scholarly journals Impact of smoke and non-smoke aerosols on radiation and low-level clouds over the southeast Atlantic from co-located satellite observations

2021 ◽  
Vol 21 (8) ◽  
pp. 6053-6077
Author(s):  
Alejandro Baró Pérez ◽  
Abhay Devasthale ◽  
Frida A.-M. Bender ◽  
Annica M. L. Ekman
Keyword(s):  
Satellite Observation ◽  
Clear Correlation ◽  
Heating Rates ◽  
Cooling Rates ◽  
Thermodynamic Structure ◽  
Aerosol Loading ◽  
Stratocumulus Clouds ◽  
Aerosol Classification ◽  
Abstract Data ◽  
Aerosol Type

Abstract. Data derived from instruments on board the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat satellites as well as meteorological parameters from reanalysis are used to explore situations when moist aerosol layers overlie stratocumulus clouds over the southeast Atlantic during the biomass burning season (June to October). To separate and quantify the impacts of aerosol loading, aerosol type, and humidity on the radiative fluxes (including cloud top cooling), the data are split into different levels of aerosol and moisture loadings. The aerosol classification available from the CALIPSO products is used to compare and contrast situations with pristine air, with smoke, and with other (non-smoke) types of aerosols. A substantial number of cases with non-smoke aerosols above clouds are found to occur under similar meteorological conditions to the smoke cases. In contrast, the meteorology is substantially different for the pristine situations, making a direct comparison with the aerosol cases ambiguous. The moisture content is enhanced within the aerosol layers, but the relative humidity does not always increase monotonously with increasing optical depth. Shortwave (SW) heating rates within the moist aerosol plumes increase with increasing aerosol loading and are higher in the smoke cases compared to the non-smoke cases. However, there is no clear correlation between moisture changes and SW absorption. Cloud top cooling rates do not show a clear correlation with moisture within the overlying aerosol layers due to the strong variability of the cooling rates caused by other meteorological factors (most notably cloud top temperature). No clear influence of aerosol type or loading on cloud top cooling rates is detected. Further, there is no correlation between aerosol loading and the thermodynamic structure of the atmosphere nor the cloud top height.

scholarly journals Impact of absorbing and non-absorbing aerosols on radiation and low-level clouds over the Southeast Atlantic from co-located satellite observations

2020 ◽  
Author(s):  
Alejandro Baró Pérez ◽  
Abhay Devasthale ◽  
Frida Bender ◽  
Annica M. L. Ekman
Keyword(s):  
Satellite Observation ◽  
Clear Correlation ◽  
Heating Rates ◽  
Cooling Rates ◽  
Thermodynamic Structure ◽  
Aerosol Loading ◽  
Stratocumulus Clouds ◽  
Aerosol Classification ◽  
Absorbing Aerosols ◽  
Aerosol Type

Abstract. We use data derived from instruments onboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) and CloudSat satellites as well as meteorological parameters from reanalysis to explore situations when moist aerosol layers overlie stratocumulus clouds over the Southeast Atlantic during the biomass burning season (June to October). One main goal is to separate and quantify the impacts of aerosol loading, aerosol type, and humidity on the radiative fluxes, including cloud top cooling. To achieve our objectives we split the data into different levels of aerosol and moisture loadings. By using the aerosol classification available from the CALIPSO products, we also separate and compare situations with pristine air, with smoke, and with other (mixed) types of aerosols. We find a substantial number of cases with mixed aerosols above clouds that occur under similar meteorological conditions as the smoke cases. In contrast, the meteorology is substantially different for the pristine situations, making a direct comparison with the aerosol cases ambiguous. The moisture content is enhanced within the aerosol layers, but we do not find a monotonous increase of the relative humidity with increasing aerosol optical depth. Shortwave (SW) heating rates within the moist aerosol plumes increase with increasing aerosol loading and are higher in the smoke cases compared to the mixed cases. However, there is no clear correlation between moisture changes and SW absorption. Cloud top cooling rates tend to decrease with increasing moisture within the overlying aerosol layers, but the influence is relatively weak and confounded by the strong variability of the cooling rates caused by other meteorological factors (most notably cloud top temperature). No clear influence of aerosol type or loading on cloud top cooling rates is detected. We also do not find any correlation between aerosol loading and the thermodynamic structure of the atmosphere nor the cloud top height, i.e. no indication of a semi-direct aerosol effect. This result is consistent with previous studies that examined clearly separated aerosol and cloud layers (in our case at least 0.4 km).

