Covariability of Components of Poleward Atmospheric Energy Transports on Seasonal and Interannual Timescales

Trenberth, Kevin E.; Stepaniak, David P.

doi:10.1175/1520-0442(2003)016<3691:cocopa>2.0.co;2

Cited by 204 publications

(183 citation statements)

References 23 publications

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“…In the NH mid-latitudes the disagreement is around 10 % where EC-Earth underestimates the total transport relative to ERA-Interim. The annual EC-Earth transports are also roughly similar to estimates from the NCEP-NCAR reanalysis reported by Trenberth and Stepaniak (2003), but are somewhat larger than the estimation based on rawinsonde measurements over the period 1963-1973 documented by Oort and Peixoto (1983).…”

Section: Atmospheric Meridional Energy Transportsupporting

confidence: 69%

Arctic climate change in 21st century CMIP5 simulations with EC-Earth

et al. 2012

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The Arctic climate change is analyzed in an ensemble of future projection simulations performed with the global coupled climate model EC-Earth2.3. EC-Earth simulates the twentieth century Arctic climate relatively well but the Arctic is about 2 K too cold and the sea ice thickness and extent are overestimated. In the twenty-first century, the results show a continuation and strengthening of the Arctic trends observed over the recent decades, which leads to a dramatically changed Arctic climate, especially in the high emission scenario RCP8.5. The annually averaged Arctic mean near-surface temperature increases by 12 K in RCP8.5, with largest warming in the Barents Sea region. The warming is most pronounced in winter and autumn and in the lower atmosphere. The Arctic winter temperature inversion is reduced in all scenarios and disappears in RCP8.5. The Arctic becomes ice free in September in all RCP8.5 simulations after a rapid reduction event without recovery around year 2060. Taking into account the overestimation of ice in the twentieth century, our model results indicate a likely ice-free Arctic in September around 2040. Sea ice reductions are most pronounced in the Barents Sea in all RCPs, which lead to the most dramatic changes in this region. Here, surface heat fluxes are strongly enhanced and the cloudiness is substantially decreased. The meridional heat flux into the Arctic is reduced in the atmosphere but increases in the ocean. This oceanic increase is dominated by an enhanced heat flux into the Barents Sea, which strongly contributes to the large sea ice reduction and surface-air warming in this region. Increased precipitation and river runoff lead to more freshwater input into the Arctic Ocean. However, most of the additional freshwater is stored in the Arctic Ocean while the total Arctic freshwater export only slightly increases.

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Section: Atmospheric Meridional Energy Transportsupporting

confidence: 69%

Arctic climate change in 21st century CMIP5 simulations with EC-Earth

et al. 2012

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“…The small-scale structure, which clearly originates from the budget calculations, relates to the divergence term. The differences of the model precipitation with observations are quite similar to those for ERA-40 for January 1989 (Trenberth and Smith 2008). However, the radiation biases are rather different and larger for JRA.…”

Section: A Vertical Integrals For January 1989supporting

confidence: 62%

“…In the current study, we report on the analysis of the atmospheric energetics and heat budget from JRA and their comparison to observational constraints, with a primary focus on one month, January 1989, in detail as a follow on to two studies which used the same month to document computational issues for the vertically-integrated (Trenberth et al 2002a) and full three dimensional (Trenberth and Smith 2008) energy quantities using other reanalyses. The mean annual cycle and monthly anomaly time series are also examined and compared with those of other reanalyses to determine reproducibility and credibility of results.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Energy Budgets in the Japanese Reanalysis: Evaluation and Variability

