Is there a stratospheric pacemaker controlling the daily cycle of tropical rainfall?

Sakazaki, Takatoshi; Hamilton, Kevin; Zhang, C.; Wang, Yuqing

doi:10.1002/2017gl072549

Cited by 17 publications

(15 citation statements)

References 36 publications

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“…In fact, significant coherence between precipitation and zonal wind extends to the 50-hPa level but again not for meridional wind (not shown). Some previous works suggest that even fast dynamical waves like atmospheric tides can modulate precipitation (e.g., Yasunaga et al 2013;Kohyama and Wallace 2016;Sakazaki et al 2017). However, this apparent modulation of precipitation by vertical motions in a deep dry Kelvin wave in Figs.…”

Section: Fig 4 As Inmentioning

confidence: 80%

Space–Time Spectral Analysis of the Moist Static Energy Budget Equation

et al. 2019

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The budget of column-integrated moist static energy (MSE) is examined in wavenumber–frequency transforms of longitude–time sections over the tropical belt. Cross-spectra with satellite-derived precipitation (TRMM-3B42) are used to emphasize precipitation-coherent signals in reanalysis [ERA-Interim (ERAI)] estimates of each term in the budget equation. Results reveal different budget balances in convectively coupled equatorial waves (CCEWs) as well as in the Madden–Julian oscillation (MJO) and tropical depression (TD)-type disturbances. The real component (expressing amplification or damping of amplitude) for horizontal advection is modest for most wave types but substantially damps the MJO. Its imaginary component is hugely positive (it acts to advance phase) in TD-type disturbances and is positive for MJO and equatorial Rossby (ERn1) wave disturbances (almost negligible for the other CCEWs). The real component of vertical advection is negatively correlated (damping effect) with precipitation with a magnitude of approximately 10% of total latent heat release for all disturbances except for TD-type disturbance. This effect is overestimated by a factor of 2 or more if advection is computed using the time–zonal mean MSE, suggesting that nonlinear correlations between ascent and humidity would be positive (amplification effect). ERAI-estimated radiative heating has a positive real part, reinforcing precipitation-correlated MSE excursions. The magnitude is up to 14% of latent heating for the MJO and much less for other waves. ERAI-estimated surface flux has a small effect but acts to amplify MJO and ERn1 waves. The imaginary component of budget residuals is large and systematically positive, suggesting that the reanalysis model’s physical MSE sources would not act to propagate the precipitation-associated MSE anomalies properly.

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Section: Fig 4 As Inmentioning

confidence: 80%

Space–Time Spectral Analysis of the Moist Static Energy Budget Equation

et al. 2019

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“…For example, the daily precipitation patterns that are characteristic in many regions of the tropics remain poorly understood (Kikuchi and Wang 2008;Sakazaki et al 2017). Recognition of biological processes may help (Makarieva and Gorshkov 2007;Sheil and Murdiyarso 2009;Sakazaki et al 2017;). We know that transpiration often ceases temporarily, or periodically, after high rates have been achieved (Zhang et al 2013).…”

Section: New Insightsmentioning

confidence: 99%

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Sheil

2018

For. Ecosyst.

145

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Theory and evidence indicate that trees and other vegetation influence the atmospheric water-cycle in various ways. These influences are more important, more complex, and more poorly characterised than is widely realised. While there is little doubt that changes in tree cover will impact the water-cycle, the wider consequences remain difficult to predict as the underlying relationships and processes remain poorly characterised. Nonetheless, as forests are vulnerable to human activities, these linked aspects of the water-cycle are also at risk and the potential consequences of large scale forest loss are severe. Here, for non-specialist readers, I review our knowledge of the links between vegetation-cover and climate with a focus on forests and rain (precipitation). I highlight advances, uncertainties and research opportunities. There are significant shortcomings in our understanding of the atmospheric hydrological cycle and of its representation in climate models. A better understanding of the role of vegetation and tree-cover will reduce some of these shortcomings. I outline and illustrate various research themes where these advances may be found. These themes include the biology of evaporation, aerosols and atmospheric motion, as well as the processes that determine monsoons and diurnal precipitation cycles. A novel theory-the 'biotic pump'-suggests that evaporation and condensation can exert a major influence over atmospheric dynamics. This theory explains how high rainfall can be maintained within those continental land-masses that are sufficiently forested. Feedbacks within many of these processes can result in non-linear behaviours and the potential for dramatic changes as a result of forest loss (or gain): for example, switching from a wet to a dry local climate (or visa-versa). Much remains unknown and multiple research disciplines are needed to address this: forest scientists and other biologists have a major role to play. New ideas, methods and data offer opportunities to improve understanding. Expect surprises.