scholarly journals Global Aerosol Classification Based on Aerosol Robotic Network (AERONET) and Satellite Observation

2021 ◽  
Vol 13 (6) ◽  
pp. 1114
Author(s):  
Jianyu Lin ◽  
Yu Zheng ◽  
Xinyong Shen ◽  
Lizhu Xing ◽  
Huizheng Che
Keyword(s):  
Radiative Forcing ◽  
Temporal Distribution ◽  
Satellite Observation ◽  
Western Africa ◽  
Deep Blue ◽  
Sensing Technology ◽  
Aerosol Classification ◽  
Linear Depolarization Ratio ◽  
Absorbing Aerosols ◽  
Single Scatter

The particle linear depolarization ratio (PLDR) and single scatter albedo (SSA) in 1020 nm from the Aerosol Robotic Network (AERONET) level 2.0 dataset was utilized among 52 stations to identify dust and dust dominated aerosols (DD), pollution dominated mixture (PDM), strongly absorbing aerosols (SA) and weakly absorbing aerosols (WA), investigate their spatial and temporal distribution, net radiative forcing and radiative forcing efficiency in global range, and further compare with VIIRS Deep Blue Production. The conclusion about net radiative forcing suggests that the high values of radiative forcing from dust and dust dominated aerosols, pollution dominated mixture both mainly come from western Africa. Strongly absorbing aerosols in South Africa and India contribute greatly to the net radiative forcing and the regions with relative high values of weakly absorbing aerosols are mainly located at East Asia and India. Lastly, the observation of VIIRS Deep Blue satellite monthly averaged products depicts the characteristics about spatial distribution of four kinds of aerosol well, the result from ground-based observation presents great significant to validate the measurements from remote sensing technology.

scholarly journals Aerosol classification from airborne HSRL and comparisons with the CALIPSO vertical feature mask

2013 ◽  
Vol 6 (1) ◽  
pp. 1815-1858 ◽  
Author(s):  
S. P. Burton ◽  
R. A. Ferrare ◽  
M. A. Vaughan ◽  
A. H. Omar ◽  
R. R. Rogers ◽  
...  
Keyword(s):  
High Spectral Resolution ◽  
Dependent Observations ◽  
Aerosol Retrieval ◽  
Direct Measurements ◽  
Aerosol Classification ◽  
Lidar Ratio ◽  
Langley Research Center ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types ◽  
Aerosol Type

Abstract. Aerosol classification products from the NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL-1) on the NASA B200 aircraft are compared with coincident V3.01 aerosol classification products from the CALIOP instrument on the CALIPSO satellite. For CALIOP, aerosol classification is a key input to the aerosol retrieval, and must be inferred using aerosol loading-dependent observations and location information. In contrast, HSRL-1 makes direct measurements of aerosol intensive properties, including the lidar ratio, that provide information on aerosol type. In this study, comparisons are made for 109 underflights of the CALIOP orbit track. We find that 62% of the CALIOP marine layers and 54% of the polluted continental layers agree with HSRL-1 classification results. In addition, 80% of the CALIOP desert dust layers are classified as either dust or dusty mix by HSRL-1. However, agreement is less for CALIOP smoke (13%) and polluted dust (35%) layers. Specific case studies are examined, giving insight into the performance of the CALIOP aerosol type algorithm. In particular, we find that the CALIOP polluted dust type is overused due to an attenuation-related depolarization bias. Furthermore, the polluted dust type frequently includes mixtures of dust plus marine aerosol. Finally, we find that CALIOP's identification of internal boundaries between different aerosol types in contact with each other frequently do not reflect the actual transitions between aerosol types accurately. Based on these findings, we give recommendations which may help to improve the CALIOP aerosol type algorithms.

scholarly journals Aerosol classification using airborne High Spectral Resolution Lidar measurements – methodology and examples

