scholarly journals Atmospheric Horizontal Resolution Affects Tropical Climate Variability in Coupled Models

2008 ◽  
Vol 21 (4) ◽  
pp. 730-750 ◽  
Author(s):  
A. Navarra ◽  
S. Gualdi ◽  
S. Masina ◽  
S. Behera ◽  
J.-J. Luo ◽  
...  
Keyword(s):  
High Resolution ◽  
Interannual Variability ◽  
Spectral Resolution ◽  
Time Scale ◽  
Negative Impact ◽  
Coupled Model ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Coupled Models ◽  
Tropical Ocean

Abstract The effect of atmospheric horizontal resolution on tropical variability is investigated within the modified Scale Interaction Experiment (SINTEX) coupled model, SINTEX-Frontier (SINTEX-F), developed jointly at Istituto Nazionale di Geofisica e Vulcanologia (INGV), L’Institut Pierre-Simon Laplace (IPSL), and the Frontier Research System. The ocean resolution is not changed as the atmospheric model resolution is modified from spectral resolution 30 (T30) to spectral resolution 106 (T106). The horizontal resolutions of the atmospheric model T30 and T106 are investigated in terms of the coupling characteristics, frequency, and variability of the tropical ocean–atmosphere interactions. It appears that the T106 resolution is generally beneficial even if it does not eliminate all the major systematic errors of the coupled model. There is an excessive shift west of the cold tongue and ENSO variability, and high resolution also has a somewhat negative impact on the variability in the east Indian Ocean. A dominant 2-yr peak for the Niño-3 variability in the T30 model is moderated in the T106 as it shifts to a longer time scale. At high resolution, new processes come into play, such as the coupling of tropical instability waves, the resolution of coastal flows at the Pacific–Mexican coasts, and improved coastal forcing along the coast of South America. The delayed oscillator seems to be the main mechanism that generates the interannual variability in both models, but the models realize it in different ways. In the T30 model it is confined close to the equator, involving relatively fast equatorial and near-equatorial modes, and in the high-resolution model, it involves a wider latitudinal region and slower waves. It is speculated that the extent of the region that is involved in the interannual variability may be linked to the time scale of the variability itself.

scholarly journals Simulation of wind-induced snow transport in alpine terrain using a fully coupled snowpack/atmosphere model

2013 ◽  
Vol 7 (3) ◽  
pp. 2191-2245 ◽  
Author(s):  
V. Vionnet ◽  
E. Martin ◽  
V. Masson ◽  
G. Guyomarc'h ◽  
F. Naaim-Bouvet ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Winter Season ◽  
Coupled Model ◽  
Deposition Process ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Blowing Snow ◽  
Erosion And Deposition ◽  
Atmospheric Flow ◽  
Snow Transport

Abstract. In alpine regions, wind-induced snow transport strongly influences the spatio-temporal evolution of the snow cover throughout the winter season. To gain understanding on the complex processes that drive the redistribution of snow, a new numerical model is developed. It couples directly the detailed snowpack model Crocus with the atmospheric model Meso-NH. Meso-NH/Crocus simulates snow transport in saltation and in turbulent suspension and includes the sublimation of suspended snow particles. A detailed representation of the first meters of the atmosphere allows a fine reproduction of the erosion and deposition process. The coupled model is evaluated against data collected around the experimental site of Col du Lac Blanc (2720 m a.s.l., French Alps). For this purpose, a blowing snow event without concurrent snowfall has been selected and simulated. Results show that the model captures the main structures of atmospheric flow in alpine terrain, the vertical profile of wind speed and the snow particles fluxes near the surface. However, the horizontal resolution of 50 m is found to be insufficient to simulate the location of areas of snow erosion and deposition observed by terrestrial laser scanning. When activated, the sublimation of suspended snow particles causes a reduction in deposition of 5.3%. Total sublimation (surface + blowing snow) is three times higher than surface sublimation in a simulation neglecting blowing snow sublimation.

