scholarly journals The Role of Isotope‐Enabled GCM Complexity in Simulating Tropical Circulation Changes in High‐CO 2 Scenarios

2020 ◽  
Vol 12 (8) ◽  
Author(s):  
Jun Hu ◽  
Sylvia Dee ◽  
Jesse Nusbaumer
Keyword(s):  
Tropical Circulation ◽  
Circulation Changes

scholarly journals Regional Changes in the Interannual Variability of U.S. Warm Season Precipitation

2016 ◽  
Vol 29 (14) ◽  
pp. 5157-5173 ◽  
Author(s):  
Scott J. Weaver ◽  
Stephen Baxter ◽  
Kirstin Harnos
Keyword(s):  
United States ◽  
The United States ◽  
Precipitation Variability ◽  
Height Anomaly ◽  
Epochal Change ◽  
Upper Level ◽  
Recent Epoch ◽  
Level Height ◽  
Circulation Changes

Abstract Intensification of regional springtime precipitation variability over the United States and the role of North American low-level jets (NALLJs) are investigated for the 1950–2010 period. The analysis reveals that the primary modes of NALLJ fluctuations are related to the strengthening of AMJ precipitation variability over the northern Great Plains and southeastern United States during the last 60 years. Examination of the epochal change in NALLJ variations shows a stronger connectivity to SST variability during 1980–2010 than in the 1950–79 period. In the context of the first three NALLJ variability modes it appears that the role of decadal SST variations (NALLJ mode 1) and the recent emergence of tropical Pacific connectivity (NALLJ modes 1 and 2) via SST-induced atmospheric heating and large-scale circulation changes may act to strengthen and spatially shift the NALLJ variability modes southward and/or eastward, intensifying regional precipitation variability in the recent epoch. Although notable NALLJ variability also exists in the earlier epoch, the upper-level height field is significantly lacking in meridional gradients, leading to weak upper-level zonal wind anomalies over the United States and diminished NALLJ variability. Conversely, the intensified and spatially shifted upper-level height anomaly in the recent epoch produces enhanced meridional height gradients in all three modes, strengthening NALLJ variability—highlighting that seemingly subtle shifts in hemispheric-scale atmospheric circulation changes can have important impacts on regional climate variability and change.

scholarly journals Uncertainty in projected changes in precipitation minus evaporation: dominant role of dynamic circulation changes and weak role for thermodynamic changes

2022 ◽  
Author(s):  
Eilat Elbaum ◽  
Chaim I Garfinkel ◽  
Ori Adam ◽  
Efrat Morin ◽  
Dorita Rostkier-Edelstein ◽  
...  
Keyword(s):  
Dominant Role ◽  
Projected Changes ◽  
Circulation Changes

scholarly journals The influence of vegetation on the ITCZ and South Asian monsoon in HadCM3

2012 ◽  
Vol 3 (1) ◽  
pp. 87-96 ◽  
Author(s):  
M. P. McCarthy ◽  
J. Sanjay ◽  
B. B. B. Booth ◽  
K. Krishna Kumar ◽  
R. A. Betts
Keyword(s):  
Land Cover ◽  
Northern Hemisphere ◽  
South Asian ◽  
Vegetation Cover ◽  
Large Scale ◽  
Asian Monsoon ◽  
South Asian Monsoon ◽  
Tropical Circulation ◽  
Global Vegetation

Abstract. The role of global vegetation on the large-scale tropical circulation is examined in the version 3 Hadley Centre climate model (HadCM3). Alternative representations of global vegetation cover from observations and a dynamic global vegetation model (DGVM) were used as the land-cover component for a number of HadCM3 experiments under a nominal present day climate state, and compared to the simulations using the standard land cover map of HadCM3. The alternative vegetation covers result in a large scale cooling of the Northern Hemisphere extra-tropics relative to the HadCM3 standard, resulting in a southward shift in the location of the inter-tropical convergence zone (ITCZ). A significant reduction in Indian monsoon precipitation is also found, which is related to a weakening of the South Asian monsoon circulation, broadly consistent with documented mechanisms relating to temperature and snow perturbations in the Northern Hemisphere extra-tropics in winter and spring, delaying the onset of the monsoon. The role of the Northern Hemisphere extra-tropics on tropical climate is demonstrated, with an additional representation of vegetation cover based on DGVM simulated changes in Northern Hemisphere vegetation from the end of the 21st Century. This experiment shows that through similar processes the simulated extra-tropical vegetation changes in the future contribute to a strengthening of the South Asian monsoon in this model. These findings provide renewed motivation to give careful consideration to the role of global scale vegetation feedbacks when looking at climate change, and its impact on the tropical circulation and South Asian monsoon in the latest generation of Earth System models.

scholarly journals Radiative-Convective Equilibrium Model Intercomparison Project

2017 ◽  
Author(s):  
Allison A. Wing ◽  
Kevin A. Reed ◽  
Masaki Satoh ◽  
Bjorn Stevens ◽  
Sandrine Bony ◽  
...  
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Cloud Fraction ◽  
Model Intercomparison ◽  
Tropical Circulation ◽  
Cloud Feedbacks ◽  
Single Column ◽  
Intercomparison Project ◽  
Self Aggregation

