A sequence of ground-based radar reflectivity images sampled in the 17 hours prior to, and during the landfall of Severe Tropical Cyclone Larry (2006) are presented and analyzed using Fourier and wavelet analysis techniques.   A range of mesoscale convective anomalies were detected, with characteristics and behavior consistent with vortex Rossby wave initiation. Cyclonically propagating eye-wall kinks, elongations and mesoscale reflectivity maxima were all observed throughout the sampling period, along with intense inner spiral bands. Various deep convective maxima propagated within the eye-wall at speeds consistent with predictions derived by linear barotropic wave theory. Three eye-wall breakdown episodes were observed during the study period, along with corresponding increases in storm-core asymmetric wave power and reductions in estimated storm intensity. Vortex Rossby wave initiated radial flows are also suggested by the presence of a possible mesovortex within a broken section of the eye-wall during landfall, and the outward ejection of filaments of deep convection from an adjacent inner spiral band. The possible influence of this wave activity upon the storm intensity and integrity is discussed.

The December 2011 disaster in the Philippines which was induced by TS Washi was investigated. This disastrous event which claimed 1,268 human lives and PhP1.455 Billion (US$63.26M) damages to infrastructure and agriculture was analyzed in terms of meteorological, hydrological, environmental and social aspects. Government’s response to the disaster was also included. Meteorological analysis was carried out using surface observations, satellite data and simulation of numerical weather prediction model. Intense short duration rainfall upstream the river basin and the damming effect along the river triggered the flashfloods downstream in Cagayan de Oro and Iligan Cities. The strong storm winds coupled with orographic lifting enhanced the rainfall activity over the mountain. The encroachment in the sandbars and the river banks due to urbanization and industrialization impeded the flow of water resulting to greater damage. In addition, the timing of the high tide constrained the flow of the flood waters that resulted to widespread flooding in the downstream areas.  This flood event on 16 December 2011 reached a maximum height of 7 meters and the extent of inundation covered about 7 to 10 meters high from the river banks of in Cagayan de Oro City. The conclusion was that the disaster was the outcoming of the interplay of climatic, environmental and social factors.As a result of the flood disaster and based on the findings of the different agencies, the Philippine government came up with various recommendations which include regulation of the development in the floodplain areas, hazard mapping and installation of early warning system.

Tropical Storm Pakhar appeared as a low pressure system over the South China Sea on March 26, 2012. It then became a tropical storm a few days later on March 29, 2012. Pakhar was really an abnormal tropical storm activated over the South China Sea in March which seldom appeared at that time. The movement of Pakhar was not very complicated because it mainly moved under the steering lines of subtropical high pressure systems. However, its intensity was still a problem for many typhoon centers, especially when Pakhar experienced a rapid intensification within 12 hours at 00Z on March 30. At that time NCHMF and JRTD (Japan) warned it as a tropical storm, while BABJ (China) and JTWC (US navy) warned as severe tropical storm and typhoon respectively. Pakhar decreased quickly when approached the onshore areas of Viet Nam. At 08Z on 1 April, upon analyzing the radar data at NhaBe station and the half-hourly observations along the coastline, NCHMF downgraded Pakhar into a tropical depression, while other typhoon centers maintained Pakhar’s intensity as a tropical storm untill 00Z on 2 April.

This paper uses China Meteorological Administration tropical cyclone (TC) best track data to analyze the characteristics of TC activity over the western North Pacific in 2011. Results derived from two other datasets, issued by the Regional Specialized Meteorological Center Tokyo and the Joint Typhoon Warning Center, were also compared. We show that the annual TC activity in 2011 was weaker than the climatology, and exhibited remarkable intraseasonal signals. The main TC genesis region migrated seasonally between the southwest (7°–17°N, 120°–140°E) and northeast (17°–25°N, 135°–165°E) quadrants. Moreover, three prevailing tracks were identified: westward tracks, recurving tracks between 125°–135°E, and northward tracks near 155°E. Special attention was paid to the intra-annual features of TC activity during 2011 and the potential modulators of this activity, including the tropical Indo-Pacific oceans, East Asian Monsoon (EAM), and Intraseasonal Oscillation (ISO). The seasonal migration of the main TC genesis region can be attributed to modulation by the EAM trough and ISO rather than the El Niño-Southern Oscillation. Both the EAM trough and ISO provided favorable conditions, including cyclonic vorticity in the low troposphere, limited vertical shear, and moisture convergence, in both of the main TC genesis quadrants, but unfavorable conditions outside the particular genesis quadrant. Moreover, both EAM and ISO generated a favorable circulation that steered TCs to move along the three prevailing tracks. These findings indicate that TC activity in 2011 was more significantly affected by both the EAM and ISO than by the ENSO.

With the development of space technology, the accuracy of weather forecasts has steadily improved over the years. Accordingly the QPE/QPF products have been improving so that it is possible to be gradually applied for hydrological purposes. However, it has been challenging to integrate QPE/QPF into real-time operational flood forecasting and disaster monitoring and warning because of the crucial gaps on temporal-spatial resolution, systematic uncertainty and methodology of application. Aiming to the challenges, meteorologists and hydrologists have made great efforts jointly and achieved evident progresses on improving QPE/QPF products to get closer to the hydrological requirements. This paper presents an overview of hydrological prospective on QPE/QPF products, challenges and gaps in QPE/QPF application in real-time operation,  and some of the recent studies on improving QPE/QPF products for hydrological purposes.

