Comparing Cyclone Life Cycle Characteristics and Their Interannual Variability in Different Reanalyses

2013 ◽  
Vol 26 (17) ◽  
pp. 6419-6438 ◽  
Author(s):  
Natalia Tilinina ◽  
Sergey K. Gulev ◽  
Irina Rudeva ◽  
Peter Koltermann
Keyword(s):  
Interannual Variability ◽  
North Atlantic ◽  
North Pacific ◽  
Storm Track ◽  
Department Of Energy ◽  
The North ◽  
Decadal Scale ◽  
The North Atlantic ◽  
Highly Correlated ◽  
The North Pacific

Abstract Characteristics of Northern Hemisphere extratropical cyclone activity were compared for five concurrent reanalyses: the NCEP–U.S. Department of Energy (DOE) reanalysis (herein NCEP–DOE), the Japanese 25-year Reanalysis Project (JRA-25), the ECMWF Interim Re-Analysis (ERA-Interim), the National Aeronautics and Space Administration's Modern-Era Retrospective Analysis for Research and Applications (NASA-MERRA), and the NCEP Climate Forecast System Reanalysis (NCEP-CFSR), for the period 1979–2010 using a single cyclone tracking algorithm. The total number of cyclones, ranging from 1400 to more than 1800 yr−1, was found to depend strongly on the spatial resolution of the respective reanalysis. The largest cyclone population was identified using NASA-MERRA data, which also showed the highest occurrence of very deep cyclones. Of the reanalyses, two (NCEP–DOE and ERA-Interim) are associated with statistically significant positive trends in the total number of cyclones from 1% to 2% decade−1. These trends result from moderate and shallow cyclones contributing to approximately 90% of the total cyclone count on average. The number of very deep cyclones (<960 hPa) in the North Atlantic increased in most reanalyses until 1990 and then declined during the last decade. In the North Pacific, the number of these events reached a peak in 2000 and then decreased during the last decade. The winter pattern is characterized by robust trends in cyclone numbers, with an enhancement of the North Atlantic storm track and a weakening of the North Pacific subtropical storm track. In the summer, there is a robust intensification of the Mediterranean storm track and a decrease in counts over the North Atlantic. Interannual variability and decadal-scale variations of the cyclone counts are highly correlated among the reanalyses, with the greatest agreement in moderate and deep cyclones.

Contributions of Downstream Eddy Development to the Teleconnection between ENSO and the Atmospheric Circulation over the North Atlantic

2012 ◽  
Vol 25 (14) ◽  
pp. 4993-5010 ◽  
Author(s):  
Ying Li ◽  
Ngar-Cheung Lau
Keyword(s):  
North America ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Storm Track ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract The spatiotemporal evolution of various meteorological phenomena associated with El Niño–Southern Oscillation (ENSO) in the North Pacific–North American–North Atlantic sector is examined using both NCEP–NCAR reanalyses and output from a 2000-yr integration of a global coupled climate model. Particular attention is devoted to the implications of downstream eddy developments on the relationship between ENSO and the atmospheric circulation over the North Atlantic. The El Niño–related persistent events are characterized by a strengthened Pacific subtropical jet stream and an equatorward-shifted storm track over the North Pacific. The wave packets that populate the storm tracks travel eastward through downstream development. The barotropic forcing of the embedded synoptic-scale eddies is conducive to the formation of a flow that resembles the negative phase of the North Atlantic Oscillation (NAO). The more frequent and higher persistence of those episodes during El Niño winters contribute to the prevalence of negative NAO conditions. The above processes are further delineated by conducting a case study for the 2009/10 winter season, in which both El Niño and negative NAO conditions prevailed. It is illustrated that the frequent and intense surface cyclone development over North America and the western Atlantic throughout that winter are associated with upper-level troughs propagating across North America, which in turn are linked to downstream evolution of wave packets originating from the Pacific storm track.

