scholarly journals Projected Future Changes in The Equatorial Wave Spectrum in CMIP6

2021 ◽  
Author(s):  
Hagar Bartana ◽  
Chaim Garfinkel ◽  
Ofer Shamir ◽  
Jian Rao
Keyword(s):  
Wave Spectrum ◽  
Power Spectra ◽  
Coupled Model ◽  
Longwave Radiation ◽  
Kelvin Waves ◽  
Control Climate ◽  
Convectively Coupled Equatorial Waves ◽  
Equatorial Wave ◽  
Systematic Biases ◽  
Intercomparison Project

Abstract The simulation of the Madden-Julian Oscillation (MJO) and convectively coupled equatorial waves (CCEWs) is considered in 13 state-of-the-art models from phase 6 of the Coupled Model Intercomparison Project (CMIP6). We use frequency-wavenumber power spectra of the models and observations for Outgoing Longwave Radiation (OLR) and zonal velocity at 250 hPa (U250), and consider the historical and end-of-century projections for the SSP245 and SSP585 scenarios. The models simulate a spectrum quantitatively resembling that observed, though systematic biases exist. MJO and Kelvin waves (KW) are mostly underestimated, while equatorial Rossby waves (ER) are overestimated. The models project a moderate future increase in power for the MJO, a robust increase for Kelvin waves (KW) and weaker power values for most other wavenumber-frequency combinations, including higher wavenumber ER. In addition to strengthening, KW also shift toward higher phase speeds (or equivalent depths). Models with a more realistic MJO in their control climate tend to simulate a stronger intensification, and models with a more realistic KW in their control climate tend to simulate a weaker intensification.

scholarly journals Interhemispheric Variability of Earth’s Radiation

2015 ◽  
Vol 72 (12) ◽  
pp. 4615-4628 ◽  
Author(s):  
Alexander Ruzmaikin ◽  
Hartmut H. Aumann ◽  
Jonathan H. Jiang
Keyword(s):  
Time Scales ◽  
Critical Role ◽  
Heat Content ◽  
Coupled Model ◽  
Longwave Radiation ◽  
Shortwave Radiation ◽  
Hemispheric Differences ◽  
Meridional Transport ◽  
The Pacific ◽  
Intercomparison Project

Abstract The variability of interhemispheric symmetry of Earth’s energy serves as an independent indicator of climate change. The analysis of updated data obtained from satellite measurements at the top of the atmosphere (TOA) shows that in accord with Earth’s orbital requirements the annually averaged incident solar radiation is the same in the Northern and Southern Hemispheres, the annual mean of the reflected shortwave radiation is almost north–south symmetric, and the annual mean of the outgoing longwave radiation is larger in the Northern Hemisphere by 1.4 W m−2. These mean radiations systematically differ from the mean radiations found from the numerical atmospheric models that participated in the Coupled Model Intercomparison Project phase 5 (CMIP5). The hemispheric differences of the TOA radiations vary on the annual and interannual time scales. The multidecadal variability in Earth’s north–south temperature difference reveals a similarity of trends in both hemispheres. The Atlantic meridional transport (in contrast to the Pacific meridional transport) is found to be coherent with the interhemispheric ocean heat content (OHC) difference on decadal and multidecadal time scales, indicating a critical role of the Atlantic in the interhemispheric energy balance change.

scholarly journals The Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6): simulation design and preliminary results

2015 ◽  
Vol 8 (10) ◽  
pp. 3379-3392 ◽  
Author(s):  
B. Kravitz ◽  
A. Robock ◽  
S. Tilmes ◽  
O. Boucher ◽  
J. M. English ◽  
...  
Keyword(s):  
Climate Model ◽  
Coupled Model ◽  
Longwave Radiation ◽  
Open Science ◽  
Model Intercomparison ◽  
Simulation Design ◽  
Preliminary Results ◽  
Climate Model Experiment ◽  
Intercomparison Project ◽  
New Feature

Abstract. We present a suite of new climate model experiment designs for the Geoengineering Model Intercomparison Project (GeoMIP). This set of experiments, named GeoMIP6 (to be consistent with the Coupled Model Intercomparison Project Phase 6), builds on the previous GeoMIP project simulations, and has been expanded to address several further important topics, including key uncertainties in extreme events, the use of geoengineering as part of a portfolio of responses to climate change, and the relatively new idea of cirrus cloud thinning to allow more longwave radiation to escape to space. We discuss experiment designs, as well as the rationale for those designs, showing preliminary results from individual models when available. We also introduce a new feature, called the GeoMIP Testbed, which provides a platform for simulations that will be performed with a few models and subsequently assessed to determine whether the proposed experiment designs will be adopted as core (Tier 1) GeoMIP experiments. This is meant to encourage various stakeholders to propose new targeted experiments that address their key open science questions, with the goal of making GeoMIP more relevant to a broader set of communities.

