Regional Analysis of Northern Hemisphere 50 kPa Geopotential Heights from 1946 to 1985

Shabbar, Amir; Higuchi, Kaz; Knox, John L.

doi:10.1175/1520-0442(1990)003<0543:raonhk>2.0.co;2

Cited by 37 publications

(23 citation statements)

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“…This timing coincides with our estimate for the end of the trend transitional period. Knox et al (1988) and Shabbar et al (1990) identify a sharp drop in the 500-hPa geopotential height and argue that the 1962-1964 period marks an abrupt transition between two different climate regimes. Higuchi (1985) documents an abrupt decrease of the 500-1000-hPa geopotential thickness in [1962][1963][1964].…”

Section: Discussionmentioning

confidence: 94%

1963: The break point of the Northern Hemisphere temperature trend during the twentieth century

Ivanov

Evtimov

2009

Intl Journal of Climatology

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Besides gradually, climate can also change abruptly. The global surface temperature series is a major indicator of such changes. Using rigorous statistical tools, we show that during the twentieth century the time series of annual Northern Hemisphere surface temperature is well described by a trend-stationary process, but the trend line breaks in 1963. After six transitory years, in 1970, the temperature course locks up into a new regime with a triple linear warming rate. For the emergence and abruptness of the break we reveal the key roles of the Mount Agung eruption and the interannual to interdecadal changes of the major modes and patterns of climate variability. We offer an abrupt climate shift scenario based on the adaptivity of climatic regimes against instant external forcings.

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Section: Discussionmentioning

confidence: 94%

1963: The break point of the Northern Hemisphere temperature trend during the twentieth century

Ivanov

Evtimov

2009

Intl Journal of Climatology

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“…Despite the somewhat inhomogeneous nature of the data set used in this study, we anticipate that the major large scale features of the eddy transport of sensible heat in the northern latitudes will be depicted realistically. For a further discussion on the nature of the data, the reader is directed to Knox et al (1988), Shabbar et al (1990), and Lambert (1990).…”

Section: Data and Proceduresmentioning

confidence: 99%

Interannual Variability of the January Tropospheric Meridional Eddy Sensible Heat Transport in the Northern Latitudes

Higuchi¹,

Lin²,

Shabbar³

et al. 1991

Journal of the Meteorological Society of Japan

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“…In particular, the extension of the upper-air network of observations prior to the National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR) reanalysis (1948), is essential to improve our understanding of tropospheric circulation changes over the last century and the role that these changes may have had on past extreme climate events. Past droughts over the Great Plains and Canadian Prairies and their possible relation to the tropical oceans can only be understood in the context of the midtropospheric circulation over the Pacific-North American (PNA) sector (see, e.g., Namias 1978;Trenberth et al 1988;Trenberth and Branstator 1992;Shabbar et al 1990;Maybank et al 1995;Trenberth and Guillemot 1996;Chen and Newman 1998;Bonsal et al 1999;Garnett 2001). The same holds for climate extremes in the Arctic.…”

Section: Introductionmentioning

confidence: 99%

An Extended Pacific–North American Index from Upper-Air Historical Data Back to 1922

2008

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This paper presents a reconstruction of a Pacific-North America (PNA) index from historical upper-level data for the period 1922-47. The data have been compiled from a number of sources and cover the Pacific-North American sector relatively well over this time period. Temperature and geopotential height profiles from aircraft, kite, and radiosonde ascents back to 1922 have been digitized and validated. Wind speed and direction from pilot balloon data back to the early 1920s, provided by NCAR, have also been used. A statistical regression approach is used for the reconstruction and calibrated in the post-1948 period using NCEP-NCAR reanalysis data. Split-sample validation experiments were performed within the NCEP-NCAR period, and sensitivity experiments with different subsets of predictors were performed. Similar reconstructions and validation experiments were carried out using a 540-yr control run from the Community Climate System Model, version 3 (CCSM3). The reconstructed index series together with validation statistics for both the historical and model data are presented. Excellent reconstruction skill is found for the winter months, while the reconstructions are somewhat worse in summer. Compared with a reconstruction based only on surface data, the addition of the newly digitized upper-air stations improves the reconstruction skill in all seasons. The historical reconstruction is presented with respect to its imprint on hemispheric fields of surface air temperature, sea level pressure, and precipitation with a special focus on extreme cases. In addition, the extended PNA index is compared with indices of the North Atlantic Oscillation, the Pacific decadal oscillation, and the El Niño-Southern Oscillation. The relationship to these indices is found to be stationary over the analysis period. Wind speed and direction from pilot balloon data back to the early 1920s, provided by NCAR, have also been used. A statistical regression approach is used for the reconstruction and calibrated in the post-1948 period using NCEP-NCAR reanalysis data. Split-sample validation experiments were performed within the NCEP-NCAR period, and sensitivity experiments with different subsets of predictors were performed. Similar reconstructions and validation experiments were carried out using a 540-yr control run from the Community Climate System Model, version 3 (CCSM3). The reconstructed index series together with validation statistics for both the historical and model data are presented. Excellent reconstruction skill is found for the winter months, while the reconstructions are somewhat worse in summer. Compared with a reconstruction based only on surface data, the addition of the newly digitized upper-air stations improves the reconstruction skill in all seasons. The historical reconstruction is presented with respect to its imprint on hemispheric fields of surface air temperature, sea level pressure, and precipitation with a special focus on extreme cases. In addition, the extended PNA index is compared with indices o...

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Regional Analysis of Northern Hemisphere 50 kPa Geopotential Heights from 1946 to 1985

Cited by 37 publications

References 0 publications

1963: The break point of the Northern Hemisphere temperature trend during the twentieth century

1963: The break point of the Northern Hemisphere temperature trend during the twentieth century

Interannual Variability of the January Tropospheric Meridional Eddy Sensible Heat Transport in the Northern Latitudes

An Extended Pacific–North American Index from Upper-Air Historical Data Back to 1922

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