scholarly journals Assessing the Impacts of Augmented Observations on the Forecast of Typhoon Wutip’s (2013) Formation Using the Ensemble Kalman Filter

2020 ◽  
Vol 35 (4) ◽  
pp. 1483-1503
Author(s):  
Tran Tan Tien ◽  
Dao Nguyen-Quynh Hoa ◽  
Cong Thanh ◽  
Chanh Kieu
Keyword(s):  
Kalman Filter ◽  
Large Scale ◽  
Early Stage ◽  
Wrf Model ◽  
Monsoon Trough ◽  
Vital Role ◽  
Weather Research And Forecasting ◽  
Atmospheric Motion ◽  
Meteorological Satellite

AbstractIn this study, the impacts of different augmented observations on forecasts of Typhoon Wutip’s (2013) formation are examined. Using the local ensemble transformed Kalman filter (LETKF) implemented for the Weather Research and Forecasting (WRF) Model, it is found that the prediction of Wutip’s formation location and timing is strongly governed by the strength of a monsoon trough that extends from the Bay of Bengal to the Philippine Sea. By properly capturing the strength of the monsoon trough after assimilating augmented observations available during Wutip’s early stage, the WRF Model could provide better forecasts of Wutip’s formation location and timing as compared to the forecasts initialized directly from global model analyses. Among different types of augmented observations, the satellite atmospheric motion wind vector (AMV) maintained by the Cooperative Institute for Meteorological Satellite Studies (CIMSS) appears to be the most critical in enhancing the large-scale representation of the monsoon trough. The benefit of augmented observations in Wutip’s formation forecast is most apparent at about 36 h prior to the observed formation time. At the shorter 24-h lead time, there is, however, no clear benefit of augmented observations in predicting the timing and the location of Wutip’s formation due to better global analyses. The results obtained in this study demonstrate the vital role of the CIMSS-AMV data in improving the large-scale environment required for TC formation that one should take into account for real-time TC forecasts.

scholarly journals The Impact of Idealized Terrain on Upstream Tropical Cyclone Track

2018 ◽  
Vol 75 (11) ◽  
pp. 3887-3910 ◽  
Author(s):  
Kuan-Chieh Huang ◽  
Chun-Chieh Wu
Keyword(s):  
Large Scale ◽  
Inner Core ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Core Dynamics ◽  
Underlying Mechanisms ◽  
Channeling Effect ◽  
The Impact ◽  
Steering Current

Abstract Tropical cyclones (TCs) encountering the terrain of Taiwan usually experience prominent track deflection, resulting in uncertainty in TC track forecasts. The underlying mechanisms of TC deflection are examined to better understand the pattern of TC tracks under various flow regimes. In this study, idealized experiments are carried out utilizing the Advanced Research version of the Weather Research and Forecasting (WRF) Model. This study investigates the motion of a TC that is deflected southward while moving westward toward an idealized terrain similar to Taiwan. An analysis of both the flow asymmetries and the potential vorticity tendency (PVT) demonstrates that horizontal advection contributes to the southward movement of the TC. The track deflection is examined in two separate time periods, with different mechanisms leading to the southward movement. Changes in the background flow induced by the terrain first cause the large-scale steering current to push the TC southward while the TC is still far from the terrain. As the TC approaches the idealized topography, the role of the inner-core dynamics becomes important, and the TC terrain-induced channeling effect results in further southward deflection. Asymmetries in the midlevel flow also develop during this period, in part associated with the effect of vertical momentum transport. The combination of the large-scale environmental flow, the low-level channeling effect, and asymmetries in the midlevel flow all contribute to the southward deflection of the TC track.

scholarly journals Relationship between the Track and Structural Evolution of Hurricane Sandy (2012) Using a Regional Ensemble