Nature of the Differences in the Intraseasonal Variability of the Pacific and Atlantic Storm Tracks: A Diagnostic Study

2006 ◽  
Vol 63 (10) ◽  
pp. 2602-2615 ◽  
Author(s):  
Yi Deng ◽  
Mankin Mak
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Intraseasonal Variability ◽  
Storm Track ◽  
Late Winter ◽  
The North ◽  
The Pacific ◽  
The North Atlantic ◽  
Early Late ◽  
The North Pacific

Abstract On the basis of an intraseasonal variability index of storm track evaluated for 40 winters (1963–64 through 2003–04) of NCEP–NCAR reanalysis data, it is found that well-defined midwinter minimum [MWMIN; (midwinter maximum MWMAX)] occurs in 21 (8) winters over the North Pacific. In contrast, MWMIN (MWMAX) occurs in 4 (25) of the 40 winters over the North Atlantic. The power spectrum of such an index for the Pacific has a broad peak between 5 and 10 yr, whereas the spectrum of the index for the Atlantic has comparable power in two spectral bands: 2–2.8 and 3.5–8 yr. Over the North Pacific, the increase in the zonal asymmetry of the background baroclinicity as well as in the corresponding horizontal deformation of the time-mean jet from early/late winter to midwinter is distinctly larger in an MWMIN winter. Associated with these changes, there is a distinctly stronger barotropic damping rate in the January of an MWMIN winter. The increase in the net conversion rate of eddy kinetic energy from early/late winter to midwinter is much larger in an MWMAX winter than that in an MWMIN winter. Even though there is a modest increase in the barotropic damping from early/late winter to midwinter over the North Atlantic, it is overcompensated by a larger increase in the baroclinic conversion rate. That would result in MWMAX. These results are empirical evidences in support of a hypothesis that a significant enhancement of the barotropic damping relative to the baroclinic growth from early/late winter to midwinter is a major contributing factor to MWMIN of the Pacific storm track.

scholarly journals Changes in Northern Hemisphere Winter Storm Tracks under the Background of Arctic Amplification

2017 ◽  
Vol 30 (10) ◽  
pp. 3705-3724 ◽  
Author(s):  
Jiabao Wang ◽  
Hye-Mi Kim ◽  
Edmund K. M. Chang
Keyword(s):  
North America ◽  
North Atlantic ◽  
North Pacific ◽  
Storm Track ◽  
Storm Tracks ◽  
Arctic Amplification ◽  
Northeastern North America ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract An interdecadal weakening in the North Atlantic storm track (NAST) and a poleward shift of the North Pacific storm track (NPST) are found during October–March for the period 1979–2015. A significant warming of surface air temperature (Ts) over northeastern North America and a La Niña–like change in the North Pacific under the background of Arctic amplification are found to be the contributors to the observed changes in the NAST and the NPST, respectively, via modulation of local baroclinicity. The interdecadal change in baroclinic energy conversion is consistent with changes in storm tracks with an energy loss from eddies to mean flow over the North Atlantic and an energy gain over the North Pacific. The analysis of simulations from the Community Earth System Model Large Ensemble project, although with some biases in storm-track and Ts simulations, supports the observed relationship between the NAST and Ts over northeastern North America, as well as the link between the NPST and El Niño–Southern Oscillation. The near-future projections of Ts and storm tracks are characterized by a warmer planet under the influence of increasing greenhouse gases and a significant weakening of both the NAST and the NPST. The potential role of the NAST in redistributing changes in Ts over the surrounding regions is also examined. The anomalous equatorward moisture flux associated with the weakening trend of the NAST would enhance the warming over its upstream region and hinder the warming over its downstream region via modulation of the downward infrared radiation.

