scholarly journals Strong Wind Speed Events over Antarctica and Its Surrounding Oceans

2019 ◽  
Vol 32 (12) ◽  
pp. 3451-3470 ◽  
Author(s):  
Lejiang Yu ◽  
Shiyuan Zhong
Keyword(s):  
Wind Speed ◽  
Sea Level ◽  
Surface Wind ◽  
Coastal Region ◽  
Southern Annular Mode ◽  
East Antarctica ◽  
Strong Wind ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Wind Events

AbstractStrong wind events (SWEs) over Antarctica and its surrounding oceans are investigated using gridded surface wind data from the ERA-Interim for the 1979–2017 period. Throughout the year, SWEs are more prevalent over the coastal region of East Antarctica where mean surface wind speeds are also higher. The occurrences of SWEs appear to be accompanied by positive anomalies in surface temperature and negative (positive) anomalies in mean sea level pressure related to cyclone (anticyclone) activity over the Ronne and Ross Ice Shelves and coastal regions (the inland areas of East Antarctica). The interannual variability of the SWE occurrences appears to be related to the southern annular mode (SAM) and, to a lesser degree, ENSO. The trends of SWE in the recent four decades exhibit considerable regional variations that are consistent with the trends in seasonal mean wind speed and surface air temperature, and can be largely explained by the variations in the sea level pressure trends across the region.

scholarly journals Position of the South Atlantic Anticyclone and Its Impact on Surface Conditions across Brazil

2018 ◽  
Vol 57 (3) ◽  
pp. 535-553 ◽  
Author(s):  
Joshua M. Gilliland ◽  
Barry D. Keim
Keyword(s):  
Wind Speed ◽  
Sea Level ◽  
Surface Wind ◽  
South Atlantic ◽  
Atmospheric Conditions ◽  
Southern Brazil ◽  
The South ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Northern Brazil

AbstractThis study examines the surface wind characteristics of Brazil on the basis of the location of the maximum high pressure center in the South Atlantic basin (SAB), known as the South Atlantic anticyclone (SAA), from three reanalysis datasets for the period of 1980–2014. Linear wind speed trends determined for Brazil are geographically related to surface and macroscale atmospheric conditions found in the SAB. The daily mean position of the SAA exhibited a latitudinal poleward shift for all seasons, and a longitudinal trend was dependent upon extratropical activity found in the SAB. Results also show that wind speed and sea level pressure for northern Brazil are dependent upon the latitudinal position of the SAA. Consequently, surface wind correlations for southern Brazil tend to be related to changes in the longitudinal position of the SAA, which result from transient anticyclones migrating over the SAB. An examination of positive and negative wind anomalies shows that shifts in the position of the SAA are coupled with changes in sea level pressure for northern Brazil and air temperature for southern Brazil. From these findings, a surface wind analysis was performed to demonstrate how the geographical location of the SAA affects wind speed anomalies across Brazil and the SAB. Results from this study can assist in understanding how atmospheric systems change within the SAB so that forthcoming socioeconomic and climate-related causes of wind for the country of Brazil can be known.

scholarly journals ANTARCTIC WIND INTENSIFICATION AS INFERRED FROM THE NCEP/NCAR REANALYSIS DATA

2020 ◽  
Vol 48 (3) ◽  
pp. 96-108
Author(s):  
N.A. Romanova ◽  
P.Yu. Romanov
Keyword(s):  
Wind Speed ◽  
Sea Level ◽  
Surface Wind ◽  
Surface Wind Speed ◽  
Reanalysis Data ◽  
Antarctic Region ◽  
Sea Level Pressure ◽  
Latitude Band ◽  
Level Pressure ◽  
The Antarctic

NCEP/NCAR reanalysis data have been used to examine variations of the sea level pressure and of the surface wind speed in the Antarctic region from 1950 to 2019. The objective of the work was to identify changes and quantify long-term trends in these two major weather and climate elements. The analysis included time series of monthly mean values of the sea level pressure and of the surface wind speed as well as their yearly means. The study has shown a gradual decrease of the sea level pressure and a gradual increase of the surface wind speed in the high latitude region of the Southern Hemisphere in the last 70 years (1950–2019). The largest pressure decrease was within 65–70°S latitude band approximately corresponding to the location of the Antarctic Circumpolar Trough (ACT). The estimated trend in the yearly averaged sea level pressure ranged from –0.058 mb/yr over the open ocean north of ACT, within the 50–60°S latitude band, to –0.148 mb/yr over the Antarctic continent, within 65–85°S latitudes. The zonal-mean wind speed trends ranged within 0.020 m/s/yr and 0.026 m/s/yr over the continent and over the open ocean with up to the 3–4 times larger values in the coastal areas of East Antarctica. Seasonally larger changes in both parameters occurred in the cold period of the year from April to August. Trends in both the sea level pressure and in the wind speed in the Antarctic region were found to generally decelerate in the last decade covered by the dataset.

