Internal variability of fine‐scale components of meteorological fields in extended‐range limited‐area model simulations with atmospheric and surface nudging

Šeparović, Leo; Husain, Syed Zahid; Yu, Wei

doi:10.1002/2015jd023350

Cited by 3 publications

(8 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Intuitively, we can imagine that the reproduction of regional climate depends on two factors, the external forcing from GCM (reproducible component depending on boundary forcing of GCM) and the internal dynamics (non‐reproducible) that develops independently in GCM and RCM. Even in a very restrictive framework, the internal dynamics developing within the region can be quite spontaneous (Christensen et al ., 2001; Separovic et al ., 2008; Separovic et al ., 2015). Whatever is the climate downscaling protocol, the internal dynamics can occur and makes RCM to deviate significantly from GCM.…”

Section: Assessment Methodologymentioning

confidence: 99%

See 1 more Smart Citation

An idealized protocol to assess the nesting procedure in regional climate modelling

Treut

2020

Intl Journal of Climatology

View full text Add to dashboard Cite

Newtonian relaxation applied at boundaries of RCM (regional climate model) is a widely‐used technique for climate downscaling and regional weather forecasting. It allows RCM to be nested into GCM (global climate model) and to follow the evolution of the latter. An idealized framework to mimic this general practice is constructed with the LMDZ (Laboratoire de Météorologie Dynamique, Zoom) modelling platform and used to assess effects of the relaxation procedure. The assessment is on both synoptic variability and long‐term mean. LMDZ is a global atmospheric general circulation model that can be configured as a regional model when the outside domain is relaxed to a driver. It thus plays the role of both GCM and RCM. Same physical parameterization and identical dynamical configuration are used to ensure a rigorous comparison between the two models. The experimental set‐up that can be referred to as “Master (GCM) versus Slave (RCM)” considers GCM as the reference to assess the behaviour of RCM. In terms of mean climate, there are noticeable differences, not only in the border areas, but also within the domain. In terms of synoptic variability, there is a general spatial resemblance and temporal concomitance between the two models. But there is a dependence on variables, seasons, spatiotemporal scales and spatial modes of atmospheric circulation. Winter/Summer has the most/least resemblance between RCM and GCM. A better similarity occurs when atmospheric circulation manifests at large scales. Weak‐correlation cases are generally remarked when the dominant circulation of the region is at smaller scales. A further experiment with identical framework but RCM in a higher resolution allows isolating the effect of relaxation from that of mesh refinement.

show abstract

Section: Assessment Methodologymentioning

confidence: 99%

“…Separovic et al . (2008, 2015) have shown that the relaxation procedure impacts firstly synoptic (intra‐seasonal) scale, an essential element of the atmospheric general circulation (Christensen et al ., 2001; Separovic et al . 2008, 2015).…”

Section: Assessment Methodologymentioning

confidence: 99%

An idealized protocol to assess the nesting procedure in regional climate modelling

Treut

2020

Intl Journal of Climatology

View full text Add to dashboard Cite

show abstract

“…Intuitively, we can imagine that the reproduction of regional climate depends on two factors, the external forcing from GCM (reproducible component depend on boundary forcing of GCM) and the internal dynamics (non reproducible) that develops independently in GCM and RCM. Even in a very restrictive framework, the internal dynamics developed within the region can be quite spontaneous (Separovic et al, 2015, Christensen et al, 2001). Whatever is the climate downscaling protocol, the internal dynamics can occur and makes the RCM to drift significantly from the GCM.…”

Section: Assessment Methodologymentioning

confidence: 99%

“…Separovic et al (2008Separovic et al ( , 2015 have shown that the relaxation procedure impacts firstly synoptic (intra-seasonal) scale, an essential element of the atmospheric general circulation (Christensen et al 2001;Separovic et al, 2015Separovic et al, , 2008. By the way, synoptic (intra-seasonal) situation is a very important criterion to represent the internal variability (Separovic et al, 2008(Separovic et al, , 2015Alexandru et al, 2007;Christensen et al, 2001;Jones et al, 1995). The comparison on the reproduction of intraseasonal between RCM and GCM is chosen to characterize the resemblance between two models who reveals the influence of Newtonian relaxation to regional climate.…”

