A Gridded Climatology of Clouds over Land (1971-1996) and Ocean (1954-2008) from Surface Observations Worldwide (NDP-026E)*

Dataset · Sat Dec 01 04:00:00 EST 2007

DOI:https://doi.org/10.3334/CDIAC/cli.ndp026e· OSTI ID:1394933

C. J. Hahn, ^[1]; S. G. Warren, ^[2]

---

1. University of Arizona, Department of Atmospheric Sciences; OSTI
2. Department of Atmospheric Sciences, University of Washington

Surface synoptic weather reports from ships and land stations worldwide were processed to produce a global cloud climatology which includes: total cloud cover, the amount and frequency of occurrence of nine cloud types within three levels of the troposphere, the frequency of occurrence of clear sky and of precipitation, the base heights of low clouds, and the non-overlapped amounts of middle and high clouds. Synoptic weather reports are made every three hours; the cloud information in a report is obtained visually by human observers. The reports used here cover the period 1971-96 for land and 1954-2008 for ocean. This digital archive provides multi-year monthly, seasonal, and annual averages in 5x5-degree grid boxes (or 10x10-degree boxes for some quantities over the ocean). Daytime and nighttime averages, as well as the diurnal average (average of day and night), are given. Nighttime averages were computed using only those reports that met an "illuminance criterion" (i.e., made under adequate moonlight or twilight), thus minimizing the "night-detection bias" and making possible the determination of diurnal cycles and nighttime trends for cloud types. The phase and amplitude of the first harmonic of both the diurnal cycle and the annual cycle are given for the various cloud types. Cloud averages for individual years are also given for the ocean for each of 4 seasons, and for each of the 12 months (daytime-only averages for the months). [Individual years for land are not gridded, but are given for individual stations in a companion data set, CDIAC's NDP-026D).] This analysis used 185 million reports from 5388 weather stations on continents and islands, and 50 million reports from ships; these reports passed a series of quality-control checks. This analysis updates (and in most ways supercedes) the previous cloud climatology constructed by the authors in the 1980s. Many of the long-term averages described here are mapped on the University of Washington, Department of Atmospheric Sciences Web site. The Online Cloud Atlas containing NDP-026E data is available via the University of Washington.For access to the data files, click this link to the CDIAC data transition website: http://cdiac.ess-dive.lbl.gov/epubs/ndp/ndp026e/ndp026e.html

• Research Organization: Environmental System Science Data Infrastructure for a Virtual Ecosystem
• Sponsoring Organization: U.S. DOE > Office of Science (SC) > Biological and Environmental Research (BER) (SC-23)
• OSTI ID: 1394933
• Report Number(s): doi:10.3334/CDIAC/CLI.NDP026E; cdiac:doi 10.3334/CDIAC/cli.ndp026.e
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Clear Sky
Climatology
Clouds
NDP-026E
Precipitation
Troposphere
University of Washington
base heights of low clouds
clear sky and precipitation frequency
nine cloud types
non-overlapped amounts of middle and high clouds
total cloud cover