scholarly journals Estimation of the Upper-Layer Rotation and Maximum Wind Speed of Tropical Cyclones via Satellite Imagery

2011 ◽  
Vol 50 (3) ◽  
pp. 750-766 ◽  
Author(s):  
Chun-Chieh Chao ◽  
Gin-Rong Liu ◽  
Chung-Chih Liu
Keyword(s):  
Wind Speed ◽  
Tropical Cyclones ◽  
Satellite Imagery ◽  
Satellite Images ◽  
Rotation Speed ◽  
Maximum Wind Speed ◽  
Maximum Wind ◽  
The Mean ◽  
Wind Intensity ◽  
The Relationship

Abstract The movement of convective rainbands embedded in a tropical cyclone (TC) is usually derived from satellite images via the atmospheric motion vector (AMV) method or through the calculation of a radar’s echo track. In estimating the rotation speed of a TC rainband, however, the land-based radar can only detect approaching tropical cyclones within the vicinity. The AMV method is unable to fully account for the TC eyewall movement, thus making it difficult to estimate the TC intensity. The widely used method in estimating the TC maximum wind speed is the Dvorak technique in which the cloud pattern is extracted from only one image. In this study, the rainband rotation speeds are computed via satellite imagery and further applied in estimating the TC maximum wind speed. In contrast to previous research, this study adopts an innovative method by using two subsequent geostationary satellite images. The TC spin rates observed by weather satellites could often be seen to be positively related to the TC intensity. Analyses of the relationship between the typhoon wind intensity and estimated rotation speed at the 130–260-km ring via infrared channels are conducted for major typhoon cases that occurred during 2000–05 in the northwestern Pacific Ocean. Results show that the correlation between the wind intensity and estimated rotation speeds is strong for most of the cases. The highest R2 value from the individual cases could reach 0.93, and on an annual basis it could attain a value of 0.67. The mean R2 value for the 2000–05 dataset was roughly 0.53. The correlation between the wind intensity and estimated rotation speeds is further improved by factoring in the previous 6-h average rotation speeds. A regression equation is derived from the chosen typhoon cases between 2000 and 2005, which is utilized in verifying the major typhoon occurrences during 2006–08. The mean absolute error (MAE) of the hourly and 6-h average intensity estimates during 2000–08 was 20 and 18.7 kt, respectively (1 kt ≃ 0.5 m s−1). The best verification result occurred during 2008, for which the R2 value and MAE could reach 0.7 and 15.6, respectively. These research results demonstrate the suitability of using geostationary satellite image data in estimating the maximum wind speed. Nevertheless, the drawback of this study is that sometimes the rotation speeds will become slower when tropical cyclones mature because of the strong outflow of the secondary circulation. It is assumed that the relationship between the estimated rotation speeds and wind intensity can be further improved if the outflow speed of the tropical cyclones is also considered.

scholarly journals Joint Use of Spaceborne Microwave Sensor Data and CYGNSS Data to Observe Tropical Cyclones

2020 ◽  
Vol 12 (19) ◽  
pp. 3124
Author(s):  
Shiwei Wang ◽  
Shuzhu Shi ◽  
Binbin Ni
Keyword(s):  
Wind Speed ◽  
Tropical Cyclones ◽  
Inner Core ◽  
Mean Absolute Error ◽  
Absolute Error ◽  
Maximum Wind Speed ◽  
Sensor Data ◽  
Maximum Wind ◽  
Microwave Sensor ◽  
The Mean

The joint use of spaceborne microwave sensor data and Cyclone Global Navigation Satellite System (CYGNSS) data to observe tropical cyclones (TCs) is presented in this paper. The Soil Moisture Active and Passive (SMAP) radiometer was taken as an example of a spaceborne microwave sensor, and its data and the CYGNSS data were fused to fix the center of a TC and to measure the maximum wind speed around the TC inner core. This process included data preprocessing, image fusion, determination of the TC center position, and the estimation of the TC’s intensity. For all of the observed hurricanes, the experimental results demonstrated that the proposed method obtains a more complete structure of the TC and can measure the surface wind speed around the TC inner core at more frequent intervals compared to the case where the SMAP radiometer data or the CYGNSS data are employed alone. Furthermore, when comparing the TC tracks obtained by the proposed method with the best tracks provided by the National Hurricane Center (NHC), we found that the mean absolute error values ranged between 18.4 and 46 km, the standard deviation varied between 15.1 and 28.2 km, and both of these were smaller than the values obtained by only using the CYGNSS data. In addition, when comparing the maximum wind speed around the TC inner core obtained by the proposed method with the best track peak winds estimated by the NHC, we found that the mean absolute error values ranged between 7.7 and 15.7 m/s, the root-mean-square difference values varied between 8.6 and 18 m/s, the correlation coefficients varied between 0.1782 and 0.9877, the bias values varied between −8.5 and 4.5 m/s, and all of these values were smaller in most cases, than those obtained by only using the CYGNSS data.