Section: Data Filtered To Retain Synoptic-scale Variabilitymentioning

confidence: 99%

Use an idealized protocol to assess the nesting procedure in regional climate modelling

Treut

2018

Preprint

View full text Add to dashboard Cite

Abstract. Newtonian relaxation allowing RCM to follow GCM is a widely used technique for climate downscaling and regional weather forecasting. A thorough assessment on effects of the relaxation procedure in an idealized framework is presented in this paper for both synoptic variability and long-term mean climate. LMDz is a global atmospheric general circulation model that can be configured as a regional model if the outside domain of the focused region is applied with a relaxation. It thus plays the role of both GCM and RCM in this paper. Same physical parameterization and identical dynamical configuration are kept to ensure a rigorous comparison between the two models. The experimental set-up that can be referred to as “Master (GCM) versus Slave (RCM)” considers the GCM as the reference to assess the behavior of RCM. A further simulation with RCM in a higher resolution configuration allows isolating the effect of relaxation procedure from that of mesh refinement. In terms of mean climate in GCM and RCM, there are noticeable differences, not only in the border areas, but also within the domain. In terms of synoptic variability, there is a general spatial resemblance and temporal concomitance between the two models. But there is a dependence on variables, seasons, spatiotemporal scales and spatial mode of atmospheric circulation. Winter/Summer has the most/least resemblance between the RCM and the GCM. A better similarity is noticed when atmospheric circulations manifested on large scales. No-correlation cases can be remarked when the dominant circulation of the region is at a small scale.

show abstract

“…Thus, the advantage of using spectral nudging in regional modeling was to enforce similarity of the large-scale state with a given state and the efficient reduction of ensemble variability. Separovic et al 2015 showed that the internal variability at scales larger than 300 km can be reduced by using spectral nudging. Recently, such constraining was also used for improving the forecast of regional details (Zhao et al 2016(Zhao et al , 2017.…”

Section: Introductionmentioning

confidence: 99%

Does Spectral Nudging Have an Effect on Dynamical Downscaling Applied in Small Regional Model Domains?

2017

View full text Add to dashboard Cite

Spectral nudging is a method that was developed to constrain regional climate models so that they reproduce the development of the large-scale atmospheric state, while permitting the formation of regional-scale details as conditioned by the large scales. Besides keeping the large-scale development in the interior close to a given state, the method also suppresses the emergence of ensemble variability. The method is mostly applied to reconstructions of past weather developments in regions with an extension of typically 1000–8000 km. In this article, the authors examine if spectral nudging is having an effect on simulations with model regions of the size of about 700 km × 500 km at midlatitudes located mainly over flat terrain. First two pairs of simulations are compared, two runs each with and without spectral nudging, and it is found that the four simulations are very similar, without systematic or intermittent phases of divergence. Smooth fields, which are mainly determined by spatial patterns, such as air pressure, show hardly any differences, while small-scale and heterogeneous fields such as precipitation vary strongly, mostly on the gridpoint scale, irrespective if spectral nudging is employed or not. It is concluded that the application of spectral nudging has little effect on the simulation when the model region is relatively small.

show abstract

Internal variability of fine‐scale components of meteorological fields in extended‐range limited‐area model simulations with atmospheric and surface nudging

Cited by 3 publications

References 33 publications

An idealized protocol to assess the nesting procedure in regional climate modelling

An idealized protocol to assess the nesting procedure in regional climate modelling

Use an idealized protocol to assess the nesting procedure in regional climate modelling

Does Spectral Nudging Have an Effect on Dynamical Downscaling Applied in Small Regional Model Domains?

Contact Info

Product

Resources

About