Recently, unexpected inundation damages from local heavy rain and typhoons due to climate changes have increased in Korea. To reduce the flood related damages, a decision support system has been developed to improve decision making and disaster assessment in which a three-dimensional semi-implicit numerical model was used to simulate inundation aspects and the geographical information, such as building information, population, utilities and land use patterns to support decision making. The Munsan City area, where there were three big inundation damages in 1996, 1998 and 1999, respectively, is selected to test the developed decision model. To test the simulation model and the simulated geographical information, hydraulic data, hydrology data and geographic data, such as digital maps of 1/1,000 and 1/5,000 scale, cadastral maps, building plan, and price of house in the test area are collected. This geographical information is used to build up the three-dimensional numerical grid and to support decision making for minimizing flood related damages based on the simulated results. The results of simulated inundated area were compared with the photo of 1999 flooding and the estimated damages are compared with real damages of Munsan Area in 1999. The simulated results well represented the flooding situation and it is expected that the new decision support system will be used to make decision for minimizing flood related damages.

Out of damage from natural disasters in recent decade, more than 60% is due to typhoon in Korea, and yearly damage has exceeded 10 billion USD as urbanization and development continue. Many local areas are affected by climate extremes such as typhoons and flash flood and great amount of coastal areas are exposed to flood risk by typhoon related winds and storm surges. These climatic impacts are expected to be severer and eventually impede development of the region. The main reasons for the high vulnerability to natural disaster are that great number of local cities are located in low land and vulnerable region and highly populated. As a scientific effort on disaster prevent and disaster risk reduction, statistical estimations of risk and regional vulnerability have been carried out. Typhoon trajectory is estimated from statistically method to determine the typhoon approaching region of interest and risk is also estimated from physical modeling of rainfall rate and wind speed, while regional vulnerability is statistically modeled from damage data of properties. This paper describes the development of typhoon risk assessment and application to Asia countries including Republic of Korea using Web GIS based technology. The system would be able to help decision makers to take informed actions during emergency situations of an approaching tropical cyclone.

This paper reviews the current state of the science on the relationship between climate change and historical tropical cyclone (TC) activity in the western North Pacific (WNP) basin, which is the region of the ESCAP/WMO Typhoon Committee members. Existing studies of observed changes of TC activity in this basin, such as frequency, intensity, precipitation, genesis location and track pattern are summarized. Results from a survey on impacts of past TC activity on various members of Typhoon Committee are reported, along with a review of studies of past WNP landfalling TCs. With considerable interannual and interdecadal variations in the TC activity in this basin, it remains uncertain whether there has been any detectable human influence on tropical cyclone frequency, intensity, precipitation, track, or related aggregated storm activity metrics. Also, the issues of homogeneity and consistency of best track data sets in the WNP further add uncertainty to relevant research studies. Observations indicate some regional shifts in TC activity in the basin, such as a decreasing trend in TC occurrence in part of the South China Sea and an increasing trend along the east coast of China during the past 40 years. This change is apparently related to local circulation changes in the eastern Asia and WNP, though the cause of the circulation changes remains unknown.

This paper reviews the latest studies on the relationship between projected late 21st century climate changes and tropical cyclone (TC) activity in the western North Pacific (WNP) basin, which is the region of the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP)/World Meteorological Organization (WMO) Typhoon Committee members. Existing studies of projected changes of TC activity in this basin, such as frequency, intensity, precipitation, genesis location and track pattern are summarized, based on an assumed A1B future climate change scenario. A review of available studies on projected future changes in WNP landfalling TC activity is also included. While it remains uncertain whether there has been any detectable human influence on tropical cyclone frequency, intensity, precipitation, track, or related aggregated storm activity metrics in the basin, modeling studies suggest changes in future tropical cyclone activity for the WNP basin. More models project decreases than increases in tropical storm frequency (range −70% to +60%); most studies project an increase in the TC intensity (range −3% to +18%); and all six available studies that include the WNP basin project increases in TC precipitation rates (range +5 to +30%).

The dependence of tropical cyclone (TC) intensification on the Coriolis parameter was investigated in an idealized hurricane model. By specifying an initial balanced vortex on an f-plane, we observed faster TC development under lower planetary vorticity environment than under higher planetary vorticity environment. The diagnosis of the model outputs indicates that the distinctive evolution characteristics arise from the extent to which the boundary layer imbalance is formed and maintained in the presence of surface friction. Under lower planetary vorticity environment, stronger and deeper subgradient inflow develops due to Ekman pumping effect, which leads to greater boundary layer moisture convergence and condensational heating. The strengthened heating further accelerates the inflow by lowing central pressure further. This positive feedback loop eventually leads to distinctive evolution characteristics. The outer size (represented by the radius of gale-force wind) and the eye of the final TC state also depend on the Coriolis parameter. The TC tends to have larger (smaller) outer size and eye under higher (lower) planetary vorticity environment. Whereas the radius of maximum wind or the eye size in the current setting is primarily determined by inertial stability, the TC outer size is mainly controlled by environmental absolute angular momentum.

This article provides a balanced, brief review on the research progress in the area of tropical cyclone (TC) structure and intensity achieved in the past three decade. Efforts have been made to introduce basic concepts and new findings relevant to the understanding of TC structure and intensity in ways as simple and appreciate as possible. After a brief discussion on the axisymmetric and asymmetric structure of mature TCs, progress in our understanding of spiral rainbands, concentric eyewall cycle, annular hurricane structure, and the inner-core size of TCs is highlighted. This is followed by discussions on the maximum potential intensity (MPI) of TCs and factors that limit TC maximum intensity. Some important remaining issues that need to be studied and addressed in the near future by the research community are identified and briefly discussed as well.