2018 ◽  
Vol 146 (12) ◽  
pp. 4279-4302 ◽  
Author(s):  
Alex M. Kowaleski ◽  
Jenni L. Evans
Keyword(s):  
Large Scale ◽  
Wrf Model ◽  
Structural Evolution ◽  
Hurricane Sandy ◽  
Weather Research And Forecasting ◽  
Extratropical Transition ◽  
Ensemble Forecasts ◽  
High Predictability ◽  
Regression Mixture ◽  
The Relationship

Abstract An ensemble of 72 Weather Research and Forecasting (WRF) Model simulations is evaluated to examine the relationship between the track of Hurricane Sandy (2012) and its structural evolution. Initial and boundary conditions are obtained from ECMWF and GEFS ensemble forecasts initialized at 0000 UTC 25 October. The 5-day WRF simulations are initialized at 0000 UTC 27 October, 48 h into the global model forecasts. Tracks and cyclone phase space (CPS) paths from the 72 simulations are partitioned into 6 clusters using regression mixture models; results from the 4 most populous track clusters are examined. The four analyzed clusters vary in mean landfall location from southern New Jersey to Maine. Extratropical transition timing is the clearest difference among clusters; more eastward clusters show later Sandy–midlatitude trough interaction, warm seclusion formation, and extratropical transition completion. However, the intercluster variability is much smaller when examined relative to the landfall time of each simulation. In each cluster, a short-lived warm seclusion forms and contracts through landfall while lower-tropospheric potential vorticity concentrates at small radii. Despite the large-scale similarity among the clusters, relevant intercluster differences in landfall-relative extratropical transition are observed. In the easternmost cluster the Sandy–trough interaction is least intense and the warm seclusion decays the most by landfall. In the second most eastward cluster Sandy retains the most intact warm seclusion at landfall because of a slightly later (relative to landfall) and weaker trough interaction compared to the two most westward clusters. Nevertheless, the remarkably similar large-scale evolution of Sandy among the four clusters indicates the high predictability of Sandy’s warm seclusion extratropical transition before landfall.

scholarly journals A Study of the Interaction between Typhoon Francisco (2013) and a Cold-Core Eddy. Part I: Rapid Weakening

2020 ◽  
Vol 77 (1) ◽  
pp. 355-377 ◽  
Author(s):  
Zhanhong Ma
Keyword(s):  
Structural Changes ◽  
Surface Wind ◽  
Wrf Model ◽  
Ocean Model ◽  
Atmospheric Environment ◽  
Weather Research And Forecasting ◽  
Eye Size ◽  
Convective Bursts ◽  
Cold Core

Abstract Typhoon Francisco (2013) experienced unusually rapid weakening (RW) with its maximum surface wind decreasing by 45 kt (1 kt ≈ 0.51 m s−1) over 24 h as measured from the satellite-derived advanced Dvorak technique (ADT) dataset, which is more than twice the weakening rate defined as RW by DeMaria. The mechanisms leading to the extreme RW event of Francisco are examined based on observational analysis and simulations by coupling the Weather Research and Forecasting (WRF) Model, version 3.7, with the Stony Brook Parallel Ocean Model (sbPOM). The RW of Francisco took place in a relatively favorable atmospheric environment while passing over detrimental oceanic conditions, dominated by the presence of a cold-core eddy. The passages of two prior typhoons apparently intensified the cold-core eddy, contributing to a major role of eddy feedback on RW for Francisco. The structural changes in Francisco accompanying eddy interaction are characterized by a substantially enlarged eye size, which evolved from ~20 to ~100 km in diameter, as indicated from satellite images. Numerical simulations suggest that the eddy is prominent in weakening the intensity of Francisco during the storm–eddy interaction, with its role less significant but still comparable to that of the cold wake. Both the cooler water and stronger upward motion in the eddy lead to a larger sea surface temperature decrease induced by Francisco, which results in a nearly 50% decrease of surface enthalpy flux, suppressed convective bursts, and a 50% reduction in latent heat release. These results underscore the potential importance of open-ocean, cold-core eddies in contributing to the RW of tropical cyclones.