scholarly journals Comments on “Reexamination of Tropical Cyclone Wind–Pressure Relationship”

2008 ◽  
Vol 23 (4) ◽  
pp. 758-761 ◽  
Author(s):  
Shyamnath Veerasamy
Keyword(s):  
Wind Speed ◽  
Tropical Cyclones ◽  
North Atlantic ◽  
Wind Pressure ◽  
Maximum Wind Speed ◽  
Central Pressure ◽  
Southwest Indian Ocean ◽  
Maximum Wind ◽  
The North ◽  
The North Atlantic

Abstract In their study on the wind–pressure relationship (WPR) that exists in tropical cyclones, Knaff and Zehr presented results of the use of the Dvorak Atlantic WPR for estimating central pressure and maximum wind speed of tropical cyclones. These show some fairly large departures of estimated central pressure and maximum surface winds from observed values. Based on a study carried out in the southwest Indian Ocean (SWIO), it is believed that improvements in the use of the Dvorak WPR can be achieved by using the size of a closed isobar (it is the 1004-hPa closed isobar in the SWIO) to determine whether to use the North Atlantic (NA), the western North Pacific (WNP), or a mean of the NA and WNP Dvorak WPR for estimating central pressure and maximum wind speed in tropical cyclones.

scholarly journals Estimating Maximum Significant Wave Height and Dominant Wave Period inside Tropical Cyclones

2018 ◽  
Vol 33 (4) ◽  
pp. 955-966 ◽  
Author(s):  
Paul A. Hwang ◽  
Edward J. Walsh
Keyword(s):  
Wind Speed ◽  
Tropical Cyclones ◽  
Wave Height ◽  
Significant Wave Height ◽  
Wave Period ◽  
Maximum Wind Speed ◽  
Power Functions ◽  
Significant Wave ◽  
Maximum Wind ◽  
Dominant Wave

Abstract Making use of the fetch- and duration-limited nature of wind-wave growth inside tropical cyclones, an algorithm is developed to estimate the maximum significant wave height and dominant wave period of surface waves generated by tropical cyclone wind fields. The results of the maximum significant wave height and dominant wave period are further approximated by simple power functions of the maximum wind speed. The exponents of the power functions are almost constant, and the proportionality coefficients can be approximated by second-order polynomial functions of the radius of maximum wind speed (RMW). The predicted maximum values agree well with results derived from simultaneous wind and wave measurements obtained during 11 hurricane reconnaissance and research missions in six hurricanes.

Estimating Tropical Cyclone Intensity from Infrared Image Data

2011 ◽  
Vol 26 (5) ◽  
pp. 690-698 ◽  
Author(s):  
Miguel F. Piñeros ◽  
Elizabeth A. Ritchie ◽  
J. Scott Tyo
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
North Atlantic Ocean ◽  
Infrared Image ◽  
Ocean Basin ◽  
Maximum Wind Speed ◽  
Tropical Cyclone Intensity ◽  
Cyclone Intensity ◽  
Maximum Wind

Abstract This paper describes results from a near-real-time objective technique for estimating the intensity of tropical cyclones from satellite infrared imagery in the North Atlantic Ocean basin. The technique quantifies the level of organization or axisymmetry of the infrared cloud signature of a tropical cyclone as an indirect measurement of its maximum wind speed. The final maximum wind speed calculated by the technique is an independent estimate of tropical cyclone intensity. Seventy-eight tropical cyclones from the 2004–09 seasons are used both to train and to test independently the intensity estimation technique. Two independent tests are performed to test the ability of the technique to estimate tropical cyclone intensity accurately. The best results from these tests have a root-mean-square intensity error of between 13 and 15 kt (where 1 kt ≈ 0.5 m s−1) for the two test sets.

Uncertainty of Tropical Cyclone Best-Track Information

2012 ◽  
Vol 27 (3) ◽  
pp. 715-729 ◽  
Author(s):  
Ryan D. Torn ◽  
Chris Snyder
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Maximum Wind Speed ◽  
Sea Level Pressure ◽  
Position Uncertainty ◽  
Maximum Wind ◽  
Intensity Information ◽  
Weather And Climate ◽  
The Mean ◽  
National Hurricane Center

Abstract With the growing use of tropical cyclone (TC) best-track information for weather and climate applications, it is important to understand the uncertainties that are contained in the TC position and intensity information. Here, an attempt is made to quantify the position uncertainty using National Hurricane Center (NHC) advisory information, as well as intensity uncertainty during times without aircraft data, by verifying Dvorak minimum sea level pressure (SLP) and maximum wind speed estimates during times with aircraft reconnaissance information during 2000–09. In a climatological sense, TC position uncertainty decreases for more intense TCs, while the uncertainty of intensity, measured by minimum SLP or maximum wind speed, increases with intensity. The standard deviation of satellite-based TC intensity estimates can be used as a predictor of the consensus intensity error when that consensus includes both Dvorak and microwave-based estimates, but not when it contains only Dvorak-based values. Whereas there has been a steady decrease in seasonal TC position uncertainty over the past 10 yr, which is likely due to additional data available to NHC forecasters, the seasonal TC minimum SLP and maximum wind speed values are fairly constant, with year-to-year variability due to the mean intensity of all TCs during that season and the frequency of aircraft reconnaissance.

