Wetteranalyse als konkrete physikalische Herausforderung: Tor Bergerons bahnbrechende Beiträge aus Bergen und Leipzig während der 1920er Jahre

<p>Computergestützte Vorhersage- und Nowcasting-Methoden berücksichtigen heutzutage eine Vielzahl von physikalischen Prozessen, die bei der Integration der dynamischen Gleichung aktiv mitwirken. Vor hundert Jahren erarbeitete der Schwede <em>Tor Bergeron</em> (1891-1977) in Bergen und zeitweise in Leipzig eine Monographie "Über die dreidimensional verknüpfende Wetteranalyse", welche eine ganze Reihe derartiger Prozesse zu quantifizieren suchte und ihre Rolle bei der Entstehung und Fortbewegung von Luftmassen und besonders von Zyklonen darlegte. Die Arbeit erschien schließlich 1928 als umfangreiche Dissertationsschrift im Band 5 der noch jungen Zeitschrift <em>Geofysiske Publikasjoner. </em></p> <p>Zu den ausführlich dargelegten atmosphärenphysikalischen Meilensteinen gehören etwa: eine Diskussion von atmosphärenphysikalischen Erhaltungsgrößen; die Berücksichtigung von Aerosolen; die Dokumentation der Blockierung einer Frontalzone an den Alpen mit nachfolgender Leezyklogenese; die Entstehung von Luftmassentypen (kalte und warme) aufgrund von diabatischen Prozessen; die Verbindung von Sichtweite, Aerosolgehalt und Luftmassentyp; die Darstellung einer Prozesskette zur Niederschlagsbildung (heute: Wegener-Bergeron-Findeisen-Prozess); die Präsentation eines kompletten Jahres (1922) von Aufstiegsdaten der potentiellen Temperatur als Beleg wechselnder Luftmassen. </p> <p>Die Präsentation folgt einer aktuellen Veröffentlichung (Schultz et al., 2020), welche die erstmalige Übersetzung von Bergerons Dissertation ins Englische begleitet. Wesentliche Abbildungen werden eingehend erläutert und mit neueren Daten verglichen. Lokale Bezüge zum Geophysikalischen Institut der Universität Leipzig unter Professor <em>Weickmann</em> werden besonders berücksichtigt.</p> <p>Literaturhinweise:</p> <p>Bergeron, T., 1928:  Über die dreidimensional verknüpfende Wetteranalyse. Erster Teil. Prinzipielle Einführung in das Problem der Luftmassen- und Frontenbildung. <em>Geofys. Publ.</em>, <strong>5</strong> (6), 1–118; online: <em>www.ngfweb.no/docs/NGF_GP_Vol05_no6.pdf</em> . </p> <p>Schultz, D.M., H. Volkert, B. Antonescu, and H.C. Davies, 2020:   Defender and Expositor of the Bergen Methods of Synoptic Analysis - Significance, History, and Translation of Bergeron’s (1928) “Three-Dimensionally Combining Synoptic Analysis”. <em>Bull. Amer. Meteorol. Soc.</em>, <strong>101</strong>, E2078-E2094; online: <em>https://doi.org/10.1175/BAMS-D-20-0021.1</em>  .  </p>

COVID CRISIS AND TOURISM EVOLUTION IN SOME EUROPEAN COUNTRIES: ADAPT TO REALITIES OR REINVENT THE FUTURE?

The health crisis has exerted a significant pressure on the global economic system, implicitly on the evolution of tourism, value chain creation and supply chains, generating shocks on various national economic sectors. In this context, the objective of the paper is to make a brief synoptic analysis on the evolution of the tourism sector in some EU countries. Two periods of time were considered - before the onset of the pandemic (2018-2019) and during the pandemic (in 2020). The results of the analysis confirm the specific trends of reducing the multiplicative effects that tourism has on the economy as well as the decrease, even contracting of the sector, a phenomenon identified through specific analyzed indicators.

Synoptic Analysis for the Daily Rains of the City of Baghdad

To know the reasons for changing the daily rainfall amount, cases study were chosen for Baghdad station by specifying the maximum and minimum daily rain for the months of the rainy season for each year of the study period (2007-2018). The behavior of daily rainfall for the rainy season varying temporally with maximum (89 mm) and minimum (0.1mm). Synoptic analysis of weather chart for pressure levels (300, 500, 700, 850, and surface) was performed. Visible images of satellites were used to determine the quantities of the cloud for the selected cases. The results showed that synoptic analysis in all cases occurs due to the presence of a jet stream in the upper atmosphere, accompanied by the presence of a basin at the level of 300 hectopascals with an enhancement of relative humidity exceeding 70% at the level of 700 hectopascals, but the presence of the front makes the amount of rain greater in the absence of it. At the level of 850 hectopascals and the surface, the depressions that affect Iraq also differ in their severity and the amount of moisture loaded.

Ciclone Michael: gênese e transição extratropical

Os ciclones de escala sinótica são responsáveis por grandes mudanças no tempo das regiões onde atuam. Nos últimos anos tem aumentado o número de sistemas tropicais severos. Por exemplo, o ciclone Michael, ocorrido em outubro de 2018, causou muitos danos nos Estados Unidos (U$25 bilhões em prejuízo), inclusive 16 óbitos. Diante desse contexto, o objetivo do presente estudo é a análise sinótica da gênese e transição extratropical do ciclone Michael. Michael teve gênese no mar do Caribe, no dia 6 de outubro de 2018, associada a uma perturbação ciclônica em baixos níveis da atmosfera. O sistema chegou a categoria 5 na escala de Saffir-Simpson no dia 10 de outubro; já no dia 11 de outubro transicionou para ciclone extratropical e decaiu no dia 18 de outubro. A análise sinótica mostra que transição extratropical ocorre à medida que o sistema interage com uma região de intenso gradiente horizontal de temperatura do ar. Cyclone Michael: genesis and extratropical transition A B S T R A C T Synoptic-scale cyclones are responsible for major changes in the weather in the regions where they act. In recent years the number of severe tropical systems has increased. For example, cyclone Michael, which occurred in October 2018, caused a lot of damage in the United States ($ 25 billion in damage) including 16 deaths. Given this context, the objective of the present study is the synoptic analysis of the genesis and extratropical transition of cyclone Michael. Michael had genesis in the Caribbean Sea on October 6, 2018, associated with a cyclonic disturbance in low levels of the atmosphere. The system reached category 5 on the Saffir-Simpson scale on 10 October; on the 11 October it transitioned to an extratropical cyclone and decayed on the 18 October. The synoptic analysis shows that extratropical transition occurs as the system interacts with a region of intense horizontal air temperature gradient. Keywords: cyclone, synoptic analysis, extratropical transition.