Trenberth

Smith

2008

Journal of the Meteorological Society of Japan

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579 IntroductionA continuing interest is to document the flow of energy through the climate system for the annual mean, its annual cycle and its variability. The main focus of our work has been on the bulk vertically-integrated atmospheric energy budget (Trenberth et al. 2001; Stepaniak 2003a, b, 2004) and especially the role of water (Trenberth et al. 2007). The main datasets required are the full atmospheric analyses of all the state variables every 6 hours to enable the computation of various energy forms (internal energy, sensible heat, latent energy, potential energy, dry static energy, moist static energy, and kinetic energy), the storage and changes in storage (tendency) of these components, and their transports and divergences. In the past we have made extensive use of reanalyses from National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) (referred to as NRA) (Kalnay et al. 1996) and the European Centre for Medium Range Weather Forecasts (ECMWF), known as ERA-40 (Uppala et al. 2005). In this paper we report on results for the recent Japanese Reanalysis (JRA) (Onogi et al. 2007) starting in 1979.Use is made of top-of-atmosphere (TOA) observed radiative fluxes from satellite measurements and computed surface fluxes into land or ocean to evaluate how well the energy budget can Journal of the Meteorological Society of Japan, Vol. 86, No. 5, pp. 579−592, 2008 Atmospheric Energy Budgets in the Japanese Reanalysis: AbstractThe vertically-integrated atmospheric energy and moisture budgets have been computed for all available months for the Japanese reanalysis (1979 to 2004), and results are described in detail for the month of January 1989 and compared with those of other reanalyses. Time series are also presented. The moistening, diabatic heating and total energy forcing of the atmosphere are computed as a residual from the analyses using the moisture, dry energy (dry static energy plus kinetic energy) and total atmospheric (moist static plus kinetic) energy budget equations. These fields are also computed from the model output based on the assimilating model parameterizations. Moreover, some component fields can also be computed from observations to evaluate the results. In particular, when the vertically-integrated forcings computed from the model parameterizations are compared with available observations and the budget-derived values, significant JRA model biases are revealed in radiation and precipitation. The energy and moisture budgetderived quantities are more realistic than the model output and better depict the real atmosphere. However, low frequency decadal variability is spurious and is mainly associated with changes in the observing system. Results also depend on the quality of the analyses which are not constructed to conserve mass, moisture or energy, owing to analysis increments. Although there has been considerable progress in depicting the diabatic components of the atmosphere, some problems remain, and suggestions are made on where research can...

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“…However {V} is non-zero on seasonal timescales owing to surface pressure tendencies on monthly timescales. Taking in to account these mass tendencies following (Trenberth and Stepaniak 2003) we find that the monthly values of the first term of Eq. (2) are two orders of magnitude smaller than the second term and have an annual mean value that is three orders of magnitude smaller than the second term.…”

Section: The Atmospheric Heat Transport Across the Equatormentioning

confidence: 99%

The ocean’s role in setting the mean position of the Inter-Tropical Convergence Zone

et al. 2013

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Through study of observations and coupled climate simulations, it is argued that the mean position of the Inter-Tropical Convergence Zone (ITCZ) north of the equator is a consequence of a northwards heat transport across the equator by ocean circulation. Observations suggest that the hemispheric net radiative forcing of climate at the top of the atmosphere is almost perfectly symmetric about the equator, and so the total (atmosphere plus ocean) heat transport across the equator is small (order 0.2 PW northwards). Due to the Atlantic ocean's meridional overturning circulation, however, the ocean carries significantly more heat northwards across the equator (order 0.4 PW) than does the coupled system. There are two primary consequences. First, atmospheric heat transport is southwards across the equator to compensate (0.2 PW southwards), resulting in the ITCZ being displaced north of the equator. Second, the atmosphere, and indeed the ocean, is slightly warmer (by perhaps 2°C) in the northern hemisphere than in the southern hemisphere. This leads to the northern hemisphere emitting slightly more outgoing longwave radiation than the southern hemisphere by virtue of its relative warmth, supporting the small northward heat transport by the coupled system across the equator. To conclude, the coupled nature of the problem is illustrated through study of atmosphere-oceanice simulations in the idealized setting of an aquaplanet, resolving the key processes at work.

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Covariability of Components of Poleward Atmospheric Energy Transports on Seasonal and Interannual Timescales

Cited by 204 publications

References 23 publications

Arctic climate change in 21st century CMIP5 simulations with EC-Earth

Arctic climate change in 21st century CMIP5 simulations with EC-Earth

Atmospheric Energy Budgets in the Japanese Reanalysis: Evaluation and Variability

The ocean’s role in setting the mean position of the Inter-Tropical Convergence Zone

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