Profiles Of Effective Radius Research Articles

An iterative algorithm to simultaneously retrieve aerosol extinction and effective radius profiles using CALIOP

Abstract. The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite has been widely used in climate and environment studies to obtain the vertical profiles of atmospheric aerosols. To retrieve the vertical profile of aerosol extinction, the CALIOP algorithm assumes column-averaged lidar ratios based on a clustering of aerosol optical properties measured at surface stations. On one hand, these lidar ratio assumptions may not be appropriate or representative at certain locations. One the other hand, the two-wavelength design of CALIOP has the potential to constrain aerosol size information, which has not been considered in the operational algorithm. In this study, we present a modified inversion algorithm to simultaneously retrieve aerosol extinction and effective radius profiles using two-wavelength elastic lidars such as CALIOP. Specifically, a lookup table is built to relate the lidar ratio with the Ångström exponent calculated using aerosol extinction at the two wavelengths, and the lidar ratio is then determined iteratively without a priori assumptions. The retrieved two-wavelength extinction at each layer is then converted to the particle effective radius assuming a lognormal distribution. The algorithm is tested on synthetic data, Raman lidar measurements and then finally the real CALIOP backscatter measurements. Results show improvements over the CALIPSO operational algorithm by comparing with ground-based Raman lidar profiles.

Establishment of an analytical model for remote sensing of typical stratocumulus cloud profiles under various precipitation and entrainment conditions

Abstract. Structural patterns of cloud effective radius (ER) and liquid water content (LWC) profiles are essential variables of cloud lifecycle and precipitation processes, while observing cloud profiles from passive remote-sensing sensors remains highly challenging. Understanding whether there are typical structural patterns of ER and LWC profiles in liquid clouds and how they are linked to cloud entrainment or precipitating status is critical in developing algorithms to derive cloud profiles from passive satellite sensors. This study aims to address these questions and provide a preliminary foundation for the development of liquid cloud profile retrievals for the Multi-viewing, Multi-channel and Multi-polarization Imaging (3MI) sensor aboard the European Organization for the Exploitation of Meteorological Satellites (EUMETSAT) Polar System-Second Generation (EPS-SG) satellite, which is scheduled to be launched in 2025. Firstly, we simulate a large ensemble of stratocumulus cloud profiles using the Colorado State University (CSU) Regional Atmospheric Modeling System (RAMS). The empirical orthogonal function (EOF) analysis is adopted to describe the shape of simulated profiles with a limited number of elemental profile variations. Our results indicate that the first three EOFs of LWC and ER profiles can explain >90 % of LWC and ER profiles. The profiles are divided into four prominent patterns and all of these patterns can be simplified as triangle-shaped polylines. The frequency of these four patterns is found to relate to intensities of the cloud-top entrainment and precipitation. Based on these analyses, we propose a simplified triangle-shaped cloud profile parameterization scheme allowing us to represent these main patterns of LWC and ER. This simple yet physically realistic analytical model of cloud profiles is expected to facilitate the representation of cloud properties in advanced retrieval algorithms such as those developed for the 3MI/EPS-SG.

Deep HST imaging of distant weak radio and field galaxies

view Abstract Citations (43) References (52) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Deep HST Imaging of Distant Weak Radio and Field Galaxies Windhorst, R. A. ; Gordon, J. M. ; Pascarelle, S. M. ; Schmidtke, P. C. ; Keel, W. C. ; Burkey, J. M. ; Dunlop, J. S. Abstract We present deep Hubble Space Telescope (HST) Wide-Field Camera V- and I-band images of three distant weak radio galaxies with z = 0.311-2.390 and seven field galaxies with z = 0.131-0.58. The images were deconvolved with both the Lucy and multiresolution CLEAN methods, which yield a restoring FWHM of <= 0.2", (nearly) preserve photons and signal-to-noise ratio at low spatial frequencies, and produce consistent light profiles down to our 2 σ surface brightness sensitivity limit of V~27.2 and I~25.9 mag arcsec^-2^. Multi-component image modeling was used to provide deconvolution-independent estimates of structural parameters for symmetric galaxies. We present 12-band (m_2750_ UBVRIgriJHK) photometry for a subset of the galaxies and bootstrap the unknown FOC/48 zero point at 2750 A in three independent ways (yielding m_2750_ = 21.34 +/- 0.09 mag for 1.0 e^-^ s^-1^). Two radio galaxies with z = 0.311 and 0.528, as well as one field galaxy with z = 0.58, have the colors and spectra of early-type galaxies, and a^1/4^-like light profiles in the HST images. The two at z > 0.5 have little or no color gradients in V-I and are likely giant ellipticals, while the z = 0.311 radio galaxy has a dim exponential disk and is likely an S0. Six of the seven field galaxies have light profiles that indicate (small) inner bulges following a^1/4^ laws and outer exponential disks, both with little or no color gradients. These are (early-type) spiral galaxies with z = 0.131-0.528. About half have faint companions or bars. One shows lumpy structure, possibly a merger. The compact narrow-line galaxy 53W002 at z = 2.390 has <= 30% +/- 10% of its HST V and I flux in the central kiloparsec (due to its weak AGN). Most of its light (V~23.3) occurs in a symmetric envelope with a regular a^1/4^-like profile of effective radius a ~ 1.1"(~12 kpc for H_0_ = 50, q_0_ = 0.1). Its (HST) V - I color varies at most from ~0.3 mag at a~0.2" to ~1.2 mag at a ~> 0.4", and possibly to ~> 2.2 mag at a ~> 1.2". Together with its I - K color (~2.5 mag for a ~> 1.0"-2.0"), this is consistent with an aging stellar population 0.3-0.5 Gyr old in the galaxy center (a <~ 2 kpc radius), and possibly ~0.5-1.0 Gyr old at a ~> 10 kpc radius. While its outer part may thus have started to collapse at z = 2.5-4, its inner part still is aligned with its redshifted Lyα cloud and its radio axis, possibly caused by star formation associated with the radio jet, or by reflection from its AGN cone. Publication: The Astrophysical Journal Pub Date: November 1994 DOI: 10.1086/174839 Bibcode: 1994ApJ...435..577W Keywords: Astronomical Photometry; Galactic Evolution; Galactic Structure; Morphology; Radio Astronomy; Radio Galaxies; Signal To Noise Ratios; Galactic Clusters; Hubble Space Telescope; Radio Spectra; Red Shift; Star Formation; Astronomy; GALAXIES: EVOLUTION; GALAXIES: PHOTOMETRY; GALAXIES: STELLAR CONTENT; GALAXIES: STRUCTURE full text sources ADS | data products NED (10) SIMBAD (3) MAST (1) ESA (1)