TY  - GEN
A1  - Siddiqui, Tarique Adnan
A1  - Maute, Astrid
A1  - Pedatella, Nick
A1  - Yamazaki, Yosuke
A1  - Lühr, Hermann
A1  - Stolle, Claudia
T1  - On the variability of the semidiurnal solar and lunar tides of the equatorial electrojet during sudden stratospheric warmings
T2  - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The variabilities of the semidiurnal solar and lunar tides of the equatorial electrojet (EEJ) are investigated during the 2003, 2006, 2009 and 2013 major sudden stratospheric warming (SSW) events in this study. For this purpose, ground-magnetometer recordings at the equatorial observatories in Huancayo and Fúquene are utilized. Results show a major enhancement in the amplitude of the EEJ semidiurnal lunar tide in each of the four warming events. The EEJ semidiurnal solar tidal amplitude shows an amplification prior to the onset of warmings, a reduction during the deceleration of the zonal mean zonal wind at 60∘ N and 10 hPa, and a second enhancement a few days after the peak reversal of the zonal mean zonal wind during all four SSWs. Results also reveal that the amplitude of the EEJ semidiurnal lunar tide becomes comparable or even greater than the amplitude of the EEJ semidiurnal solar tide during all these warming events. The present study also compares the EEJ semidiurnal solar and lunar tidal changes with the variability of the migrating semidiurnal solar (SW2) and lunar (M2) tides in neutral temperature and zonal wind obtained from numerical simulations at E-region heights. A better agreement between the enhancements of the EEJ semidiurnal lunar tide and the M2 tide is found in comparison with the enhancements of the EEJ semidiurnal solar tide and the SW2 tide in both the neutral temperature and zonal wind at the E-region altitudes.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1075 
KW  - middle atmosphere
KW  - latitude ionosphere
KW  - temperature changes
KW  - lower thermosphere
KW  - magnetic field
KW  - TIME-GCM
KW  - winds
KW  - circulation
KW  - events
KW  - winter
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-468389
SN  - 1866-8372
IS  - 1075
SP  - 1545
EP  - 1562
ER  - 
TY  - JOUR
A1  - Hierro, Rodrigo
A1  - Burgos Fonseca, Y.
A1  - Ramezani Ziarani, Maryam
A1  - Llamedo, P.
A1  - Schmidt, Torsten
A1  - de la Torre, Alejandro
A1  - Alexander, P.
T1  - On the behavior of rainfall maxima at the eastern Andes
JF  - Atmospheric Research
N2  - In this study, we detect high percentile rainfall events in the eastern central Andes, based on Tropical Rainfall Measuring Mission (TRMM) with a spatial resolution of 0.25 × 0.25°, a temporal resolution of 3 h, and for the duration from 2001 to 2018. We identify three areas with high mean accumulated rainfall and analyze their atmospheric behaviour and rainfall characteristics with specific focus on extreme events. Extreme events are defined by events above the 95th percentile of their daily mean accumulated rainfall. Austral summer (DJF) is the period of the year presenting the most frequent extreme events over these three regions. Daily statistics show that the spatial maxima, as well as their associated extreme events, are produced during the night. For the considered period, ERA-Interim reanalysis data, provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) with 0.75° x0.75° spatial and 6-hourly temporal resolutions, were used for the analysis of the meso- and synoptic-scale atmospheric patterns. Night- and day-time differences indicate a nocturnal overload of northerly and northeasterly low-level humidity flows arriving from tropical South America. Under these conditions, cooling descending air from the mountains may find unstable air at the surface, giving place to the development of strong local convection. Another possible mechanism is presented here: a forced ascent of the low-level flow due to the mountains, disrupting the atmospheric stratification and generating vertical displacement of air trajectories. A Principal Component Analysis (PCA) in T-mode is applied to day- and night-time data during the maximum and extreme events. The results show strong correlation areas over each subregion under study during night-time, whereas during day-time no defined patterns are found. This confirms the observed nocturnal behavior of rainfall within these three hotspots.
KW  - South-America
KW  - rainy-season
KW  - part I
KW  - precipitation
KW  - TRMM
KW  - climate
KW  - summer
KW  - circulation
KW  - monsoon
KW  - systems
Y1  - 2019
U6  - https://doi.org/10.1016/j.atmosres.2019.104792
SN  - 0169-8095
VL  - 234
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  -