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All sourcesNASA NTRSDOE OSTI
NASA NTRS2003

Space Borne Cloud and Aerosol Measurements by the Geoscience Laser Altimeter System: Initial Results

In January 2003 the Geoscience Laser Altimeter System (GLAS) was successfully launched into orbit. Beginning in March 2003 GLAS will provide global coverage lidar measurement of the height distribution of clouds and aerosol in the atmosphere for up to five years. The characteristic and value of the unique data will be presented. The instrument is a basic backscatter lidar that operates at two wavelengths, 532 and 1064 nm. The mission data products for atmospheric observations include the calibrated, observed, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data is expected to significantly enhance knowledge in several areas of atmospheric science, in particular the distribution, transport and influence of atmospheric aerosol and thin clouds. Measurements of the coverage and height of polar and cirrus cloud should be significantly more accurate than previous global observations. In March and April 2003, airborne and ground based data verification experiments will be carried out. Initial results from the verification experiments and the first several months of operation will be presented.

Spinhirne, James D.↗
NASA NTRSDate not supplied

Evaluating Combined Lidar and Polarimeter Measurements of Cloud Top Parameters (Extinction, Scattering Cross Sections, and Droplet Number Density, Liquid Water Content)

We present a new method to derive profiles of extinction from a lidar which is then combined with polarimeter measurements to derive cloud droplet number density (CDNC) in the tops of warm clouds. The method employs polarization-sensitive elastic backscatter lidar measurements to estimate attenuation of the lidar signal within the cloud and polarimeter estimates of cloud droplet size distributions. The measurements used for this demonstration are from NASA Langley Research Center’s High Spectral Resolution Lidar – Generation 2 (HSRL-2) and NASA GISS’s Research Scanning Polarimeter (RSP). The measurements were acquired on NASA’s ACTIVATE mission, during which the instruments were deployed in a down-looking mode from a high-altitude aircraft, which flew in coordination with a low-flying aircraft acquiring coincident in situ measurements of cloud droplet size and number. The high vertical (1.25 m) and horizontal (~50 m) sampling resolution of the HSRL-2 data enabled retrievals of single-scattering extinction profiles to within ~2.5 optical depths of cloud top. Another key feature of the method was the well-calibrated measurement of backscatter at cloud top due to using the HSRL technique. The RSP retrievals of cloud droplet effective radius and variance were accomplished using the “cloud-bow” technique. Overall, the technique provides extinction profile estimates for the top 2.5 optical depths of water clouds that can be used to estimate the cloud droplet number density in various types of warm clouds. The mean extinction values at cloud top (0-1 optical depth) are compared against cloud drop size and number concentration acquired from wing-mounted probes (e.g., DMT Cloud Droplet Probe - CDP, SPEC Fast Cloud Droplet Probe FCDP, and SPEC 2D Stereo Probe - 2DS) that were deployed on the low-flying aircraft. Comparisons between the effective radius and variance from the polarimeter, lidar ratio (extinction to backscatter) from the lidar and polarimeter, and LWC are also presented. All measurements were acquired over the Western North Atlantic over 3 years from 2020 to 2022.

lidar↗
NASA NTRS2005

Aerosol and Cloud Observations and Data Products by the GLAS Polar Orbiting Lidar Instrument

The Geoscience Laser Altimeter System (GLAS) launched in 2003 is the first polar orbiting satellite lidar. The instrument was designed for high performance observations of the distribution and optical scattering cross sections of clouds and aerosol. The backscatter lidar operates at two wavelengths, 532 and 1064 nm. Both receiver channels meet and exceed their design goals, and beginning with a two month period through October and November 2003, an excellent global lidar data set now exists. The data products for atmospheric observations include the calibrated, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data sets are now in open release through the NASA data distribution system. The initial results on global statistics for cloud and aerosol distribution has been produced and in some cases compared to other satellite observations. The sensitivity of the cloud measurements is such that the 70% global cloud coverage result should be the most accurate to date. Results on the global distribution of aerosol are the first that produce the true height distribution for model inter-comparison.

