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Tropical cyclone wind retrievals from the Advanced Microwave Sounding Unit: Application to surface wind analysis
- J. APPL. METEOR. CLIMATOL.,45
, 2006
"... Horizontal winds at 850 hPa from tropical cyclones retrieved using the nonlinear balance equation, where the mass field was determined from Advanced Microwave Sounding Unit (AMSU) temperature soundings, are compared with the surface wind fields derived from NASA’s Quick Scatterometer (QuikSCAT) and ..."
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Horizontal winds at 850 hPa from tropical cyclones retrieved using the nonlinear balance equation, where the mass field was determined from Advanced Microwave Sounding Unit (AMSU) temperature soundings, are compared with the surface wind fields derived from NASA’s Quick Scatterometer (QuikSCAT) and Hurricane Research Division H*Wind analyses. It was found that the AMSU-derived wind speeds at 850 hPa have linear relations with the surface wind speeds from QuikSCAT or H*Wind. There are also characteristic biases of wind direction between AMSU and QuikSCAT or H*Wind. Using this information to adjust the speed and correct for the directional bias, a new algorithm was developed for estimation of the tropical cyclone surface wind field from the AMSU-derived 850-hPa winds. The algorithm was evaluated in two independent cases from Hurricanes Floyd (1999) and Michelle (2001), which were observed simulta-neously by AMSU, QuikSCAT, and H*Wind. In this evaluation the AMSU adjustment algorithm for wind speed worked well. Results also showed that the bias correction algorithm for wind direction has room for improvement.
Regional accuracy of QuikSCAT gridded winds
- Int. J. Remote Sens. 2005
"... Laboratory (JPL) are analysed over the Bay of Bengal during May–August 2001. Additionally, an examination of these fields is performed over the Gulf of Mexico for the May–August period from 2001 to 2003. Both 00 UTC and 12 UTC time almost coincide with QuikSCAT sampling times (twice a day) and corre ..."
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Laboratory (JPL) are analysed over the Bay of Bengal during May–August 2001. Additionally, an examination of these fields is performed over the Gulf of Mexico for the May–August period from 2001 to 2003. Both 00 UTC and 12 UTC time almost coincide with QuikSCAT sampling times (twice a day) and correspond to either early morning or late evening local time over these regions. The primary restriction for generating accurate maps with a temporal resolution of 12 hours and less is a lack of adequate sampling. Due to non-uniform spatial-temporal sampling of the scatterometer, interpolation procedures cannot provide proper estimates in data gaps over the regions not covered by a swath. Wind speed autocorrelation coefficients for gridded datasets have been compared with that of original QuikSCAT data and buoy winds. It is shown that the spatial and temporal interpolation used to obtain these datasets results in smoothing of the QuikSCAT wind speeds, reducing their original variance. This smoothing is amplified where substantial diurnal wind variability occurs. A comparison with buoy data shows that FSU and JPL gridded fields are unable to reproduce correctly observed low correlations in wind speed between morning and evening breeze flows and diurnal variability of winds, leading to a reduced difference between 00 UTC and 12 UTC values in comparison with buoys and swath QuikSCAT data. Rather, the FSU and JPL maps describe daily mean fields. Another consequence of the spatial-temporal interpolation is that the winds are distorted at a frequency matching the dominant sampling interval (3–4 days) of QuikSCAT measurements over the Bay of Bengal. 1.
Estimation of Rain Height from Rain Rate using Regression-based Statistical Model: Application
"... Date of thesis defense: 28 th January 2004This thesis is dedicated to my grand father ..."
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Date of thesis defense: 28 th January 2004This thesis is dedicated to my grand father
An Evaluation of QuikSCAT UHR Wind Product’s Effectiveness in Determining Selected Tropical Cyclone Characteristics
, 2009
"... While the standard wind product (L2B) available operationally in near-real time from SeaWinds on QuikSCAT is only 25 km in resolution, QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) product. The latter can be used to help estimate Tropical Cyclone (TC) characteristics su ..."