scholarly journals Analysis of Synoptic Disturbance in Maritim Continent Using Spherical Harmonics Transformation Method

Agromet ◽  
2020 ◽  
Vol 34 (2) ◽  
pp. 89-99
Author(s):  
Sayful Amri ◽  
Faiz Rohman Fajary ◽  
Tri Wahyu Hadi
Keyword(s):  
Spherical Harmonics ◽  
Spectrum Analysis ◽  
Wave Spectrum ◽  
Longwave Radiation ◽  
Transformation Method ◽  
Wave Number ◽  
Wave Disturbances ◽  
Equatorial Wave ◽  
Wave Numbers ◽  
Symmetrical Component

This study aims to modify the idea of ​​WK99-analyzing the existence of signature in wave-number and frequency spectrum when the analyzed Outgoing Longwave Radiation (OLR) data is associated with a unique phenomenon in Maritime Continent (MC), Borneo vortex (BV). Although BV is often related to easterly equatorial wave disturbances, there was no specific study to examine its behavior in the spectral domain. The purpose of this study is to develop a method to diagnose certain signatures of BV through spectrum analysis of OLR data when BV occurs. In contrast to previous studies, to present the unique phenomenon in MC as a target for diagnostics, spectrum analysis is performed by Spherical Harmonics (SH). The results of the OLR data spectrum comparison when BV occurs with the OLR data spectrum when BV does not occur that in the anti-symmetrical component when BV occurs, the tropical depression-mixed Rossby gravity (TD-MRG) wave spectrum is stronger, especially in zonal wave-numbers 5 to 10 and frequencies 0.12 to 0.2. Similar to the anti-symmetrical component, the TD-MRG spectrum of the symmetrical component is also stronger at zonal wave-numbers 5 to 10 and frequencies 0.12 to 0.2. Moreover,  the westward-propagating inertio-gravity (WIG) wave spectrum in the symmetrical component is also stronger at the time of BV than when there is no BV, especially at zonal wave-numbers 7 to 13 and frequencies 0.38 to 0.5. It can be concluded that when BV occurs, equatorial waves that propagate to the west, especially the types of TD-MRG and WIG waves are stronger than when BV did not occur. The results of durational grouped spectrum analysis of OLR data when BV occurs indicate that the longer the duration of BV occurs, the stronger the spectrum of TD-MRG and WIG wave types gets.

scholarly journals An evaluation of tropical waves and wave forcing of the QBO in the QBOi models

2020 ◽  
Author(s):  
Laura Holt ◽  
Francois Lott ◽  
Keyword(s):  
Gravity Waves ◽  
Phase 1 ◽  
Coupled Model ◽  
Cmip5 Models ◽  
Flux Divergence ◽  
Quasi Biennial Oscillation ◽  
Wave Forcing ◽  
Convectively Coupled Waves ◽  
Systematic Biases ◽  
Intercomparison Project

<p>We analyze the stratospheric waves in models participating in phase 1 of the Stratosphere–troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi). All models have robust Kelvin and mixed Rossby-gravity wave modes in winds and temperatures at and represent them better than most of the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. There is still some spread among the models, especially concerning the mixed Rossby-gravity waves. We attribute the variability in equatorial waves among the QBOi models in part to the varying horizontal and vertical resolutions, to systematic biases in zonal winds, and to the considerable variability in convectively coupled waves in the troposphere among the models: only roughly half of the QBOi models have realistic convectively coupled Kelvin waves and only a few models have convectively coupled mixed Rossby-gravity waves. The models with stronger convectively coupled waves produce larger zonal mean forcing due to resolved waves in the QBO region. Finally we evaluate the Eliassen-Palm (EP) flux and EP flux divergence of the resolved waves in the QBOi models. We find that there is a large spread in the forcing from resolved waves in the QBO region, and the resolved wave forcing has a robust correlation with model vertical resolution</p>

scholarly journals MJO and Convectively Coupled Equatorial Waves Simulated by CMIP5 Climate Models

