Methods for estimate the dynamic and thermal characteristics of smoke plumes

Space observations of the propagation of smoke flares from the chimneys of industrial enterprises provide information on the physical characteristics of the emitted gas-air mixtures. Models for estimating the parameters of the rise of impurities under the influence of dynamic and thermal factors are proposed. The basic relations in the estimation models are the solutions of the equations of hydrothermodynamics of the atmosphere. The case of neutral atmospheric stratification is considered in detail. Using satellite information and meteorological observation data, a numerical study of the stage of ascent of smoke jets from the chimneys of the Gusinoozerskaya State District Power Plant was carried out.

Wind Speed Analysis of Hurricane Sandy

The database of the HWind project sponsored by the National Oceanic and Atmospheric Administration (NOAA) for hurricanes between 1994 and 2013 is analysed. This is the first objective of the current research. Among these hurricanes, Hurricane Sandy was selected for a detailed study due to the number of files available and its social relevance, with this being the second objective of this study. Robust wind speed statistics showed a sharp increase in wind speed, around 6 m s−1 at the initial stage as Category 1, and a linear progression of its interquartile range, which increased at a rate of 0.54 m s−1 per day. Wind speed distributions were initially right-skewed. However, they evolved to nearly symmetrical or even left-skewed distributions. Robust kurtosis was similar to that of the Gaussian distribution. Due to the noticeable fraction of wind speed intermediate values, the Laplace distribution was used, its scale parameter increasing slightly during the hurricane’s lifecycle. The key features of the current study were the surface and recirculation factor calculation. The surface area with a category equal to, or higher than, a tropical storm was calculated and assumed to be circular. Its radius increased linearly up to 600 km. Finally, parcel trajectories were spirals in the lower atmosphere but loops in the mid-troposphere due to wind translation and rotation. The recirculation factor varied, reaching values close to 0.9 and revealing atmospheric stratification.

Atmospheric stratification over Namibia and the southeast Atlantic Ocean

We currently have a limited understanding of the spatial and temporal variability in vertically stratified atmospheric layers over Namibia and the southeast Atlantic (SEA) Ocean. Stratified layers are relevant to the transport and dilution of local and long-range transported atmospheric constituents. This study used eleven years of global positioning system radio occultation (GPS-RO) signal refractivity data (2007–2017) over Namibia and the adjacent ocean surfaces, and three years of radiosonde data from Walvis Bay, Namibia, to study the character and variability in stratified layers. From the GPS-RO data and up to a height of 10 km, we studied the spatial and temporal variability in the point of minimum gradient in refractivity, and the temperature inversion height, depth and strength. We also present the temporal variability of temperature inversions and the boundary layer height (BLH) from radiosondes. The BLH was estimated by the parcel method, the top of a surface-based inversion, the top of a stable layer identified by the bulk Richardson number (RN), and the point of minimum gradient in the refractivity (for comparison with GPS-RO data). A comparison between co-located GPS-RO to radiosonde temperature profiles found good agreement between the two, and an average underestimation of GPS-RO to radiosonde temperatures of −0.45 ± 1.25 °C, with smaller differences further from the surface and with decreasing atmospheric moisture content. The minimum gradient (MG) of refractivity, calculated from these two datasets were generally in good agreement (230 ± 180 m), with an exeption of a few cases when differences exceeded 1000 m. The surface of MG across the region of interest was largely affected by macroscale circulation and changes in atmospheric moisture and cloud, and was not consistent with BLH(RN). We found correlations in the character of low-level inversions with macroscale circulation, radiation interactions with the surface, cloud cover over the ocean and the seasonal maximum in biomass burning over southern Africa. Radiative cooling on diurnal scales also affected elevated inversions between 2.5 and 10 km, with more co-occurring inversions observed at night and in the morning. Elevated inversions formed most frequently over the subcontinent and under subsidence by high-pressure systems in the colder months. Despite this macroscale influence peaking in the winter, the springtime inversions, like those at low levels, were strongest.

