A Study of the Effects of Anthropogenic Gaseous Emissions on the Microphysical Properties of Landfalling Typhoon Nida (2016) over China

Using the Weather Research and Forecasting model with chemistry module (WRF-Chem), Typhoon Nida (2016) was simulated to investigate the effects of anthropogenic gaseous emissions on the vortex system. Based on the Multi-resolution Emission Inventory for China (MEIC), three certain experiments were conducted: one with base-level emission intensity (CTRL), one with one-tenth the emission of SO2 (SO2_C), and one with one-tenth the emission of NH3 (NH3_C). Results show that the simulations reasonably reproduced the typhoon’s track and intensity, which were slightly sensitive to the anthropogenic gaseous emissions. When the typhoon was located over the ocean, a prolonged duration of raindrop growth and more precipitation occurred in CTRL run. The strongest updraft in CTRL is attributed to the maximum latent heating through water vapor condensation. During the landfalling period, larger (smaller) differential reflectivities in the main-core of the vortex were produced in NH3_C (SO2_C) run. Such opposite changes of raindrop size distributions may lead to stronger (weaker) rainfall intensity, and the ice-related microphysical processes and the relative humidity in low troposphere were two possible influential factors. Moreover, additional ten-member ensemble results in which white noise perturbations were added to the potential temperature field, indicated that the uncertainty of thermodynamic field in the current numerical model should not be ignored when exploring the impacts of aerosol on the microphysics and TC precipitation.

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Post-Combustion Evolution of Soot Properties in an Aircraft Engine

Volume 2: Turbo Expo 2005 ◽

10.1115/gt2005-69113 ◽

2005 ◽

Cited By ~ 3

Author(s):

Pierre M. Dakhel ◽

Stephen P. Lukachko ◽

Ian A. Waitz ◽

Richard C. Miake-Lye ◽

Robert C. Brown

Keyword(s):

Particulate Matter ◽

Gas Phase ◽

Cloud Condensation Nuclei ◽

Aircraft Engine ◽

Vapor Condensation ◽

Gaseous Emissions ◽

Aircraft Engines ◽

Volatile Content ◽

Particulate Matter Emissions ◽

Microphysical Processes

Recent measurements have suggested that soot properties can evolve downstream of the combustor, changing the characteristics of aviation particulate matter (PM) emissions and possibly altering the subsequent atmospheric impacts. This paper addresses the potential for the post-combustion thermodynamic environment to influence aircraft non-volatile PM emissions. Microphysical processes and interactions with gas phase species have been modeled for temperatures and pressures representative of in-service engines. Time-scale arguments are used to evaluate the relative contributions that various phenomena may make to the evolution of soot, including coagulation growth, ion-soot attachment, and vapor condensation. Then a higher-fidelity microphysics kinetic is employed to estimate the extent to which soot properties evolve as a result of these processes. Results suggest that limited opportunities exist for the modification of the size distribution of the soot, its charge distribution, or its volatile content, leading to the conclusion that the characteristics of the turbine and nozzle of an aircraft engine have little or no influence on aircraft non-volatile emissions. Combustor processing determines the properties of soot particulate matter emissions from aircraft engines, setting the stage for interactions with gaseous emissions and development as cloud condensation nuclei in the exhaust plume.

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Reflectivity and Liquid Water Content Vertical Decomposition Diagrams to Diagnose Vertical Evolution of Raindrop Size Distributions

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-15-0208.1 ◽

2016 ◽

Vol 33 (3) ◽

pp. 579-595 ◽

Cited By ~ 21

Author(s):

Christopher R. Williams

Keyword(s):