2013 ◽  
Vol 26 (17) ◽  
pp. 6185-6214 ◽  
Author(s):  
Meng-Pai Hung ◽  
Jia-Lin Lin ◽  
Wanqiu Wang ◽  
Daehyun Kim ◽  
Toshiaki Shinoda ◽  
...  
Keyword(s):  
Climate Models ◽  
Intraseasonal Variability ◽  
Coupled Model ◽  
Static Stability ◽  
Cmip5 Models ◽  
Equatorial Waves ◽  
Intergovernmental Panel ◽  
Assessment Report ◽  
Convectively Coupled Equatorial Waves ◽  
Intercomparison Project

Abstract This study evaluates the simulation of the Madden–Julian oscillation (MJO) and convectively coupled equatorial waves (CCEWs) in 20 models from the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) and compares the results with the simulation of CMIP phase 3 (CMIP3) models in the IPCC Fourth Assessment Report (AR4). The results show that the CMIP5 models exhibit an overall improvement over the CMIP3 models in the simulation of tropical intraseasonal variability, especially the MJO and several CCEWs. The CMIP5 models generally produce larger total intraseasonal (2–128 day) variance of precipitation than the CMIP3 models, as well as larger variances of Kelvin, equatorial Rossby (ER), and eastward inertio-gravity (EIG) waves. Nearly all models have signals of the CCEWs, with Kelvin and mixed Rossby–gravity (MRG) and EIG waves being especially prominent. The phase speeds, as scaled to equivalent depths, are close to the observed value in 10 of the 20 models, suggesting that these models produce sufficient reduction in their effective static stability by diabatic heating. The CMIP5 models generally produce larger MJO variance than the CMIP3 models, as well as a more realistic ratio between the variance of the eastward MJO and that of its westward counterpart. About one-third of the CMIP5 models generate the spectral peak of MJO precipitation between 30 and 70 days; however, the model MJO period tends to be longer than observations as part of an overreddened spectrum, which in turn is associated with too strong persistence of equatorial precipitation. Only one of the 20 models is able to simulate a realistic eastward propagation of the MJO.

scholarly journals The Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6): simulation design and preliminary results

2015 ◽  
Vol 8 (6) ◽  
pp. 4697-4736 ◽  
Author(s):  
B. Kravitz ◽  
A. Robock ◽  
S. Tilmes ◽  
O. Boucher ◽  
J. M. English ◽  
...  
Keyword(s):  
Climate Model ◽  
Coupled Model ◽  
Longwave Radiation ◽  
Open Science ◽  
Model Intercomparison ◽  
Simulation Design ◽  
Preliminary Results ◽  
Climate Model Experiment ◽  
Intercomparison Project ◽  
New Feature

Abstract. We present a suite of new climate model experiment designs for the Geoengineering Model Intercomparison Project (GeoMIP). This set of experiments, named GeoMIP6 (to be consistent with the Coupled Model Intercomparison Project Phase 6), builds on the previous GeoMIP simulations, and has been expanded to address several further important topics, including key uncertainties in extreme events, the use of geoengineering as part of a portfolio of responses to climate change, and the relatively new idea of cirrus cloud thinning to allow more longwave radiation to escape to space. We discuss experiment designs, as well as the rationale for those designs, showing preliminary results from individual models when available. We also introduce a new feature, called the GeoMIP Testbed, which provides a platform for simulations that will be performed with a few models and subsequently assessed to determine whether the proposed experiment designs will be adopted as core (Tier 1) GeoMIP experiments. This is meant to encourage various stakeholders to propose new targeted experiments that address their key open science questions, with the goal of making GeoMIP more relevant to a broader set of communities.

scholarly journals Wavelet Analysis of the Convectively Coupled Equatorial Waves in the Wavenumber–Frequency Domain

2009 ◽  
Vol 66 (1) ◽  
pp. 209-212 ◽  
Author(s):  
Martin L. M. Wong
Keyword(s):  
Wavelet Analysis ◽  
Frequency Domain ◽  
Power Spectra ◽  
Longwave Radiation ◽  
Equatorial Region ◽  
Equatorial Waves ◽  
Tropical Depression ◽  
Radiation Data ◽  
Convectively Coupled Equatorial Waves ◽  
Zonal Wavenumber

Abstract Wavelet analysis is performed on 31 yr (1975–2007, except 1978 and 1979) of daily outgoing longwave radiation data in the global equatorial region (15°S–15°N). Power spectra in the zonal wavenumber–frequency domain are obtained. With different scales and bandwidths than in previous Fourier-based analysis, peaks of variances that are associated with the various convectively coupled waves are found. Further, possibly because of the ability to resolve shorter waves that have limited zonal extent, significant variances are also found at tropical depression–type scales. However, waves of zonal wavenumber zero cannot be explicitly analyzed.

