A new paradigm for intensity modification of tropical cyclones: thermodynamic impact of vertical wind shear on the inflow layer

Riemer, Michael; Montgomery, Michael T.; Nicholls, Melville E.

doi:10.5194/acp-10-3163-2010

Cited by 237 publications

(204 citation statements)

References 52 publications

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“…11c), suggesting an amplified negative impact of dry air intrusion there. Although it remains unclear precisely how the drier air enters the eyewall updrafts and limits the strengthening of storms due to the coarser resolution of the GFS data we used, the apparent difference of DFX between the two groups demonstrates clear links between the environmental moisture content and TC intensity, which complements recent idealized studies of Riemer et al (2010Riemer et al ( , 2013.…”

Section: Subsets Of Composites With Similar Geographic Locationssupporting

confidence: 58%

“…An alternative manifestation of the ventilation effect is the outward eddy flux of warm core air by the shear-induced asymmetric flow in the upper levels, causing a decrease of the warm core from top to bottom and thus weakening the TC (Frank and Ritchie, 2001). An alternative hypothesis was recently presented in Riemer et al (2010Riemer et al ( , 2013: the cooler and drier (lower θ e) air could be brought into the boundary layer from above by shear-induced downdrafts flux, which significantly reduces eyewall θe values and subsequently constrains the storm intensity when the lower θe air enters the eyewall updrafts. Riemer and Montgomery (2011) further argued that the environmental vertical wind shear might promote or impede the interaction with the environmental air depending on the direction of the shear vector.…”

Section: Shoujuan Shu Et Al: Environmental Influences On the Intensimentioning

confidence: 99%

“…Previous studies suggested that the intruding drier air may negatively impact the intensity of TCs in the following pathways: (1) intrusion of the low-entropy air frustrates the conversion of heat into kinetic energy within the TC's power engine, as mentioned by Tang and Emanuel (2010); (2) entrainment of dry air into the convective cloud reduces buoyancy (James and Markowski, 2010); and (3) the drier and cooler air (low θ e) could serve as "anti-fuel" for the TC power when shear-induced downward-flux low θe air enters the inflow layer of the TC from above, especially at midlevels where mixing of low θ e air into the eyewall is thought to be particularly effective (Riemer et al, 2010(Riemer et al, , 2013. Consistent with findings from these idealized results, the current composite study with a large number of observed TCs over the WNP shows that a broad area of drier air is brought into the western half of the TC circulation that lowers the relative humidity and suppresses the moisture supply.…”

Section: Subsets Of Composites With Similar Geographic Locationsmentioning

confidence: 99%

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Environmental influences on the intensity changes of tropical cyclones over the western North Pacific

et al. 2014

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Abstract. The influence of environmental conditions on the intensity changes of tropical cyclones (TCs) over the western North Pacific (WNP) is investigated through examination of 37 TCs during 2000-2011 that interacted directly with the western North Pacific subtropical high (WNPSH). Comprehensive composite analysis of the environmental conditions is performed for two stages of storms: one is categorized as intensifying events (maximum wind speed increases by 15 kn over 48 h) and the other is categorized as weakening events (maximum wind speed decreases by 15 kn over 48 h). Comparison of the composite analysis of these two cases show that environmental conditions associated with the WNPSH play important roles in the intensity changes of TCs over the WNP. When a TC moves along the southern periphery of the WNPSH, the relatively weaker easterly environmental vertical wind shear helps bring warm moist air from the south and southeast to its southeast quadrant within 500 km, which is favorable for the TC to intensify. However, when a TC moves along the western edge of the WNPSH, under the combined influences of the WNPSH and an upper-level westerly trough, a strong westerly vertical shear promotes the intrusion of dry environmental air associated with the WNPSH from the north and northwest, which may lead to the inhibition of moisture supply and convection over the western half of the TC and thus its weakening. These composite results are consistent with those with additional geographic restrictions, suggesting that the dry air intrusion and the vertical wind shear (VWS) associated with the WNPSH, indeed affect the intensity changes of TCs over the WNP beyond the difference related solely to variations in geographical locations. The average sea surface temperature (SST) of 27.6 • C for the weakening events is also lower than an average of 28.9 • C for the strengthening events, but remains above the critical value of 27 • C for TC intensification, suggesting that the SST may be regarded as a less positive factor for the weakening events.