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“…Previous studies evaluating the representation of solar tides in the stratosphere and the lower mesosphere in re-analyses have mainly considered only S 1 (24 h) tides. An early study by Swinbank et al (1999) investigated the S 1 migrating tide in the stratosphere as represented in the Goddard Earth Observing System (GEOS) version 2 analysis data (one of the predecessors of MERRA and MERRA-2 reanalyses). They found that the GEOS-2 tidal amplitude in the free-running model is reduced by assimilating satellite data, particularly data from the stratospheric sounding unit (SSU).…”

Section: Introductionmentioning

confidence: 99%

Representation of solar tides in the stratosphere and lower mesosphere in state-of-the-art reanalyses and in satellite observations

Sakazaki¹,

Fujiwara²,

Shiotani³

2017

Preprint

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<p><strong>Abstract.</strong> Atmospheric solar tides in the stratosphere and the lower mesosphere are investigated using temperature data from five state-of-the-art reanalysis data sets (MERRA-2, MERRA, JRA-55, ERA-Interim and CFSR) as well as TIMED/SABER and Aura/MLS satellite measurements. The main focus is on the period 2006&#8211;2012 during which the satellite observations are available for direct comparison with the reanalyses. Diurnal migrating tides, semidiurnal migrating tides, and nonmigrating tides are diagnosed. Overall the reanalyses agree reasonably well with each other and with the satellite observations for both migrating and nonmigrating components including their vertical structure and the seasonality. However, the agreement among reanalyses is more pronounced in the lower stratosphere and relatively weaker in the upper stratosphere and mesosphere. A systematic difference between SABER and reanalyses is found for diurnal migrating tides in the upper stratosphere and the lower mesosphere, specifically that the amplitude of trapped modes in reanalyses is significantly smaller than that in SABER, although such difference is less clear between MLS and reanalyses. The interannual variability and the possibility of long-term changes of migrating tides are also examined using the reanalyses during 1980-2012. All the reanalyses agree in exhibiting a clear quasi biennial oscillation (QBO) in the tides, but the most significant indications of long-term changes in the tides represented in the reanalyses are most plausibly explained by the evolution of the satellite observing systems during this period. The tides are also compared in the full reanalyses produced by the Japan Meteorological Agency (i.e. JRA-55) and in two parallel data sets from this agency: one (JRA-55C) which repeats the reanalysis procedure but without any satellite data assimilated, and one (JRA-55AMIP) that is a free-running integration of the model constrained only by observed sea surface temperatures. Many aspects of the tides are closer in JRA-55C and JRA-55AMIP than these are to the full reanalysis JRA-55, demonstrating the importance of the assimilation of satellite data in representing the diurnal variability of the middle atmosphere. In contrast to the assimilated data sets, the free running model has no QBO in equatorial stratospheric mean circulation and our results show that it displays no quasibiennial variability in the tides.</p>

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Is there a stratospheric pacemaker controlling the daily cycle of tropical rainfall?

Cited by 17 publications

References 36 publications

Space–Time Spectral Analysis of the Moist Static Energy Budget Equation

Space–Time Spectral Analysis of the Moist Static Energy Budget Equation

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Representation of solar tides in the stratosphere and lower mesosphere in state-of-the-art reanalyses and in satellite observations

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