scholarly journals SEA-LEVEL PRESSURE TRENDS IN THE SOUTHERN OCEAN AND ANTARCTICA FROM REANALYSIS AND IN SITU DATA

2021 ◽  
Vol 49 (4) ◽  
pp. 63-85
Author(s):  
P. Yu. Romanov ◽  
N. A. Romanova
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Reanalysis Data ◽  
Environmental Research ◽  
Sea Level Pressure ◽  
Mean Values ◽  
Level Pressure ◽  
High Latitude Region ◽  
In Situ Observations

Trends in the mean sea-level pressure (SLP) in Antarctica in the last four decades (1980– 2020) have been examined using in situ observations and reanalysis data. The analysis involved time series of monthly mean, season-mean and yearly-mean values of the SLP derived from four reanalysis datasets, NCEP/NCAR, ERA5, JRA55, MERRA2, and from surface observations acquired from the Reference Antarctic Data for Environmental Research (READER) dataset. With this data we have evaluated the trends, characterized their seasonal peculiarities and variation across the high-latitude region of the Southern Hemisphere. The results of the analysis confirmed the dominance of decreasing trends in the annual mean SLP in Antarctica. Larger negative trends were found in the Western Antarctica with the most pronounced pressure drop in the South Pacific. The long-term decrease in the annual mean SLP in Antarctica was due to strong negative pressure trends in the austral summer and fall season whereas in winter and in spring the trends turn to mixed and mostly positive. The comparison of multiyear time series of SLP reanalysis data with in situ observations at Antarctic stations revealed a considerable overestimate of negative SLP trends in the NCEP/NCAR dataset. Among the four examined reanalysis datasets, ERA5 provided the best agreement with the station data on the annual mean and monthly mean SLP trend values.

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.

scholarly journals Studying Recorded lightning over Iraq for Period 1998-2011

2018 ◽  
Vol 28 (3) ◽  
pp. 1
Author(s):  
Lena Mohammed Abbas
Keyword(s):  
Relative Humidity ◽  
Sea Level ◽  
Vertical Velocity ◽  
Mean Value ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Mean Values ◽  
Level Pressure ◽  
Special Cases ◽  
The Hours

This research studies distribution of thunderstorm in Iraq for the period (1998-2011), the result showed that  the largest regions which had been hit by lightning stroke were between latitude (35-36◦)E and longitude (45-46◦)N, and April was the most frequent of lightning occurrence, also the results showed  that the number of flashes of most lightning cases were between (50-100) with higher number of flashes for some special cases. The studying of meteorological parameters which accompanied thunderstorm formation such as (Mean sea level pressure, Lifting index, relative humidity and Vertical velocity) illustrates the values of mean sea level pressure were increased during the hours after lightning occurrence comparing with their values before and at the time of lightning occurrence and their monthly mean value much greater than that recorded at the time of lightning occurrence, in addition the values of lifting index were negative at the time of lightning occurrence that refer to instability whereas their monthly average showed positive values. The values of relative humidity were greater at lightning recorded time at the three levels (500, 700, 1000)mb and also through the hours before and after this time comparing with their monthly mean. Vertical velocity values were negative for the three levels at the time of lightning occurrence that is referring to upward motion which is necessary for thundercloud initiation, and their monthly mean values were mostly negative at (500, 700)mb whereas were positive at the surface level

scholarly journals Physical Mechanisms of the Wintertime Surface Air Temperature Variability in South Korea and the near-7-Day Oscillations

2010 ◽  
Vol 23 (8) ◽  
pp. 2197-2212 ◽  
Author(s):  
Kwang-Yul Kim ◽  
Joon-Woo Roh
Keyword(s):  
Time Series ◽  
South Korea ◽  
Surface Temperature ◽  
Sea Level ◽  
Seasonal Cycle ◽  
Rossby Waves ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
The Third ◽  
Second Mode

