World Library  

Add to Book Shelf
Flag as Inappropriate
Email this Book

A Better Understanding of Polder's Cloud Droplet Size Retrieval: Impact of Cloud Horizontal Inhomogeneity and Directional Sampling : Volume 8, Issue 7 (01/07/2015)

By Shang, H.

Click here to view

Book Id: WPLBN0004000516
Format Type: PDF Article :
File Size: Pages 39
Reproduction Date: 2015

Title: A Better Understanding of Polder's Cloud Droplet Size Retrieval: Impact of Cloud Horizontal Inhomogeneity and Directional Sampling : Volume 8, Issue 7 (01/07/2015)  
Author: Shang, H.
Volume: Vol. 8, Issue 7
Language: English
Subject: Science, Atmospheric, Measurement
Collections: Periodicals: Journal and Magazine Collection, Copernicus GmbH
Publication Date:
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications


APA MLA Chicago

Wang, Z., Bréon, F., Chen, L., Letu, H., Li, S., Shang, H., & Su, L. (2015). A Better Understanding of Polder's Cloud Droplet Size Retrieval: Impact of Cloud Horizontal Inhomogeneity and Directional Sampling : Volume 8, Issue 7 (01/07/2015). Retrieved from

Description: State Key Laboratory of Remote Sensing Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing, China. The principles of the Polarization and Directionality of the Earth's Reflectance (POLDER) cloud droplet size retrieval requires that clouds are horizontally homogeneous. Nevertheless, the retrieval is applied by combining all measurements from an area of 150 km × 150 km to compensate for POLDER's insufficient directional sampling. Using the POLDER-like data simulated with the RT3 model, we investigate the impact of cloud horizontal inhomogeneity and directional sampling on the retrieval, and then analyze which spatial resolution is potentially accessible from the measurements. Case studies show that the sub-scale variability in droplet effective radius (CDR) can mislead both the CDR and effective variance (EV) retrievals. Nevertheless, the sub-scale variations in EV and cloud optical thickness (COT) only influence the EV retrievals and not the CDR estimate. In the directional sampling cases studied, the retrieval is accurate using limited observations and is largely independent of random noise.

Several improvements have been made to the original POLDER droplet size retrieval. For example, the measurements in the primary rainbow region (137–145°) are used to ensure accurate large droplet (> 15 Μm) retrievals and reduce the uncertainties caused by cloud heterogeneity. We apply the improved method using the POLDER global L1B data for June 2008, the new CDR results are compared with the operational CDRs. The comparison show that the operational CDRs tend to be underestimated for large droplets. The reason is that the cloudbow oscillations in the scattering angle region of 145–165° are weak for cloud fields with CDR > 15 Μm. Lastly, a sub-scale retrieval case is analyzed, illustrating that a higher resolution, e.g., 42 km × 42 km, can be used when inverting cloud droplet size parameters from POLDER measurements.

A better understanding of POLDER's cloud droplet size retrieval: impact of cloud horizontal inhomogeneity and directional sampling

