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Środowiskowe Seminarium Fizyki Atmosfery

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Zapraszamy do sali B0.14, ul. Pasteura 5 o godzinie 13:15

mgr inż. Patryk Grzybowski (Międzydziedzinowa Szkoła Doktorska, Uniwersytet Warszawski)

Intercomparison of the ESA Sentinel-5P NO2 tropospheric column number density product against in-situ ground measurements

Air pollution is a severe threat to public health and has been proven as the main cause of many fatal diseases. Across Europe, air quality in Poland is one of the worst. Thus, there is a strong demand for air quality monitoring in Poland in order to raise public awareness and to develop policies that will mitigate this huge problem. The Chief Inspectorate for Environmental Protection (GIOS) performs in-situ measurement of pollutants in a few selected, densely populated locations in Poland. In smaller cities, there is no information on the level of air pollution. This study have contributed to support the air quality monitoring in Poland by means of satellite data.The main objective of the research was to verify potential of the Sentinel-5 Precursor (Sentinel-5P, S-5P) satellite Tropospheric NO2 Column Number Density product (NO2 TVCD) generated by the European Space Agency (ESA), to support air pollution monitoring in Poland. In this respect, the product was compared to in-situ measurements provided by the GIOS. The secondary objective of the project was to establish a relationship between air pollution (based on Sentinel-5P products) and meteorological data provided by European Centre for Medium-Range Weather Forecasts (ECMWF) by ERA5 reanalysis model.

Zapraszamy do sali B0.14, ul. Pasteura 5 o godzinie 13:15

mgr Wojciech Szkółka (IGF PAN)

Tropospheric winds over Sumatra – the diurnal evolution and its variability in response to large-scale phenomena

Sumatra - the westernmost island of the Maritime Continent (MC) - is strongly affected by propagating tropical phenomena. Previous research identified numerous interactions between weather modes - both local and large-scale – that affect local environment in the MC area. However, still, the mechanisms of these interactions are not fully understood.In this talk, the primary mode of variability in tropospheric winds – the diurnal cycle – will be discussed based on data from Equatorial Atmospheric Radar (EAR), which provides powerful information about tropospheric dynamics over a wide range of altitudes, with high temporal frequency and over a long period. The effects of interannual and subseasonal modes on tropospheric winds will be analyzed. These variations and interactions will be combined with diurnal evolution of clouds and precipitation over Sumatra.

Zapraszamy do sali B0.14, ul. Pasteura 5 o godzinie 13:15

prof. dr hab. Wojciech W. Grabowski (National Center for Atmospheric Research NCAR)

Daytime convective development over land: the role of surface forcing

Diurnal cycle of solar radiation over tropical and midlatitude summertime continents forces strong evolution of atmospheric convection. As surface sensible and latent heat fluxes increase after sunrise, a dry convective boundary layer develops in the early morning hours. It proceeds with the formation of shallow convective clouds as the convective boundary layer deepens and may eventually lead to the transition from shallow to deep precipitating convection. Factors affecting shallow-to-deep convection transition have been studied in the past, but the early evolution of dry convection and how it affects development of shallow convection and eventual transition to deep convection attracted much less attention.This presentation will discuss a set of large-eddy simulations that considers the impact of the surface flux Bowen ratio, the partitioning of the surface heat flux into sensible and latent components, on the development of dry and eventually moist convection. The key point is that the Bowen ratio affects the surface buoyancy flux and thus growth of dry convective boundary layer before the moist convection onset. This has a strong impact on the development and organization of shallow convection and eventual transition to deep convection. Details of the simulation results will be discussed at the conference.

Zapraszamy do sali B0.14, ul. Pasteura 5 o godzinie 13:15

dr Sylwester Arabas (University of Illinois at Urbana-Champaign & Jagiellonian University)

Immersion freezing: singular vs. time-dependent models

Water droplets containing immersed insoluble surfaces freeze at higher temperatures than that of homogeneous freezing. This process, referred to as immersion freezing, is one of the myriad of phenomena contributing to aerosol-cloud interactions in the atmosphere. Immersion freezing is also crucial for artificial snow production. Modelling studies addressing immersion freezing embrace either the so-called "singular" or the "time-dependent" description of the process. In the talk, both approaches will be juxtaposed and presented in the context of particle-based cloud microphysics modelling techniques.

