Contribution of the two types of Ekman pumping induced eddy heat flux to the total vertical eddy heat flux

2021 ◽  
Author(s):  
Dapeng Li ◽  
Ping Chang ◽  
Sanjiv Ramachandran ◽  
Zhao Jing ◽  
Qiuying Zhang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Ekman Pumping ◽  
Eddy Heat Flux ◽  
Vertical Eddy

scholarly journals Influence of Northern Hemispheric Winter Warming on the Pacific Storm Track

2021 ◽  
Author(s):  
Hyung-Ju Park ◽  
Kwang-Yul Kim
Keyword(s):  
Heat Flux ◽  
Global Warming ◽  
Energy Conversion ◽  
Storm Track ◽  
The Arctic ◽  
Late Winter ◽  
Turbulent Heat ◽  
Early Winter ◽  
Eddy Heat Flux ◽  
Northern Hemispheric

AbstractEffect of global warming on the sub-seasonal variability of the Northern Hemispheric winter (NDJFM) Pacific storm-track (PST) activity has been investigated. Previous studies showed that the winter-averaged PST has shifted northward and intensified, which was explained in terms of energy exchange with the mean field. Effect of global warming exhibits spatio-temporal heterogeneity with predominance over the Arctic region and in the winter season. Therefore, seasonal averaging may hide important features on sub-seasonal scales. In this study, distinct sub-seasonal response in storm track activities to winter Northern Hemispheric warming is analyzed applying cyclostationary empirical orthogonal function analysis to ERA5 data. The key findings are as follows. Change in the PST is not uniform throughout the winter; the PST shifts northward in early winter (NDJ) and intensifies in late winter (FM). In early winter, the combined effect of weakened baroclinic process to the south of the climatological PST and weakened barotropic damping to the north is responsible for the northward shift. In late winter, both processes contribute to the amplification of the PST. Further, change in baroclinic energy conversion is quantitatively dominated by eddy heat flux, whereas axial tilting of eddies is primarily responsible for change in barotropic energy conversion. A close relationship between anomalous eddy heat flux and anomalous boundary heating, which is largely determined by surface turbulent heat flux, is also demonstrated.

On the quality of eddy heat flux calculations in the vicinity of the Antarctic lower stratosphere

1990 ◽  
Vol 17 (11) ◽  
pp. 1901-1904
Author(s):  
Richard D. Rosen ◽  
David A. Salstein ◽  
Alvin J. Miller
Keyword(s):  
Heat Flux ◽  
Lower Stratosphere ◽  
Eddy Heat Flux ◽  
The Antarctic

Eddy Modulation of Air–Sea Interaction and Convection

2008 ◽  
Vol 38 (1) ◽  
pp. 65-83 ◽  
Author(s):  
Ivana Cerovečki ◽  
John Marshall
Keyword(s):  
Heat Flux ◽  
Heat Budget ◽  
Formation Rate ◽  
Mean Flow ◽  
Mode Water ◽  
Ocean Eddies ◽  
Eddy Heat Flux ◽  
Water Formation ◽  
Transformed Eulerian Mean

Abstract Eddy modulation of the air–sea interaction and convection that occurs in the process of mode water formation is analyzed in simulations of a baroclinically unstable wind- and buoyancy-driven jet. The watermass transformation analysis of Walin is used to estimate the formation rate of mode water and to characterize the role of eddies in that process. It is found that diabatic eddy heat flux divergences in the mixed layer are comparable in magnitude, but of opposite sign, to the surface air–sea heat flux and largely cancel the direct effect of buoyancy loss to the atmosphere. The calculations suggest that mode water formation estimates based on climatological air–sea heat flux data and outcrops, which do not fully resolve ocean eddies, may neglect a large opposing term in the heat budget and are thus likely to significantly overestimate true formation rates. In Walin’s watermass transformation framework, this manifests itself as a sensitivity of formation rate estimates to the averaging period over which the outcrops and air–sea fluxes are subjected. The key processes are described in terms of a transformed Eulerian-mean formalism in which eddy-induced mean flow tends to cancel the Eulerian-mean flow, resulting in weaker residual mean flow, subduction, and mode water formation rates.

scholarly journals Influence of Early Winter Upward Wave Activity Flux on Midwinter Circulation in the Stratosphere and Troposphere

2004 ◽  
Vol 17 (22) ◽  
pp. 4443-4452 ◽  
Author(s):  
Alexei Karpetchko ◽  
Grigory Nikulin
Keyword(s):  
Heat Flux ◽  
Reanalysis Data ◽  
Wave Activity ◽  
Heat Fluxes ◽  
Early Winter ◽  
Polar Night ◽  
Wave Refraction ◽  
Eddy Heat Flux ◽  
Wave Flux