Convection Initiation Aided by Lake-Breeze Convergence over the Niagara Peninsula

2019 ◽  
Vol 147 (11) ◽  
pp. 3955-3979 ◽  
Author(s):  
Chun-Chih Wang ◽  
Daniel J. Kirshbaum ◽  
David M. L. Sills
Keyword(s):  
Large Scale ◽  
Inversion Layer ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Lake Breeze ◽  
Moist Convection ◽  
Warm Advection ◽  
American Science ◽  
Convection Initiation ◽  
Cloud Tops

Abstract Observations from the 2015 Environment and Climate Change Canada Pan/Parapan American Science Showcase (ECPASS) and real-case, cloud-resolving numerical simulations with the Weather Research and Forecasting (WRF) Model are used to investigate two cases of moist convection forced by lake-breeze convergence over southern Ontario (18 July and 15 August 2015). The two cases shared several characteristics, including high pressure conditions, similar morning soundings, and isolated afternoon convection along a line of lake-breeze convergence between Lakes Erie and Ontario. However, the convection was significantly stronger in the August case, with robustly deeper clouds and larger radar reflectivities than in the July case. Synoptic and mesoscale analyses of these events reveal that the key difference between them was their large-scale forcing. The July event exhibited a combination of strong warm advection and large-scale descent at midlevels (850–650 hPa), which created an inversion layer that capped cloud tops at 4–6 km. The August case exhibited similar features (large-scale descent and warm advection), but these were focused at higher levels (700–400 hPa) and weaker. As a consequence, the convection in the August case was less suppressed at midlevels and ascended deeper (reaching over 8 km). Although the subcloud updraft along the lake-breeze convergence zone was also found to be stronger in the August case, this difference was found to be an effect, rather than a cause, of stronger moist convection within the cloud layer.

scholarly journals Sudden Track Changes of Tropical Cyclones in Monsoon Gyres: Full-Physics, Idealized Numerical Experiments*

2015 ◽  
Vol 72 (4) ◽  
pp. 1307-1322 ◽  
Author(s):  
Jia Liang ◽  
Liguang Wu
Keyword(s):  
Tropical Cyclones ◽  
Numerical Experiments ◽  
Large Scale ◽  
Wrf Model ◽  
Weather Research And Forecasting ◽  
Coalescence Process ◽  
The West ◽  
Steering Flow ◽  
Sharp Turn ◽  
Wind Profiles

Abstract Tropical cyclones (TCs) in the eastern semicircle of large-scale monsoon gyres (MGs) were observed to take either a northward (sudden northward and northward without a sharp turn) or a westward TC turn, but only the northward turn was previously simulated in a barotropic model. To understand what controls TC track types in MGs, idealized numerical experiments are performed using the full-physics Weather Research and Forecasting (WRF) Model. These experiments indicate that TCs initially located in the eastern semicircle of MGs can generally take three types of tracks: a sudden northward track, a westward track, and a northward track without a sharp turn. The track types depend upon the TC movement relative to the MG center. In agreement with barotropic simulations, the WRF simulation confirms that approaching and being collocated with the MG center is crucial to the occurrence of sudden northward TC track changes and that sudden northward track changes can be generally accounted for by changes in the steering flow. TCs that take westward tracks and northward tracks without a sharp turn do not experience such a coalescence process. Westward TCs move faster than MGs and are then located to the west of the MG center, while TCs move more slowly than MGs and then take a northward track without a sharp turn. This study reveals that the specific TC track in the eastern semicircle of an MG is sensitive to the initial wind profiles of both MGs and TCs, suggesting that improvement in the observation of TC and MG structures is very important for predicting TC track types in MGs.