Zapraszamy do sali B0.14, ul. Pasteura 5 o godzinie 13:15

dr inż. Marta Wacławczyk (IGF UW)

On the fractal reconstruction of velocity and scalar fields in turbulent flow

In this talk the reconstruction of sub-grid velocity and scalar fields in large eddy simulation (LES) of turbulent flows will be addressed. The approach is based on the assumption of fractality of these fields. The characteristics of the reconstructed signal depend on the stretching parameter d, which is related to the fractal dimension of the signal. In many previous studies the parameter d was assumed to be constant in space and time. As it will be discussed, such a model is too limited to describe the turbulence properties of interest in a satisfactory manner. Improved results can be obtained after the variability of the stretching parameter is accounted for.

Zapraszamy do sali B0.14, ul. Pasteura 5 o godzinie 13:15

mgr Beata Latos (IGF PAN)

The role of tropical waves in the genesis of tropical cyclone Seroja

Tropical cyclones are among the most destructive natural phenomena, threatening lives and property. However, the physical mechanisms that drive their genesis still need more investigation. In this talk, the genesis of a Tropical Cyclone (TC) Seroja will be discussed. Seroja formed over the Maritime Continent and in April 2021 brought historic flooding and landslides to southern Indonesia and East Timor, and also impacted Western Australia. Its genesis in the Indonesian region of Timor and Suvu Seas was associated with enhanced equatorial convection on March 28, 2021 which was preceded by warm sea surface anomalies in that region. This equatorial convection developed on the leading edge of Madden-Julian Oscillation (MJO), ahead of the convective phase. The initial equatorial convection moved southwest, boosted by environmental cyclonic vorticity associated with convectively coupled equatorial Rossby wave. The interaction between Rossby wave and two convectively coupled Kelvin waves embedded within the larger-scale envelope of the MJO provided supportive environment for strengthening of TC Seroja precursor. Each of the two Kelvin Waves that arrived over the Maritime Continent had a unique contribution in this event; structuring the convection, winds and precipitation patterns. This concurrence of factors created perfect storm conditions and led to the genesis and development of TC Seroja - one of the first tropical cyclones to have a significant impact on Indonesian land. These results indicate that forecasting of TCs genesis and tracks should consider the dynamics of tropical waves in the Maritime Continent.

Zapraszamy do sali B0.14, ul. Pasteura 5 o godzinie 13:15

mgr Robert Grosz (IGF UW)

Contactless optical hygrometry in turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T)

Highly accurate and high resolution (spatial or temporal) measurements of water vapor concentration, both in ﬁeld and laboratory experiments, are increasingly demanded to address contemporary research questions regarding cloud microphysics and cloud–turbulence interactions. At the Institute of Geophysics UW, we adapted the Fast Infrared Hygrometer (FIRH), an instrument employing tunable diode laser absorption, to perform humidity measurements at the turbulent Leipzig Aerosol Cloud Interaction Simulator (LACIS-T). The goal of the series of experiments was two-fold: (1) to evaluate the properties of FIRH under a wide range of well-deﬁned reproducible conditions resembling those in the real atmosphere, (2) to characterize the humidity ﬁeld and turbulent ﬂuctuations of humidity inside LACIS-T for different settings of the tunnel. It is an ideal facility to test FIRH because temperature and humidity in each of the two streams entering the measurement volume can be precisely controlled, while the turbulent mixing of the streams produces fast ﬂuctuations of temperature and humidity. On the other hand, FIRH is well-suited to resolve small-scale and quickly changing features of the humidity ﬁeld inside LACIS-T because it provides high temporal resolution and its typical optical path roughly corresponds to the width of the LACIS-T measurement section. This enables contactless optical sampling from outside the tunnel which eliminates the inﬂuence of the instrument on the investigated processes. https://us04web.zoom.us/j/72838451151?pwd=WHYCQJExuPOfEDdlA4gP832Fk3-Ftk.1 Meeting ID: 728 3845 1151 Passcode: v9bQpA