Abstract. RCEMIP, an intercomparison of multiple types of models configured in radiative-convective equilibrium (RCE), is proposed. RCE is an idealization of the climate system in which there is a balance between radiative cooling of the atmosphere and heating by convection. The scientific objectives of RCEMIP are three-fold. First, clouds and climate sensitivity will be investigated in the RCE setting. This includes determining how cloud fraction changes with warming and the role of self-aggregation of convection. Second, RCEMIP will quantify the dependence of the degree of convective aggregation and tropical circulation regimes on temperature. Finally, by providing a common baseline, RCEMIP will allow the robustness of the RCE state, cloud feedbacks, and convective aggregation across the spectrum of models to be assessed. A novel aspect and major advantage of RCEMIP is the accessibility of the RCE framework to a variety of models, including cloud-resolving models, general circulation models, global cloud-resolving models, and single column models.

scholarly journals Future changes to the Indonesian Throughflow and Pacific circulation: The differing role of wind and deep circulation changes

2016 ◽  
Vol 43 (4) ◽  
pp. 1669-1678 ◽  
Author(s):  
Alex Sen Gupta ◽  
Shayne McGregor ◽  
Erik Sebille ◽  
Alexandre Ganachaud ◽  
Jaclyn N. Brown ◽  
...  
Keyword(s):  
Indonesian Throughflow ◽  
Deep Circulation ◽  
Circulation Changes

scholarly journals Understanding the Effects of Convective Momentum Transport on Climate Simulations: The Role of Convective Heating

2008 ◽  
Vol 21 (19) ◽  
pp. 5034-5047 ◽  
Author(s):  
Xiaoliang Song ◽  
Xiaoqing Wu ◽  
Guang Jun Zhang ◽  
Raymond W. Arritt
Keyword(s):  
General Circulation ◽  
Meridional Circulation ◽  
Momentum Transport ◽  
Convective Heating ◽  
Dynamical Processes ◽  
Climate Simulations ◽  
Convective Momentum Transport ◽  
The Tropics ◽  
Circulation Changes

Abstract A simplified general circulation model (GCM), consisting of a complete dynamical core, simple specified physics, and convective momentum transport (CMT) forcing, is used to understand the effects of CMT on climate simulations with a focus on the role of convective heating in the response of circulation to the CMT forcing. It is found that the convective heating dominates the meridional circulation response and dynamical processes dominate the zonal wind response to the CMT forcing in the tropics; the simplified model reproduces some of the key features of CMT-induced circulation changes observed in the full GCM in the tropics. These results suggest that the CMT-induced zonal and meridional circulation changes in the tropics in the full GCM are dominated by dynamical processes and the convective heating, respectively. Inclusion of the CMT in the model induces a marked change in convective heating, which negatively correlates with the change in vertical velocity, indicating the existence of CMT-induced convective heating–circulation feedback. The sensitivity experiment with the removal of mean convective heating feedback demonstrates that the convective heating affects the response of the meridional circulation to the CMT forcing through the CMT-induced convective heating–circulation feedback.

scholarly journals The Role of Tropical, Midlatitude, and Polar Cloud-Radiative Changes for the Midlatitude Circulation Response to Global Warming

2020 ◽  
Vol 33 (18) ◽  
pp. 7927-7943 ◽  
Author(s):  
Nicole Albern ◽  
Aiko Voigt ◽  
David W. J. Thompson ◽  
Joaquim G. Pinto
Keyword(s):  
Global Warming ◽  
Storm Track ◽  
Radiative Heating ◽  
Sea Surface ◽  
Relative Importance ◽  
Upper Troposphere ◽  
The Mean ◽  
The Impact ◽  
Circulation Changes

AbstractPrevious studies showed that global cloud-radiative changes contribute half or more to the midlatitude atmospheric circulation response to global warming. Here, we investigate the relative importance of tropical, midlatitude, and polar cloud-radiative changes for the annual-mean, wintertime, and summertime circulation response across regions in AMIP-like simulations. To this end, we study global warming simulations from the ICON model run with the cloud-locking method and prescribed sea surface temperatures, which isolate the impact of changes in atmospheric cloud-radiative heating. Tropical cloud changes dominate the global cloud impact on the 850 hPa zonal wind, jet strength, and storm track responses across most seasons and regions. For the jet shift, a more diverse picture is found. In the annual mean and DJF, tropical and midlatitude cloud changes contribute substantially to the poleward jet shift in all regions. The poleward jet shift is further supported by polar cloud changes across the Northern Hemisphere but not in the Southern Hemisphere. In JJA, the impact of regional cloud changes on the jet position is small, consistent with an overall small jet shift during this season. The jet shift can be largely understood via the anomalous atmospheric cloud-radiative heating in the tropical and midlatitude upper troposphere. The circulation changes are broadly consistent with the influence of cloud-radiative changes on upper-tropospheric baroclinicity and thus the mean potential energy available for conversion into eddy kinetic energy. Our results help to explain the jet response to global warming and highlight the importance of tropical and midlatitude cloud-radiative changes for this response.

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor
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