scholarly journals Simulations of Global Hurricane Climatology, Interannual Variability, and Response to Global Warming Using a 50-km Resolution GCM

2009 ◽  
Vol 22 (24) ◽  
pp. 6653-6678 ◽  
Author(s):  
Ming Zhao ◽  
Isaac M. Held ◽  
Shian-Jiann Lin ◽  
Gabriel A. Vecchi
Keyword(s):  
Global Warming ◽  
Interannual Variability ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Vertical Shear ◽  
Shallow Convection ◽  
Coupled Models ◽  
Lower Boundary Condition ◽  
Atlantic Hurricane ◽  
Sst Anomalies

Abstract A global atmospheric model with roughly 50-km horizontal grid spacing is used to simulate the interannual variability of tropical cyclones using observed sea surface temperatures (SSTs) as the lower boundary condition. The model’s convective parameterization is based on a closure for shallow convection, with much of the deep convection allowed to occur on resolved scales. Four realizations of the period 1981–2005 are generated. The correlation of yearly Atlantic hurricane counts with observations is greater than 0.8 when the model is averaged over the four realizations, supporting the view that the random part of this annual Atlantic hurricane frequency (the part not predictable given the SSTs) is relatively small (<2 hurricanes per year). Correlations with observations are lower in the east, west, and South Pacific (roughly 0.6, 0.5, and 0.3, respectively) and insignificant in the Indian Ocean. The model trends in Northern Hemisphere basin-wide frequency are consistent with the observed trends in the International Best Track Archive for Climate Stewardship (IBTrACS) database. The model generates an upward trend of hurricane frequency in the Atlantic and downward trends in the east and west Pacific over this time frame. The model produces a negative trend in the Southern Hemisphere that is larger than that in the IBTrACS. The same model is used to simulate the response to the SST anomalies generated by coupled models in the World Climate Research Program Coupled Model Intercomparison Project 3 (CMIP3) archive, using the late-twenty-first century in the A1B scenario. Results are presented for SST anomalies computed by averaging over 18 CMIP3 models and from individual realizations from 3 models. A modest reduction of global and Southern Hemisphere tropical cyclone frequency is obtained in each case, but the results in individual Northern Hemisphere basins differ among the models. The vertical shear in the Atlantic Main Development Region (MDR) and the difference between the MDR SST and the tropical mean SST are well correlated with the model’s Atlantic storm frequency, both for interannual variability and for the intermodel spread in global warming projections.

scholarly journals Interannual variability of precipitable water

1996 ◽  
Vol 14 (4) ◽  
pp. 464-467 ◽  
Author(s):  
R. P. Kane
Keyword(s):  
Interannual Variability ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Precipitable Water ◽  
Radiosonde Data ◽  
High Latitudes ◽  
Zonal Winds ◽  
Low Latitudes ◽  
Linear Trends

Abstract. The 12-month running means of the surface-to-500 mb precipitable water obtained from analysis of radiosonde data at seven selected locations showed three types of variability viz: (1) quasi-biennial oscillations; these were different in nature at different latitudes and also different from the QBO of the stratospheric tropical zonal winds; (2) decadal effects; these were prominent at middle and high latitudes and (3) linear trends; these were prominent at low latitudes, up trends in the Northern Hemisphere and downtrends in the Southern Hemisphere.

scholarly journals Tropical Cyclone Climatology from Satellite Passive Microwave Measurements

2020 ◽  
Vol 12 (21) ◽  
pp. 3610
Author(s):  
Song Yang ◽  
Richard Bankert ◽  
Joshua Cossuth
Keyword(s):  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Wind Shear ◽  
Vertical Wind Shear ◽  
Passive Microwave ◽  
Vertical Wind ◽  
Vertical Shear ◽  
Shear Direction ◽  
Motion Direction ◽  
Horizontal Structure