2012 ◽  
Vol 5 (1) ◽  
pp. 73-98 ◽  
Author(s):  
S. P. Burton ◽  
R. A. Ferrare ◽  
C. A. Hostetler ◽  
J. W. Hair ◽  
R. R. Rogers ◽  
...  
Keyword(s):  
Spectral Resolution ◽  
High Spectral Resolution ◽  
Color Ratio ◽  
Lidar Measurements ◽  
Aerosol Classification ◽  
Langley Research Center ◽  
High Spectral Resolution Lidar ◽  
Aerosol Types ◽  
532 Nm ◽  
Aerosol Type

Abstract. The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical depth (AOD) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOD and inferences of aerosol types are used to apportion AOD to aerosol type; results of this analysis are shown for several experiments.

Thermodynamic structure of a grass fire plume

2010 ◽  
Vol 19 (7) ◽  
pp. 895 ◽  
Author(s):  
Craig B. Clements
Keyword(s):  
Short Duration ◽  
Combustion Zone ◽  
Rapid Heating ◽  
Ground Level ◽  
Heating Rates ◽  
Fire Plume ◽  
Thermodynamic Structure ◽  
Rate Of Spread ◽  
Fire Front ◽  
Plume Temperature

High-frequency thermocouple measurements were made during an experimental grass fire conducted during ideal weather with overcast and windy conditions. Analysis of the thermodynamic structure of the fire plume showed that a maximum plume temperature of 295.2°C was measured directly above the combustion zone. Plume heating rates were on the order of 26–45 kW m–2 and occurred in the region just above the combustion zone between 10 and 15 m above ground level and were followed by cooling of approximately –37 and –44 kW m–2. The observed cooling was caused by strong entrainment that occurred behind the fire front and plume. The rapid heating and subsequent cooling indicate that the heating caused by a fire front is limited to a small volume around the flaming front and that the rates of heat gain occur for a short duration. The short duration of plume heating is due to the fast rate of spread of the fire front and ambient wind.

Performance of a Multi-Cell MgCl2/NH3 Thermo-Chemical Battery During Recharge and Operation

2015 ◽  
Author(s):  
Kent S. Udell ◽  
Bidzina Kekelia ◽  
Peng Fan ◽  
Chengshang Zhou ◽  
Zhigang Fang
Keyword(s):  
Heat Transfer ◽  
Waste Heat ◽  
Gaseous Ammonia ◽  
Air Cooling ◽  
Ammonia Vapor ◽  
Heating Rates ◽  
Cell Array ◽  
Cooling Rates ◽  
Operational Test ◽  
Storage Technologies

The development of thermal energy storage technologies to match sustainable energy production is of interest. A prototype of a multi-cell thermochemical battery consisting of connected cells containing MgCl2 salt, and additional air-cooled or air-heated cells containing liquid ammonia of varying quality, was constructed and tested. Each of the 17 cells contained thermocouple probes at three different axial locations within the cylindrical cells. Heat transfer rates, pressures, and ammonia condensation and vaporization rates were measured. Three tests were run. In the first test, the hot bed containing 10 cells was heated using cartridge heaters, driving vaporous ammonia from the salt phase once sufficient salt temperatures were reached. The evolved gaseous ammonia was condensed in an additional 7 empty air-cooled cells. Once the recharging cycle was complete, a valve in the ammonia vapor line connecting the cold and hot beds was closed, allowing indefinite storage of cooling or heating capacity. The second operational test involved the opening of the valve while simultaneous air-cooling the hot bed cells and air-heating the cold bed cells. Heating rates and cooling rates to/from air forced through the hot bed and cold bed, respectively, were monitored to gauge HVAC performance. The second recharge was performed by using a air/air heat exchanger that captured waste heat from an automobile engine exhaust manifold and transferred it to air that was re-circulated through the hot bed array. Temperatures, pressures, heating rates, cooling rates, and cell array heat transfer specifications are reported.

scholarly journals A global aerosol classification algorithm incorporating multiple satellite data sets of aerosol and trace gas abundances