Spinhirne, J. D.↗
NASA NTRS2017

CATS Version 2 Aerosol Feature Detection and Applications for Data Assimilation

The Cloud Aerosol Transport System (CATS) lidar has been operating onboard the International Space Station (ISS) since February 2015 and provides vertical observations of clouds and aerosols using total attenuated backscatter and depolarization measurements. From February March 2015, CATS operated in Mode 1, providing backscatter and depolarization measurements at 532 and 1064 nm. CATS began operation in Mode 2 in March 2015, providing backscatter and depolarization measurements at 1064 nm and has continued to operate to the present in this mode. CATS level 2 products are derived from these measurements, including feature detection, cloud aerosol discrimination, cloud and aerosol typing, and optical properties of cloud and aerosol layers. Here, we present changes to our level 2 algorithms, which were aimed at reducing several biases in our version 1 level 2 data products. These changes will be incorporated into our upcoming version 2 level 2 data release in summer 2017. Additionally, owing to the near real time (NRT) data downlinking capabilities of the ISS, CATS provides expedited NRT data products within 6 hours of observation time. This capability provides a unique opportunity for supporting field campaigns and for developing data assimilation techniques to improve simulated cloud and aerosol vertical distributions in models. We additionally present preliminary work toward assimilating CATS observations into the NASA Goddard Earth Observing System version 5 (GEOS-5) global atmospheric model and data assimilation system.

data assimilation↗
DOE OSTI2024

EPCAPE-PT-LANL Measurements: Humidified Cavity Attenuated Phase Shift Spectroscopy

Coastal cities offer a unique environment for studying aerosol-cloud interactions and the effects of urban emissions on cloud properties. As part of the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE), the Partitioning Thrust by Los Alamos National Laboratory (EPCAPE-PT-LANL) was conducted. Our campaign focused on measuring the optical and chemical properties of aerosols and their interactions within marine stratocumulus clouds in La Jolla, California. EPCAPE-PT-LANL enhances the primary goals of EPCAPE through innovative observations of vapor-phase transitions between aerosols and cloud droplets, the impact of black carbon on aerosol-cloud dynamics, and the effects of cloud processing on aerosol optical properties. Instrument: Humidified Cavity Attenuated Phase Shift Particulate Matter Single Scattering Albedo (H-CAPS-PMSSA, Aerodyne Inc) Data Notes: The scattering truncation correction was not applied to Bsca. The Bext needs no correction. Files: data_10sec_CAPS.csv, data_10min_CAPS.csv Header: - Bext_wet_CAPS_450nm[1/Mm]: Wet aerosol extinction coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹). - Bsca_wet_CAPS_450nm[1/Mm]: Wet aerosol scattering coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹). - Temp_wet_CAPS[K]: Temperature inside the wet CAPS measurement chamber, in Kelvin. - Bext_dry_CAPS_450nm[1/Mm]: Dry aerosol extinction coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹). - Bsca_dry_CAPS_450nm[1/Mm]: Dry aerosol scattering coefficient measured at 450 nm by the CAPS, in inverse megameters (Mm⁻¹). - Temp_dry_CAPS[K]: Temperature inside the dry CAPS measurement chamber, in Kelvin. - Wet_RH_preCAPS[%]: Relative humidity before entering the wet CAPS, in percent. - Wet_RH_postCAPS[%]: Relative humidity after exiting the wet CAPS, in percent. - Humidifier_RH_CAPS[%]: Relative humidity inside the humidifier used with the CAPS, in percent. - dualCAPS_inlet_RH[%]: Relative humidity at the inlet of the dual (wet/dry) CAPS setup, in percent. - Wet_Temp_preCAPS[C]: Temperature before entering the wet CAPS, in degrees Celsius. - Wet_Temp_postCAPS[C]: Temperature after exiting the wet CAPS, in degrees Celsius. - Humidifier_Temp[C]: Temperature inside the humidifier used with the CAPS, in degrees Celsius. - dualCAPS_inlet_Temp[C]: Temperature at the inlet of the dual (wet/dry) CAPS setup, in degrees Celsius. - Zero_dry_CAPS: 1 is a calibration check for the dry CAPS to ensure zero reading under filter air conditions. - Zero_wet_CAPS: 1 is a calibration check for the wet CAPS to ensure zero reading under filter air conditions. - CVI_Flag[bool]: A boolean flag indicating whether the Counterflow Virtual Impactor (CVI) was active (true) or inactive (false) during the measurement.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRSDate not supplied

