scholarly journals Long-Lived Concentric Eyewalls in Typhoon Soulik (2013)

2014 ◽  
Vol 142 (9) ◽  
pp. 3365-3371 ◽  
Author(s):  
Yi-Ting Yang ◽  
Eric A. Hendricks ◽  
Hung-Chi Kuo ◽  
Melinda S. Peng
Keyword(s):  
Western North Pacific ◽  
Heat Content ◽  
Precipitable Water ◽  
Radar Data ◽  
Time Sequence ◽  
Convective Activity ◽  
Typhoon Intensity ◽  
Concentric Eyewalls ◽  
Second Period ◽  
Western North Pacific Typhoon

The authors report on western North Pacific Typhoon Soulik (2013), which had two anomalously long-lived concentric eyewall (CE) episodes, as identified from microwave satellite data, radar data, and total precipitable water data. The first period was 25 h long and occurred while Soulik was at category 4 intensity. The second period was 34 h long and occurred when Soulik was at category 2 intensity. A large moat and outer eyewall width were present in both CE periods, and there was a significant contraction of the inner eyewall radius from the first period to the second period. The typhoon intensity decrease was partially due to encountering unfavorable environmental conditions of low ocean heat content and dry air, even though inner eyewall contraction would generally support intensification. The T–Vmax diagram (where T is the brightness temperature and Vmax is the best track–estimated intensity) is used to analyze the time sequence of the intensity and convective activity. The convective activity (and thus the integrated kinetic energy) increased during the CE periods despite the weakening of intensity.

scholarly journals Western North Pacific Typhoons with Concentric Eyewalls

2009 ◽  
Vol 137 (11) ◽  
pp. 3758-3770 ◽  
Author(s):  
Hung-Chi Kuo ◽  
Chih-Pei Chang ◽  
Yi-Ting Yang ◽  
Hau-Jang Jiang
Keyword(s):  
Time Series ◽  
North Pacific ◽  
Western North Pacific ◽  
Maximum Intensity ◽  
Passive Microwave ◽  
Intensity Change ◽  
Secondary Eyewall Formation ◽  
Peak Intensity ◽  
Typhoon Intensity ◽  
Concentric Eyewalls

Abstract This study examines the intensity change and moat dynamics of typhoons with concentric eyewalls using passive microwave data and best-track data in the western North Pacific between 1997 and 2006. Of the 225 typhoons examined, 55 typhoons and 62 cases with concentric eyewalls have been identified. The data indicate that approximately 57% of category 4 and 72% of category 5 typhoons possessed concentric eyewalls at some point during their lifetime. While major typhoons are most likely to form concentric eyewalls, the formation of the concentric structure may not be necessarily at the lifetime maximum intensity. Approximately one-third of concentric eyewall cases are formed at the time of maximum intensity. The moat is known to be heavily influenced by the subsidence forced by the two eyewalls. Rozoff et al. proposed that the rapid filamentation dynamics may also contribute to the organization of the moat. This paper examines the possibility of rapid filamentation dynamics by devising a filamentation moat width parameter. This parameter can be computed from the best-track typhoon intensity and the passive microwave satellite-estimated inner eyewall radius for each typhoon with concentric eyewalls. The filamentation moat width explains 40% of the variance of the satellite-observed moat width in the group with concentric eyewall formation intensity greater than 130 kt. The typhoon intensity time series in both the concentric and nonconcentric composites are studied. The time series of intensity is classified according to the 24-h intensity change before and after the concentric eyewalls formation. The averaged concentric eyewall formation latitudes in the groups with negative intensity change before concentric eyewall formation are at higher latitudes than that of the positive intensity change groups. Intensity of the concentric typhoons tends to peak at the time of secondary eyewall formation, but the standard model of intensification followed by weakening is valid for only half of the cases. Approximately 74% of the cases intensify 24 h before secondary eyewall formation and approximately 72% of the cases weaken 24 h after formation. The concentric composites have a much slower intensification rate 12 h before the peak intensity (time of concentric formation) than that of the nonconcentric composites. For categories 4 and 5, the peak intensity of the concentric typhoons is comparable to that of the nonconcentric typhoons. However, 60 h before reaching the peak the concentric composites are 25% more intense than the nonconcentric composites. So a key feature of concentric eyewall formation appears to be the maintenance of a relatively high intensity for a longer duration, rather than a rapid intensification process that can reach a higher intensity.