Abstract The first three principal modes of wintertime surface temperature variability in Seoul, South Korea (37.33°N, 126.59°E), are extracted from the 1979–2008 observed records via cyclostationary EOF (CSEOF) analysis. The first mode represents the seasonal cycle, the principle physical mechanism of which is associated with the continent–ocean sea level pressure contrast. The second mode mainly describes the overall wintertime warming or cooling. The third mode depicts subseasonal fluctuations of surface temperature. Sea level pressure anomalies to the west of South Korea (eastern China) and those with an opposite sign to the east of South Korea (Japan) are a major physical factor both for the second mode and the third mode. These sea level pressure anomalies with opposite signs alter the amount of warm air to the south of South Korea, which changes the surface temperature in South Korea. The PC time series of the seasonal cycle is significantly correlated with the East Asian winter monsoon index and exhibits a conspicuous downward trend. The PC time series of the second mode exhibits a positive trend. These trends imply that the wintertime surface temperature in South Korea has increased and the seasonal cycle has weakened gradually over the past 30 yr; the sign of greenhouse warming is clear in both PC time series. The ∼7-day oscillations are a major component of high-frequency variability in much of the analysis domain and are a manifestation of Rossby waves. Rossby waves aloft result in the concerted variation of physical variables in the atmospheric column. Due to the stronger mean zonal wind, the disturbances by Rossby waves propagate eastward at ∼8–12 m s−1; the passing of Rossby waves with alternating signs produces the ∼7-day temperature oscillations in South Korea.

scholarly journals On the Leading Patterns of Northern Hemisphere Sea Level Pressure Variability*

2015 ◽  
Vol 72 (9) ◽  
pp. 3469-3486 ◽  
Author(s):  
Brian V. Smoliak ◽  
John M. Wallace
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Northern Hemisphere ◽  
Surface Air Temperature ◽  
Sea Level Pressure ◽  
Annular Mode ◽  
Level Pressure ◽  
The Pacific ◽  
Reversed Polarity ◽  
A Chain

Abstract The leading patterns of variability of the monthly mean Northern Hemisphere (NH) sea level pressure (SLP) field, as derived from empirical orthogonal teleconnection (EOT) analysis of a 93-yr (1920–2012) record of NOAA–CIRES 20th Century Reanalyses, are presented and discussed, with emphasis on wintertime patterns. The analysis yields nine or more highly reproducible wintertime hemispheric EOTs, the first six of which closely resemble EOF1 or EOF2 in their respective sectors of the hemisphere. Collectively, the first nine wintertime patterns account for 70% of the variance of NH SLP, 40% of the variance of NH surface air temperature (SAT), and 52% of the variance of the time series of NH-mean SAT poleward of 20°N. Wintertime EOT1 corresponds to the NH annular mode (NAM) and EOT2 corresponds to the SLP expression of the Pacific–North America pattern. The remaining wintertime EOT patterns are monopoles arranged like the links of a chain wrapped around the primary center of action of the annular mode. The NH summertime and Southern Hemisphere patterns are arranged in a similar manner. The continental NH wintertime patterns exhibit strong temperature anomalies of reversed polarity to their respective SLP monopoles. The interannual variability of wintertime EOTs 3–9 and summertime EOTs 2–9 is dominated by sampling fluctuations. Over the 93-yr record, the more prominent continental wintertime patterns exhibit weak trends toward falling SLP and rising SAT, particularly over Russia and Alaska. The interpretation of shorter-term trends is more ambiguous.

scholarly journals KAJIAN PERTUMBUHAN AWAN HUJAN PADA SAAT BANJIR BANDANG BERBASIS CITRA SATELIT DAN CITRA RADAR (STUDI KASUS : PADANG, 2 NOVEMBER 2018)

2019 ◽  
Vol 6 (2) ◽  
pp. 1-6
Author(s):  
Abdul Hamid Al Habib ◽  
Yoga Wahyu Pradana ◽  
Dany Pangestu ◽  
Paulus Agus Winarso ◽  
Jusa Sujana
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Level Pressure