2015 ◽  
Vol 15 (18) ◽  
pp. 10597-10618 ◽  
Author(s):  
M. J. M. Penning de Vries ◽  
S. Beirle ◽  
C. Hörmann ◽  
J. W. Kaiser ◽  
P. Stammes ◽  
...  
Keyword(s):  
Classification Algorithm ◽  
Atmospheric Composition ◽  
Trace Gas ◽  
Aerosol Composition ◽  
Ångström Exponent ◽  
Aerosol Classification ◽  
Aerosol Index ◽  
Aerosol Types ◽  
Good Agreement ◽  
Aerosol Type

Abstract. Detecting the optical properties of aerosols using passive satellite-borne measurements alone is a difficult task due to the broadband effect of aerosols on the measured spectra and the influences of surface and cloud reflection. We present another approach to determine aerosol type, namely by studying the relationship of aerosol optical depth (AOD) with trace gas abundance, aerosol absorption, and mean aerosol size. Our new Global Aerosol Classification Algorithm, GACA, examines relationships between aerosol properties (AOD and extinction Ångström exponent from the Moderate Resolution Imaging Spectroradiometer (MODIS), UV Aerosol Index from the second Global Ozone Monitoring Experiment, GOME-2) and trace gas column densities (NO2, HCHO, SO2 from GOME-2, and CO from MOPITT, the Measurements of Pollution in the Troposphere instrument) on a monthly mean basis. First, aerosol types are separated based on size (Ångström exponent) and absorption (UV Aerosol Index), then the dominating sources are identified based on mean trace gas columns and their correlation with AOD. In this way, global maps of dominant aerosol type and main source type are constructed for each season and compared with maps of aerosol composition from the global MACC (Monitoring Atmospheric Composition and Climate) model. Although GACA cannot correctly characterize transported or mixed aerosols, GACA and MACC show good agreement regarding the global seasonal cycle, particularly for urban/industrial aerosols. The seasonal cycles of both aerosol type and source are also studied in more detail for selected 5° × 5° regions. Again, good agreement between GACA and MACC is found for all regions, but some systematic differences become apparent: the variability of aerosol composition (yearly and/or seasonal) is often not well captured by MACC, the amount of mineral dust outside of the dust belt appears to be overestimated, and the abundance of secondary organic aerosols is underestimated in comparison with GACA. Whereas the presented study is of exploratory nature, we show that the developed algorithm is well suited to evaluate climate and atmospheric composition models by including aerosol type and source obtained from measurements into the comparison, instead of focusing on a single parameter, e.g., AOD. The approach could be adapted to constrain the mix of aerosol types during the process of a combined data assimilation of aerosol and trace gas observations.

scholarly journals Theoretical basis for convective invigoration due to increased aerosol concentration

2011 ◽  
Vol 11 (11) ◽  
pp. 5407-5429 ◽  
Author(s):  
Z. J. Lebo ◽  
J. H. Seinfeld
Keyword(s):  
Number Concentration ◽  
Latent Heating ◽  
Heating Rates ◽  
Microphysics Scheme ◽  
Convective Clouds ◽  
Aerosol Loading ◽  
Significant Difference ◽  
Deep Convective Clouds ◽  
Bin Microphysics ◽  
Cumulative Precipitation

Abstract. The potential effects of increased aerosol loading on the development of deep convective clouds and resulting precipitation amounts are studied by employing the Weather Research and Forecasting (WRF) model as a detailed high-resolution cloud resolving model (CRM) with both detailed bulk and bin microphysics schemes. Both models include a physically-based activation scheme that incorporates a size-resolved aerosol population. We demonstrate that the aerosol-induced effect is controlled by the balance between latent heating and the increase in condensed water aloft, each having opposing effects on buoyancy. It is also shown that under polluted conditions, increases in the CCN number concentration reduce the cumulative precipitation due to the competition between the sedimentation and evaporation/sublimation timescales. The effect of an increase in the IN number concentration on the dynamics of deep convective clouds is small and the resulting decrease in domain-averaged cumulative precipitation is shown not to be statistically significant, but may act to suppress precipitation. It is also shown that even in the presence of a decrease in the domain-averaged cumulative precipitation, an increase in the precipitation variance, or in other words, andincrease in rainfall intensity, may be expected in more polluted environments, especially in moist environments. A significant difference exists between the predictions based on the bin and bulk microphysics schemes of precipitation and the influence of aerosol perturbations on updraft velocity within the convective core. The bulk microphysics scheme shows little change in the latent heating rates due to an increase in the CCN number concentration, while the bin microphysics scheme demonstrates significant increases in the latent heating aloft with increasing CCN number concentration. This suggests that even a detailed two-bulk microphysics scheme, coupled to a detailed activation scheme, may not be sufficient to predict small changes that result from perturbations in aerosol loading.