The satellite passive microwave (PMW) sensor brightness temperatures (TBs) of all tropical cyclones (TCs) from 1987–2012 have been carefully calibrated for inter-sensor frequency differences, center position fixing using the Automated Rotational Center Hurricane Eye Retrieval (ARCHER) scheme, and application of the Backus–Gilbert interpolation scheme for better presentation of the TC horizontal structure. With additional storm motion direction and the 200–850 hPa wind shear direction, a unique and comprehensive TC database is created for this study. A reliable and detailed climatology for each TC category is analyzed and discussed. There is significant annual variability of the number of storms at hurricane intensity, but the annual number of all storms is relatively stable. Results based on the analysis of the 89 GHz horizontal polarization TBs over oceans are presented in this study. An eyewall contraction is clearly displayed with an increase in TC intensity. Three composition schemes are applied to present a reliable and detailed TC climatology at each intensity category and its geographic characteristics. The global composition relative to the North direction is not able to lead a realistic structure for an individual TC. Enhanced convection in the down-motion quadrants relative to direction of TC motion is obvious for Cat 1–3 TCs, while Cat 4–5 TCs still have a concentric pattern of convection within 200 km radius. Regional differences are evident for weak storms. Results indicate the direction of TC movement has more impact on weak storms than on Cat 4–5 TCs. A striking feature is that all TCs have a consistent pattern of minimum TBs at 89 GHz in the downshear left quadrant (DSLQ) for the northern hemisphere basins and in the downshear right quadrant (DSRQ) for the southern hemisphere basin, regarding the direction of the 200–850 hPa wind shear. Tropical depression and tropical storm have the minimum TBs in the downshear quadrants. The axis of the minimum TBs is slightly shifted toward the vertical shear direction. There is no geographic variation of storm structure relative to the vertical wind shear direction except over the southern hemisphere which shows a mirror image of the storm structure over the northern hemisphere. This study indicates that regional variation of storm structure relative to storm motion direction is mainly due to differences of the vertical wind shear direction among these basins. Results demonstrate the direction of the 200–850 hPa wind shear plays a critical role in TC structure.

scholarly journals The Hadley and Walker Circulation Changes in Global Warming Conditions Described by Idealized Atmospheric Simulations

2009 ◽  
Vol 22 (14) ◽  
pp. 3993-4013 ◽  
Author(s):  
Guillaume Gastineau ◽  
Laurent Li ◽  
Hervé Le Treut
Keyword(s):  
Global Warming ◽  
Large Scale ◽  
Hydrological Cycle ◽  
Coupled Model ◽  
Hadley Circulation ◽  
Hadley Cell ◽  
Coupled Models ◽  
The Mean ◽  
Sst Anomalies ◽  
Atmospheric Simulations

Abstract Sea surface temperature (SST) changes constitute a major indicator and driver of climate changes induced by greenhouse gas increases. The objective of the present study is to investigate the role played by the detailed structure of the SST change on the large-scale atmospheric circulation and the distribution of precipitation. For that purpose, simulations from the Institut Pierre-Simon Laplace Coupled Model, version 4 (IPSL-CM4) are used where the carbon dioxide (CO2) concentration is doubled. The response of IPSL-CM4 is characterized by the same robust mechanisms affecting the other coupled models in global warming simulations, that is, an increase of the hydrological cycle accompanied by a global weakening of the large-scale circulation. First, purely atmospheric simulations are performed to mimic the results of the coupled model. Then, specific simulations are set up to further study the underlying atmospheric mechanisms. These simulations use different prescribed SST anomalies, which correspond to a linear decomposition of the IPSL-CM4 SST changes in global, longitudinal, and latitudinal components. The simulation using a globally uniform increase of the SST is able to reproduce the modifications in the intensity of the hydrological cycle or in the mean upward mass flux, which also characterize the double CO2 simulation with the coupled model. But it is necessary (and largely sufficient) to also take into account the zonal-mean meridional structure of the SST changes to represent correctly the changes in the Hadley circulation strength or the zonal-mean precipitation changes simulated by the coupled model, even if these meridional changes by themselves do not change the mean thermodynamical state of the tropical atmosphere. The longitudinal SST anomalies of IPSL-CM4 also have an impact on the precipitation and large-scale tropical circulation and tend to introduce different changes over the Pacific and Atlantic Oceans. The longitudinal SST changes are demonstrated to have a smaller but opposite effect from that of the meridional anomalies on the Hadley cell circulations. Results indicate that the uncertainties in the simulated meridional patterns of the SST warming may have major consequences on the assessment of the changes of the Hadley circulation and zonal-mean precipitation in future climate projections.

scholarly journals Interannual Variability and Trends of Extratropical Ozone. Part II: Southern Hemisphere

2008 ◽  
Vol 65 (10) ◽  
pp. 3030-3041 ◽  
Author(s):  
Xun Jiang ◽  
Steven Pawson ◽  
Charles D. Camp ◽  
J. Eric Nielsen ◽  
Run-Lie Shia ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Climate Model ◽  
Observation System ◽  
Stationary Waves ◽  
Quasi Biennial Oscillation ◽  
Total Column Ozone ◽  
The Third ◽  
Column Ozone