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 Analysis of Atmospheric and Ionospheric Variations Due to Impacts of Super Typhoon Mangkhut (1822) in the Northwest Pacific Ocean

2021 ◽  
Vol 13 (4) ◽  
pp. 661
Author(s):  
Mohamed Freeshah ◽  
Xiaohong Zhang ◽  
Erman Şentürk ◽  
Muhammad Arqim Adil ◽  
B. G. Mousa ◽  
...  
Keyword(s):  
Wind Speed ◽  
Pacific Ocean ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Northwest Pacific ◽  
Northwest Pacific Ocean ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Super Typhoon ◽  
The Northwest Pacific Ocean

The Northwest Pacific Ocean (NWP) is one of the most vulnerable regions that has been hit by typhoons. In September 2018, Mangkhut was the 22nd Tropical Cyclone (TC) over the NWP regions (so, the event was numbered as 1822). In this paper, we investigated the highest amplitude ionospheric variations, along with the atmospheric anomalies, such as the sea-level pressure, Mangkhut’s cloud system, and the meridional and zonal wind during the typhoon. Regional Ionosphere Maps (RIMs) were created through the Hong Kong Continuously Operating Reference Stations (HKCORS) and International GNSS Service (IGS) data around the area of Mangkhut typhoon. RIMs were utilized to analyze the ionospheric Total Electron Content (TEC) response over the maximum wind speed points (maximum spots) under the meticulous observations of the solar-terrestrial environment and geomagnetic storm indices. Ionospheric vertical TEC (VTEC) time sequences over the maximum spots are detected by three methods: interquartile range method (IQR), enhanced average difference (EAD), and range of ten days (RTD) during the super typhoon Mangkhut. The research findings indicated significant ionospheric variations over the maximum spots during this powerful tropical cyclone within a few hours before the extreme wind speed. Moreover, the ionosphere showed a positive response where the maximum VTEC amplitude variations coincided with the cyclone rainbands or typhoon edges rather than the center of the storm. The sea-level pressure tends to decrease around the typhoon periphery, and the highest ionospheric VTEC amplitude was observed when the low-pressure cell covers the largest area. The possible mechanism of the ionospheric response is based on strong convective cells that create the gravity waves over tropical cyclones. Moreover, the critical change state in the meridional wind happened on the same day of maximum ionospheric variations on the 256th day of the year (DOY 256). This comprehensive analysis suggests that the meridional winds and their resulting waves may contribute in one way or another to upper atmosphere-ionosphere coupling.

scholarly journals Evaluation of a Mesoscale Short-Range Ensemble Forecast System over the Northeast United States

2007 ◽  
Vol 22 (1) ◽  
pp. 36-55 ◽  
Author(s):  
Matthew S. Jones ◽  
Brian A. Colle ◽  
Jeffrey S. Tongue
Keyword(s):  
United States ◽  
Wind Speed ◽  
Sea Level ◽  
Short Range ◽  
Warm Season ◽  
Ensemble Forecast ◽  
Cool Season ◽  
Forecast System ◽  
Sea Level Pressure ◽  
Level Pressure

Abstract A short-range ensemble forecast system was constructed over the northeast United States down to 12-km grid spacing using 18 members from the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5). The ensemble consisted of 12 physics members with varying planetary boundary layer schemes and convective parameterizations as well as seven different initial conditions (ICs) [five National Centers for Environmental Prediction (NCEP) Eta-bred members at 2100 UTC and the 0000 UTC NCEP Global Forecast System (GFS) and Eta runs]. The full 18-member ensemble (ALL) was verified at the surface for the warm (May–September 2003) and cool (October 2003–March 2004) seasons. A randomly chosen subset of seven physics (PHS) members at each forecast hour was used to quantitatively compare with the seven IC members. During the warm season, the PHS ensemble predictions for surface temperature and wind speed had more skill than the IC ensemble and a control (shared PHS and IC member) run initialized 12 h later (CTL12). During the cool and warm seasons, a 14-day running-mean bias calibration applied to the ALL ensemble (ALLBC) added 10%–30% more skill for temperature, wind speed, and sea level pressure, with the ALLBC far outperforming the CTL12. For the 24-h precipitation, the PHS ensemble had comparable probabilistic skill to the IC ensemble during the warm season, while the IC subensemble was more skillful during the cool season. All ensemble members had large diurnal surface biases, with ensemble variance approximating ensemble uncertainty only for wind direction. Selection of ICs was also important, because during the cool season the NCEP-bred members introduced large errors into the IC ensemble for sea level pressure, while none of the subensembles (PHS, IC, or ALL) outperformed the GFS–MM5 for sea level pressure.

scholarly journals Daily to intraseasonal oscillations at Antarctic research station Neumayer

2013 ◽  
Vol 26 (2) ◽  
pp. 193-204 ◽  
Author(s):  
N. Rimbu ◽  
G. Lohmann ◽  
G. König-Langlo ◽  
C. Necula ◽  
M. Ionita
Keyword(s):  
Time Series ◽  
Wind Speed ◽  
Sea Level ◽  
Intraseasonal Variability ◽  
Research Station ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Intraseasonal Oscillations ◽  
Antarctic Research ◽  
And Sea Level

