling ◽

Regional Climate ◽

Critical Role ◽

Wrf Model ◽

Regional Climate Modeling ◽

Anticyclonic Circulation ◽

Persistent Drought

AbstractPersistent drought events that cause serious damages to economy and environment are usually intensified by the feedback between land surface and atmosphere. Therefore, reasonably modeling land-atmosphere coupling is critical for skillful prediction of persistent droughts. However, most high-resolution regional climate modeling focused on the amplification effect of land-atmosphere coupling on local anticyclonic circulation anomaly, while less attention was paid to the non-local influence through altering large-scale atmospheric circulation. Here we investigate how the antecedent land-atmosphere coupling over the area south to Lake Baikal (ASLB) influences the drought events occurred over its downstream region (Northeast China; NEC) by using Weather Research and Forecasting (WRF) model and linear baroclinic model (LBM). When the ASLB is artificially forced to be wet in the WRF simulations during March-May, the surface sensible heating is weakened and results in a cooling anomaly in low level atmosphere during May-July. Consequently, the anticyclonic circulation anomalies over ASLB and NEC are weakened, and the severity of NEC drought during May-July cannot be captured due to the upstream wetting in March-May. In the LBM experiments, idealized atmospheric heating anomaly that mimics the diabatic heating associated with surface wetness is imposed over ASLB, and the quasi-steady response pattern of 500-hPa geopotential height to the upstream wetting is highly consistent with that in the WRF simulation. In addition, the lower level heating instead of the upper level cooling makes a major contribution to the high pressure anomaly over NEC. This study implies the critical role of modeling upstream land-atmosphere coupling in capturing downstream persistent droughts.

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Atmospheric Moisture Pathways to the Highlands of the Tropical Andes: Analyzing the Effects of Spectral Nudging on Different Driving Fields for Regional Climate Modeling

Atmosphere ◽

10.3390/atmos9110456 ◽

2018 ◽

Vol 9 (11) ◽

pp. 456 ◽

Cited By ~ 3

Author(s):

Katja Trachte

Keyword(s):

Climate Modeling ◽

Regional Climate ◽

Regional Climate Modeling ◽

Andes Mountains ◽

Back Trajectory ◽

Atmospheric Moisture ◽

Tropical Andes ◽

Air Masses ◽

Spectral Nudging ◽

The Andes

Atmospheric moisture pathways to the highlands of the tropical Andes Mountains were investigated using the Weather Research and Forecasting (WRF) model, as well as back-trajectory analysis. To assess model uncertainties according to the initial and lateral boundary conditions (ILBCs), the effects of spectral nudging and different driving fields on regional climate modeling were tested. Based on the spatio-temporal patterns of the large-scale atmospheric features over South America, the results demonstrated that spectral nudging compared to traditional long-term integration generally produced greater consistency with the reference data (ERA5). These WRF simulations further revealed that the location of the inter-tropical convergence zone (ITCZ), as well as the precipitation over the Andes Mountains were better reproduced. To investigate the air mass pathways, the most accurate WRF simulation was used as atmospheric conditions for the back-trajectory calculations. Three subregions along the tropical Andean chain were considered. Based on mean cluster trajectories and the water vapor mixing ratio along the pathways, the contributions of eastern and western water sources were analyzed. In particular, the southernmost subregion illustrated a clear frequency of occurrences of Pacific trajectories mostly during September–November (40%) when the ITCZ is shifted to the Northern Hemisphere and the Bolivian high pressure system is weakened. In the northernmost subregion, Pacific air masses as well reached the Andes highlands with rather low frequencies regardless of the season (2–12%), but with a moisture contribution comparable to the eastern trajectories. Cross-sections of the equivalent-potential temperature as an indicator of the moisture and energy content of the atmosphere revealed a downward mixing of the moisture aloft, which was stronger in the southern subregion. Additionally, low-level onshore breezes, which developed in both subregions, indicated the transport of warm-moist marine air masses to the highlands, highlighting the importance of the representation of the terrain and, thus, the application of dynamical downscaling using regional climate models.

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Changes in Hurricanes from a 13-Yr Convection-Permitting Pseudo–Global Warming Simulation

Journal of Climate ◽

10.1175/jcli-d-17-0391.1 ◽

2018 ◽

Vol 31 (9) ◽

pp. 3643-3657 ◽

Cited By ~ 32

Author(s):

Ethan D. Gutmann ◽

Roy M. Rasmussen ◽

Changhai Liu ◽

Kyoko Ikeda ◽

Cindy L. Bruyere ◽

...

