Mean Distribution of 500-mb Topography and Sea-Level Pressure in Middle and High Latitudes of the Northern Hemisphere during the 1950–59 Decade, January and July

1963 ◽  
Vol 2 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Willam R. Gommel
Keyword(s):  
Sea Level ◽  
Northern Hemisphere ◽  
High Latitudes ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
And Sea Level

Improved Skill of Northern Hemisphere Winter Surface Temperature Predictions Based on Land–Atmosphere Fall Anomalies

2007 ◽  
Vol 20 (16) ◽  
pp. 4118-4132 ◽  
Author(s):  
Judah Cohen ◽  
Christopher Fletcher
Keyword(s):  
Snow Cover ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Land Surface ◽  
Northern Eurasia ◽  
Dynamical Models ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Skill Scores ◽  
And Sea Level

Abstract A statistical forecast model, referred to as the snow-cast (sCast) model, has been developed using observed October mean snow cover and sea level pressure anomalies to predict upcoming winter land surface temperatures for the extratropical Northern Hemisphere. In operational forecasts since 1999, snow cover has been used for seven winters, and sea level pressure anomalies for three winters. Presented are skill scores for these seven real-time forecasts and also for 33 winter hindcasts (1972/73–2004/05). The model demonstrates positive skill over much of the eastern United States and northern Eurasia—regions that have eluded skillful predictions among the existing major seasonal forecast centers. Comparison with three leading dynamical forecast systems shows that the statistical model produces superior skill for the same regions. Despite the increasing complexity of the dynamical models, they continue to derive their forecast skill predominantly from tropical atmosphere–ocean coupling, in particular from ENSO. Therefore, in the Northern Hemisphere extratropics, away from the influence of ENSO, the sCast model is expected to outperform the dynamical models into the foreseeable future.

scholarly journals Dynamical properties and extremes of Northern Hemisphere climate fields over the past 60 years

2017 ◽  
Vol 24 (4) ◽  
pp. 713-725 ◽  
Author(s):  
Davide Faranda ◽  
Gabriele Messori ◽  
M. Carmen Alvarez-Castro ◽  
Pascal Yiou
Keyword(s):  
Phase Space ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Atmospheric Dynamics ◽  
Complex Nature ◽  
Human Welfare ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Dimensional Phase Space ◽  
Dynamical Properties

Abstract. Atmospheric dynamics are described by a set of partial differential equations yielding an infinite-dimensional phase space. However, the actual trajectories followed by the system appear to be constrained to a finite-dimensional phase space, i.e. a strange attractor. The dynamical properties of this attractor are difficult to determine due to the complex nature of atmospheric motions. A first step to simplify the problem is to focus on observables which affect – or are linked to phenomena which affect – human welfare and activities, such as sea-level pressure, 2 m temperature, and precipitation frequency. We make use of recent advances in dynamical systems theory to estimate two instantaneous dynamical properties of the above fields for the Northern Hemisphere: local dimension and persistence. We then use these metrics to characterize the seasonality of the different fields and their interplay. We further analyse the large-scale anomaly patterns corresponding to phase-space extremes – namely time steps at which the fields display extremes in their instantaneous dynamical properties. The analysis is based on the NCEP/NCAR reanalysis data, over the period 1948–2013. The results show that (i) despite the high dimensionality of atmospheric dynamics, the Northern Hemisphere sea-level pressure and temperature fields can on average be described by roughly 20 degrees of freedom; (ii) the precipitation field has a higher dimensionality; and (iii) the seasonal forcing modulates the variability of the dynamical indicators and affects the occurrence of phase-space extremes. We further identify a number of robust correlations between the dynamical properties of the different variables.

scholarly journals The influence of solar variability and the quasi-biennial oscillation on sea level pressure

2010 ◽  
Vol 10 (12) ◽  
pp. 30453-30471
Author(s):  
I. Roy ◽  
J. D. Haigh
Keyword(s):  
Solar Activity ◽  
Sea Level ◽  
The State ◽  
Solar Variability ◽  
The Sun ◽  
High Latitudes ◽  
Quasi Biennial Oscillation ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Biennial Oscillation

Abstract. We investigate an apparent inconsistency between two published results concerning the temperature of the winter polar stratosphere and its dependence on the state of the Sun and the phase of the Quasi-Biennial Oscillation (QBO). We find that the differences can be explained by the use of the authors of different pressure levels to define the phase of the QBO. We identify QBO and solar cycle signals in sea level pressure (SLP) data using a multiple linear regression approach. First we used a standard QBO time series dating back to 1953. In the SLP observations dating back to that time we find at high latitudes that individually the solar and QBO signals are weak but that a temporal index representing the combined effects of the Sun and the QBO shows a significant signal. This is such that combinations of low solar activity with westerly QBO and high solar activity with easterly QBO are both associated with a strengthening in the polar modes; while the opposite combinations coincide with a weakening. This result is true irrespective of the choice of QBO pressure level. By employing a QBO dataset reconstructed back to 1900, we extended the analysis and also find a robust signal in the surface SAM; though weaker for surface NAM. Our results suggest that solar variability, modulated by the phase of QBO, influences zonal mean temperatures at high latitudes in the lower stratosphere and subsequently affect sea level pressure near the poles. Thus a knowledge of the state of the Sun, and the phase of the QBO might be useful in surface climate prediction.

Atlas of Five-Day Normal Sea-Level Pressure Charts for the Northern Hemisphere

1958 ◽  
Vol 124 (3) ◽  
pp. 409
Author(s):  
S. Gregory ◽  
J. F. Lahey ◽  
R. A. Bryson ◽  
E. W. Wahl
Keyword(s):  
Sea Level ◽  
Northern Hemisphere ◽  
Sea Level Pressure ◽  
Level Pressure
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