TPSAS-NF1676L-23557-DND

The Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) measures both parallel and perpendicular backscatter of linearly polarized 532 nm light from cloud particles in the atmosphere. The perpendicular component of the return signal allows differentiation between cloud layers consisting of spherical water droplets from those with non-spherical ice particles. A two-way distribution of layer-integrated 532 nm total backscatter and the layer-integrated 532 nm depolarization ratio further differentiates between water cloud layers with significant multiple scattering, horizontally-oriented ice particles that cause specular reflections, and randomly-oriented ice particles, as described in Hu et al., 2009. The cloud phase algorithm functions well for the majority of clouds, but there have been some recent changes and improvements that are described in this poster. The impact of the CALIOP viewing angle change from near-nadir (0.3 degrees) to slightly tilted (3.0 degrees) on the optical properties of the various CALIOP cloud particle phases is also shown. A major improvement to the phase algorithm is the limitation of a spatial coherence test for horizontally-oriented ice to cloud layers that have sufficient integrated attenuated backscatter to likely contain HOI. This change reduces a "striping" effect caused by noisiness in the spatial coherence test for thin cloud layers. Additional temperature tests are considered, and the regional and vertical distribution of cloud layers with the various CALIOP cloud phases is shown. Only one cloud particle phase is allowed for each 5 km portion of a cloud layer that is considered by the cloud phase algorithm, so we use in situ aircraft and CloudSat observations to determine how the CALIOP cloud phase algorithm is treating optically and thermally thick clouds, which may be mixed-phase.

Melody Avery↗
NASA NTRS2004

Cloud Coverage and Height Distribution from the GLAS Polar Orbiting Lidar: Comparison to Passive Cloud Retrievals

The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global cloud cover. Initial analysis indicates that cloud and aerosol layers are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of cloud and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global cloud coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive layers. Processing includes a multi-variable separation of cloud and aerosol layers. An initial application of the data results is to compare monthly cloud means from several months of GLAS observations in 2003 to existing cloud climatologies from other satellite measurement. In some cases direct comparison to passive cloud retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive cloud retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in cloud cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in cloud detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).

Spinhime, J. D.↗
NASA NTRS1981

Remote sensing of sea surface temperature in the 3.7 micron CO2 band

The main sources of error in remote sensing of sea surface temperature are discussed. The interfering effects of reflected solar radiation, reflected thermal flux, clouds and haze and atmospheric attenuation are examined. The components of measured sea surface radiances, such as clear column radiance, surface emission, atmospheric emission, reflected thermal downward flux, and reflection of solar flux, are analytically presented. The use of the 3.7 micron region window to obtain the radiance to four percent accuracy is discussed. The advantages to be obtained by the use of narrow bandpass channels are assessed.

Chahine, M. T.↗
NASA NTRS1990

Multi-spectral window radiance observations of Cirrus from satellite and aircraft, November 2, 1986 Project FIRE

High resolution infrared radiance spectra achieved from the NASA ER2 airborne HIS experiment are used to analyze the spectral emissivity properties of cirrus clouds within the 8 to 12 micron atmospheric window region. Observations show that the cirrus emissivity generally decreases with increasing wavenumber (i.e., decreasing wavelength) within this band. A very abrupt decrease in emissivity (increase in brightness temperature) exists between 930/cm (10.8 microns) and 1000/cm (10.0 microns), the magnitude of the change being associated with the cirrus optical thickness as observed by lidar. The HIS observations are consistent with theoretical calculations of the spectral absorption coefficient for ice. The HIS observations imply that cirrus clouds can be detected unambiguously from the difference in brightness temperatures observed within the 8.2 and 11.0 micron window regions of the HIRS sounding radiometer flying on the operational NOAA satellites. This ability is demonstrated using simultaneous 25 km resolution HIRS observations and 1 km resolution AVHRR imagery achieved from the NOAA-9 satellite. Finally, the cirrus cloud location estimates combined with the 6.7 micron channel moisture imagery portray the boundaries of the ice/vapor phase of the upper troposphere moisture. This phase distinction is crucial for infrared radiative transfer considerations for weather and climate models, since upper tropospheric water vapor has little effect on the Earth's outgoing radiation whereas cirrus clouds have a very large attenuating effect.