Keyword(s):

Tropical Cyclones ◽

Climate Modeling ◽

Global Climate ◽

Regional Climate ◽

Good Reason ◽

Wrf Model ◽

Coupled Model ◽

Regional Climate Modeling ◽

Climate Signal ◽

Wind Speeds

Abstract Tropical cyclones have enormous costs to society through both loss of life and damage to infrastructure. There is good reason to believe that such storms will change in the future as a result of changes in the global climate system and that such changes may have important socioeconomic implications. Here a high-resolution regional climate modeling experiment is presented using the Weather Research and Forecasting (WRF) Model to investigate possible changes in tropical cyclones. These simulations were performed for the period 2001–13 using the ERA-Interim product for the boundary conditions, thus enabling a direct comparison between modeled and observed cyclone characteristics. The WRF simulation reproduced 30 of the 32 named storms that entered the model domain during this period. The model simulates the tropical cyclone tracks, storm radii, and translation speeds well, but the maximum wind speeds simulated were less than observed and the minimum central pressures were too large. This experiment is then repeated after imposing a future climate signal by adding changes in temperature, humidity, pressure, and wind speeds derived from phase 5 of the Coupled Model Intercomparison Project (CMIP5). In the current climate, 22 tracks were well simulated with little changes in future track locations. These simulations produced tropical cyclones with faster maximum winds, slower storm translation speeds, lower central pressures, and higher precipitation rates. Importantly, while these signals were statistically significant averaged across all 22 storms studied, changes varied substantially between individual storms. This illustrates the importance of using a large ensemble of storms to understand mean changes.

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Urban Climates and Climate Change

Annual Review of Environment and Resources ◽

10.1146/annurev-environ-012320-083623 ◽

2020 ◽

Vol 45 (1) ◽

pp. 411-444 ◽

Cited By ~ 1

Author(s):

Valéry Masson ◽

Aude Lemonsu ◽

Julia Hidalgo ◽

James Voogt

Keyword(s):

Climate Change ◽

Climate Modeling ◽

Regional Climate ◽

Urban Climate ◽

Regional Climate Modeling ◽

Climate Impact ◽

Local Climate ◽

Urban Climatology ◽

Recent Developments ◽

Global Agenda

Cities are particularly vulnerable to extreme weather episodes, which are expected to increase with climate change. Cities also influence their own local climate, for example, through the relative warming known as the urban heat island (UHI) effect. This review discusses urban climate features (even in complex terrain) and processes. We then present state-of-the-art methodologies on the generalization of a common urban neighborhood classification for UHI studies, as well as recent developments in observation systems and crowdsourcing approaches. We discuss new modeling paradigms pertinent to climate impact studies, with a focus on building energetics and urban vegetation. In combination with regional climate modeling, new methods benefit the variety of climate scenarios and models to provide pertinent information at urban scale. Finally, this article presents how recent research in urban climatology contributes to the global agenda on cities and climate change.

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Impacts of anthropogenic heat and building height on urban precipitation over the Seoul Meteropolitan area in regional climate modeling

Journal of Geophysical Research Atmospheres ◽

10.1029/2021jd035348 ◽

2021 ◽

Author(s):

Gayoung Kim ◽

Dong‐Hyun Cha ◽

Chang‐Keun Song ◽

Hyungjun Kim

Keyword(s):

Climate Modeling ◽

Regional Climate ◽

Regional Climate Modeling ◽

Anthropogenic Heat ◽

Building Height

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The influence of convection-permitting regional climate modeling on future projections of extreme precipitation: dependency on topography and timescale

Climate Dynamics ◽

10.1007/s00382-018-4454-2 ◽

2018 ◽

Vol 52 (9-10) ◽

pp. 5303-5324 ◽

Cited By ~ 9

Author(s):

Sam Vanden Broucke ◽

Hendrik Wouters ◽

Matthias Demuzere ◽

Nicole P. M. van Lipzig

Keyword(s):

Extreme Precipitation ◽

Climate Modeling ◽

Regional Climate ◽

Regional Climate Modeling ◽

Future Projections

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Synoptic-Scale Variability and Its Relationship with Total Ozone and Antarctic Vortex Displacements

Monthly Weather Review ◽

10.1175/mwr2977.1 ◽

2005 ◽

Vol 133 (8) ◽

pp. 2374-2386 ◽

Cited By ~ 4

Author(s):

Paula K. Vigliarolo ◽

Carolina S. Vera ◽

Susana B. Díaz

Keyword(s):