scholarly journals Relationship between Typhoons with Concentric Eyewalls and ENSO in the Western North Pacific Basin

2015 ◽  
Vol 28 (9) ◽  
pp. 3612-3623 ◽  
Author(s):  
Yi-Ting Yang ◽  
Hung-Chi Kuo ◽  
Eric A. Hendricks ◽  
Yi-Chin Liu ◽  
Melinda S. Peng
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
El Nino ◽  
Southern Oscillation ◽  
Pacific Basin ◽  
Convective Activity ◽  
Cold Episode ◽  
Concentric Eyewalls ◽  
Favorable Conditions ◽  
North Pacific Basin

Abstract The typhoons with concentric eyewalls (CE) over the western North Pacific in different phases of the El Niño–Southern Oscillation (ENSO) between 1997 and 2012 are studied. They find a good correlation (0.72) between the annual CE typhoon number and the oceanic Niño index (ONI), with most of the CE typhoons occurring in the warm and neutral episodes. In the warm (neutral) episode, 55% (50%) of the typhoons possessed a CE structure. In contrast, only 25% of the typhoons possessed a CE structure in the cold episode. The CE formation frequency is also significantly different with 0.9 (0.2) CEs per month in the warm (cold) episode. There are more long-lived CE cases (CE structure maintained more than 20 h) and typhoons with multiple CE formations in the warm episodes. There are no typhoons with multiple CE formations in the cold episode. The warm episode CE typhoons generally have a larger size, stronger intensity, and smaller variation in convective activity and intensity. This may be due to the fact that the CE formation location is farther east in the warm episodes. Shifts in CE typhoon location with favorable conditions thus produce long-lived CE typhoons and multiple CE formations. The multiple CE formations may lead to expansion of the typhoon size.

Impact of radar data assimilation on simulations of precipitable water with the Harmonie model: A case study over Cyprus

2021 ◽  
Vol 253 ◽  
pp. 105473
Author(s):  
Serguei Ivanov ◽  
Silas Michaelides ◽  
Igor Ruban ◽  
Demetris Charalambous ◽  
Filippos Tymvios
Keyword(s):  
Data Assimilation ◽  
Precipitable Water ◽  
Radar Data ◽  
Radar Data Assimilation

scholarly journals Global Extratropical Response to Diabatic Heating Variability of the Asian Summer Monsoon

2009 ◽  
Vol 66 (9) ◽  
pp. 2697-2713 ◽  
Author(s):  
Hai Lin
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Convective Activity ◽  
Mean Flow ◽  
Asian Summer ◽  
Circulation Anomalies

Abstract Global teleconnections associated with the Asian summer monsoon convective activities are investigated based on monthly data of 29 Northern Hemisphere summers defined as June–September (JJAS). Two distinct teleconnection patterns are identified that are associated respectively with variabilities of the Indian summer monsoon and the western North Pacific summer monsoon. The Indian summer monsoon convective activity is associated with a global pattern that has a far-reaching connection in both hemispheres, whereas the western North Pacific summer monsoon convective activity is connected to a Southern Hemisphere wave train that influences the high-latitude South Pacific and South America. A global primitive equation model is utilized to assess the cause of the global circulation anomalies. The model responses to anomalous heatings of both monsoon systems match the general features of the observed circulation anomalies well, and they are mainly controlled by linear processes. The response patterns are largely determined by the summertime large-scale background mean flow and the location of the heating anomaly relative to the upper easterly jet in the monsoon region.

scholarly journals Upper-Ocean Thermal Structure and the Western North Pacific Category 5 Typhoons. Part II: Dependence on Translation Speed