Banjir besar kembali melanda enam kecamatan di kota Padang, Sumatera Barat pada tanggal 2 November 2018.  Banjir terjadi disebabkan oleh debit sungai yang meluap akibat hujan sangat lebat yang terjadi di bagian hulu dan hilir. Dampak banjir bandang tersebut mengakibatkan 600 rumah terendam banjir, 3 jembatan putus dan menelan korban jiwa. Karena dampak tersebut maka penelitian ini dilakukan untuk meninjau kondisi suhu permukaan laut, mean sea level pressure, nilai transport uap air, streamline, data citra satelit Himawari-8 dan data citra radar cuaca C-Band. Data diolah dalam bentuk grafik dan peta spasial kemudian dilakukan analisis deskriptif yang meliputi analisis temporal dan analisis spasial. Berdasarkan hasil analisis hujan sangat lebat yang terjadi di wilayah Padang dipicu oleh gangguan cuaca skala regional berupa adanya pola shearline atau komponen zona arah lintasan angin yang mengalami perubahan secara tiba-tiba yang sejajar dengan angin horizontal dan daerah tekanan rendah yang menimbulkan konvergensi di pesisir kota Padang, kemudian nilai transport uap air yang cukup tinggi yaitu kisaran antara 700-1100 Kg/ms-1 pada lapisan 1000-300 mb. Terjadinya hujan lebat seringkali terkait dengan keberadaan awan Cumulonimbus (Cb). Hal ini dikarenakan karakteristik awan Cb dengan dimensi yang besar serta mengandung banyak partikel presipitasi seperti  air dan kristal es. Kondisi ini didukung dengan keberadaan awan Cb berdasarkan analisis time series citra satelit Himawari-8 dan nilai reflektifitas radar berada pada nilai 45-60 dBz. Pada tanggal 2 November 2018, hampir seluruh awan hujan yang muncul mempunyai ketebalan lebih dari 7 km, dimana suhu puncak awan terendah mencapai nilai      -72.5°C.

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 The climate signal recorded in the oxygen-isotope, accumulation and major-ion time series from the Eclipse ice core, YukonTerritory, Canada

2002 ◽  
Vol 35 ◽  
pp. 416-422 ◽  
Author(s):  
Cameron P. Wake ◽  
Kaplan Yalcin ◽  
Niels S. Gundestrup
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Accumulation Rate ◽  
Ice Core ◽  
Yukon Territory ◽  
High Accumulation ◽  
Sea Level Pressure ◽  
Climate Signal ◽  
Level Pressure ◽  
Cross Correlation Analysis

AbstractThe high accumulation rate, nearly complete preservation and detailed chronology of the Eclipse ice core, Yukon Territory, Canada, are well suited for comparison of the glaciochemical recordwith instrumental time series of temperature, precipitation and sea-level pressure. Results of cross-correlation analysis of instrumental temperature records with the Eclipse δ18O time series reveal a significant positive relationship between summertime δ18O at Eclipse and summer (April–September) temperatures in northwestern North America. the results indicate that the Eclipse δ18O time series provides a better proxy for regional temperature than does the δ18O time series from the Mount Logan ice-core record for which only negative correlations were found. Winter accumulation at Eclipse is significantly correlated with several sites in Alaska, but not with any sites in the Yukon. the δ18O, accumulation and glaciochemical time series also display significant correlations with the Northern Hemisphere sea-level pressure dataset, especially between wintertime sulfate and nitrate concentrations at Eclipse and the intensity of the wintertime Siberian high and Aleutian and Icelandic lows. These results suggest that year-to-year variability in the deposition of pollutants at Eclipse can be linked to changes in atmospheric circulation, while long-term trends can be explained by changes in source strength.

scholarly journals A mean-sea-level pressure time series for Trieste, Italy (1841–2018)

2021 ◽  
Author(s):  
Fabio Raicich ◽  
Renato R. Colucci
Keyword(s):  
Time Series ◽  
Sea Level ◽  
Historical Documents ◽  
Sea Level Pressure ◽  
Mean Sea Level ◽  
Level Pressure ◽  
Pressure Time ◽  
Hourly Data ◽  
Quality Checks ◽  
Basic Quality

Abstract. A time series of mean-sea-level pressure was built from observations performed in Trieste from 1 January 1841 to 31 December 2018. Original historical documents provided information on the instruments and on the observation sites. Mercury barometers have been always available. Until 1877 they represented the only instruments in operation, while from 1878 onwards barograph records became available. The time series consists of mean daily values, that were computed from 24 hourly data, when possible, or otherwise adjusted to 24-hr means on the basis of climatological daily pressure cycles. The time series was homogenized on the basis of the available metadata, reducing pressure to 0° C and to mean sea level. Basic quality checks were applied, including the comparison with pressure time series from nearby stations. As a result, the data prior to 1865 turned out to be suspect. A mean-sea-level pressure trend of 0.5 ± 0.2 hPa per century was estimated for the 1865–2018 period. The data are available through PANGAEA https://doi.pangaea.de/10.1594/PANGAEA.926896; Raicich and Colucci, 2021).

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