Abstract Using NCEP–NCAR reanalysis data the authors show that the November–December averaged stratospheric eddy heat flux is strongly anticorrelated with the January–February averaged eddy heat flux in the midlatitude stratosphere and troposphere. This finding further emphasizes differences between early and midwinter stratospheric wave flux behavior, which has recently been found in long-term variations. Analysis suggests that the intraseasonal anticorrelation of stratospheric heat fluxes results from changes in the upward wave propagation in the troposphere. Stronger (weaker) upward wave fluxes in early winter lead to weaker (stronger) upward wave fluxes from the troposphere during midwinter. Also, enhanced equatorward wave refraction during midwinter (due to the stronger polar night jet) is associated with weak heat flux in the early winter. It is suggested that the effect of enhanced midwinter upward wave flux from the troposphere in the years with weak early winter heat flux overcompensates the effect of increased equatorward wave refraction in midwinter, leading to a net increase of midwinter upward wave fluxes into the stratosphere.

scholarly journals Vertical Structure and Energetics of the Western Pacific Teleconnection Pattern

2016 ◽  
Vol 29 (18) ◽  
pp. 6597-6616 ◽  
Author(s):  
Sho Tanaka ◽  
Kazuaki Nishii ◽  
Hisashi Nakamura
Keyword(s):  
Heat Flux ◽  
North Pacific ◽  
Thermal Gradient ◽  
Far East ◽  
Storm Track ◽  
Lower Troposphere ◽  
Western Pacific ◽  
Mean Flow ◽  
Eddy Heat Flux ◽  
The Western Pacific

Abstract The western Pacific (WP) pattern, characterized by north–south dipolar anomalies in pressure over the Far East and western North Pacific, is known as one of the dominant teleconnection patterns in the wintertime Northern Hemisphere. Composite analysis reveals that monthly height anomalies exhibit baroclinic structure with their phase lines tilting southwestward with height in the lower troposphere. The anomalies can thus yield not only a poleward heat flux across the climatological thermal gradient across the strong Pacific jet but also a westward heat flux across the climatological thermal gradient between the North Pacific and the cooler Asian continent. The resultant baroclinic conversion of available potential energy (APE) from the climatological-mean flow contributes most efficiently to the APE maintenance of the monthly WP pattern, acting against strong thermal damping effects by anomalous heat exchanges with the underlying ocean and anomalous precipitation in the subtropics and by the effect of anomalous eddy heat flux under modulated storm-track activity. Kinetic energy (KE) of the pattern is maintained through barotropic feedback forcing associated with modulated activity of transient eddies and the conversion from the climatological-mean westerlies, both of which act against frictional damping. The net feedback forcing by transient eddies is therefore not particularly efficient. The present study suggests that the WP pattern has a characteristic of a dynamical mode that can maintain itself through efficient energy conversion from the climatological-mean fields even without external forcing, including remote influence from the tropics.

scholarly journals The mean meridional circulation and midlatitude ozone buildup

2005 ◽  
Vol 5 (3) ◽  
pp. 4223-4256
Author(s):  
G. Nikulin ◽  
A. Karpechko
Keyword(s):  
Heat Flux ◽  
North Pacific ◽  
Meridional Circulation ◽  
Residual Velocity ◽  
The North ◽  
Eddy Heat Flux ◽  
Mean Meridional Circulation ◽  
The Mean ◽  
Temperature Tendency ◽  
The North Pacific

Abstract. The development of wintertime ozone buildup over the Northern Hemisphere (NH) midlatitudes and its connection with the mean meridional circulation in the stratosphere are examined statistically on a monthly basis from October to March (1980–2002). The ozone buildup begins locally in October with positive ozone tendencies over the North Pacific, which spread eastward and westward in November and finally cover all midlatitudes in December. During October–January a longitudinal distribution of the ozone tendencies mirrors a structure of quasi-stationary planetary waves in the lower stratosphere and has less similarity with this structure in February–March when chemistry begins to play a more important role. From November to March, zonal mean ozone tendencies (50°–60° N) show strong correlation (|r|=0.7) with different parameters used as proxies of the mean meridional circulation, namely: eddy heat flux, the vertical residual velocity (diabatically-derived) and temperature tendency. The correlation patterns between ozone tendency and the vertical residual velocity or temperature tendency are more homogeneous from month to month than ones for eddy heat flux. A partial exception is December when correlation is strong only for the vertical residual velocity. In October zonal mean ozone tendencies have no coupling with the proxies. However, positive tendencies averaged over the North Pacific correlate well, with all of them suggesting that intensification of northward ozone transport starts locally over the Pacific already in October. We show that the NH midlatitude ozone buildup has stable statistical relation with the mean meridional circulation in all months from October to March and half of the interannual variability in monthly ozone tendencies can be explained by applying different proxies of the mean meridional circulation.

scholarly journals Total ozone trends and variability during 1979–2012 from merged datasets of various satellites

2013 ◽  
Vol 13 (11) ◽  
pp. 30407-30452 ◽  
Author(s):  
W. Chehade ◽  
J. P. Burrows ◽  
M. Weber
Keyword(s):  
Heat Flux ◽  
Solar Cycle ◽  
Trend Analysis ◽  
Total Ozone ◽  
Montreal Protocol ◽  
The Other ◽  
The Arctic ◽  
Eddy Heat Flux ◽  
Other Hand