scholarly journals Characterization of Temperature Fields in Laser Beam Welded Hollow-Cylindrical Cold Crack Samples from High Strength Steel 100Cr6

2021 ◽  
Author(s):  
Eric Wasilewski ◽  
Nikolay Doynov ◽  
Ralf Ossenbrink ◽  
Vesselin Michailov
Keyword(s):  
Laser Beam ◽  
High Strength Steel ◽  
Unit Length ◽  
Laser Beam Welding ◽  
High Strength ◽  
Temperature Fields ◽  
Deep Penetration ◽  
Heating Rates ◽  
Hydrogen Distribution ◽  
Cooling Rates

Abstract This work presents a comparative study of thermal conditions that occur during laser beam welding of high strength steel 100Cr6 that often leads to a loss of technological strength and may conditionally produce cold cracks. The results from both experiments and thermal-metallurgical FE-simulations indicate that the type of heat coupling changes significantly when welding with different process parameters, e.g., in the transition between conduction and deep penetration welding. Further, the simulations show that as a result of the high welding speeds and reduced energy per unit length, extremely high heating rates of up to 2x104 K s-1 (set A) resp. 4x105 K s-1 (set B) occur in the material. Both welds thus concern a range of values for which conventional Time-Temperature-Austenitization (TTA) diagrams are not currently defined, so that the material models can only be calibrated using general assumptions. This noted change in energy per unit length and welding speeds causes significantly steep temperature gradients with a slope of approximately 5x103 K mm-1 and strong drops in the heating and cooling rates, particularly in the heat affected zone near the weld metal. This means that even short distances along the length present a staggering difference in relation to the temperature peaks. The temperature cycles also show very different cooling rates for the respective parameter sets, although in both cases they are well below a cooling time t8/5 of one second, so that the phase transformation always leads to the formation of martensite. The results from this study are intended to be used for further detailed experimental and numerical investigation of microstructure, hydrogen distribution, and stress-strain development at different restrain conditions.

scholarly journals Thermal stress, cooling-rate and fictive temperature of silicate melts

2021 ◽  
Vol 176 (10) ◽  
Author(s):  
Sharon L. Webb
Keyword(s):  
Heat Capacity ◽  
Cooling Rate ◽  
Heating Rate ◽  
Calibration Curve ◽  
Silicate Melts ◽  
Internal Stresses ◽  
Heating Rates ◽  
Fictive Temperature ◽  
Slow Cooling ◽  
Cooling Rates

AbstractThe unknown cooling-rate history of natural silicate melts can be investigated using differential scanning heat capacity measurements together with the limiting fictive temperature analysis calculation. There are a range of processes occurring during cooling and re-heating of natural samples which influence the calculation of the limiting fictive temperature and, therefore, the calculated cooling-rate of the sample. These processes occur at the extremes of slow cooling and fast quenching. The annealing of a sample at a temperature below the glass transition temperature upon cooling results in the subsequent determination of cooling-rates which are up to orders of magnitude too low. In contrast, the internal stresses associated with the faster cooling of obsidian in air result in an added exothermic signal in the heat capacity trace which results in an overestimation of cooling-rate. To calculate cooling-rate of glass using the fictive temperature method, it is necessary to create a calibration curve determined using known cooling- and heating-rates. The calculated unknown cooling-rate of the sample is affected by the magnitude of mismatch between the original cooling-rate and the laboratory heating-rate when using the matched cooling-/heating-rate method to derive a fictive temperature/cooling-rate calibration curve. Cooling-rates slower than the laboratory heating-rate will be overestimated, while cooling-rates faster than the laboratory heating-rate are underestimated. Each of these sources of error in the calculation of cooling-rate of glass materials—annealing, stress release and matched cooling/heating-rate calibration—can affect the calculated cooling-rate by factor of 10 or more.

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