Water Content ◽

Liquid Water ◽

Liquid Water Content ◽

Doppler Velocity ◽

Size Distributions ◽

Vertical Column ◽

Vertical Decomposition ◽

Air Motion ◽

Raindrop Size ◽

Microphysical Processes

AbstractThis study consists of two parts. The first part describes the way in which vertical air motions and raindrop size distributions (DSDs) were retrieved from 449-MHz and 2.835-GHz (UHF and S band) vertically pointing radars (VPRs) deployed side by side during the Midlatitude Continental Convective Clouds Experiment (MC3E) held in northern Oklahoma. The 449-MHz VPR can measure both vertical air motion and raindrop motion. The S-band VPR can measure only raindrop motion. These differences in VPR sensitivities facilitates the identification of two peaks in 449-MHz VPR reflectivity-weighted Doppler velocity spectra and the retrieval of vertical air motion and DSD parameters from near the surface to just below the melting layer.The second part of this study used the retrieved DSD parameters to decompose reflectivity and liquid water content (LWC) into two terms, one representing number concentration and the other representing DSD shape. Reflectivity and LWC vertical decomposition diagrams (Z-VDDs and LWC-VDDs, respectively) are introduced to highlight interactions between raindrop number and DSD shape in the vertical column. Analysis of Z-VDDs provides indirect measure of microphysical processes through radar reflectivity. Analysis of LWC-VDDs provides direct investigation of microphysical processes in the vertical column, including net raindrop evaporation or accretion and net raindrop breakup or coalescence. During a stratiform rain event (20 May 2011), LWC-VDDs exhibited signatures of net evaporation and net raindrop coalescence as the raindrops fell a distance of 2 km under a well-defined radar bright band. The LWC-VDD is a tool to characterize rain microphysics with quantities related to number-controlled and size-controlled processes.

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Improved Attenuation-Based Radar Precipitation Estimation Considering the Azimuthal Variabilities of Microphysical Properties

Journal of Hydrometeorology ◽

10.1175/jhm-d-19-0265.1 ◽

2020 ◽

Vol 21 (7) ◽

pp. 1605-1620

Author(s):

Hao Huang ◽

Kun Zhao ◽

Haonan Chen ◽

Dongming Hu ◽

Peiling Fu ◽

...

Keyword(s):

Variational Approach ◽

Optimization Approach ◽

Radar Rainfall ◽

Microphysical Properties ◽

Quantitative Precipitation Estimation ◽

Hourly Rainfall ◽

Precipitation Estimation ◽

Raindrop Size ◽

Differential Reflectivity ◽

The Impact

AbstractThe attenuation-based rainfall estimator is less sensitive to the variability of raindrop size distributions (DSDs) than conventional radar rainfall estimators. For the attenuation-based quantitative precipitation estimation (QPE), the key is to accurately estimate the horizontal specific attenuation AH, which requires a good estimate of the ray-averaged ratio between AH and specific differential phase KDP, also known as the coefficient α. In this study, a variational approach is proposed to optimize the coefficient α for better estimates of AH and rainfall. The performance of the variational approach is illustrated using observations from an S-band operational weather radar with rigorous quality control in south China, by comparing against the α optimization approach using a slope of differential reflectivity ZDR dependence on horizontal reflectivity factor ZH. Similar to the ZDR-slope approach, the variational approach can obtain the optimized α consistent with the DSD properties of precipitation on a sweep-to-sweep basis. The attenuation-based hourly rainfall estimates using the sweep-averaged α values from these two approaches show comparable accuracy when verified against the gauge measurements. One advantage of the variational approach is its feasibility to optimize α for each radar ray, which mitigates the impact of the azimuthal DSD variabilities on rainfall estimation. It is found that, based on the optimized α for radar rays, the hourly rainfall amounts derived from the variational approach are consistent with gauge measurements, showing lower bias (1.0%), higher correlation coefficient (0.92), and lower root-mean-square error (2.35 mm) than the results based on the sweep-averaged α.