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Section: Subsets Of Composites With Similar Geographic Locationssupporting

confidence: 58%

Section: Shoujuan Shu Et Al: Environmental Influences On the Intensimentioning

confidence: 99%

Section: Subsets Of Composites With Similar Geographic Locationsmentioning

confidence: 99%

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Environmental influences on the intensity changes of tropical cyclones over the western North Pacific

et al. 2014

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“…To date, the physical processes that govern this intensity evolution are not well understood. In a recent publication (Riemer et al, 2010, referred to as RMN10 hereafter) a new framework for the intensity modification of TCs in vertical wind shear was proposed. While previous hypotheses have focused almost exclusively on processes above the boundary layer, RMN10 showed that vertical wind shear has a significant impact on the thermodynamic properties of the TC's inflow layer 1 .…”

Section: A New Framework For Intensity Modification Of Tropical Cyclomentioning

confidence: 99%

Further examination of the thermodynamic modification of the inflow layer of tropical cyclones by vertical wind shear

2013

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Abstract. Recent work has developed a new framework for the impact of vertical wind shear on the intensity evolution of tropical cyclones. A focus of this framework is on the frustration of the tropical cyclone's power machine by shearinduced, persistent downdrafts that flush relatively cool and dry (lower equivalent potential temperature, θ e ) air into the storm's inflow layer. These previous results have been based on idealised numerical experiments for which we have deliberately chosen a simple set of physical parameterisations. Before efforts are undertaken to test the proposed framework with real atmospheric data, we assess here the robustness of our previous results in a more realistic and representative experimental setup by surveying and diagnosing five additional numerical experiments. The modifications of the experimental setup comprise the values of the exchange coefficients of surface heat and momentum fluxes, the inclusion of experiments with ice microphysics, and the consideration of weaker, but still mature tropical cyclones.In all experiments, the depression of the inflow layer θ e values is significant and all tropical cyclones exhibit the same general structural changes when interacting with the imposed vertical wind shear. Tropical cyclones in which strong downdrafts occur more frequently exhibit a more pronounced depression of inflow layer θ e outside of the eyewall in our experiments. The magnitude of the θ e depression underneath the eyewall early after shear is imposed in our experiments correlates well with the magnitude of the ensuing weakening of the respective tropical cyclone. Based on the evidence presented, it is concluded that the newly proposed framework is a robust description of intensity modification in our suite of experiments.

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“…Shear has been shown to have a negative influence on the TC-intensity change (e.g., DeMaria et al 2005) through several proposed mechanisms. One hypothesized mechanism is the thermodynamic modification of the inflow layer by downdrafts induced by asymmetric convection outside the inner core (Riemer et al 2010(Riemer et al , 2013. To assess this, the position of each dropsonde was rotated with respect to the environmental vertical wind shear following Corbosiero and Molinari (2002).…”

Section: Scientific Highlightsmentioning

confidence: 99%

A Long-Term, High-Quality, High-Vertical-Resolution GPS Dropsonde Dataset for Hurricane and Other Studies

Wang

Young

Hock

et al. 2015

Bulletin of the American Meteorological Society

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A GPS dropsonde is a scientific instrument deployed from research and operational aircraft that descends through the atmosphere by a parachute. The dropsonde provides high-quality, high-vertical-resolution profiles of atmospheric pressure, temperature, relative humidity, wind speed, and direction from the aircraft flight level to the surface over oceans and remote areas. Since 1996, GPS dropsondes have been routinely dropped during hurricane reconnaissance and surveillance flights to help predict hurricane track and intensity. From 1996 to 2012, NOAA has dropped 13,681 dropsondes inside hurricane eye walls or in the surrounding environment for 120 tropical cyclones (TCs). All NOAA dropsonde data have been collected, reformatted to one format, and consistently and carefully quality controlled using state-of-the-art quality-control (QC) tools. Three value-added products, the vertical air velocity and the radius and azimuth angle of each dropsonde location, are generated and added to the dataset. As a result, a long-term (1996–2012), high-quality, high-vertical-resolution (∼5–15 m) GPS dropsonde dataset is created and made readily available for public access. The dropsonde data collected during hurricane reconnaissance and surveillance flights have improved TC-track and TC-intensity forecasts significantly. The impact of dropsonde data on hurricane studies is summarized. The scientific applications of this long-term dropsonde dataset are highlighted, including characterizing TC structures, studying TC environmental interactions, identifying surface-based ducts in the hurricane environment that affect electromagnetic wave propagation, and validating satellite temperature and humidity profiling products.

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A new paradigm for intensity modification of tropical cyclones: thermodynamic impact of vertical wind shear on the inflow layer

Cited by 237 publications

References 52 publications

Environmental influences on the intensity changes of tropical cyclones over the western North Pacific

Environmental influences on the intensity changes of tropical cyclones over the western North Pacific

Further examination of the thermodynamic modification of the inflow layer of tropical cyclones by vertical wind shear

A Long-Term, High-Quality, High-Vertical-Resolution GPS Dropsonde Dataset for Hurricane and Other Studies

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