Abstract. The study presents a~long term statistical trend analysis of total ozone datasets obtained from various satellites. A multi-variate linear regression was applied to annual mean zonal mean data using various natural and anthropogenic explanatory variables that represent dynamical and chemical processes which modify global ozone distributions in a changing climate. The study investigated the magnitude and zonal distribution of the different atmospheric chemical and dynamical factors to long-term total ozone changes. The regression model included the equivalent effective stratospheric chlorine (EESC), the 11 yr solar cycle, the Quasi-Biennial Oscillation (QBO), stratospheric aerosol loading describing the effects from major volcanic eruptions, the El Niño/Southern Oscillation (ENSO), the Arctic and Antarctic Oscillation (AO/AAO), and accumulated eddy heat flux (EHF), the latter representing changes due to the Brewer–Dobson circulation. The total ozone column dataset used here comprises the SBUV/TOMS/OMI merged data (1979–2012) MOD V8.0, the SBUV/SBUV-2 merged V8.6 and the merged GOME/SCIAMACHY/GOME-2 (GSG) WFDOAS merged data (1995–2012). The trend analysis was performed for twenty six 5° wide latitude bands from 65° S to 65° N, the analysis explained most of the ozone variability. The results show that QBO dominates the ozone variability in the tropics (±7 DU) while at higher latitudes, the dynamical indices, AO/AAO and eddy heat flux, have substantial influence on total ozone variations by up to ±10 DU. Volcanic aerosols are only prominent during the eruption periods and these together with the ENSO signal are more evident in the Northern Hemisphere. The signature of the solar cycle is evident over all latitudes and contributes about 10 DU from solar maximum to solar minimum. EESC is found to be a main contributor to the long-term ozone decline and the trend changes after the end of 1990s. A positive significant trend in total ozone columns is found after 1997 (between 1 and 8.2 DU decade−1) which points at the slowing of ozone decline and the onset of ozone recovery. The EESC based trends are compared with the trends obtained from the statistical piecewise linear trend (PWLT or hockey stick) model with a turnaround in 1997 to examine the differences between both approaches. Similar and significant pre-turnaround trends are observed. On the other hand, our results do indicate that the positive PWLT turnaround trends are larger than indicated by the EESC trends, however, they agree within 2-sigma, thus demonstrating the success of the Montreal Protocol phasing out of the ozone depleting substances (ODS). A sensitivity study is carried out by comparing the regression results, using SBUV MOD 8.0 merged time series (1979–2012) and a merged dataset combining TOMS/SBUV (1979–June 1995) and GOME/SCIAMACHY/GOME-2 ("GSG") WFDOAS (Weighting Function DOAS) (July 1995–2012) as well as SBUV/SBUV-2 MOD 8.6 (1979–2012) in the regression analysis in order to investigate the uncertainty in the long-term trends due to different ozone datasets and data versions. Replacing the late SBUV merged data record with GSG data (unscaled and adjusted) leads to very similar results demonstrating the high consistency between satellite datasets. However, the comparison of the new SBUV merged Mod V8.6 with the V8.0 data showed somewhat smaller sensitivities with regard to several proxies, however, the EESC and PWLT trends are very similar. On the other hand, the new MOD 8.6 data in the PWLT model revealed a~reduced ODS related upward trend after 1997.

New estimates for the heat flux across the Polar Front: spatial and temporal variability in recent years

2013 ◽  
Vol 25 (3) ◽  
pp. 433-444 ◽  
Author(s):  
João Marcos Azevedo Correia De Souza ◽  
Afonso De Moraes Paiva ◽  
Karina Von Schuckmann
Keyword(s):  
Heat Flux ◽  
Heat Balance ◽  
Polar Front ◽  
Spatial And Temporal Variability ◽  
Large Contribution ◽  
Direct Estimate ◽  
Atlantic Sector ◽  
Eddy Heat Flux ◽  
Temporal And Spatial Variability ◽  
Eddy Fluxes

AbstractTwo different methodologies are applied in order to quantify the eddy contribution to the heat flux across the Polar Front, between January 2006 and December 2009. First, the eddy fluxes are indirectly estimated through a heat balance based on geostrophic fluxes obtained from the Argo climatological temperature and salinity. Second, a parametric model based on sea level anomaly data from a merged satellite product is used to obtain a direct estimate of the eddy heat flux and its temporal and spatial variability. The results obtained through the heat balance (-80.5 ± 16.45 x 1013 W) and the parameterization (-56.2 ± 4.18 x 1013 W) are within the range established by previous studies. The eddy heat flux is observed to be concentrated in a few narrow regions, with a particularly large contribution from the Atlantic sector. A trend of intensification of the southward heat flux is observed in the study period (-0.44 x 1013 W year-1), compatible with recent modelling and observational studies.

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