A Non-MLE Approach for Satellite Scatterometer Wind Vector Retrievals in Tropical Cyclones

Satellite microwave scatterometers are the principal source of global synoptic-scale ocean vector wind (OVW) measurements for a number of scientific and operational oceanic wind applications. However, for extreme wind events such as tropical cyclones, their performance is significantly degraded. This paper presents a novel OVW retrieval algorithm for tropical cyclones which improves the accuracy of scatterometer based ocean surface winds when compared to low-flying aircraft with in-situ and remotely sensed observations. Unlike the traditional maximum likelihood estimation (MLE) wind vector retrieval technique, this new approach sequentially estimates scalar wind directions and wind speeds. A detailed description of the algorithm is provided along with results for ten QuikSCAT hurricane overpasses (from 2003-2008) to evaluate the performance of the new algorithm. Results are compared with independent surface wind analyses from the National Oceanic and Atmospheric Administration (NOAA) Hurricane Research Division\u27s H*Wind surface analyses and with the corresponding SeaWinds Project\u27s L2B-12.5 km OVW products. They demonstrate that the proposed algorithm extends the SeaWinds capability to retrieve wind speeds beyond the current range of approximately 35 m/s (minimal hurricane category-1) with improved wind direction accuracy, making this new approach a potential candidate for current and future conically scanning scatterometer wind retrieval algorithms

Effect of Plai cream [Zingiber montanum (J.Koenig) Link ex A.Dietr. syn. Zingiber cassumunar Roxb.] combined with ultrasound on delayed onset muscle soreness

Plai cream (Zingiber cassumunar Roxb.) has been used as a remedy for release pain and inflammation of musculoskeletal problems. The enhancement of the anti-inflammatory effect of Plai cream by phonoporesis or ultrasound therapy is questionable. The aim of this study was to evaluate the effect of Plai cream combined with ultrasound in the treatment of delayed onset muscle soreness (DOMS). Seventy-five volunteers were randomly allocated into 3 groups; 14 % Plai cream (5 cm long strip), ultrasound treatment (1MHz, 1watt.cm⁻²) for 5 min, and combined 14 % Plai cream and ultrasound for 5 min. The participants performed eccentric exercise (4 sets of 25 repetitions at a speed of 60°.s⁻¹) of dominant quadriceps using isokinetic dynamometry to induce DOMS. All participants received their allocated treatment once per day for the next 7 days. We found pain score, thigh circumference and serum creatine kinase were increased, while pressure pain threshold and muscle strength were decreased, but small changes of joint motion after intensive exercise (post-exercise day 1, 2, 3 & 7). However, there was no significant difference changes of all outcomes among three groups. In conclusion, combined 14 % Plai cream with ultrasound had no additional benefit at reducing DOMS compared to either14 % Plai cream alone or ultrasound alone

Calibration/Validation Of The Seawinds Radiometer Rain Rate Algorithm

The Sea Winds scatterometer, which has been flown on both the QuikSCAT and ADEOS-II satellites, was designed to remotely sense ocean surface wind vectors. Because ocean wind retrievals are occasionally contaminated by rain in the tropics and because there is no independent rain measurement on QuikSCAT, a SeaWinds rain-estimation method was developed and implemented. This technique utilizes the SeaWinds receiver noise to measure ocean radiometric brightness temperature (Tb) and then applies a statistical regression algorithm to estimate the integrated rain rate. This rain algorithm was originally trained with QuikSCAT SeaWinds Tb and near-simultaneous rain rate measurements from the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI). In this study, the SeaWinds instrument on ADEOS-II and the Advanced Microwave Scanning Radiometer (AMSR), also onboard ADEOS-II, were used to refine the algorithm. This provided truly simultaneous and collocated measurements from the same platform and over the same swath, which was ideal for improving the SeaWinds rain algorithm. The improved algorithm can now be applied on QuikSCAT using the SeaWinds radiometric measurement

Seawinds Hurricane Wind Retrievals And Comparisons With H*Wind Surface Winds Analyses

This paper describes recent developments of an improved geophysical ocean wind vector retrieval algorithm that uses both active and passive measurements from QuikSCAT. This algorithm results in significant improvements in wind vector measurements in hurricanes and better rain-flagging of severely rain contaminated areas than does NASA\u27s standard wind vector product (L2B). By using a combined active/passive approach, we are able to infer wind estimates in the presence of light to moderate rain using the SeaWinds scatterometer. Rain effects (attenuation and volume scattering) are determined passively and then used to correct the measured ocean sigma-0 at 12.5 km wind vector cell resolution. Wind retrievals are performed using an improved geophysical model function (GMF) tuned for extreme wind events These ocean vector wind retrievals, known as Q-Winds, are compared with surface winds products from the NOAA Hurricane Research Division\u27s H*Wind Analysis System, which assimilates near-simultaneous measurements from insitu and remote sensors, such as, the Stepped Frequency Microwave Radiometer (SFMR), GPS dropsondes, and flight-level inertial navigation winds. Comparisons to H*Wind are presented for Q-Winds and the SeaWinds Project\u27s new L2B-12.5km ocean vector winds products. © 2008 IEEE

An Improved Active/Passive Oceanic Wind Vector Retrieval Technique

This paper describes the advantages of combining passive and active microwave remote sensing observations for the purpose of ocean wind vectors retrievals. Previous studies have shown that a linear combination of horizontal and vertical polarized brightness temperatures contains a robust wind direction signal. In this paper, we present results from an end-to-end simulation of ocean measurements from a Kuband (13.4 GHz) active/passive conical scanning satellite instrument. For this simulation, realistic wind fields from the NOAA National Center for Environmental Prediction (NCEP) numerical weather model were used to produce simultaneous brightness temperatures and radar backscatter measurements. These measurements were processed using a maximum likelihood estimation technique to yield ocean wind vector retrievals that were compared to NCEP fields. Results demonstrate significant improvements over simulated measurements for an active (radar scatterometer) sensor. © 2010 IEEE

SeaWinds Hurricane Wind Retrievals and Comparisons with H *

This paper describes recent developments of an improved geophysical ocean wind vector retrieval algorithm that uses both active and passive measurements from QuikSCAT. This algorithm results in significant improvements in wind vector measurements in hurricanes and better rain-flagging of severely rain contaminated areas than does NASA\u27s standard wind vector product (L2B). By using a combined active/passive approach, we are able to infer wind estimates in the presence of light to moderate rain using the SeaWinds scatterometer. Rain effects (attenuation and volume scattering) are determined passively and then used to correct the measured ocean sigma-0 at 12.5 km wind vector cell resolution. Wind retrievals are performed using an improved geophysical model function (GMF) tuned for extreme wind events These ocean vector wind retrievals, known as Q-Winds, are compared with surface winds products from the NOAA Hurricane Research Division\u27s H*Wind Analysis System, which assimilates near-simultaneous measurements from insitu and remote sensors, such as, the Stepped Frequency Microwave Radiometer (SFMR), GPS dropsondes, and flight-level inertial navigation winds. Comparisons to H*Wind are presented for Q-Winds and the SeaWinds Project\u27s new L2B-12.5km ocean vector winds products. © 2008 IEEE