Baroclinic Development in Observations and NASA GSFC General Circulation Models

2006 ◽  
Vol 134 (4) ◽  
pp. 1161-1173 ◽  
Author(s):  
Dennis P. Robinson ◽  
Robert X. Black
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
General Circulation ◽  
Storm Track ◽  
Model Simulations ◽  
The North ◽  
The Pacific ◽  
The North Atlantic ◽  
The North Pacific ◽  
Midwinter Suppression

Abstract Comparative diagnostic analyses of developing synoptic-scale baroclinic disturbances in NCEP–NCAR reanalyses and the NASA–NCAR (NASCAR) and Aries [NASA’s Seasonal-to-Interannual Prediction Project (NSIPP)] general circulation model simulations are performed. In particular, lag composite analyses of wintertime cyclonic and anticyclonic events occurring in the North Pacific and North Atlantic storm tracks are constructed to pursue a synoptic and dynamic characterization of eddy development. The data are also seasonally stratified to study aspects of the North Pacific midwinter suppression phenomenon. Winter-averaged results indicate that the model-simulated events are generally too weak in amplitude, particularly in the upper troposphere. For the North Pacific storm track, model-simulated events are also anomalously distended in the meridional direction. The existing model biases in eddy structure and magnitude lead to anomalously weak baroclinic energy conversions for both cyclonic and anticyclonic events over the North Pacific. For the North Atlantic storm track the NASCAR model provides a very good representation of the structure of developing cyclonic events. However, growing North Atlantic cyclones in the NSIPP model are anomalously weak and horizontally too isotropic (meridionally retracted). These latter two characteristics are also observed in both models for developing anticyclonic flow anomalies over the North Atlantic. The relative weakness of NSIPP synoptic events over the North Atlantic region is largely responsible for the 50% deficiency in areal-averaged baroclinic energy conversions. Conversely, the NASCAR model climatology features anomalously strong temperature gradients over the western North Atlantic that provide local enhancements to the baroclinic energy conversion field. A seasonally stratified diagnostic analysis reveals that the simulated climatological storm tracks over the North Pacific undergo larger spatial migrations during the cool season compared to observations. It is further determined that the suppression of synoptic eddy activity observed in the Pacific storm track is associated with a relative midwinter weakness in the magnitude of the growing cyclonic anomalies. Specifically, during midwinter the cyclonic perturbations entering the Pacific storm track are deficient in magnitude compared to their early and late winter counterparts. It is also discovered that the midwinter suppression pattern over the North Pacific region has a clear organized extension upstream into Siberia, the region from which incipient upper-tropospheric short-wave features emanate. This behavior is found in both observations and the model simulations. The results herein support the idea that the North Pacific midwinter suppression phenomenon is linked to a midwinter weakness in the upstream formation of upper-level short waves, leading to anomalously weak “seeding” of baroclinic disturbances in the Pacific storm track.

The Role of Oscillating Southern Hemisphere Westerly Winds: Global Ocean Circulation

2020 ◽  
Vol 33 (6) ◽  
pp. 2111-2130
Author(s):  
Woo Geun Cheon ◽  
Jong-Seong Kug
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
North Pacific ◽  
Global Ocean ◽  
The North ◽  
Westerly Winds ◽  
The North Atlantic ◽  
Global Ocean Circulation ◽  
The Antarctic ◽  
The North Pacific

AbstractIn the framework of a sea ice–ocean general circulation model coupled to an energy balance atmospheric model, an intensity oscillation of Southern Hemisphere (SH) westerly winds affects the global ocean circulation via not only the buoyancy-driven teleconnection (BDT) mode but also the Ekman-driven teleconnection (EDT) mode. The BDT mode is activated by the SH air–sea ice–ocean interactions such as polynyas and oceanic convection. The ensuing variation in the Antarctic meridional overturning circulation (MOC) that is indicative of the Antarctic Bottom Water (AABW) formation exerts a significant influence on the abyssal circulation of the globe, particularly the Pacific. This controls the bipolar seesaw balance between deep and bottom waters at the equator. The EDT mode controlled by northward Ekman transport under the oscillating SH westerly winds generates a signal that propagates northward along the upper ocean and passes through the equator. The variation in the western boundary current (WBC) is much stronger in the North Atlantic than in the North Pacific, which appears to be associated with the relatively strong and persistent Mindanao Current (i.e., the southward flowing WBC of the North Pacific tropical gyre). The North Atlantic Deep Water (NADW) formation is controlled by salt advected northward by the North Atlantic WBC.