Alexandrov, M. D., Cairns, B., Emde, C., Ackerman, A. S., and van Diedenhoven, B.: Accuracy assessments of cloud droplet size retrievals from polarized reflectance measurements by the research scanning polarimeter, Remote Sens. Environ., 125, 92–111, doi:10.1016/j.rse.2012.07.012, 2012.; Baum, B. A., Kratz, D. P., Yang, P., Ou, S. C., Hu, Y. X., Soulen, P. F., and Tsay, S. C.: Remote sensing of cloud properties using MODIS airborne simulator imagery during SUCCESS 1. Data and models, J. Geophys. Res.-Atmos., 105, 11767–11780, doi:10.1029/1999jd901089, 2000.; Bodhaine, B. A., Wood, N. B., Dutton, E. G., and Slusser, J. R.: On Rayleigh optical depth calculations, J. Atmos. Ocean. Tech., 16, 1854–1861,;2>10.1175/1520-0426(1999)016<1854:orodc>;2, 1999.; Bréon, F.-M. and Colzy, S.: Global distribution of cloud droplet effective radius from POLDER polarization measurements, Geophys. Res. Lett., 27, 4065–4068, doi:10.1029/2000gl011691, 2000.; Breon, F. M. and Doutriaux-Boucher, M.: A comparison of cloud droplet radii measured from space, IEEE T. Geosci. Remote, 43, 1796–1805, doi:10.1109/TGRS.2005.852838, 2005.; Bréon, F.-M. and Goloub, P.: Cloud droplet effective radius from spaceborne polarization measurements, Geophys. Res. Lett., 25, 1879–1882, doi:10.1029/98gl01221, 1998.; Cairns, B., Russell, E. E., LaVeigne, J. D., and Tennant, P. M. W.: Research scanning polarimeter and airborne usage for remote sensing of aerosols, in: Polarization Science and Remote Sensing, edited by: Shaw, J. A. and Tyo, J. S., Proceedings of SPIE – The International Society for Optical Engineering, 33–44, 2003.; Cheng, T. H., Gu, X. F., Chen, L. F., Yu, T., and Tian, G. L.: Multi-angular polarized characteristics of cirrus clouds, Acta Phys. Sin., 57, 5323–5332, 2008.; Coddington, O. M., Pilewskie, P., Redemann, J., Platnick, S., Russell, P. B., Schmidt, K. S., Gore, W. J., Livingston, J., Wind, G., and Vukicevic, T.: Examining the impact of overlying aerosols on the retrieval of cloud optical properties from passive remote sensing, J. Geophys. Res., 115, D10211, doi:10.1029/2009jd012829, 2010.; Dandin, P., Pontikis, C., and Hicks, E.: Sensitivity of a GCM to changes in the droplet effective radius parameterization, Geophys. Res. Lett., 24, 437–440, doi:10.1029/97gl00214, 1997.; Di Girolamo, L., Liang, L., and Platnick, S.: A global view of one-dimensional solar radiative transfer through oceanic water clouds, Geophys. Res. Lett., 37, L18809, doi:10.1029/2010gl044094, 2010.; Evans, K. F. and Stephens, G. L.: A new polarized atmospheric radiative-transfer model, J. Quant. Spectrosc. Ra., 46, 413–423, doi:10.1016/0022-4073(91)90043-p, 1991.; Fougnie, B., Bracco, G., Lafrance, B., Ruffel, C., Hagolle, O., and Tinell, C.: PARASOL in-flight calibration and performance, Appl. Optics, 46, 5435–5451, doi:10.1364/ao.46.005435, 2007.; Goloub, P., Herman, M., Chepfer, H., Riedi, J., Brogniez, G., Couvert, P., and Séze, G.: Cloud thermodynamical phase classification from the POLDER spaceborne instrument, J. Geophys. Res., 105, 14747, doi:10.1029/1999jd901183, 2000.; Gryspeerdt, E., Stier, P., and Partridge, D. G.: Satellite observations of cloud regime development: th


Click To View

Additional Books

  • Quality-based Generation of Weather Rada... (by )
  • Ionospheric Assimilation of Radio Occult... (by )
  • Interannual Variability of Upper Troposp... (by )
  • Simultaneous Stable Isotope Analysis of ... (by )
  • Towards a Consistent Eddy-covariance Pro... (by )
  • Modelling Ag-particle Activation and Gro... (by )
  • Lidar Multiple Scattering Factors Inferr... (by )
  • Scatterometer Hurricane Wind Speed Retri... (by )
  • A Network of Autonomous Surface Ozone Mo... (by )
  • Study of the Regional Co2 Mole Fractions... (by )
  • Scanning Supersaturation Condensation Pa... (by )
  • Constrained Two-stream Algorithm for Cal... (by )
Scroll Left
Scroll Right


Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.