scholarly journals The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

2016 ◽  
Vol 9 (10) ◽  
pp. 3655-3670 ◽  
Author(s):  
Helene T. Hewitt ◽  
Malcolm J. Roberts ◽  
Pat Hyder ◽  
Tim Graham ◽  
Jamie Rae ◽  
...  
Keyword(s):  
High Resolution ◽  
Coupled Model ◽  
Ocean Model ◽  
The Body ◽  
Western Boundary ◽  
Coupled Models ◽  
Technical Developments ◽  
Enhanced Resolution ◽  
Circumpolar Current ◽  
The Impact

Abstract. There is mounting evidence that resolving mesoscale eddies and western boundary currents as well as topographically controlled flows can play an important role in air–sea interaction associated with vertical and lateral transports of heat and salt. Here we describe the development of the Met Office Global Coupled Model version 2 (GC2) with increased resolution relative to the standard model: the ocean resolution is increased from 1/4 to 1/12° (28 to 9 km at the Equator), the atmosphere resolution increased from 60 km (N216) to 25 km (N512) and the coupling period reduced from 3 hourly to hourly. The technical developments that were required to build a version of the model at higher resolution are described as well as results from a 20-year simulation. The results demonstrate the key role played by the enhanced resolution of the ocean model: reduced sea surface temperature (SST) biases, improved ocean heat transports, deeper and stronger overturning circulation and a stronger Antarctic Circumpolar Current. Our results suggest that the improvements seen here require high resolution in both atmosphere and ocean components as well as high-frequency coupling. These results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.

scholarly journals The co-influence of the sea breeze and the coastal upwelling at Cabo Frio: a numerical investigation using coupled models

2011 ◽  
Vol 59 (2) ◽  
pp. 131-144 ◽  
Author(s):  
Flávia Noronha Dutra Ribeiro ◽  
Jacyra Soares ◽  
Amauri Pereira de Oliveira
Keyword(s):  
Positive Feedback ◽  
Coastal Upwelling ◽  
Coupled Model ◽  
Sea Breeze ◽  
Atmospheric Model ◽  
Breeze Circulation ◽  
Coupled Models ◽  
Initial Field ◽  
Oceanic Model ◽  
Cabo Frio

A coupled atmospheric-oceanic model was used to investigate whether there is a positive feedback between the coastal upwelling and the sea breeze at Cabo Frio - RJ (Brazil). Two experiments were performed to ascertain the influence of the sea breeze on the coastal upwelling: the first one used the coupled model forced with synoptic NE winds of 8 m s-1 and the sign of the sea breeze circulation was set by the atmospheric model; the second experiment used only the oceanic model with constant 8 m s-1 NE winds. Then, to study the influence of the coastal upwelling on the sea breeze, two more experiments were performed: one using a coastal upwelling representative SST initial field and the other one using a constant and homogeneous SST field of 26°C. Finally, two more experiments were conducted to verify the influence of the topography and the spatial distribution of the sea surface temperature on the previous results. The results showed that the sea breeze can intensify the coastal upwelling, but the coastal upwelling does not intensify the sea breeze circulation, suggesting that there is no positive feedback between these two phenomena at Cabo Frio.

scholarly journals The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

2016 ◽  
Author(s):  
Helene T. Hewitt ◽  
Malcolm J. Roberts ◽  
Pat Hyder ◽  
Tim Graham ◽  
Jamie Rae ◽  
...  
Keyword(s):  
High Resolution ◽  
Coupled Model ◽  
Ocean Model ◽  
The Body ◽  
Coupled Models ◽  
Surface Ocean ◽  
Technical Developments ◽  
Enhanced Resolution ◽  
Circumpolar Current ◽  
The Impact

Abstract. There is mounting evidence that resolving mesoscale eddies and boundary currents in the surface ocean field can play an important role in air-sea interaction associated with vertical and lateral transports of heat and salt. Here we describe the development of the Met Office Global Coupled Model version 2 (GC2) with increased resolution relative to the standard model: the ocean resolution is increased from 1/4° to 1/12° (28 km to 9 km at the Equator), the atmosphere resolution increased from 60 km (N216) to 25 km (N512) and the coupling frequency increased from 3-hourly to hourly. The technical developments that were required to build a version of the model at higher resolution are described as well as results from a 20 year simulation. The results demonstrate the key role played by the enhanced resolution of the ocean model: reduced Sea Surface Temperature biases, improved ocean heat transports, deeper and stronger overturning circulation and a stronger Antarctic Circumpolar Current. Our results suggest that the improvements seen here require high resolution in both atmosphere and ocean components as well as high frequency coupling. These results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.

