Results 41 to 50 of about 668 (190)

The 1986–1989 ENSO cycle in a chemical climate model [PDF]

Atmospheric Chemistry and Physics, 2006
A pronounced ENSO cycle occurred from 1986 to 1989, accompanied by distinct dynamical and chemical anomalies in the global troposphere and stratosphere.
S. Brönnimann, M. Schraner, B. Müller, A. Fischer, D. Brunner, E. Rozanov, E. Rozanov, T. Egorova   +7 more
doaj  

The impact of different CO2 and ODS levels on the mean state and variability of the springtime Arctic stratosphere

Environmental Research Letters, 2023
Rising greenhouse gases (GHG) and decreasing anthropogenic ozone-depleting substances (ODS) are the main drivers of the stratospheric climate evolution in the 21st century.
Jessica Kult-Herdin, Timofei Sukhodolov, Gabriel Chiodo, Ramiro Checa-Garcia, Harald E Rieder   +4 more
doaj   +1 more source

Tropopause-level planetary wave source and its role in two-way troposphere–stratosphere coupling [PDF]

Weather and Climate Dynamics, 2020
Atmospheric planetary waves play a fundamental role in driving stratospheric dynamics, including sudden stratospheric warming (SSW) events. It is well established that the bulk of the planetary wave activity originates near the surface.
L. Boljka, T. Birner
doaj   +1 more source

The benefits of a hybrid‐3DEnVar data assimilation scheme for the convection‐permitting NWP model AROME–Austria

Quarterly Journal of the Royal Meteorological Society, EarlyView.
The climatological‐error covariance matrix used in three‐dimensional variational data assimilation (3DVar) provides smooth and isotropic increments spread to long distances. In contrast, three‐dimensional ensemble variational data assimilation (3DEnVar) with a purely ensemble‐error covariance matrix provides inhomogeneous increments and contains the ...
Kaushambi Jyoti, Philipp Griewank, Florian Meier, Martin Weissmann   +3 more
wiley   +1 more source

Forecast‐Error Diagnostics in Neural Weather Models

Quarterly Journal of the Royal Meteorological Society, EarlyView.
Deep learning weather prediction models enable efficient forecast‐error diagnostics through auto‐differentiation and low computational cost. We apply grid‐point relaxation and gradient‐based error sensitivity to identify key forecast‐error sources. Results show that medium‐range forecasts in the midlatitudes benefit most from relaxing the stratosphere ...
Uroš Perkan, Gregor Skok, Žiga Zaplotnik   +2 more
wiley   +1 more source

Ensemble reliability and the signal‐to‐noise paradox in ECMWF subseasonal forecasts

Quarterly Journal of the Royal Meteorological Society, EarlyView.
We derive a general expression for the ratio of predictable components (RPC) in terms of correlation, spread–error ratio, and total variance ratio. Physical constraints on the admissible solutions (i.e., real‐valued and non‐negative variances) provide a mechanism to identify statistically paradoxical sample combinations of reliability and correlation ...
Christopher D. Roberts, Frederic Vitart
wiley   +1 more source

Regime Behavior in the Upper Stratosphere as a Precursor of Stratosphere-Troposphere Coupling in the Northern Winter

Journal of Climate, 2021
AbstractA new regime index is constructed to capture the seasonal development of the stratospheric polar vortex in the northern winter, based on the standard deviation of Ertel’s potential vorticity in the upper stratosphere in November-December. The narrow-jet flow regime is characterized by a polar vortex that is more confined to high latitudes in ...
Lu, Hua, Gray, Lesley J., Martineau, Patrick, King, John C., Bracegirdle, Thomas J.   +4 more
openaire   +2 more sources

Scaling turbulence drives the general circulation

Quarterly Journal of the Royal Meteorological Society, EarlyView.
The NOAA Gulfstream SP4, which deployed the GPS dropsondes over the NE Pacific Ocean as part of the Winter Storms Project during the January–March periods of 2004, 2005 and 2006. Abstract Statistical multifractal analysis of airborne and dropsonde observations is used to show that persistence of velocity after molecular collisions breaks the continuous
Adrian F. Tuck
wiley   +1 more source

Tropospheric amplification of stratosphere–troposphere coupling

Quarterly Journal of the Royal Meteorological Society
Abstract During northern winter the stratospheric polar vortex is highly variable — even breaking down completely during sudden stratospheric warmings. The strength of the stratospheric polar vortex is observed to be coupled to surface weather, primarily through swings in the phase of the Northern Annular Mode — which is nearly ...
Mark P. Baldwin, Thomas Birner, Blanca Ayarzagüena   +2 more
openaire   +1 more source

Impact of Weak‐Constraint Four‐Dimensional Variational data assimilation on the prediction of a sudden stratospheric warming event in 2024

Quarterly Journal of the Royal Meteorological Society, EarlyView.
The Weak‐Constraint Four‐Dimensional Variational (WC‐4DVAR) system markedly improved the analysis and forecasting of the 2024 sudden stratospheric warming (SSW) event. It reduced biases and enhanced 7–9 day predictions of temperature across the SSW life cycle, with the most pronounced gains for winds also during the critical onset period.
Shaoying Li, Weimin Zhang, Shuo Ma, Bainian Liu, Yanlai Zhao, Xiaoqun Cao   +5 more
wiley   +1 more source