Multi-Dimension and Multi-Channel Seismic-Ionospheric Coupling: Case Study of Mw 8.8 Concepcion Quake on 27 February 2010

GPS radio occultation (RO) technology can fully describe the subtle structure of the ionosphere. This paper discusses the dynamic abnormity observed by the RO data from the Constellation Observing System for Meteorology Ionosphere and Climate (FORMOSAT-3/COSMIC) before the great earthquake case in Concepcion, Chile (27 February 2010, Mw 8.8). Traditional ground-based GPS monitoring was considered as the external conditions and references to the excitation response. Using kriging interpolation, the global Nmf2 map (GNM) was first constructed to study the ionosphere deviation from the normal state. Successively, the ionosphere abnormality in the F2 region (Nmf2), vertical structure (RO profiles), and multiple heights (electron density) of traveling are unfolded. The Nmf2 disturbances in the possibility of seismic influences were excluded from non-seismic noise factors, including the external input (e.g., space weather activity, 15 February) and meteorological events (e.g., lower atmospheric forcing in quiet periods). However, the results show that there were apparent local Nmf2 perturbations for up to 5 h in the epicenter area on 21 and 25 February. The disturbances of the RO profiles and the interaction of other layers of the ionosphere implied the fluctuation signals of prominent long-wavelength fluctuations >50 km in the F layer. The ionospheric fluctuates wildly, and these wave signals considered as the trace of gravity wave propagating upward are mainly distributed at the elevation of 200–300 km. The simultaneous reaction of GNSS TEC further evidenced the potential possibility of acoustic gravity by the COSMIC RO profiles, reflecting the compounding couplings of seismo-ionosphere effects. In terms of the presentation of VLF radiation noise and the aerosol ion clusters, the electromagnetic and chemical channels have been previously completed by DEMETER and Terra/Aqua satellites. These findings implied the great potential of the FORMOSAT-7/COSMIC-2 system (now in the testing phase), with ~5000 soundings to investigate the subtle atmospheric stratification.

Influence of Atmospheric Stability on the flow dynamics within and above a dense Amazonian forest

<p>This study provides a detailed analysis of the influence of atmospheric stratification on the flow dynamics above and within a dense forest for a 19-days campaign at the Amazon Tall Tower Observatory (ATTO) site. Observations taken at seven levels within and above the forest along an 81-meter and a 325-meter towers allow a unique investigation of the vertical evolution of the turbulent field in the roughness sublayer and in the surface layer above it.</p><p>Five different stability classes were defined on the basis of the behavior of turbulent heat, momentum and CO<sub>2</sub> fluxes and variance ratio as a function of h/L stability parameter (where h is the canopy height and L is the Obukhov length). The novelty is the identification of a ‘super-stable’ (SS) regime (h/L>3) characterized by extremely low wind speeds, the almost completely suppression of turbulence and a clear dominance of submeso motions both above and within the forest.</p><p>The obtained data classification was used to study the influence of atmospheric stratification on the vertical profiles of turbulent statistics. The spectral characteristics of coherent structures and of submeso motions (that may influence the energy and mass exchange above the Amazon forest) have been analyzed by wavelet analyses. The role of the main structures in momentum, heat and CO<sub>2 </sub>transport at the different levels inside and above the forest and in different diabatic conditions was thoroughly investigated through multiresolution and quadrant analyses.</p><p>In unstable and neutral stability, the flow above the canopy appears modulated by ejections, whereas downward and intermittent sweeps dominate the transport inside the canopy. In the roughness sublayer (z £ 2h) the coherent structures dominating the transport within and above the canopy have a characteristic temporal scale of about 100 sec, whereas above this layer the transport is mainly driven by larger scale convection (temporal scale of about 15 min).</p><p>In stable conditions the height of roughness sublayer progressively decreases with increasing stability reaching the minimum value (z<1.35h) in the SS regime. Above the canopy the flow is clearly dominated by ejections but characterized by a higher intermittency mainly in SS conditions. On the other hand, the rapid shear stress absorption in the highest part of the vegetation produces a less clear dominance of sweeps and a less defined role of odd and even quadrants inside the canopy in the transport of momentum, heat and CO<sub>2</sub>. In the weakly stable regime (0.15<h/L<1) transport is dominated in the roughness sublayer by canopy coherent structures with a characteristic temporal scale of about 60 sec. As stability increases the influence of low-frequency (submeso) processes, with a temporal scale of 20-30 min, on flow dynamics progressively increases and becomes dominant in the SS regime where the buoyancy strongly dampens or completely inhibits turbulent structures whereas the large-scale oscillations propagate in the interior of the canopy modulating the heat and CO<sub>2 </sub>transport.</p><p> </p>

