NDP-026E: Global Gridded Cloud Climatology from Surface Observations

185 million land and 50 million ship-based synoptic weather reports underpin this global climatology of cloud cover and types. It provides multi-year monthly, seasonal, and annual averages on 5x5-degree grids, with separate daytime and nighttime averages computed to minimize night-detection bias. The dataset updates a previous 1980s climatology and includes the phase and amplitude of diurnal and annual cycles for nine cloud types.

Use Cases

• Validating cloud parameterizations in climate models based on observed cloud type frequencies and amounts.
• Analyzing long-term trends in cloud cover over oceans using data spanning 1954-2008.
• Studying the diurnal cycle of convection by comparing daytime and nighttime averages of low clouds.
• Mapping the global distribution and base heights of low clouds for aviation or solar energy studies.
• Investigating cloud-precipitation relationships using co-occurrence frequency data.

Strengths

• Derived from a large volume of quality-controlled human observations: 185 million land reports from 5,388 stations and 50 million ship reports.
• Addresses observational bias by applying an illuminance criterion to compute valid nighttime averages for diurnal cycle analysis.
• Provides data at multiple temporal aggregations (monthly, seasonal, annual) and spatial resolutions (5x5 and 10x10-degree grids).

Limitations

• License is listed as 'closed' on one platform and unspecified on another, restricting potential reuse.
• Key metadata such as specific column names, row counts, and exact update dates are unavailable from the provided sources.
• Land and ocean data have different temporal coverages (1971-1996 vs. 1954-2008) and gridding details, complicating fully unified analysis.

Provenance

Source

Carole J. Hahn, University of Arizona (likely associated with University of Washington and CDIAC based on description).

Collection Method

Visual human observations from worldwide synoptic weather reports from ships and land stations, processed through quality checks and gridded.

Time Range

1954 to 2008 (Ocean: 1954-2008; Land: 1971-1996).

Geography

Global, with separate analyses over land and ocean.