A principal component analysis (PCA) is applied to the Southern Hemisphere (SH) total column ozone following the method established for analyzing the data in the Northern Hemisphere (NH) in a companion paper. The interannual variability (IAV) of extratropical O3 in the SH is characterized by four main modes, which account for 75% of the total variance. The first two leading modes are approximately zonally symmetric and relate to the Southern Hemisphere annular mode and the quasi-biennial oscillation. The third and fourth modes exhibit wavenumber-1 structures. Contrary to the Northern Hemisphere, the third and fourth modes are not related to stationary waves. Similar results are obtained for the 30–100-hPa geopotential thickness. The decreasing O3 trend in the SH is captured in the first mode. The largest trend is at the South Pole, with value ∼−2 Dobson Units (DU) yr−1. Both the spatial pattern and trends in the column ozone are captured by the Goddard Earth Observation System chemistry–climate model (GEOS-CCM) in the SH.

scholarly journals Hemispheric ozone variability indices derived from satellite observations and as diagnostics for coupled chemistry-climate models

2006 ◽  
Vol 6 (3) ◽  
pp. 5671-5709
Author(s):  
T. Erbertseder ◽  
V. Eyring ◽  
M. Bittner ◽  
M. Dameris ◽  
V. Grewe
Keyword(s):  
Interannual Variability ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Total Ozone ◽  
Large Scale ◽  
Model Simulation ◽  
Polar Vortex ◽  
Satellite Observations ◽  
Ozone Hole ◽  
Wave Number

Abstract. Dynamics and chemistry of the lower and middle stratosphere are characterized by manifold processes on different scales in time and space. The total column density of ozone, measured by numerous instruments, can be used to trace the resulting variability. In particular, satellite-borne spectrometers allow global observation of the total ozone distribution with proven accuracy and high temporal and spatial resolution. In order to analyse the zonal and hemispherical ozone variability a spectral statistical Harmonic Analysis is applied to multi-year total ozone observations from the Total Ozone Monitoring Spectrometer (TOMS). As diagnostic variables we introduce the hemispheric ozone variability indices one and two. They are defined as the hemispheric means of the amplitudes of the zonal waves number one and two, respectively, as traced by the total ozone field. In order to demonstrate the capability of the diagnostic for intercomparison studies we apply the hemispheric ozone variability indices to evaluate total ozone fields of the coupled chemistry-climate model ECHAM4.L39(DLR)/CHEM (hereafter: E39/C) against satellite observations. Results of a multi-year model simulation representing ''2000" climate conditions with an updated version of E39/C and corresponding total ozone data of TOMS from 1996 to 2004 (Version 8.0) are used. It is quantified to what extent E39/C is able to reproduce the zonal and hemispherical large scale total ozone variations. The different representations of the hemispheric ozone variability indices are discussed. Summarizing the main differences of model and reference observations, we show that both indices, one and two, in E39/C are preferably too high in the Northern Hemisphere and preferably too low in the Southern Hemisphere. In the Northern Hemisphere, where the coincidence is generally better, E39/C produces a too strong planetary wave one activity in winter and spring as well as a too high interannual variability. For the Southern Hemisphere we conclude that model and observations differ significantly during the ozone hole season. In October and November amplitudes of wave number one and two are underestimated. This explains that E39/C exhibits a too stable polar vortex and a too low interannual variability of the ozone hole. Further, a strong negative bias of wave number one amplitudes in the tropics and subtropics from October to December is identified, which may also contribute to the zonal-symmetric polar vortex. The lack of wave two variability in October and November leads to weak vortex elongation and eventually a too late final warming. Contrary, too high wave number two amplitudes in July and August indicate why the polar vortex is formed too late in season by E39/C. In general, the hemispheric ozone variability indices can be regarded as a simple and robust approach to quantify differences in total ozone variability on a monthly mean basis. Therefore, the diagnostic represents a core diagnostic for model intercomparisons within the CCM Validation Activity for WCRP's (World Climate Research Programme) SPARC (Stratospheric Processes and their Role in Climate) regarding stratospheric dynamics.

scholarly journals Weakening of Northwest Pacific Anticyclone Anomalies during Post–El Niño Summers under Global Warming

2018 ◽  
Vol 31 (9) ◽  
pp. 3539-3555 ◽  
Author(s):  
Wenping Jiang ◽  
Gang Huang ◽  
Ping Huang ◽  
Kaiming Hu
Keyword(s):  
Global Warming ◽  
Indian Ocean ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Northwest Pacific ◽  
Tropospheric Temperature ◽  
Coupled Models ◽  
Northwest Pacific Anticyclone ◽  
Sst Anomalies