The role of Bora winds in generating short-period O(30 min) seiches in the Adriatic sea

<p>An array of oceanographic instruments deployed on an approx. 1.2-km long transect on the Senigallia Adriatic shelf fronting Misa River mouth captured persistent (approx. 2 days), low-frequency oscillations of sea level and cross-shore velocity, following the strong Bora event of Jan, 24-25th, 2014 (the field experiment is described in Brocchini et al., 2017). The Bora storm generated remarkably energetic waves, with 10-s peak period and 3-m significant height.  Following the storm, pressure and velocity records show  20 to 120 min oscillations, with amplitudes in the order of 10-20 cm/s, and  2-10 cm. Pressure  oscillations were in phase across the entire 1.2-km transect. Pressure and cross-shore velocity spectra show well-defined, distinct peaks at frequencies close to multiples of 0.01 1/min, which suggests a seiche process. The  velocity spectrum decays fast at frequencies < 0.03 1/min, while the pressure spectrum exhibits additional peaks at 0.01 and 0.02 1/ min, a behavior consistent with the neighbourhood of the shoreline antinode of a cross-shore standing wave.<br><br>Although the oscillations follow, and are obviously related to, a strong Bora event, the forcing mechanism and their large scale structure and dynamics are not well understood (details of Bora events themselves have only recently been clarified; Grisogono and Belusic, 2008). Due to its basin shape and topography, the Adriatic may exhibit both longitudinal and transversal seiches. Longitudinal seiches are typically associated with intense winds out of SE, large frontal systems, or with cyclonic activity, with a dominant 22-hour fundamental mode that persists for days. The much shorter period of the observed oscillations observed suggests seiche modes that are dominantly transversal.<br><br>Here, we use theoretical and numerical models to investigate the spatio-temporal structure and the generation mechanism of these oscillations. The generation mechanism could be a combination of stress fluctuations in the Bora wind, and convection cells associated with unstable atmospheric stratification in the wake of the Bora event. As narrow jets,  Bora winds exhibit significant instability and velocity fluctuations  (10-min oscillations between 15 and 25 m/s; Grisogono and Belusic 2008). Convection cells forming in an unstable atmospheric stratification in the wake of a cold-front passage over the North sea were shown to be the forcing of ocean surface oscillations on a similar scale observed at Port of Rotterdamwere, the Netherlands (DeJong and Battjes, 2004).<br><br>The study highlights aspects of the relation between Bora events and transversal seiches that are not well documented and poorly understood, but relevant in relation with other air-sea interaction processes that have a significant shoreline impact, such as wave activity, meteotsunamis, and flooding induced by storm surges.</p>

Sensitivity of Aeolus HLOS winds to temperature and pressure specification in the L2B processor

The retrieval of wind from the first Doppler wind lidar of Europen Space Agency (ESA) launched in space in August 2018 is based on a series of corrections necessary to provide observations of a quality useful for Numerical Weather Prediction (NWP). In this paper we examine properties of the Rayleigh-Brillouin correction necessary for the retrieval of horizontal line-of-sight wind (HLOS) from a Fabry-Perot interferometer. This correction is taking into account the atmospheric stratification, namely temperature and pressure information that are provided by a NWP model as suggested prior launch. Since NWP models contain errors the main goal in the study is to evaluate the impact of these errors on the HLOS sensitivity by comparing the Integrated Forecast System (IFS) and Action de Recherche Petite Echelle Grande Echelle (ARPEGE) global model temperature and pressure short term forecasts collocated with the Aeolus orbit. The model error is currently not taken into account in the computation of the HLOS error estimate since its contribution is believed small. This study largely confirms this statement to be a valid assumption, although it also shows that model errors could locally (i.e. jet-stream regions, below 700 hPa over both earth poles and as well in stratosphere) be significant. For a future Aeolus follow-on missions this study suggests to consider realistic estimations of model errors in the HLOS retrieval algorithms, since this will lead to an improved estimation of the Rayleigh-Brillouin sensitivity uncertainty contributing to the HLOS error estimate and better exploitation of space lidar winds in NWP systems.