Potential Tropical Cyclone Disaster Loss Assessment based on Multiple Hazard Indicators

2020 ◽  
Author(s):  
Jian Li
Keyword(s):  
Wind Speed ◽  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
Storm Surge ◽  
Maximum Wind Speed ◽  
Central Pressure ◽  
Loss Assessment ◽  
Maximum Wind ◽  
Disaster Loss ◽  
Potential Loss

<p><span>Tropical cyclones could cause large casualties and economic loss in coastal area of China. It is of great importance to develop a method that can provide pre-event rapid loss assessment in a timely manner prior to the landing of a tropical cyclone. In this study, a pre-event tropical cyclone disaster loss assessment method based on similar tropical cyclone retrieval with multiple hazard indicators is proposed. Multiple indicators include tropical cyclone location, maximum wind speed, central pressure, radius of maximum wind, forward speed, Integrated Kinetic Energy (IKE), maximum storm surge, and maximum significant wave height. Firstly, the track similarity is measured by similarity deviation considering only the locations of tropical cyclone tracks. Secondly, the intensity similarity is measured by best similarity coefficient using central pressure, radius of maximum wind, maximum wind speed, moving speed, wind, storm surge, and wave intensity indices. Then, the potential loss of current tropical cyclone is assessed based on the retrieved similar tropical cyclones loss. Taking tropical cyclone Utor (2013) that affected China as an example, the potential loss is predicted according to the five most similar historical tropical cyclones which are retrieved from all the historical tropical cyclones. The method is flexible for rapid disaster loss assessment since it provides a relatively satisfactory result based on two scenarios of input dataset availability.</span></p>

scholarly journals Environmental influences on the intensity changes of tropical cyclones over the Western North Pacific

2013 ◽  
Vol 13 (12) ◽  
pp. 31815-31853
Author(s):  
Shoujuan Shu ◽  
Fuqing Zhang ◽  
Jie Ming ◽  
Yuan Wang
Keyword(s):  
Wind Speed ◽  
Tropical Cyclones ◽  
Environmental Conditions ◽  
North Pacific ◽  
Western North Pacific ◽  
The Other ◽  
Maximum Wind Speed ◽  
Composite Analysis ◽  
Maximum Wind ◽  
Intensity Changes

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 kts over 48 h) and the other is categorized as weakening events (maximum wind speed decreases by 15 kts 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 edge of the WNPSH, the relatively weaker easterly environmental vertical wind shear helps bring warm moist air from the south and southeast, which is favorable for the TC to intensify. On the other hand, 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 west half of the TC and thus its weakening. The average sea surface temperature (SST) of 27.8 °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.

scholarly journals Estimating the Intensity of Hurricanes from Historical Radar Data Using the Hyperbolic-logarithmic approximation of Spiral Rainbands

2020 ◽  
Vol 1 (4) ◽  
Author(s):  
Boris S. Yurchak ◽  
Keyword(s):  
Wind Speed ◽  
Logarithmic Spiral ◽  
Radar Data ◽  
Maximum Wind Speed ◽  
Logarithmic Approximation ◽  
Maximum Wind ◽  
Radar Signature ◽  
The Mean ◽  
Spiral Rainbands

To increase the amount of information on the intensities of tropical cyclones (TC) used in climate research, the possibility of additional estimates of the intensity of a TC by exploring historical data of conventional (non-Doppler) airborne and coastal radars is considered. Based on the hyperbolic-logarithmic spiral (HLS) model of the streamline in the TC, an assessment of the maximum wind speed in hurricanes Cleo (1958), Carolina (1975) and Alicia (1983) was made. Literature sources containing radar signatures of spiral cloud-rain bands (SCRBs) of these hurricanes and the corresponding results of synchronous aircraft soundings were used. The HLS-approximation of the radar signature of the SCRB consisted of determining the “expected” (mean) spiral of a set of HLSs “fitted” into a pattern of the signature. The maximum wind speed was determined from coefficients of the mean HLS. The estimates obtained were in satisfactory agreement with in situ aircraft measurements. The considered examples manifest the possibility of applying the HLS-approximation to determine the intensity of hurricanes by using the historical radar data with satisfactory accuracy.

Sign in / Sign up

Export Citation Format

Share Document