Ultra-high-resolution future coupled model projections of atmospheric rivers

2020 ◽  
Author(s):  
Arjun Nellikkattil ◽  
Bin Guan ◽  
June-Yi Lee ◽  
Axel Timmermann ◽  
Sun-Seon Lee ◽  
...  
Keyword(s):  
High Resolution ◽  
Extreme Precipitation ◽  
Hydrological Cycle ◽  
Coupled Model ◽  
The United States ◽  
Horizontal Resolution ◽  
Greenhouse Warming ◽  
Polar Regions ◽  
Atmospheric Rivers ◽  
Extreme Precipitation Events

<p>Atmospheric rivers (ARs) are narrow, elongated structures, transporting large amounts of water vapor from the tropics towards polar regions. These synoptic scale features play an important role in the global hydrological cycle and for extreme precipitation events. To study how ARs will change in response to greenhouse warming we use a series of century-long fully coupled ultra-high-resolution simulations conducted with CESM 1.2.2 with an approximate horizontal resolution of ~25 km in the atmosphere and 10 km in the ocean. The simulations were carried out for present-day, 2xCO2 and 4xCO2 conditions. In this high atmospheric resolution, we obtain a much more realistic representation of complex orographic features (such as the Rocky Mountains), which can greatly influence the extreme precipitation often associated with ARs. Results from the present-day simulation are compared with ERA-Interim data to validate the model's fidelity in representing ARs. Our analysis focuses on future greenhouse-warming induced changes in AR frequency, geometry, landfalling latitude and strength. We find a global increase in the frequency of ARs amounting to ~0.5% for 2xCO2 and 0.9% for 4xCO2 respectively. In subtropical areas, such as the southwestern part of the United States AR frequencies increase by up to 7%. The presentation will further document the underlying processes for this increase.</p>

Distributions of Tropical Precipitation Cluster Power and Their Changes under Global Warming. Part II: Long-Term Time Dependence in Coupled Model Intercomparison Project Phase 5 Models

2017 ◽  
Vol 30 (20) ◽  
pp. 8045-8059 ◽  
Author(s):  
Kevin M. Quinn ◽  
J. David Neelin
Keyword(s):  
Global Warming ◽  
High Resolution ◽  
Rain Rate ◽  
Climate Model ◽  
Coupled Model ◽  
Atmospheric Model ◽  
Department Of Energy ◽  
Model Intercomparison ◽  
Intense Storm ◽  
Intercomparison Project

Abstract Distributions of precipitation cluster power (latent heat release rate integrated over contiguous precipitating pixels) are examined in 1°–2°-resolution members of phase 5 of the Coupled Model Intercomparison Project (CMIP5) climate model ensemble. These approximately reproduce the power-law range and large event cutoff seen in observations and the High Resolution Atmospheric Model (HiRAM) at 0.25°–0.5° in Part I. Under the representative concentration pathway 8.5 (RCP8.5) global warming scenario, the change in the probability of the most intense storm clusters appears in all models and is consistent with HiRAM output, increasing by up to an order of magnitude relative to historical climate. For the three models in the ensemble with continuous time series of high-resolution output, there is substantial variability on when these probability increases for the most powerful storm clusters become detectable, ranging from detectable within the observational period to statistically significant trends emerging only after 2050. A similar analysis of National Centers for Environmental Prediction (NCEP)–U.S. Department of Energy (DOE) AMIP-II reanalysis and Special Sensor Microwave Imager and Imager/Sounder (SSM/I and SSMIS) rain-rate retrievals in the recent observational record does not yield reliable evidence of trends in high power cluster probabilities at this time. However, the results suggest that maintaining a consistent set of overlapping satellite instrumentation with improvements to SSM/I–SSMIS rain-rate retrieval intercalibrations would be useful for detecting trends in this important tail behavior within the next couple of decades.