scholarly journals On the Relationship between Synoptic Wintertime Atmospheric Variability and Path Shifts in the Gulf Stream and the Kuroshio Extension

2009 ◽  
Vol 22 (12) ◽  
pp. 3177-3192 ◽  
Author(s):  
Terrence M. Joyce ◽  
Young-Oh Kwon ◽  
Lisan Yu
Keyword(s):  
North Atlantic ◽  
North Pacific ◽  
Gulf Stream ◽  
Kuroshio Extension ◽  
Storm Track ◽  
Western Boundary ◽  
Atmospheric Variability ◽  
The North ◽  
The Kuroshio ◽  
The North Pacific

Abstract Coherent, large-scale shifts in the paths of the Gulf Stream (GS) and the Kuroshio Extension (KE) occur on interannual to decadal time scales. Attention has usually been drawn to causes for these shifts in the overlying atmosphere, with some built-in delay of up to a few years resulting from propagation of wind-forced variability within the ocean. However, these shifts in the latitudes of separated western boundary currents can cause substantial changes in SST, which may influence the synoptic atmospheric variability with little or no time delay. Various measures of wintertime atmospheric variability in the synoptic band (2–8 days) are examined using a relatively new dataset for air–sea exchange [Objectively Analyzed Air–Sea Fluxes (OAFlux)] and subsurface temperature indices of the Gulf Stream and Kuroshio path that are insulated from direct air–sea exchange, and therefore are preferable to SST. Significant changes are found in the atmospheric variability following changes in the paths of these currents, sometimes in a local fashion such as meridional shifts in measures of local storm tracks, and sometimes in nonlocal, broad regions coincident with and downstream of the oceanic forcing. Differences between the North Pacific (KE) and North Atlantic (GS) may be partly related to the more zonal orientation of the KE and the stronger SST signals of the GS, but could also be due to differences in mean storm-track characteristics over the North Pacific and North Atlantic.

Satellite-Derived Tropical Cyclone Intensity in the North Pacific Ocean Using the Deviation-Angle Variance Technique

2014 ◽  
Vol 29 (3) ◽  
pp. 505-516 ◽  
Author(s):  
Elizabeth A. Ritchie ◽  
Kimberly M. Wood ◽  
Oscar G. Rodríguez-Herrera ◽  
Miguel F. Piñeros ◽  
J. Scott Tyo
Keyword(s):  
Tropical Cyclone ◽  
North Atlantic ◽  
North Pacific ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Deviation Angle ◽  
Intensity Estimation ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract The deviation-angle variance technique (DAV-T), which was introduced in the North Atlantic basin for tropical cyclone (TC) intensity estimation, is adapted for use in the North Pacific Ocean using the “best-track center” application of the DAV. The adaptations include changes in preprocessing for different data sources [Geostationary Operational Environmental Satellite-East (GOES-E) in the Atlantic, stitched GOES-E–Geostationary Operational Environmental Satellite-West (GOES-W) in the eastern North Pacific, and the Multifunctional Transport Satellite (MTSAT) in the western North Pacific], and retraining the algorithm parameters for different basins. Over the 2007–11 period, DAV-T intensity estimation in the western North Pacific results in a root-mean-square intensity error (RMSE, as measured by the maximum sustained surface winds) of 14.3 kt (1 kt ≈ 0.51 m s−1) when compared to the Joint Typhoon Warning Center best track, utilizing all TCs to train and test the algorithm. The RMSE obtained when testing on an individual year and training with the remaining set lies between 12.9 and 15.1 kt. In the eastern North Pacific the DAV-T produces an RMSE of 13.4 kt utilizing all TCs in 2005–11 when compared with the National Hurricane Center best track. The RMSE for individual years lies between 9.4 and 16.9 kt. The complex environment in the western North Pacific led to an extension to the DAV-T that includes two different radii of computation, producing a parametric surface that relates TC axisymmetry to intensity. The overall RMSE is reduced by an average of 1.3 kt in the western North Pacific and 0.8 kt in the eastern North Pacific. These results for the North Pacific are comparable with previously reported results using the DAV for the North Atlantic basin.

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