ASOS 30-Second Ceilometer Data

ASOS 30-Second Ceilometer Data is digital data set DSI-6404, archived at the National Climatic Data Center (NCDC). A major part of the National Weather Service (NWS) modernization effort in the 1990s is the implementation of the Automated Surface Observing System (ASOS). The ASOS Cloud Height Indicator (CHI) is a laser ceilometer that features a rapid pulse and sampling rate. The pulse rate varies from 620 Hz to 1,120 Hz according to ambient air temperature. At a nominal pulse rate of 770 Hz, the ceilometer outputs 9,240 pulses during a 12-second sampling period. The vertical resolution is 50 feet up to 12,600 feet above ground level (AGL). The maximum reporting height is 12,000 ft. The ceilometer data are sampled by the ASOS software once every 30 seconds. The accumulated 30-second data are arranged by height and averaged over a time-weighted 30-minute period to determine up to three cloud layers for each observation. Because ceilometer data is high-resolution and high-volume, at present only 25 ASOS sites contribute data, out of hundreds that currently exist. All are in the 48 contiguous United States of America. The earliest data is from June, 1998. Meteorological parameters include how many cloud layer bases, if any, were detected, and the height and thickness of each cloud layer. Other parameters include ceilometer status information and quality control parameters. This 30-second Ceilometer data set contains the 30-second samples and sensor status information for twenty-five ASOS reference sites below: Station and Call Sign Astoria, OR AST Atlanta, GA ATL Atlantic City, NJ ACY Brownsville, TX BRO Bismarck, ND BIS Charleston, SC CHS Dallas-Ft. Worth, TX DFW Denver, CO DEN Grand Rapids, MI GRR Great Falls, MT GTF Lincoln, NE LNK Los Angeles, CA LAX Minneapolis-St. Paul, MN MSP Mobile, AL MOB Paducah, KY PAH Pittsburgh, PA PIT Portland, ME PWM Raleigh-Durham, NC RDU Salt Lake City, UT SLC San Francisco, CA SFO Sault Ste. Marie, MI CUI Syracuse, NY SYR Tucson, AZ TUS Tulsa, OK TUL West Palm Beach, FL PBI