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Exploring the use of a column model for the characterization of microphysical processes in warm rain: results from a homogeneous rainshaft model

Advances in Geosciences ◽

10.5194/adgeo-10-145-2007 ◽

2007 ◽

Vol 10 ◽

pp. 145-152 ◽

Cited By ~ 23

Author(s):

O. P. Prat ◽

A. P. Barros

Keyword(s):

Field Experiments ◽

Ground Surface ◽

Cloud Base ◽

Column Model ◽

Raindrop Size Distribution ◽

State Boundary ◽

Raindrop Size ◽

Microphysical Processes ◽

Rain Events ◽

Rain Rates

Abstract. A study of the evolution of raindrop spectra (raindrop size distribution, DSD) between cloud base and the ground surface was conducted using a column model of stochastic coalescense-breakup dynamics. Numerical results show that, under steady-state boundary conditions (i.e. constant rainfall rate and DSD at the top of the rainshaft), the equilibrium DSD is achieved only for high rain rates produced by midlevel or higher clouds and after long simulation times (~30 min or greater). Because these conditions are not typical of most rainfall, the results suggest that the theoretical equilibrium DSD might not be attainable for the duration of individual rain events, and thus DSD observations from field experiments should be analyzed conditional on the specific storm environment under which they were obtained.

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First Look at the Occurrence of Horizontally Oriented Ice Crystals over Summit, Greenland

10.5194/acp-2016-1134 ◽

2017 ◽

Author(s):

Sebastian Cole ◽

Ryan R. Neely III. ◽

Robert A. Stillwell

Keyword(s):

Ground Level ◽

Cirrus Clouds ◽

Ice Crystals ◽

Wind Speeds ◽

Microphysical Properties ◽

Stratiform Clouds ◽

Monthly Changes ◽

Microphysical Processes ◽

Monthly Variations

Abstract. The microphysical properties of clouds play a significant role in determining their radiative effect; one of these properties is the orientation of ice crystals. A source of error in current microphysical retrievals and model simulations is the assumption that clouds are composed of only randomly oriented ice crystals (ROIC). This assumption is frequently not true, as evidenced by optical phenomena such as parhelia (commonly referred to as sundogs). Here, observations from the Cloud, Aerosol and Polarization Backscatter Lidar (CAPABL) at Summit, Greenland are utilized along with instruments that are part of the Integrated Characterization of Energy, Clouds, Atmospheric state and Precipitation at Summit (ICECAPS) project in order to determine when, where and under what conditions horizontally oriented ice crystals (HOIC) occur at Summit, Greenland. Between July 2015 and May 2016, HOIC are observed on 86 days of the 335-day study. HOIC occurred within stratiform clouds on 48 days, in precipitation on 32 days and in cirrus clouds on 14 days. Analysis of all of the cases found that, on average, in comparison to ROIC, HOIC occur at higher temperatures, higher wind speeds and lower heights above ground level. Differences were also present in the relative humidities (RHs) at which HOIC and ROIC occurred in stratiform clouds and precipitation but not in cirrus clouds. Analysis over the whole study period revealed monthly variations in the abundance of HOIC with the number of detections peaking in April and October. Monthly changes were also present in the number of days containing HOIC. The results presented here aim to be the first step towards a comprehensive climatology and understanding of the microphysical processes that lead to the formation of HOIC at Summit, Greenland.

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Vertical redistribution of moisture and aerosol in orographic mixed-phase clouds

10.5194/acp-2019-940 ◽

2020 ◽

Author(s):

Annette K. Miltenberger ◽

Paul R. Field ◽

Adrian H. Hill

Keyword(s):

Air Temperature ◽

Unified Model ◽

Mixed Phase ◽

Atmospheric Models ◽

Microphysical Properties ◽

Cloud Microphysical Processes ◽

Microphysical Processes ◽

Mixed Phase Clouds ◽

Natural Laboratory

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The ATAL and its aerosol microphysical properties in the Asian Monsoon Anticyclone

10.5194/egusphere-egu2020-6759 ◽

2020 ◽

Author(s):

Christoph Mahnke ◽

Stephan Borrmann ◽

Ralf Weigel ◽

Francesco Cairo ◽

Armin Afchine ◽

...