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While the standard wind product (L2B) available operationally in near-real time from SeaWinds on QuikSCAT is only 25 km in resolution, QuikSCAT data can be enhanced to yield a 2.5 km ultra-high resolution (UHR) product. The latter can be used to help estimate Tropical Cyclone (TC) characteristics such as TC eye center and wind radii. Two studies are conducted in this thesis, in which QuikSCAT UHR wind product’s effectiveness in estimating these TC characteristics is evaluated. First, a comparison is made between the analyst’s choice of eye location based on UHR images and interpolated best-track position. In this analysis, the UHR images are divided into two categories, based on the analyst’s confidence
CORRECTING FOR PRECIPITATION EFFECTS IN SATELLITE-BASED PASSIVE MICROWAVE TROPICAL CYCLONE INTENSITY ESTIMATES
, 2005
"... Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments ..."
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Public reporting burden for this collection of Information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
CORRECTING FOR PRECIPITATION EFFECTS IN SATELLITE-BASED PASSIVE MICROWAVE TROPICAL CYCLONE INTENSITY ESTIMATES
, 2005
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The Possibility of Determining Whether Organized Cloud Clusters Will Develop into Tropical Storms by Detecting Warm Core Structures from Advanced Microwave Sounding Unit Observations
"... The air temperature profiles of organized cloud clusters developing or not developing into tropical storms (TSs) over the western North Pacific in 2004 were investigated from Advanced Microwave Sounding Unit (AMSU) observations and the results of Dvorak analyses for the cloud clusters. First, typica ..."
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The air temperature profiles of organized cloud clusters developing or not developing into tropical storms (TSs) over the western North Pacific in 2004 were investigated from Advanced Microwave Sounding Unit (AMSU) observations and the results of Dvorak analyses for the cloud clusters. First, typical temperature profiles of the clusters developing or not developing into TSs were compared. From this comparison, positive temperature anomalies in the upper troposphere were found in both clusters, while the values and spatial sizes of the anomalies for the clusters that developed into TS were larger than those for the ones that did not. Statistical analysis was then performed on the temperature anomalies near the center of all clusters retrieved from AMSU observational data. The average anomalies increased along with the intensity of the clusters indicated by the T-number, as estimated using the Dvorak technique. Time series analysis of temperature anomalies in the upper levels of the clusters was performed, and warm core structures were defined by the threshold derived from these anomalies. Using this definition, almost 70 % of the clusters that had warm cores developed into TSs, while 85 % of those that did not finally dissipated without such development. For the warm-core clusters that developed into TSs, the lead time from the detection of their warm core using AMSU observations to their recognition as TS was 27.7 hours. It is suggested that there is a strong possibility of detecting and forecasting the genesis of TSs using air temperature anomalies derived from AMSU data.
EFFECTIVENESS OF QUIKSCAT’S ULTRA-HIGH RESOLUTION IMAGES IN DETERMINING TROPICAL CYCLONE EYE LOCATION
"... The 25km resolution standard wind products (L2B) are available operationally in near-real time from SeaWinds on QuikSCAT. This relatively low resolution can be enhanced to yield a 2.5km ultra-high resolution (UHR) product that can be used to identify hurricane eye centers more accurately. A comparis ..."
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The 25km resolution standard wind products (L2B) are available operationally in near-real time from SeaWinds on QuikSCAT. This relatively low resolution can be enhanced to yield a 2.5km ultra-high resolution (UHR) product that can be used to identify hurricane eye centers more accurately. A comparison is made between the analyst’s choice of eye location based on UHR images and interpolated best-track position. In this analysis, the UHR images are divided into two categories based on the analyst’s confidence level of finding the eye center location. In each category, statistical error quantities are computed. UHR images within the high-confidence category can provide, for a given year and basin, mean error distance as small as 15km with a 9km standard deviation. The use of these categories may facilitate the realization of QuikSCAT’s effectiveness in helping to identify and track hurricane eye centers. Index Terms — Remote sensing, resolution enhancement, storms, weather forecasting, wind