scholarly journals Impacts of Tropical Cyclones in the Northern Atlantic on Adverse Phenomena Formation in Northeastern Brazil

2020 ◽  
Author(s):  
Natalia Fedorova ◽  
Vladimir Levit ◽  
Lucas Carvalho Vieira Cavalcante
Keyword(s):  
Tropical Cyclones ◽  
Weather Forecasting ◽  
Reanalysis Data ◽  
Northeastern Brazil ◽  
Tropical Region ◽  
Study Analysis ◽  
Forecasting Methods ◽  
Circulation Patterns ◽  
Northern Atlantic ◽  
Rain Formation

Tropical cyclone (TC) impacts on adverse phenomena in the tropical region of Northeastern Brazil (NEB) have been analyzed. TC influence on fog and rain formation was not described in the previous papers. The main goal of the chapter is to evaluate the existence of such influence and thus to improve the weather forecasting in this area. TC information from the NHC of the NOAA was used. METAR and SYNOP data were used for the adverse phenomena study. Analysis of the synoptic systems was based on different maps at the pattern levels and on satellite images. These maps were elaborated using reanalysis data from the ECMWF. Thermodynamic analysis was also used. Middle tropospheric cyclonic vortexes (MTCV) in the tropical region of the Southern Atlantic were described recently. Five from 10 MTCVs were associated with tropical cyclones and disturbances in the Northern Atlantic. Circulation patterns between TC and synoptic systems at the NEB are described. These circulations create sinking over the BNE and, as a result, form fog, mist and weak rain in the BNE during TC days. Mechanisms of TC influence on weather formation in the BNE are presented. This information is important for improving weather forecasting methods.

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

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.

scholarly journals Retrieval of Layer Averaged Relative Humidity Profiles from MHS Observations over Tropical Region

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
R. K. Gangwar ◽  
B. S. Gohil ◽  
A. K. Mathur
Keyword(s):  
Relative Humidity ◽  
Radiative Transfer ◽  
Reanalysis Data ◽  
Tropical Region ◽  
Atmospheric Layer ◽  
Ncep Reanalysis ◽  
Microwave Humidity Sounder ◽  
Using Data ◽  
Profile Errors ◽  
Humidity Profiles

The present paper deals with the retrieval of the atmospheric layer averaged relative humidity profiles using data from the Microwave Humidity Sounder (MHS) onboard the MetOp satellite. The retrieval has been innovatively performed by firstly retrieving humidity for pairs of thick overlapping layers (TOLs) used subsequently to derive humidity for associated thin isolated layer (TIL). A water vapour dependent (WVD) algorithm has been developed and applied to infer the humidity of TOLs. Thus, the retrieved profiles have been finally compared with standard algorithm (NORM). These algorithms have been developed based on radiative transfer simulations and study of sensitivities of MHS channels on humidity of various types of layers (TOL, TIL). The algorithm has been tested with MHS data and validated using concurrent radiosonde as well as NCEP reanalysis data indicating profile errors of ~15% and ~19%, respectively.

scholarly journals Comparison of Reanalysis Data Sets to Comprehend the Evolution of Tropical Cyclones Over North Indian Ocean

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
P. Malakar ◽  
A.P. Kesarkar ◽  
J.N. Bhate ◽  
V. Singh ◽  
A. Deshamukhya
Keyword(s):  
Indian Ocean ◽  
Tropical Cyclones ◽  
Reanalysis Data ◽  
North Indian Ocean ◽  
Data Sets

scholarly journals Dehydration and low ozone in the tropopause layer over the Asian monsoon caused by tropical cyclones: Lagrangian transport calculations using ERA-Interim and ERA5 reanalysis data

2020 ◽  
Vol 20 (7) ◽  
pp. 4133-4152 ◽  
Author(s):  
Dan Li ◽  
Bärbel Vogel ◽  
Rolf Müller ◽  
Jianchun Bian ◽  
Gebhard Günther ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Water Vapour ◽  
Tropical Cyclones ◽  
Summer Monsoon ◽  
Asian Summer Monsoon ◽  
Deep Convection ◽  
Reanalysis Data ◽  
Trajectory Calculations ◽  
Asian Summer ◽  
The Western Pacific