South America ◽

Total Ozone ◽

Lower Stratosphere ◽

Meteorological Data ◽

Atmospheric Model ◽

Meridional Wind ◽

Department Of Energy ◽

Synoptic Scale ◽

Austral Spring ◽

Anomaly Pattern

Abstract The main synoptic-scale circulation anomaly pattern over extratropical South America during the austral spring (September–November) is identified by means of rotated extended empirical orthogonal function techniques, applied to the meridional wind perturbation time series at 300 hPa. The dataset is based on 15 spring seasons (1979–93) of meteorological data from the National Centers for Environmental Prediction–Department of Energy Atmospheric Model Intercomparison Project version-2 daily averaged reanalyses, given in 17 vertical levels from 1000 to 10 hPa. The total-ozone daily measurements for the same period are from the Total Ozone Mapping Spectrometer instrument (version 7). The principal synoptic-scale anomaly pattern is associated with an anticyclone–cyclone pair evolving eastward along subpolar latitudes (and hence it is termed the subpolar mode), with a typical length scale of 5000 km and a phase velocity of 8 m s−1. The subpolar-mode waves, which display the main characteristics of midlatitude baroclinic waves, typically maximize near or above the tropopause and propagate upward into the lower stratosphere, showing large amplitudes even at 50 hPa and above. Subpolar-mode-related circulation anomalies are found to be responsible for large total-ozone daily fluctuations near southern South America and nearby regions. In the positive phase of the subpolar mode, total-ozone fluctuations, which are negative, adopt a sigmoid structure, with a zonal scale as large as the anticyclone–cyclone pair. Moreover, it is herein shown that the associated anticyclone produces a local ozone-column decrease to the north and east of its center, due to adiabatic uplift of air parcels in the upper troposphere and lower stratosphere. At the same time, the downstream cyclonic disturbance is responsible for large negative total-ozone anomalies to the west and south of its center. As the cyclone develops in the lower stratosphere, it promotes the northward incursion of the Antarctic vortex up to about 55°S, along with air masses of highly depleted ozone levels.

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The state of the art and fundamental aspects of regional climate modeling in South America

Annals of the New York Academy of Sciences ◽

10.1111/nyas.13932 ◽

2018 ◽

Vol 1436 (1) ◽

pp. 98-120 ◽

Cited By ~ 15

Author(s):

Tércio Ambrizzi ◽

Michelle Simões Reboita ◽

Rosmeri Porfírio da Rocha ◽

Marta Llopart

Keyword(s):

South America ◽

State Of The Art ◽

Climate Modeling ◽

Regional Climate ◽

Regional Climate Modeling ◽

The State

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Generating long-term high-resolution land-use change datasets for regional climate modeling in CORDEX domains

10.5194/egusphere-egu21-14967 ◽

2021 ◽

Author(s):

Peter Hoffmann ◽

Diana Rechid ◽

Vanessa Reinhart ◽

Christina Asmus ◽

Edouard L. Davin ◽

...

Keyword(s):

Land Use ◽

High Resolution ◽

Land Use Change ◽

Land Cover ◽

Climate Modeling ◽

Regional Climate ◽

Regional Climate Modeling ◽

Local Scale ◽

Modeling Studies

Land-use and land cover (LULC) are continuously changing due to environmental changes and anthropogenic activities. Many observational and modeling studies show that LULC changes are important drivers altering land surface feedbacks and land-atmosphere exchange processes that have substantial impact on climate on the regional and local scale. Yet, most long-term regional climate modeling studies do not account for these changes. Therefore, within the WCRP CORDEX Flagship Pilot Study LUCAS (Land Use Change Across Scales) a new workflow was developed to generate high-resolution annual land cover change time series based on past reconstructions and future projections. First, the high-resolution global land cover dataset ESA-CCI LC (~300 m resolution) is aggregated and converted to a 0.1&#176; resolution, fractional plant functional type (PFT) dataset. Second, the land use change information from the land-use harmonized dataset (LUH2), provided at 0.25&#176; resolution as input for CMIP6 experiments, is translated into PFT changes employing a newly developed land use translator (LUT). The new LUT was first applied to the EURO-CORDEX domain. The resulting LULC maps for past and future - the LUCAS LUC dataset - can be applied as land use forcing to the next generation RCM simulations for downscaling CMIP6 by the EURO-CORDEX community and in the framework of FPS LUCAS. The dataset includes land cover and land management practices changes important for the regional and local scale such as urbanization and irrigation. The LUCAS LUC workflow is applied to further CORDEX domains, such as Australasia and North America. The resulting past and future land cover changes will be presented, and challenges regarding the application of the new workflow to different regions will be addressed. In addition, issues related to the implementation of the dataset into different RCMs will be discussed.

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