COLOCATED CloudSat, AMSR-E, AND SSM/I LIQUID WATER PATH (LWP) GRIDS OVER THE SOUTHEAST PACIFIC PI: Xubin Zeng CO-PI AND CONTACT PERSON: Michael Brunke The University of Arizona Department of Atmospheric Sciences P.O. Box 210081 Tucson, AZ 85721-0081 E-mail: brunke@atmo.arizona.edu MAPS OF THE 2008 DATA CAN BE FOUND AT http://www.atmo.arizona.edu/~brunke/VOCALS. OVERVIEW Colocated measurements of liquid water path (LWP) from the Cloud Profiling Radar (CPR) on board CloudSat, the Advanced Microwave Scanning Radiometer-EOS on board the Aqua satellite, andthe Special Sensor Microwave Image (SSM/I) on board the Defense Meteorological Satellite Program satellites have been compiled for 0.25 deg x 0.25 deg grids in the southeast Pacific region (40S-0, 60W-110W). The data spans the austral spring seasons (October-December) of 2006, 2007, and 2008. SATELLITE DATA The CPR is a nadir-viewing 94-GHz radar which is the sole instrument aboard CloudSat (Stephens et al. 2008). Used here are the LWPs from Release 4 of the 2B-CWC-RO product provided by the CloudSat Data Processing Center (http://www.cloudsat.cira.colostate.edu). AMSR-E and SSM/I are both passive microwave instruments. AMSR-E LWPs from the version 2 level 2B global swath ocean product downloaded from the National Snow and Ice Data Center (NSIDC, http://nsidc.org/daac/index.html) and SSM/I version 6 ocean algorithm LWPs from Remote Sensing Systems (RSS, http://www.remss.com, Wentz 1997) are included here. DATA PROCESSING For the version of the collocated CloudSat LWPs included here, only good quality data indicated by a 0 data quality flag, have a fractional uncertainty of < 50%, and have not been flagged as having used bad input data. Furthermore, LWPs are only included if a cloud is also detected by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite that follows closely behind CloudSat. Additionally, only LWPs for clouds with tops >= 1000 m have been included to eliminate the possibility of missed drizzle in shallow, low clouds (Leon et al. 2008). To further reduce the impact of precipitation contaminating LWP, only LWPs for profiles in which the maximum reflectivity (Zmax) > -15 dBZ below mid-cloud are kept. Each CloudSat ray (profile) is nominally 1.1 km apart with a 1.3 km across-track x 1.7 km along-track footprint (CloudSat Project 2008). For this product, we have averaged LWPs for every qualified ray that has a timestamp location within each 0.25 deg x 0.25 deg grid box. No further processing is done to the 0.25 deg x 0.25 deg grid values of LWP from AMSR-E or SSM/I. SSM/I data is the average of the data from the F13 and F15 satellites which were operationally during this period. More information on the data processing can be found in Brunke, M. A., S. P. de Szoeke, P. Zuidema, and X. Zeng, 2010: A comparison of ship and satellite measurements of cloud properties with global climate model simulations in the southeast Pacific stratus deck. Atmospheric Chemistry and Physics, 10, 6527-6536. DATA FORMAT The daily collocated satellite LWPs are in NetCDF format. The file naming convention is: YYYYMMDD_colloc_v3.nc YYYY = year (2006, 2007, or 2008) MM = month (10, 11, or 12) DD = day Data variables are: lat = latitude (of the 0.25 deg x 0.25 deg regular grid) (deg N) lon = longitude (of the 0.25 deg x 0.25 deg regular grid) (deg E) alat = average latitude of the CloudSat rays included in the regular grid boxes (deg N) alon = average longitude of the CloudSat rays included in the regular grid boxes (deg E) LWP = liquid water path (g/m^2) There are four dimensions in the data files: satellite = 3 (0 = CloudSat, 1 = AMSR-E, and 2 = SSM/I) pass = 2 (0 = morning, 1 = afternoon) lat = 160 lon = 200 Missing values are assigned to the fill value given in the NetCDF header. If there is a missing day in the record, there were no CloudSat profiles available for the region on that day. DATA REMARKS While the version available for download from UCAR/JOSS is the latest version to come out of our VOCALS research, it is still subject to possible revision if time permits. Please e-mail Michael Brunke at brunke@atmo.arizona.edu so that you can be updated if a revision is produced. Being in NetCDF format, it should be able to be accessed to view and manipulate the data by Fortran, C, NCL, IDL, or Matlab. REFERENCES Brunke, M. A., S. P. de Szoeke, P. Zuidema, and X. Zeng, 2010: A comparison of ship and satellite measurements of cloud properties with global climate model simulations in the southeast Pacific stratus deck. Atmospheric Chemistry and Physics, 10, 6527-6536. CloudSat Project, cited 2008: CloudSat Standard Data Products Handbook, available at http://www.cloudsat.cira.colostate.edu/ cloudsat_documentation/CloudSat_Data_Users_Handbook.pdf. Stephens, G. L., and 19 co-authors, 2008: CloudSat mission: Performance and early science after the first year of operation. Journal of Geophysical Research, 113, D00A18, doi:10.1029/2008JD009982. Wentz, F. J., 1997: A well-calibrated ocean algorithm for Special Sensor Microwave/Imager. Journal of Geophysical Research, 102, 8703-8718.