A Record Minimum Sea Level Pressure Observed in Hurricane Gilbert

Abstract The assimilation of official advisory minimum sea level pressure observations has been developed and tested in the National Centers for Environmental Prediction (NCEP) Global Data Assimilation System (GDAS) to address forecaster concerns regarding some tropical systems being far too weak in operational Global Forecast System (GFS) analyses. The assimilation of these observations has been operational in the GFS since December 2009. Using the T574 version of the NCEP GFS model, it is demonstrated that the assimilation of these observations results in a substantial reduction in the initial intensity bias for tropical systems, resulting in improved track and intensity guidance for lead times out to 5 days.

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Reexamination of Tropical Cyclone Wind–Pressure Relationships

Weather and Forecasting ◽

10.1175/waf965.1 ◽

2007 ◽

Vol 22 (1) ◽

pp. 71-88 ◽

Cited By ~ 138

Author(s):

John A. Knaff ◽

Raymond M. Zehr

Keyword(s):

Tropical Cyclone ◽

Sea Level ◽

Wind Pressure ◽

Sea Level Pressure ◽

Environmental Pressure ◽

Level Pressure ◽

Wind Speeds ◽

Aircraft Data ◽

Minimum Sea Level Pressure ◽

Central North Pacific

Abstract Tropical cyclone wind–pressure relationships are reexamined using 15 yr of minimum sea level pressure estimates, numerical analysis fields, and best-track intensities. Minimum sea level pressure is estimated from aircraft reconnaissance or measured from dropwindsondes, and maximum wind speeds are interpolated from best-track maximum 1-min wind speed estimates. The aircraft data were collected primarily in the Atlantic but also include eastern and central North Pacific cases. Global numerical analyses were used to estimate tropical cyclone size and environmental pressure associated with each observation. Using this dataset (3801 points), the influences of latitude, tropical cyclone size, environmental pressure, and intensification trend on the tropical cyclone wind–pressure relationships were examined. Findings suggest that latitude, size, and environmental pressure, which all can be quantified in an operational and postanalysis setting, are related to predictable changes in the wind–pressure relationships. These factors can be combined into equations that estimate winds given pressure and estimate pressure given winds with greater accuracy than current methodologies. In independent testing during the 2005 hurricane season (524 cases), these new wind–pressure relationships resulted in mean absolute errors of 5.3 hPa and 6.2 kt compared with the 7.7 hPa and 9.0 kt that resulted from using the standard Atlantic Dvorak wind–pressure relationship. These new wind–pressure relationships are then used to evaluate several operational wind–pressure relationships. These intercomparisons have led to several recommendations for operational tropical cyclone centers and those interested in reanalyzing past tropical cyclone events.

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Trends in Intense Typhoon Minimum Sea Level Pressure

Atmosphere ◽

10.3390/atmos3010124 ◽

2012 ◽

Vol 3 (1) ◽

pp. 124-131 ◽

Cited By ~ 1

Author(s):

Stephen L. Durden

Keyword(s):

Sea Level ◽

Sea Level Pressure ◽

Level Pressure ◽

Minimum Sea Level Pressure

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Strength and Challenges of global model MPAS with regional mesh refinement for mid-latitude storm forecasting: a case study

Advances in Geosciences ◽

10.5194/adgeo-56-77-2021 ◽

2021 ◽

Vol 56 ◽

pp. 77-87

Author(s):

Marc Imberger ◽

Xiaoli Guo Larsén ◽

Neil Davis

Keyword(s):