AbstractHigh temporal resolution (three hours) records of temperature, wind speed and sea level pressure recorded at Antarctic research station Neumayer (70°S, 8°W) during 1982–2011 are analysed to identify oscillations from daily to intraseasonal timescales. The diurnal cycle dominates the three-hourly time series of temperature during the Antarctic summer and is almost absent during winter. In contrast, the three-hourly time series of wind speed and sea level pressure show a weak diurnal cycle. The dominant pattern of the intraseasonal variability of these quantities, which captures the out-of-phase variation of temperature and wind speed with sea level pressure, shows enhanced variability at timescales of ∼ 40 days and ∼ 80 days, respectively. Correlation and composite analysis reveal that these oscillations may be related to tropical intraseasonal oscillations via large-scale eastward propagating atmospheric circulation wave-trains. The second pattern of intraseasonal variability, which captures in-phase variations of temperature, wind and sea level pressure, shows enhanced variability at timescales of ∼ 35, ∼ 60 and ∼ 120 days. These oscillations are attributed to the Southern Annular Mode/Antarctic Oscillation (SAM/AAO) which shows enhanced variability at these timescales. We argue that intraseasonal oscillations of tropical climate and SAM/AAO are related to distinct patterns of climate variables measured at Neumayer.

scholarly journals The 16-Year Periodicity In The Winter Surface Temperature Variations In The Antarctic Peninsula Region

2021 ◽  
Author(s):  
Oleksandr Evtushevsky ◽  
Asen Grytsai ◽  
Oleksiy Agapitov ◽  
Volodymyr Kravchenko ◽  
Gennadi Milinevsky
Keyword(s):  
Surface Temperature ◽  
Sea Level ◽  
Antarctic Peninsula ◽  
Southern Annular Mode ◽  
Meridional Wind ◽  
Environmental Research ◽  
Southwestern Atlantic ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Antarctic

Abstract The aim of this work is a comprehensive study of the 16-year periodicity of winter surface temperature in the Antarctic Peninsula (AP) region, described earlier, and its possible source based on weather station records over the 1952–2019 period making use of the Scientific Committee on Antarctic Research (SCAR) Reference Antarctic Data for Environmental Research (READER) database, as well as Fourier and wavelet analysis methods. It is shown that interdecadal oscillation with a period of about 16 years dominates in the northern AP (Esperanza and Orcadas), which is consistent with previous results. The 16-year periodicity is found to closely correlate with the sea level pressure anomaly in the southwestern Atlantic associated with the zonal wave-3 and the Southern Annular Mode patterns. The correlation maximum in the southwestern Atlantic, having the characteristic features of the anticyclonic circulation, affects the surface temperature in the northern AP through the related structure of the zonal and meridional wind anomalies. This effect is weaker to the south, where the Vernadsky station data do not show a regular interdecadal periodicity. Due to the correlated variability in the wave-3 ridges, the pronounced 16-year periods exist also in the surface temperature of southern Australia–New Zealand region, as well as in the zonal mean sea level pressure at 30–50°S. The sea surface temperatures are much less involved in the 16-year oscillation suggesting that atmospheric rather than oceanic processes appear to be more important for its occurrence.

The Strong, Dry Winds of Central and Northern California: Climatology and Synoptic Evolution

2020 ◽  
Vol 35 (5) ◽  
pp. 2163-2178
Author(s):  
Brandon McClung ◽  
Clifford F. Mass
Keyword(s):  
Sea Level ◽  
Sierra Nevada ◽  
Critical Role ◽  
Northern California ◽  
Maximum Frequency ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Bay Area ◽  
Downslope Wind ◽  
Wind Events

AbstractStrong, dry downslope winds over Northern and central California have played a critical role in regional wildfires. These events, sometimes called Diablo or North winds, are more frequent over the Bay Area and nearby coastal terrain than along the western slopes of the Sierra Nevada, where the highest frequency occurs over the midslopes of the barrier. For the Bay Area, there is a frequency minimum during midsummer, a maximum in October, and a declining trend from November to June. The Sierra Nevada locations have their minimum frequency from February to August, and a maximum from October to January. There is little trend in event frequency during the past two decades over either region. For the Bay Area sites, there is a maximum frequency during the early morning hours and a large decline midday, while the Sierra Nevada locations have a maximum frequency approximately three hours earlier. Before the onset of these downslope wind events, there is substantial amplification of upper-level ridging over the eastern Pacific, with sea level pressure increasing first over the Pacific Northwest and then over the Intermountain West. The coincident development of a coastal sea level pressure trough leads to a large pressure gradient over the Sierra Nevada and Northern California. Diablo–North wind events are associated with below-normal temperatures east of the Sierra Nevada, with rapid warming of the air as it subsides into coastal California. The large horizontal variability in the frequency and magnitude of these events suggests the importance of exposure, elevation, and mountain-wave-related downslope acceleration.

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