Smith, William L.↗
NASA NTRS1993

Global blackout following the K/T Chicxulub impact: Results of impact and atmospheric modeling

Several recent studies have suggested that shock decomposition of anhydrite (CaSO4) target rocks during the K/T Chicxulub impact would have ejected tremendous amounts of sulfur gas into the stratosphere. One of the many potential biospheric effects of this sulfur gas is the generation of a sulfuric acid (H2SO4) aerosol layer capable of causing darkness and severe disruption of photosynthesis for periods of years. In this paper we report the preliminary results of our modeling of shock pressures within the anhydrites and of light attenuation by the H2SO4 aerosol cloud. These models indicate that earlier studies over-estimated the amount of sulfur gas produced, but that more than enough was produced to extend global blackout conditions 4-6 times longer than the approximately 3 month predictions for silicate dust alone.

Pope, K. O.↗
NASA NTRS1994

Producing the universal spectrum of cosmological gamma-ray bursts with the Klein-Nishina cross section

A power-law spectrum attenuated through Compton scattering by an optically thick medium produces spectra that have a characteristic energy of several hundred keV. Add a redshift, and one finds that this model can qualitatively reproduce the color-color diagrams found for individual gamma-ray bursts. This model is easily tested through model fits to burst spectra and through comparisons of the parameters derived from model fits to the limits on parameters derived from the burst log N - log P(sub max) curve. The heavy attenuation makes the amount of energy released in the burst approximately equal to 10(exp 3) times larger than is inferred from the observed flux. The requirements of high optical depth and no photon-photon pair creation place a lower limit on the size of the scattering region. This size suggests that the attenuation occurs in giant molecular clouds in the cores of galaxies. This indicates that gamma-ray bursts are probably from supermassive black holes. If the Lorentz factor of the radiation source is large, the optical depth, and therefore the hardness ratio of a burst, can change over the duration of the burst.

Brainerd, J. J.↗
NASA NTRS1995

High-performance passive microwave survey on Josephson Junctions

The quasi-optical generations of images of objects with their internal structure in millimeter (MM) and submillimeter (SMM) bands is one of prime problems of modern radioelectronics. The main advantage of passive MM imaging systems in comparison with visible and infrared (IR) systems is small attenuation of signals in fog, cloud, smoke, dust and other obscurants. However, at a panoramic scanning of space the observation time lengthens and thereby the information processing rate becomes restricted so that single-channel system cannot image in real time. Therefore we must use many radiometers in parallel to reduce the observation time. Such system must contain receiving sensors as pixels in multibeam antenna. The use of Josephson Junctions (JJ) for this purpose together with the cryoelectronic devices like GaAs FET (field effect transistors) or SQUIDS for signal amplifications after JJ is of particular interest in this case.

Denisov, A. G.↗
NASA NTRS1995

ACTS broadband aeronautical terminal

This paper discusses the design of, and experiments with, the ACTS Broadband Aeronautical Terminal. As part of the ongoing effort to investigate commercial applications of ACTS technologies, NASA's Jet Propulsion Laboratory and various industry/government partners are developing a broadband mobile terminal for aeronautical applications. The ACTS Broadband Aeronautical Terminal is designed to explore the use of K/Ka-band for high data rate aeronautical satellite communications. Currently available commercial aeronautical satellite communications systems are only capable of achieving data rates on the order of tens of kilobits per second. The broadband terminal used in conjunction with the ACTS mechanically steerable antenna, can achieve data rates of 384 kilobits per second, while use of an ACTS spot beam antenna with this terminal will allow up to T1 data rates (1.544 megabits per second). The aeronautical terminal will be utilized to test a variety of applications that require a high data rate communications link. The use of the K/Ka-band for wideband aeronautical communications has the advantages of spectrum availability and smaller antennas, while eliminating the one major drawback of this frequency band, rain attenuation, by flying above the clouds the majority of the time.