Keyword(s):

Particle Size ◽

Asian Monsoon ◽

Extreme Values ◽

Monsoon Season ◽

Measurement Techniques ◽

Potential Temperature ◽

Particle Diameter ◽

Size Distributions ◽

Particle Size Distributions ◽

Microphysical Properties

During the StratoClim 2017 measurement campaign in Nepal, within the Asian Monsoon Anticyclone (AMA), measurements of the aerosols&#8217; microphysical properties up to UT/LS altitudes were successfully completed with a modified version of the commercially available (Droplet Measurement Technologies Inc.) aerosol spectrometer UHSAS-A. Technical rearrangements of parts of the UHSAS-A were developed and implemented, which improve the instrument&#8217;s measuring performance and extend its airborne application range from around 12 km altitude to the extreme ambient conditions in the stratosphere at heights of 20 km. The measurement techniques used for this purpose were characterized by laboratory experiments.Within the AMA region, extreme values of the particle mixing ratio (PMR) ranging between 6 mg-1 and about 10000 mg-1 were found with the UHSAS-A (particle diameter range: 65 nm to 1000 nm). The median of the PMR for all research flights was about 1300 mg-1 close to the ground. Within tropospheric altitudes, the PMR was highly variable and median values between 70 mg-1 and 400 mg-1 were observed. &#160;At levels of 370 K potential temperature, the median PMR maximally reaches about 700 mg-1 while the 1 Hz resolved measurements show values up to about 10000 mg-1. Between 450 K and 475 K, median PMR between 40 mg-1 and 50 mg-1 were observed. The aerosol size distributions (measured by the UHSAS-A) were extended by an additional diameter size bin obtained from the 4-channel Condensation Particle counting System (COPAS), i.e. for aerosol diameter between 10&#160;nm and 65&#160;nm.The UHSAS-A measured aerosol particle size distributions were compared with balloon-borne measurements (by T. Deshler et al., Dep. of Atmospheric Science, University of Wyoming, USA) at altitudes of up to 20 km. These show that the size distributions measured during the StratoClim 2017 campaign fit well within the range of the balloon-borne measurements during the Asian Monsoon season over India (Hyderabad) in 2015 and the USA (Laramie) in 2013. Further analyses of measured particle size distributions by means of backscatter ratio show remarkable consistency with CALIOP satellite observations of the ATAL during the StratoClim mission period.

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Rainfall parameters affect canopy storage capacity under controlled conditions

Forest Research Papers ◽

10.2478/frp-2014-0032 ◽

2015 ◽

Vol 75 (4) ◽

pp. 353-358 ◽

Cited By ~ 2

Author(s):

Anna Klamerus-Iwan

Keyword(s):

Sprinkler System ◽

Influential Factors ◽

Tree Model ◽

Precipitation Characteristics ◽

Simulated Precipitation ◽

Maximum Water ◽

The Subject ◽

Raindrop Size ◽

Set Up ◽

Time Required

Abstract The subject of this research was the interception of precipitation, which is defined as the amount of water that can be retained by the entire surface of a tree. The aim was to measure the rate of interception under laboratory conditions in order to determine influential factors. To eliminate water absorption that would occur in living trees, we employed models of deciduous and coniferous trees enabling us to examine the effect of precipitation characteristics and the surface area individually. A sprinkler system that automatically recorded the amounts of water retained on the models was set up in the laboratory. Precipitation was simulated using 5 different intensities with 3 different raindrop sizes. Interception rates were affected by both, the intensity of the precipitation and raindrop size. The time required to reach maximum crown filling with water was variable and depended on plant surface parameters as well as simulated precipitation. The maximum water capacity of crowns was not a constant value even within one tree model, but changed depending on precipitation characteristics

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Impacts of Instrument Limitations on Estimated Raindrop Size Distribution, Radar Parameters, and Model Microphysics during Mei-Yu Season in East China

Journal of Atmospheric and Oceanic Technology ◽

10.1175/jtech-d-16-0225.1 ◽

2017 ◽

Vol 34 (5) ◽

pp. 1021-1037 ◽

Cited By ~ 18

Author(s):