scholarly journals Manipulating intense XUV coherent light in the temporal domain

2004 ◽  
Vol 22 (3) ◽  
pp. 275-278 ◽  
Author(s):  
H. MERDJI ◽  
J.-F. HERGOTT ◽  
M. KOVACEV ◽  
E. PRIORI ◽  
P. SALIÈRES ◽  
...  
Keyword(s):  
High Resolution ◽  
Frequency Domain ◽  
Spectral Resolution ◽  
Time Scale ◽  
Relative Phase ◽  
High Sensitivity ◽  
Coherent Light ◽  
Temporal Domain

In this article, we demonstrate the generation of four phase-locked harmonic pulses separated in time using frequency-domain interferometry. The spectra present a high sensitivity to a change of the relative phase on an attosecond time scale. The spectral resolution and the control of this relative phase could be used to perform high resolution measurements.

A Weather-Type-Based Cross-Time-Scale Diagnostic Framework for Coupled Circulation Models

2017 ◽  
Vol 30 (22) ◽  
pp. 8951-8972 ◽  
Author(s):  
Ángel G. Muñoz ◽  
Xiaosong Yang ◽  
Gabriel A. Vecchi ◽  
Andrew W. Robertson ◽  
William F. Cooke
Keyword(s):  
Time Scales ◽  
Spatial Patterns ◽  
Atmospheric Model ◽  
Horizontal Resolution ◽  
Weather Type ◽  
Multiple Time Scales ◽  
Multiple Time ◽  
Coupled Models ◽  
Circulation Regime ◽  
Diagnostic Framework

Abstract This study proposes an integrated diagnostic framework based on atmospheric circulation regime spatial patterns and frequencies of occurrence to facilitate the identification of model systematic errors across multiple time scales. To illustrate the approach, three sets of 32-yr-long simulations are analyzed for northeastern North America and for the March–May season using the Geophysical Fluid Dynamics Laboratory’s Low Ocean–Atmosphere Resolution (LOAR) and Forecast-Oriented Low Ocean Resolution (FLOR) coupled models; the main difference between these two models is the horizontal resolution of the atmospheric model used. Regime-dependent biases are explored in the light of different atmospheric horizontal resolutions and under different nudging approaches. It is found that both models exhibit a fair representation of the observed circulation regime spatial patterns and frequencies of occurrence, although some biases are present independently of the horizontal resolution or the nudging approach and are associated with a misrepresentation of troughs centered north of the Great Lakes and deep coastal troughs. Moreover, the intraseasonal occurrence of certain model regimes is delayed with respect to observations. On the other hand, interexperiment differences in the mean frequencies of occurrence of the simulated weather types, and their variability across multiple time scales, tend to be negligible. This result suggests that low-resolution models could be of potential use to diagnose and predict physical variables via their simulated weather type characteristics.

scholarly journals A two-step scheme for high-resolution regional atmospheric trace gas inversions based on independent models

2009 ◽  
Vol 9 (14) ◽  
pp. 5331-5342 ◽  
Author(s):  
C. Rödenbeck ◽  
C. Gerbig ◽  
K. Trusilova ◽  
M. Heimann
Keyword(s):  
High Resolution ◽  
Transport Model ◽  
Coupled Model ◽  
Region Of Interest ◽  
Trace Gas ◽  
Coupled Models ◽  
Temporal Domain ◽  
Data Vector ◽  
Atmospheric Tracers ◽  
Atmospheric Trace Gas

Abstract. Mixing ratio measurements of atmospheric tracers like CO2 can be used to estimate regional surface-air tracer fluxes using inverse methods, involving a numerical transport model. Currently available transport models are either global but rather coarse, or more accurate but only over a limited spatial and temporal domain. To obtain higher-resolution flux estimates within a region of interest, existing studies use zoomed or coupled models. The two-step scheme developed here uses global and regional models sequentially in separate inversion steps, coupled only via the data vector. This provides a nested atmospheric inversion scheme without the necessity of a direct coupled model implementation. For example, the scheme allows an easy nesting of Lagrangian models with their potential of very high resolution into global inversions based on Eulerian models.

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