Ruolo dell'ER e del PSA nello screening per la diagnosi precoce del carcinoma prostatico: The role of ER and PSA in screening for early diagnosis of prostatic carcinoma

1995 ◽  
Vol 62 (2) ◽  
pp. 300-304
Author(s):  
M. Fini ◽  
G. Vagliani
Keyword(s):  
Early Diagnosis ◽  
Large Scale ◽  
Prostatic Carcinoma ◽  
Early Stage ◽  
Time Required ◽  
Oncological Screening ◽  
Sensitivity Specificity ◽  
Diagnosi Precoce

From September 1992 to February 1994, 1441 men aged between 50 and 70 years underwent screening with PSA and ER measurement for early diagnosis of prostatic carcinoma. A neoplasm was diagnosed in 1.73% (25/1441) of cases, which being found at an early stage, made it possible to perform prostatectomy and radical radiotherapy on 37.5% and 16.6% of patients respectively. The incidence of the disease was higher than in a previous screening with just ER dosage (1.73% vs 1.1%). Combined PSA and ER also gave higher sensitivity, specificity, overall accuracy and predictiveness compared to the methods taken individually. This combination seems preferable, in view of the greater efficacy and “practicability” compared to protocols which involve the use of USTR, which is less practicable on a large scale due to the length of time required and high costs. The utility of periodic determination of PSA levels in those over fifty years old is emphasised, both for oncological screening controls and to increase the diagnostic accuracy of other clinical tests.

scholarly journals Analyzing Simulated Convective Bursts in Two Atlantic Hurricanes. Part I: Burst Formation and Development

2017 ◽  
Vol 145 (8) ◽  
pp. 3073-3094 ◽  
Author(s):  
Andrew T. Hazelton ◽  
Robert F. Rogers ◽  
Robert E. Hart
Keyword(s):  
Radial Flow ◽  
Inner Core ◽  
Wrf Model ◽  
Tropical Meteorology ◽  
Core Region ◽  
Weather Research And Forecasting ◽  
Convective Bursts ◽  
Atlantic Hurricanes ◽  
Radial Outflow

Understanding the structure and evolution of the tropical cyclone (TC) inner core remains an elusive challenge in tropical meteorology, especially the role of transient asymmetric features such as localized strong updrafts known as convective bursts (CBs). This study investigates the formation of CBs and their role in TC structure and evolution using high-resolution simulations of two Atlantic hurricanes (Dean in 2007 and Bill in 2009) with the Weather Research and Forecasting (WRF) Model. Several different aspects of the dynamics and thermodynamics of the TC inner-core region are investigated with respect to their influence on TC convective burst development. Composites with CBs show stronger radial inflow in the lowest 2 km, and stronger radial outflow from the eye to the eyewall around z = 2–4 km, than composites without CBs. Asymmetric vorticity associated with eyewall mesovortices appears to be a major factor in some of the radial flow anomalies that lead to CB development. The anomalous outflow from these mesovortices, along with outflow from supergradient parcels above the boundary layer, favors low-level convergence and also appears to mix high- θ e air from the eye into the eyewall. Analyses of individual CBs and parcel trajectories show that parcels are pulled into the eye and briefly mix with the eye air. The parcels then rapidly move outward into the eyewall, and quickly ascend in CBs, in some cases with vertical velocities of over 20 m s−1. These results support the importance of horizontal asymmetries in forcing extreme asymmetric vertical velocity in tropical cyclones.

Tamoxifen and Endometrial Cancer

1996 ◽  
Vol 3 (2) ◽  
pp. 107-112 ◽  
Author(s):  
Richard R. Barakat
Keyword(s):  
Breast Cancer ◽  
Endometrial Cancer ◽  
Large Scale ◽  
Early Stage ◽  
Tamoxifen Treatment ◽  
Breast Cancer Patients ◽  
Menopausal Women ◽  
Overall Survival Benefit ◽  
Post Menopausal