Long Wen ◽

Kun Zhao ◽

Guifu Zhang ◽

Su Liu ◽

Gang Chen

Keyword(s):

Rain Gauge ◽

Rainfall Amount ◽

East China ◽

Physical Parameters ◽

High Concentration ◽

Derived Relations ◽

Raindrop Size Distribution ◽

Accretion Rates ◽

Raindrop Size ◽

Microphysical Processes

AbstractInstrumentation limitations on measured raindrop size distributions (DSDs) and their derived relations and physical parameters are studied through a comparison of the DSD measurements during mei-yu season in east China by four collocated instruments, that is, a two-dimensional video disdrometer (2DVD), a vertically pointing Micro Rain Radar (MRR), and two laser-optical OTT Particle Size Velocity (PARSIVEL) disdrometers (first generation: OTT-1; second generation: OTT-2). Among the four instruments, the 2DVD provides the most accurate DSD and drop velocity measurements, so its measured rainfall amount has the best agreement with the reference rain gauge. Other instruments tend to miss more small drops (D < 1 mm), leading to inaccurate DSDs and a lower rainfall amount. The low rainfall estimation becomes significant during heavy rainfall. The impacts of instrument limitations on the microphysical processes (e.g., evaporation and accretion rates) and convective storm morphology are evaluated. This is important especially for mei-yu precipitation, which is dominated by a high concentration of small drops. Hence, the instrument limitations need to be taken into account in both QPE and microphysics parameterization.

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Vertical redistribution of moisture and aerosol in orographic mixed-phase clouds

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-7979-2020 ◽

2020 ◽

Vol 20 (13) ◽

pp. 7979-8001

Author(s):

Annette K. Miltenberger ◽

Paul R. Field ◽

Adrian H. Hill ◽

Andrew J. Heymsfield

Keyword(s):

Cloud Droplet ◽

Wave Structure ◽

Specific Humidity ◽

Dust Particles ◽

Microphysical Properties ◽

Microphysical Processes ◽

The Right ◽

A Minor ◽

Mixed Phase Clouds ◽

The Impact

Abstract. Orographic wave clouds offer a natural laboratory to investigate cloud microphysical processes and their representation in atmospheric models. Wave clouds impact the larger-scale flow by the vertical redistribution of moisture and aerosol. Here we use detailed cloud microphysical observations from the Ice in Clouds Experiment – Layer Clouds (ICE-L) campaign to evaluate the recently developed Cloud Aerosol Interacting Microphysics (CASIM) module in the Met Office Unified Model (UM) with a particular focus on different parameterizations for heterogeneous freezing. Modelled and observed thermodynamic and microphysical properties agree very well (deviation of air temperature <1 K; specific humidity <0.2 g kg−1; vertical velocity <1 m s−1; cloud droplet number concentration <40 cm−3), with the exception of an overestimated total condensate content and too long a sedimentation tail. The accurate reproduction of the environmental thermodynamic and dynamical wave structure enables the model to reproduce the right cloud in the right place and at the right time. All heterogeneous freezing parameterizations except Atkinson et al. (2013) perform reasonably well, with the best agreement in terms of the temperature dependency of ice crystal number concentrations for the parameterizations of DeMott et al. (2010) and Tobo et al. (2013). The novel capabilities of CASIM allowed testing of the impact of assuming different soluble fractions of dust particles on immersion freezing, but this is found to only have a minor impact on hydrometeor mass and number concentrations. The simulations were further used to quantify the modification of moisture and aerosol profiles by the wave cloud. The changes in both variables are on order of 15 % of their upstream values, but the modifications have very different vertical structures for the two variables. Using a large number of idealized simulations we investigate how the induced changes depend on the wave period (100–1800 s), cloud top temperature (−15 to −50 ∘C), and cloud thickness (1–5 km) and propose a conceptual model to describe these dependencies.

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