Abstract. Low ozone and high water vapour mixing ratios are common features in the Asian summer monsoon (ASM) anticyclone; however, low ozone and low water vapour values were observed near the tropopause over Kunming, China, within the ASM using balloon-borne measurements performed during the SWOP (sounding water vapour, ozone, and particle) campaign in August 2009 and 2015. Here, we investigate low ozone and water vapour signatures in the upper troposphere and lower stratosphere (UTLS) using FengYun-2D, FengYun-2G, and Aura Microwave Limb Sounder (MLS) satellite measurements and backward trajectory calculations. Trajectories with kinematic and diabatic vertical velocities were calculated using the Chemical Lagrangian Model of the Stratosphere (CLaMS) trajectory module driven by both ERA-Interim and ERA5 reanalysis data. All trajectory calculations show that air parcels with low ozone and low water vapour values in the UTLS over Kunming measured by balloon-borne instruments originate from the western Pacific boundary layer. Deep convection associated with tropical cyclones over the western Pacific transports ozone-poor air from the marine boundary layer to the cold tropopause region. Subsequently, these air parcels are mixed into the strong easterlies on the southern side of the Asian summer monsoon anticyclone. Air parcels are dehydrated when passing the lowest temperature region (< 190 K) at the convective outflow of tropical cyclones. However, trajectory calculations show different vertical transport via deep convection depending on the employed reanalysis data (ERA-Interim, ERA5) and vertical velocities (diabatic, kinematic). Both the kinematic and the diabatic trajectory calculations using ERA5 data show much faster and stronger vertical transport than ERA-Interim primarily because of ERA5's better spatial and temporal resolution, which likely resolves convective events more accurately. Our findings show that the interplay between the ASM anticyclone and tropical cyclones has a significant impact on the chemical composition of the UTLS during summer.

Exposure to weather risk: a new information paradigm

2015 ◽  
Vol 55 (2) ◽  
pp. 424
Author(s):  
David Farr ◽  
Andrew Tupper
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
Weather Forecasting ◽  
Working Environment ◽  
Response Planning ◽  
New Information ◽  
Maximum Benefit ◽  
Weather Risk ◽  
Resource Sector ◽  
Safe Working

When forecasting the weather, simple outcome statements do not always adequately describe what could eventuate for a particular location. Importantly, some weather situations are finely balanced, and cannot be forecast five days in advance; sometimes forecasting 24 hours ahead is difficult, particularly if tropical cyclones are present. To address these weather forecasting complexities, the Bureau of Meteorology is moving towards providing more probability based guidance, such as more information on potential rainfall ranges, wind speed probabilities, wave height probabilities, tropical cyclone formation risk and potential tropical cyclone tracks. For response planning purposes these changes will bring their own challenges. For example, previous chances of a tropical cyclone impact have been described with yes or no forecasts. In the future these risks could be described in percentages. Responding to a 5% risk suggests that 19 out of 20 responses could be perceived to be unnecessary, while on the other hand not responding to a 5% risk could be assessed as dangerous. Developing these new information types is only part of the process. To achieve better practice, it will also be critical to create presentation strategies that express the content in a usable manner, work with clients so they gain maximum benefit from the guidance, and enable clients to develop response plans that are aligned with the forecasts. The Bureau of Meteorology is seeking to work in a closer partnership with the resource sector on this to help maximise operational efficiencies, while ensuring a safe working environment.

scholarly journals Rainfall Prediction in the State of Paraíba, Northeastern Brazil Using Generalized Additive Models

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2478
Author(s):  
Leydson G. Dantas ◽  
Carlos A. C. dos Santos ◽  
Ricardo A. de Olinda ◽  
José I. B. de Brito ◽  
Celso A. G. Santos ◽  
...  
Keyword(s):  
Water Resources ◽  
Generalized Additive Models ◽  
Warning System ◽  
The State ◽  
Additive Models ◽  
Northeastern Brazil ◽  
Economic Losses ◽  
Tropical Region ◽  
Rainfall Prediction ◽  
Semi Arid Region

The state of Paraíba is part of the semi-arid region of Brazil, where severe droughts have occurred in recent years, resulting in significant socio-economic losses associated with climate variability. Thus, understanding to what extent precipitation can be influenced by sea surface temperature (SST) patterns in the tropical region can help, along with a monitoring system, to set up an early warning system, the first pillar in drought management. In this study, Generalized Additive Models for Location, Scale and Shape (GAMLSS) were used to filter climatic indices with higher predictive efficiency and, as a result, to perform rainfall predictions. The results show the persistent influence of tropical SST patterns in Paraíba rainfall, the tropical Atlantic Ocean impacting the rainfall distribution more effectively than the tropical Pacific Ocean. The GAMLSS model showed predictive capability during summer and southern autumn in Paraíba, highlighting the JFM (January, February and March), FMA (February, March and April), MAM (March, April and May), and AMJ (April, May and June) trimesters as those with the highest predictive potential. The methodology demonstrates the ability to be integrated with regional forecasting models (ensemble). Such information has the potential to inform decisions in multiple sectors, such as agriculture and water resources, aiming at the sustainable management of water resources and resilience to climate risk.