Agan, M. J.↗
NASA NTRS1999

Highlights of Part I: Propagation Through Mars Environment: Propagation through Mars Environment - Part 1

We recommend using the dayside Martian ionosphere as a reflector for global communication, because it has a stable density peak and usable critical frequency. This is very crucial for the future Mars ground to ground communication. The dayside ionosphere has been well modeled as a Chapman layer. We suggest performing the Martian nightside ionosphere modeling study. Because the nightside ionosphere has very little measurements available, we propose to drop a digital ionosound instrument into the Mars surface for data collection. Even though the Martian tropospheric radio refractivity had a small value, it still can cause ray bending and multipath effects. We recommend performing an accurate calculation on excess phase and group delays (range and time delays). Other effects, such as range rate errors, appearance angle deviation, defocusing loss on Mars, etc. should be estimated. Ice depolarization effects due to Martian clouds on radio waves are unknown yet, but they are expected to be small, because of lower optical depth and the thinner layer of cloud. Total Martian atmospheric gaseous attenuation is expected to be less than 1 dB on microwaves and, because the Martian atmosphere had very low concentration in uncondensed H2O and O2. An accurate calculation for zenith opacity requires the information about scale heights of H2O and O2 distribution. An accurate water vapor altitude profile at Mars is not available et. Under the normal condition, CO2 and N2 gases ddo not have electric or magnetic dipoles and do not absorb electromagnetic energy from the waves. However, they may generate the dipoles through a collision and interact with waves under a high density condition and absorb electromagnetic waves in the infrared and visible band. Dust storm is the most dominant factor on the radio wave attenuation. Large Martian dust storms can cause at least 3 dB or higher loss to Ka band wave. For a normal dust storm, the attenuation is about 1 dB. The attenuation much depends on dust mass loading, dust size distribution, etc. Most large dust storms occur in the southern hemisphere during later spring and early summer when the southern hemisphere becomes suddenly hot.

Ho, Christian↗
NASA NTRS1999

Radio Wave Propagation for Communication on and around Mars: Highlights: Propagation Through Mars Environment - Part 1

We recommend to use the dayside Martian ionosphere as a reflector for global communication, because the dayside ionosphere has stable density peak and usable critic frequency. This is very crucial for the future Mars ground to around communication. The dayside ionosphere has been well modeled as a Chapman layer. We suggest to perform the Martian nightside ionospheric modeling study. Because the nightside ionosphere has very little measurements available, we propose to drop a digital ionosond instrument into the Mars surface for data collection. Even though the Martian tropospheric radio refractivity has small value, it still can cause the ray bending and multipath effects. We recommend to perform an accurate calculation on excess phase and group delays (range and time delays). Other effects, such as range rate errors, appearance angle deviation, defocusing loss on Mars, etc. are also needed to be estimated. Ice depolarization effects due to Martian clouds on radio waves is unknown yet, which is expected to be small, because lower optical depth and thinner layer of cloud: Total Martian atmospheric gaseous attenuation is expected to be less than 1 dB on microwaves band, because the Martian atmosphere has very low concentration in uncondensed H2O and O2. An accurate calculation for zenith opacity requires the information about scale heights of H2O and O2 distribution. An accurate water vapor altitude profile at Mars is not available yet. Under the normal condition, CO2 and N2 gases do not have electric or magnetic dipoles and do not absorb electromagnetic energy from the waves. However, they may generate the dipoles through a collision and interact with waves under a high density condition and absorb electromagnetic waves in the infrared and visible band. Dust storm is most dominant factor to the radio wave attenuation. Large Martian dust storm can cause at least 3 dB or higher loss to Ka band wave. For a normal dust storm, the attenuation is about 1 dB. The attenuation much depends on dust mass loading, dust size distribution, etc. Most large dust storm occur in the southern hemisphere during later spring and early summer when the southern hemisphere become suddenly hot.