The northwest Pacific anticyclone (NWPAC) anomalies during post–El Niño summers are a key predictor of the summer climate in East Asia and the northwestern Pacific (NWP). Understanding how this will change under global warming is crucial to project the changes in the variability of the northwest Pacific summer monsoon. Outputs from 18 selected coupled models from phase 5 of the Coupled Model Intercomparison Project show that the anomalous NWPAC response to El Niño will likely be weakened under global warming, which is attributed to the decreased zonal contrast between the tropical Indian Ocean (TIO) warming and the NWP cooling during post–El Niño summers. Under global warming, the NWPAC anomalies during the El Niño mature winter are weakened because of decreased atmospheric circulation in response to El Niño–Southern Oscillation (ENSO), which leads to the weakening of local air–sea interaction and then decreases the cold NWP SST anomalies. Furthermore, the decreased surface heat flux anomalies, the weakened anticyclone anomalies over the southeastern Indian Ocean, and the slackened anomalous easterlies over the north Indian Ocean weaken the warm TIO SST anomalies. However, the strengthened tropospheric temperature anomalies could enhance the anomalous TIO warming. Although the changes in TIO SST anomalies are indistinctive, the weakening of the SST anomaly gradient between the TIO and the NWP is robust to weaken the NWPAC anomalies during post–El Niño summers. Moreover, the positive feedback between the TIO–NWP SST anomalies and the NWPAC anomalies will enhance the weakening of NWPAC under global warming.

scholarly journals Long-Term Variations of Broad-Scale Asian Summer Monsoon Circulation and Possible Causes

2013 ◽  
Vol 26 (22) ◽  
pp. 8947-8961 ◽  
Author(s):  
Zhiyan Zuo ◽  
Song Yang ◽  
Renhe Zhang ◽  
Pinping Jiang ◽  
Li Zhang ◽  
...  
Keyword(s):  
Global Warming ◽  
Indian Ocean ◽  
Interannual Variability ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Vertical Shear ◽  
Tropospheric Temperature ◽  
The Indian Ocean ◽  
Asian Summer ◽  
Broad Scale

Abstract The widely applied Webster–Yang index (WYI), which measures the broad-scale dynamical features of the Asian summer monsoon (ASM), has experienced robust interannual and interdecadal variations and a decreasing tendency, with apparent shifts in 1972. The WYI exhibits moderate variability and frequent positive phases before 1972, intensive interannual variability during 1972–98, and an obvious decreasing tendency and mainly negative phase afterward. The vertical shear easterly anomalies over the tropics/subtropics and the anomalous vertical shear anticyclonic circulation over Eurasia (Eu) are the background for the decreasing WYI, associated with reduced summer precipitation around the Bay of Bengal and Sumatra. On interdecadal time scales, the negative (positive) Atlantic multidecadal oscillation (AMO) is characterized by cooling (warming) in Eurasian tropospheric temperature (TT) via the North Atlantic Oscillation. Global warming manipulates the increasing tendency and the interannual variability of TT over the Indian Ocean (IO). The mutual effects of AMO on Eurasian TT and global warming on Indian Ocean TT correspond to the similar decreasing tendency and interdecadal shift of the difference in TT between Eurasia and the Indian Ocean (EuTT − IOTT) with those of the ASM. Thus, the AMO and global warming seem to cause the interdecadal variability of ASM. Although the interannual relationship between Niño-3 SST and ASM weakens recently as a result of the weakening tendency of ASM, the Niño-3 SST still plays an important role in ASM variability via EuTT − IOTT anomalies. In addition, the WYI in the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis shows a larger decreasing tendency for 1999–2010 compared to other reanalysis products, a plausible reason for the inconsistent variations between land–sea thermal contrast and the NCEP–NCAR WYI during that period.

scholarly journals Changes in Global Blocking Character in Recent Decades

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 92 ◽  
Author(s):  
Anthony Lupo ◽  
Andrew Jensen ◽  
Igor Mokhov ◽  
Alexander Timazhev ◽  
Timothy Eichler ◽  
...  
Keyword(s):  
Interannual Variability ◽  
20Th Century ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
21St Century ◽  
Southern Oscillation ◽  
Late 20Th Century ◽  
Early 21St Century ◽  
Comprehensive List ◽  
Interannual Scale

A global blocking climatology published by this group for events that occurred during the late 20th century examined a comprehensive list of characteristics that included block intensity (BI). In addition to confirming the results of other published climatologies, they found that Northern Hemisphere (NH) blocking events (1968–1998) were stronger than Southern Hemisphere (SH) blocks and winter events are stronger than summer events in both hemispheres. This work also examined the interannual variability of blocking as related to El Niño and Southern Oscillation (ENSO). Since the late 20th century, there is evidence that the occurrence of blocking has increased globally. A comparison of blocking characteristics since 1998 (1998–2018 NH; 2000–2018 SH) shows that the number of blocking events and their duration have increased significantly in both hemispheres. The blocking BI has decreased by about six percent in the NH, but there was little change in the BI for the SH events. Additionally, there is little or no change in the primary genesis regions of blocking. An examination of variability related to ENSO reveals that the NH interannual-scale variations found in the earlier work has reversed in the early 21st century. This could either be the result of interdecadal variability or a change in the climate. Interdecadal variations are examined as well.