2009 ◽  
Vol 137 (11) ◽  
pp. 3744-3757 ◽  
Author(s):  
I-I. Lin ◽  
Iam-Fei Pun ◽  
Chun-Chieh Wu
Keyword(s):  
Mixed Layer ◽  
North Pacific ◽  
Western North Pacific ◽  
Thermal Structure ◽  
Subsurface Layer ◽  
Heat Content ◽  
Correlation Coefficients ◽  
Upper Ocean ◽  
Translation Speed

Abstract Using new in situ ocean subsurface observations from the Argo floats, best-track typhoon data from the U.S. Joint Typhoon Warning Center, an ocean mixed layer model, and other supporting datasets, this work systematically explores the interrelationships between translation speed, the ocean’s subsurface condition [characterized by the depth of the 26°C isotherm (D26) and upper-ocean heat content (UOHC)], a cyclone’s self-induced ocean cooling negative feedback, and air–sea enthalpy fluxes for the intensification of the western North Pacific category 5 typhoons. Based on a 10-yr analysis, it is found that for intensification to category 5, in addition to the warm sea surface temperature generally around 29°C, the required subsurface D26 and UOHC depend greatly on a cyclone’s translation speed. It is observed that even over a relatively shallow subsurface warm layer of D26 ∼ 60–70 m and UOHC ∼ 65–70 kJ cm−2, it is still possible to have a sufficient enthalpy flux to intensify the storm to category 5, provided that the storm can be fast moving (typically Uh ∼ 7–8 m s−1). On the contrary, a much deeper subsurface layer is needed for slow-moving typhoons. For example at Uh ∼ 2–3 m s−1, D26 and UOHC are typically ∼115–140 m and ∼115–125 kJ cm−2, respectively. A new concept named the affordable minimum translation speed Uh_min is proposed. This is the minimum required speed a storm needs to travel for its intensification to category 5, given the observed D26 and UOHC. Using more than 3000 Argo in situ profiles, a series of mixed layer numerical experiments are conducted to quantify the relationship between D26, UOHC, and Uh_min. Clear negative linear relationships with correlation coefficients R = −0.87 (−0.71) are obtained as Uh_min = −0.065 × D26 + 11.1, and Uh_min = −0.05 × UOHC + 9.4, respectively. These relationships can thus be used as a guide to predict the minimum speed a storm has to travel at for intensification to category 5, given the observed D26 and UOHC.

scholarly journals Water Budget and Intensity Change of Tropical Cyclones over the Western North Pacific

2017 ◽  
Vol 145 (8) ◽  
pp. 3009-3023 ◽  
Author(s):  
Si Gao ◽  
Shunan Zhai ◽  
Baiqing Chen ◽  
Tim Li
Keyword(s):  
Boundary Layer ◽  
Tropical Cyclones ◽  
North Pacific ◽  
Water Budget ◽  
Western North Pacific ◽  
Precipitable Water ◽  
Moisture Flux ◽  
Intensity Change ◽  
Surface Evaporation ◽  
Total Precipitable Water

Three satellite observational datasets and a reanalysis dataset during the period 2001–09 are used to examine four water budget components (total precipitable water, surface evaporation, precipitation, and column-integrated moisture flux convergence) associated with western North Pacific tropical cyclones (TCs) of different intensity change categories: rapidly intensifying, slowly intensifying, neutral, and weakening. The results show that surface evaporation plays an important role in storm rapid intensification (RI) and the highest evaporation associated with rapidly intensifying TCs is associated with the highest sea surface temperature. Total precipitable water in the outer environment, where moisture is mainly provided by surface evaporation, is also vital to storm RI because RI is favored when there is less dry air intruded into the storm circulation. The roles of surface evaporation and total precipitable water in storm RI are related to the enhanced convective available potential energy by moistening and warming the boundary layer. The largest amount of column-integrated moisture flux convergence associated with weakening TCs, which results in the heaviest precipitation, is because their strongest mean intensity promotes moisture transport. It is suggested that different water budget components play different roles in TC intensity change. The results agree with the notion that TC intensity change results from a competition between surface moisture and heat fluxes and low-entropy downdrafts into the boundary layer.

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