Ho, Christian↗
NASA NTRS2003

Aerosol Measurements by the GLAS Space Borne Lidar

Beginning in February 2003, the Geoscience Laser Altimeter System (GLAS) provides global coverage lidar measurement of the height distribution of aerosol in the atmosphere. The characteristic and value of the unique data will be presented. The instrument is a basic backscatter lidar that operates at two wavelengths, 532 and 1064 nm. The mission data products for atmospheric observations include the calibrated, observed, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data is expected to significantly enhance knowledge of the distribution, transport and influence of atmospheric aerosol and thin clouds. Initial results from the 1064 nm channel show strong aerosol loading in many regions of the world. From the initial performance and verification experiments, aerosol backscatter cross sections down to sever times 10(exp -6)I/m-sr are detected. In August the 532 nm channel will also provide aerosol profiles but with a projected order of magnitude more sensitivity, and full data products including aerosol optical depths will be generated. Results from these first several months of operation will be presented.

Spinhirne, James D.↗
NASA NTRS2016

Cassini Ring Plane Crossings: Hypervelocity Impact Risks to Sun Sensor Assemblies

For both F/G and D-ring crossings: Probability of a penetration damage of the SSH (Sun Sensor Head) window glass is very low; Optical attenuation due to craters on the surface of the window glass caused by direct HVI (Hyper-Velocity Impact) by dust particle is estimated to be less than 1 percent; Optical attenuation due to secondary debris cloud generated by the disintegrated ring dust particles is estimated to be less than 1 percent. To better manage the Sun sensor damage risk during selected proximal orbit crossings, it is highly desirable to follow the contingency procedures mentioned in Section VII of the paper: Details of this contingency procedure are given in the paper entitled "Cassini Operational Sun Sensor Risk Management During Proximal Orbit Saturn Ring Plane Crossings" authored by David M. Bates. Based on results of risk analyses documented in this work and contingency planning work described in the paper mentioned above, we judge that the proximal orbit campaign will be safe from the viewpoint of dust HVI hazard.

dust particles↗
NASA NTRS2012

Impact of Aerosols on Convective Clouds and Precipitation

Aerosols are a critical.factor in the atmospheric hydrological cycle and radiation budget. As a major agent for clouds to form and a significant attenuator of solar radiation, aerosols affect climate in several ways. Current research suggests that aerosols have a major impact on the dynamics, microphysics, and electrification properties of continental mixed-phase convective clouds. In addition, high aerosol concentrations in urban environments could affect precipitation variability by providing a significant source of cloud condensation nuclei (CCN). Such pollution . effects on precipitation potentially have enormous climatic consequences both in terms of feedbacks involving the land surface via rainfall as well as the surface energy budget and changes in latent heat input to the atmosphere. Basically, aerosol concentrations can influence cloud droplet size distributions, the warm-rain process, the cold-rain process, cloud-top heights, the depth of the mixed-phase region, and the occurrence of lightning. Recently, many cloud resolution models (CRMs) have been used to examine the role of aerosols on mixed-phase convective clouds. These modeling studies have many differences in terms of model configuration (two- or three-dimensional), domain size, grid spacing (150-3000 m), microphysics (two-moment bulk, simple or sophisticated spectral-bin), turbulence (1st or 1.5 order turbulent kinetic energy (TKE)), radiation, lateral boundary conditions (i.e., closed, radiative open or cyclic), cases (isolated convection, tropical or midlatitude squall lines) and model integration time (e.g., 2.5 to 48 hours). Among these modeling studies, the most striking difference is that cumulative precipitation can either increase or decrease in response to higher concentrations of CCN. In this presentation, we review past efforts and summarize our current understanding of the effect of aerosols on convective precipitation processes. Specifically, this paper addresses the following topics: observational evidence of the effect of aerosols on precipitation processes, and results from (CRM) simulations. Note that this presentation is mainly based on a recent paper published in Geophy. Rev. (Tao et al. 2012).

Tao, Wei-Kuo↗