Which regional cloud-radiative changes are most important for the global warming response of the midlatitude jet streams?

2020 ◽  
Author(s):  
Nicole Albern ◽  
Aiko Voigt ◽  
David W. J. Thompson ◽  
Joaquim G. Pinto
Keyword(s):  
Global Warming ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
North Atlantic ◽  
Radiative Heating ◽  
Jet Stream ◽  
Jet Streams ◽  
The North ◽  
The North Atlantic ◽  
The Impact

<p>Clouds and the midlatitude circulation are strongly coupled via radiation. Previous studies showed that global cloud-radiative changes contribute significantly to the global warming response of the midlatitude circulation. Here, we investigate the impact of regional cloud-radiative changes and identify which regional cloud-radiative changes are most important for the impact of global cloud-radiative changes. We show how tropical, midlatitude and polar cloud-radiative changes modify the annual-mean, wintertime and summertime jet stream response to global warming across ocean basins. To this end, we perform global simulations with the atmospheric component of the ICOsahedral Nonhydrostatic (ICON) model. We prescribe sea surface temperatures (SST) to isolate the impact of cloud-radiative changes via the atmospheric pathway, i.e. changes in atmospheric cloud-radiative heating, and mimic global warming by a uniform 4K SST increase. We apply the cloud-locking method to break the cloud-radiation-circulation coupling and to decompose the circulation response into contributions from cloud-radiative changes and from the SST increase.</p><p>In response to global warming, the North Atlantic, North Pacific, Northern Hemisphere and Southern Hemisphere jet streams shift poleward and the North Atlantic, Northern Hemisphere and Southern Hemisphere jets strengthen. Global cloud-radiative changes contribute to these jet responses in all ocean basins. <span>In the annual-mean and DJF, tropical and midlatitude cloud-radiative changes contribute significantly to the poleward jet shift in all ocean basins. </span><span>P</span><span>olar cloud-radiative changes shift the jet streams </span><span>poleward </span><span>in the northern hemispheric ocean basins </span><span>but</span> <span>equatorward </span><span>in the Southern Hemisphere. In JJA, the poleward jet shift is small in all ocean basins. In contrast to the jet shift, the global cloud-radiative impacts on the 850hPa zonal wind and jet strength responses </span><span>result predominantly from </span><span>tropical cloud-radiative </span><span>changes</span><span>.</span></p><p><span>The cloud-radiative impact on the jet shift can be related to changes in upper-tropospheric baroclinicity via increases in upper-tropospheric meridional temperature gradients, enhanced wave activity and increased eddy momentum fluxes. However, the response of the atmospheric temperature to cloud-radiative heating is </span><span>more difficult to understand because it is modulated by other small-scale processes such as convection and the circulation.</span><span> Our results help to understand the jet stream response to global warming and highlight the importance of regional cloud-radiative changes for this response, </span><span>in particular those in the tropics</span><span>.</span></p>

scholarly journals CO<sub>2</sub> Surface Variability, from the Stratosphere or Not?

2021 ◽  
Author(s):  
Michael J. Prather
Keyword(s):  
Interannual Variability ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Transport Modeling ◽  
Great Precision ◽  
Recent Success ◽  
Potential Source ◽  
Measurement Analysis ◽  
Surface Variability ◽  
Natural Cycles

Abstract. Fluctuations in atmospheric CO2 can be measured with great precision and are used to identify human-driven sources as well as natural cycles of ocean and land carbon. One source of variability is the stratosphere, where the influx of aged CO2-depleted air can produce fluctuations at the surface. This process has been speculated a potential source of interannual variability (IAV) in CO2 that might obscure the quantification of other sources of IAV. Given the recent success in demonstrating that the stratospheric influx of N2O- and chlorofluorocarbon-depleted air is a dominant source of their surface IAV in the southern hemisphere, we here apply the same model and measurement analysis to CO2. Using chemistry-transport modeling or scaling of the observed N2O variability, we find that the stratosphere-driven surface variability in CO2 is at most 10 % of the observed IAV and is not an important source. The southern hemisphere stations with multi-decadal CO2 records can provide clues to sources through the phase shifts of the IAV relative to the northern hemisphere.

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