scholarly journals Forecasting Intense Cut-Off Lows in South Africa Using the 4.4 km Unified Model

Climate ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 129
Author(s):  
Tshimbiluni Percy Muofhe ◽  
Hector Chikoore ◽  
Mary-Jane Morongwa Bopape ◽  
Nthaduleni Samuel Nethengwe ◽  
Thando Ndarana ◽  
...  
Keyword(s):  
South Africa ◽  
South African ◽  
Weather Forecasting ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Unified Model ◽  
Severe Weather ◽  
Economic Activities ◽  
Circulation Patterns ◽  
Extreme Cold

Mid-tropospheric cut-off low (COL) pressure systems are linked to severe weather, heavy rainfall and extreme cold conditions over South Africa. They occur during all the above and often result in floods and snowfalls during the winter months, disrupting economic activities and causing extensive damage to infrastructure. This paper examines the evolution and circulation patterns associated with cases of severe COLs over South Africa. We evaluate the performance of the 4.4 km Unified Model (UM) which is currently used operationally by the South African Weather Service (SAWS) to simulate daily rainfall. Circulation variables and precipitation simulated by the UM were compared against European Centre for Medium-Range Weather Forecast’s (ECMWF’s) ERA Interim re-analyses and GPM precipitation at 24-hour timesteps. We present five recent severe COLs, which occurred between 2016 and 2019, that had high impact and found a higher model skill when simulating heavy precipitation during the initial stages than the dissipating stages of the systems. A key finding was that the UM simulated the precipitation differently during the different stages of development and location of the systems. This is mainly due to inaccurate placing of COL centers. Understanding the performance and limitations of the UM model in simulating COL characteristics can benefit severe weather forecasting and contribute to disaster risk reduction in South Africa.

A Eulerian Explosive Cyclogenesis climatology from the ERA5 reanalysis, 1979-2018

2020 ◽  
Author(s):  
Thomas Cropper ◽  
Stephanie Allen
Keyword(s):  
Tropical Cyclones ◽  
North Atlantic ◽  
Weather Forecasting ◽  
Southern Oscillation ◽  
Medium Range ◽  
Potential Applications ◽  
Hemisphere Winter ◽  
Avalon Peninsula ◽  
Resolution Data ◽  
Northern Hemisphere Winter

&lt;p&gt;Using the criterion of one Bergeron (24 hPa change over 24 h at 60&amp;#176;), we present the creation of a Eulerian explosive cyclogenesis climatology using hourly-temporal resolution data from the European Centre for Medium Range Weather Forecasting&amp;#8217;s ERA5 reanalysis (1979-2018). This approach differs to the typically used Lagrangian methodologies adopted by many studies. The climatology created by this approach results in similar patterns to previous studies.&lt;/p&gt;&lt;p&gt;Assessments on the dataset are undertaken to analyse the influence of seasonality, teleconnections, climate change and individual events (the method picks up tropical cyclones as well as mid-latitude storms). The location experiencing the most consistent explosive cyclongenesis conditions (15% of the time during the Northern Hemisphere winter) is to the east of the Avalon Peninsula, Newfoundland. The preferred location of explosive cyclogenesis is shown to change in relation to patterns such as the El Ni&amp;#241;o Southern Oscillation and North Atlantic Oscillation. Potential applications of the dataset are suggested.&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;/p&gt;

A Comparison of Weather Forecasting Methods in Australia

1942 ◽  
Vol 23 (9) ◽  
pp. 366-370
Author(s):  
V. R. Alldis
Keyword(s):  
Weather Forecasting ◽  
Forecasting Methods

DEVELOPMENT OF TROPICAL CYCLONES IN RELATION TO CIRCULATION PATTERNS AT THE 200-MILLIBAR LEVEL*

1963 ◽  
Vol 91 (7) ◽  
pp. 329-336 ◽  
Author(s):  
JOSÉ A. COLÓN ◽  
WILLIAM R. NIGHTINGALE
Keyword(s):  
Tropical Cyclones ◽  
Circulation Patterns
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