Sea Level ◽

Local Minimum ◽

Mesh Refinement ◽

Sea Level Pressure ◽

Variable Resolution ◽

Level Pressure ◽

Storm Duration ◽

Buoy Measurements ◽

Minimum Sea Level Pressure

Abstract. With the rising share of renewable energy sources like wind energy in the energy mix, high-impact weather events like mid-latitude storms increasingly affect energy production, grid stability and safety and reliable forecasting becomes very relevant for e.g. transmission system operators to allow for actions to reduce imbalances. Traditionally, meteorological forecasts are provided by limited-area weather prediction models (LAMs), which can use high enough model resolution to represent the range of atmospheric scales of motions associated with such storm structures. While generally satisfactory, deterioration and insufficient deepening of large-scale storm structures are observed when they are introduced near the lateral boundaries of the LAM due to inadequate spatial and temporal interpolation. Global models with regional mesh refinement capabilities like the Model for Prediction Across Scales (MPAS) have the potential to provide an alternative, while avoiding sharp resolution jumps and lateral boundaries. In this study, MPAS' capabilities of simulating key evaluation metrics like storm intensity, storm location and storm duration are investigated based on a case study and assessed in comparison with buoy measurements, forecast products from the Climate Forecast System (CFSv2) and simulations with the Weather Research and Forecasting (WRF) LAM. Quasi-uniform and variable-resolution MPAS mesh configurations with different model physics settings are designed to analyze the impact of the mesh refinement and model physics on the model performance. MPAS shows good performance in predicting storm intensity based on the local minimum sea level pressure, while time of local minimum sea level pressure (storm duration) was generally estimated too late (too long) in comparison with the buoy measurements in part due to an early west-wards shift of the storm center in MPAS. The variable-resolution configurations showed a combination of an additional south-westwards shift and deviations in the sea level pressure field south-west of the storm center that introduced additional bias to the time of local minimum sea level pressure at some locations. The study highlights the need for a more detailed analysis of applied mesh refinements for particular applications and emphasizes the importance of methods like data assimilation techniques to prevent model drifts.

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Complex network approach for detecting tropical cyclones

Climate Dynamics ◽

10.1007/s00382-021-05871-0 ◽

2021 ◽

Author(s):

Shraddha Gupta ◽

Niklas Boers ◽

Florian Pappenberger ◽

Jürgen Kurths

Keyword(s):

Sea Level ◽

Tropical Cyclones ◽

Complex Network ◽

Time Scales ◽

Southern Oscillation ◽

Volcanic Eruptions ◽

Network Approach ◽

Sea Level Pressure ◽

Level Pressure ◽

Climate Networks

AbstractTropical cyclones (TCs) are one of the most destructive natural hazards that pose a serious threat to society, particularly to those in the coastal regions. In this work, we study the temporal evolution of the regional weather conditions in relation to the occurrence of TCs using climate networks. Climate networks encode the interactions among climate variables at different locations on the Earth’s surface, and in particular, time-evolving climate networks have been successfully applied to study different climate phenomena at comparably long time scales, such as the El Niño Southern Oscillation, different monsoon systems, or the climatic impacts of volcanic eruptions. Here, we develop and apply a complex network approach suitable for the investigation of the relatively short-lived TCs. We show that our proposed methodology has the potential to identify TCs and their tracks from mean sea level pressure (MSLP) data. We use the ERA5 reanalysis MSLP data to construct successive networks of overlapping, short-length time windows for the regions under consideration, where we focus on the north Indian Ocean and the tropical north Atlantic Ocean. We compare the spatial features of various topological properties of the network, and the spatial scales involved, in the absence and presence of a cyclone. We find that network measures such as degree and clustering exhibit significant signatures of TCs and have striking similarities with their tracks. The study of the network topology over time scales relevant to TCs allows us to obtain crucial insights into the effects of TCs on the spatial connectivity structure of sea-level pressure fields.

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Tropical cyclone simulations over Bangladesh at convection permitting 4.4 km & 1.5 km resolution

Scientific Data ◽

10.1038/s41597-021-00847-5 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Hamish Steptoe ◽

Nicholas Henry Savage ◽

Saeed Sadri ◽

Kate Salmon ◽

Zubair Maalick ◽

...

Keyword(s):

Wind Speed ◽

Tropical Cyclone ◽

Sea Level ◽

Tropical Cyclones ◽

Weather Forecasting ◽

Sea Level Pressure ◽

Mean Sea Level ◽

Level Pressure ◽

Medium Range ◽

Gust Speed

AbstractHigh resolution simulations at 4.4 km and 1.5 km resolution have been performed for 12 historical tropical cyclones impacting Bangladesh. We use the European Centre for Medium-Range Weather Forecasting 5th generation Re-Analysis (ERA5) to provide a 9-member ensemble of initial and boundary conditions for the regional configuration of the Met Office Unified Model. The simulations are compared to the original ERA5 data and the International Best Track Archive for Climate Stewardship (IBTrACS) tropical cyclone database for wind speed, gust speed and mean sea-level pressure. The 4.4 km simulations show a typical increase in peak gust speed of 41 to 118 knots relative to ERA5, and a deepening of minimum mean sea-level pressure of up to −27 hPa, relative to ERA5 and IBTrACS data. The downscaled simulations compare more favourably with IBTrACS data than the ERA5 data suggesting tropical cyclone hazards in the ERA5 deterministic output may be underestimated. The dataset is freely available from 10.5281/zenodo.3600201.

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