scholarly journals Future Changes in Simulated Evapotranspiration across Continental Africa Based on CMIP6 CNRM-CM6

2021 ◽  
Vol 18 (13) ◽  
pp. 6760
Author(s):  
Isaac Kwesi Nooni ◽  
Daniel Fiifi T. Hagan ◽  
Guojie Wang ◽  
Waheed Ullah ◽  
Jiao Lu ◽  
...  
Keyword(s):  
Extreme Events ◽  
Coupled Model ◽  
Baseline Period ◽  
Model Intercomparison ◽  
Additional Information ◽  
Intercomparison Project ◽  
Key Drivers ◽  
Model Ensembles ◽  
Projected Changes ◽  
Near Future

The main goal of this study was to assess the interannual variations and spatial patterns of projected changes in simulated evapotranspiration (ET) in the 21st century over continental Africa based on the latest Shared Socioeconomic Pathways and the Representative Concentration Pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) provided by the France Centre National de Recherches Météorologiques (CNRM-CM) model in the Sixth Phase of Coupled Model Intercomparison Project (CMIP6) framework. The projected spatial and temporal changes were computed for three time slices: 2020–2039 (near future), 2040–2069 (mid-century), and 2080–2099 (end-of-the-century), relative to the baseline period (1995–2014). The results show that the spatial pattern of the projected ET was not uniform and varied across the climate region and under the SSP-RCPs scenarios. Although the trends varied, they were statistically significant for all SSP-RCPs. The SSP5-8.5 and SSP3-7.0 projected higher ET seasonality than SSP1-2.6 and SSP2-4.5. In general, we suggest the need for modelers and forecasters to pay more attention to changes in the simulated ET and their impact on extreme events. The findings provide useful information for water resources managers to develop specific measures to mitigate extreme events in the regions most affected by possible changes in the region’s climate. However, readers are advised to treat the results with caution as they are based on a single GCM model. Further research on multi-model ensembles (as more models’ outputs become available) and possible key drivers may provide additional information on CMIP6 ET projections in the region.

scholarly journals Convectively Coupled Equatorial Waves. Part I: Horizontal and Vertical Structures

2007 ◽  
Vol 64 (10) ◽  
pp. 3406-3423 ◽  
Author(s):  
Gui-Ying Yang ◽  
Brian Hoskins ◽  
Julia Slingo
Keyword(s):  
Composite Structures ◽  
Wave Structure ◽  
Wave Theory ◽  
Western Hemisphere ◽  
Equatorial Waves ◽  
Kelvin Wave ◽  
Ambient Flow ◽  
Convectively Coupled Equatorial Waves ◽  
Eastern Hemisphere ◽  
Equatorial Wave

Abstract Multilevel 15-yr ECMWF Re-Analysis (ERA-15) and satellite-observed brightness temperature (Tb) data for the period May–October 1992 are used to examine the horizontal and vertical structures of convectively coupled equatorial waves. Dynamical waves are isolated using a methodology developed previously. Composite structures of convectively coupled equatorial waves are obtained using linear regression/correlation between convection (Tb) and dynamical structures. It is found that the relationship depends on the ambient flow and the nature of the convective coupling, and varies between off-equatorial- and equatorial-centered convection, different hemispheres, and seasons. The Kelvin wave structure in the Western Hemisphere is generally consistent with classic equatorial wave theory and has its convection located in the region of low-level convergence. In the Eastern Hemisphere the Kelvin wave tends to have convection in the region of enhanced lower-tropospheric westerlies and a tilted vertical structure. The Kelvin wave also tends to have a third peak in zonal wind amplitude at 500 hPa and exhibits upward propagation into the lower stratosphere. Lower-tropospheric westward-moving mixed Rossby–gravity (WMRG) and n = 1 Rossby (R1) wave structures and their relationship with convection are consistent with classic equatorial wave theory and the implied lower-tropospheric convergences. In the Eastern Hemisphere the WMRG and R1 waves have first baroclinic mode structures in the vertical. However, in the Western Hemisphere, the R1 wave has a barotropic structure. In the Eastern Hemisphere the R1 wave, like the Kelvin wave, tends to have equatorial convection in the region of enhanced lower-level westerlies, suggesting that enhanced surface energy fluxes associated with these waves may play an important organizing role for equatorial convection in this warm-water hemisphere. In the upper troposphere, eastward-moving Rossby–gravity (EMRG) and n = 1 gravity waves are found in the Eastern Hemisphere, and eastward-moving WMRG and R1 waves are found in the Western Hemisphere, suggestive of Doppler shifting of waves by the ambient flow.

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