Tamoxifen is commonly used in the management of patients with breast cancer. Clinical trials of tamoxifen involving over 75,000 patients demonstrate an improved recurrence-free and overall survival benefit in both pre- and post-menopausal women. Large-scale trials also are evaluating the role of tamoxifen as a chemopreventive agent in women considered to be at high risk for developing breast cancer based on family history. Endometrial cancer is an uncommon complication of tamoxifen therapy. Since the majority of these cancers will be detected at an early stage when they are highly curable, however, the overall benefit of tamoxifen treatment in breast cancer patients outweighs this risk. All women receiving tamoxifen who have a uterus should undergo regular gynecologic examinations.

scholarly journals A Combined Approach to Improving the Regional Model Forecasts for the Rainy Season in China

2017 ◽  
Vol 145 (11) ◽  
pp. 4593-4603
Author(s):  
Yanfeng Zhao ◽  
Donghai Wang ◽  
Jianjun Xu
Keyword(s):  
Rainy Season ◽  
Large Scale ◽  
Initial Conditions ◽  
Wrf Model ◽  
Regional Model ◽  
Weather Research And Forecasting ◽  
Small Scale ◽  
Wind Fields ◽  
Accumulated Rainfall ◽  
Combined Forecasting

A combined forecasting methodology, into which the spectral nudging, lateral boundary filtering, and update initial conditions methods are incorporated, was employed in the regional Weather Research and Forecasting (WRF) Model. The intent was to investigate the potential for improving the prediction capability for the rainy season in China via using as many merits of the global model having better predictability as it does for the large-scale circulation and of the regional model as it does for the small-scale features. The combined methodology was found to be successful in improving the prediction of the regional atmospheric circulation and precipitation. It performed best for the larger magnitude precipitation, the relative humidity above 800 hPa, and wind fields below 300 hPa. Furthermore, the larger the magnitude and the longer the lead time, the more obvious is the improvement in terms of the accumulated rainfall of persistent severe rainfall events.

scholarly journals Kalman Filter and Analog Schemes to Postprocess Numerical Weather Predictions

2011 ◽  
Vol 139 (11) ◽  
pp. 3554-3570 ◽  
Author(s):  
Luca Delle Monache ◽  
Thomas Nipen ◽  
Yubao Liu ◽  
Gregory Roux ◽  
Roland Stull
Keyword(s):  
Kalman Filter ◽  
Forecast Error ◽  
Wrf Model ◽  
Rank Correlation ◽  
Weighted Average ◽  
Weather Research And Forecasting ◽  
Random Errors ◽  
Numerical Weather ◽  
Regime Changes ◽  
Predictive Skill

Abstract Two new postprocessing methods are proposed to reduce numerical weather prediction’s systematic and random errors. The first method consists of running a postprocessing algorithm inspired by the Kalman filter (KF) through an ordered set of analog forecasts rather than a sequence of forecasts in time (ANKF). The analog of a forecast for a given location and time is defined as a past prediction that matches selected features of the current forecast. The second method is the weighted average of the observations that verified when the 10 best analogs were valid (AN). ANKF and AN are tested for 10-m wind speed predictions from the Weather Research and Forecasting (WRF) model, with observations from 400 surface stations over the western United States for a 6-month period. Both AN and ANKF predict drastic changes in forecast error (e.g., associated with rapid weather regime changes), a feature lacking in KF and a 7-day running-mean correction (7-Day). The AN almost eliminates the bias of the raw prediction (Raw), while ANKF drastically reduces it with values slightly worse than KF. Both analog-based methods are also able to reduce random errors, therefore improving the predictive skill of Raw. The AN is consistently the best, with average improvements of 10%, 20%, 25%, and 35% with respect to ANKF, KF, 7-Day, and Raw, as measured by centered root-mean-square error, and of 5%, 20%, 25%, and 40%, as measured by rank correlation. Moreover, being a prediction based solely on observations, AN results in an efficient downscaling procedure that eliminates representativeness discrepancies between observations and predictions.

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