NOAA Highly Reflective Clouds

Federal Geographic Data Committee (FGDC) Metadata:

• Identification_Information
• Data_Quality_Information
• Spatial_Reference_Information
• Distribution_Information
• Metadata_Reference_Information

Identification_Information:

Citation:

Citation_Information:

Originator: NOAA-CIRES Climate Diagnostics Center

Publication_Date: 19880131

Title: NOAA Highly Reflective Clouds

Edition:

Geospatial_Data_Presentation_Form:

Series_Information:

Series_Name:

Issue_Identification:

Publication_Information:

Publication_Place: Boulder, CO

Publisher: NOAA-CIRES Climate Diagnostics Center

Other_Citation_Details:

Online_Linkage: http://www.cdc.noaa.gov/data/gridded/data.noaa.hrc.html

Description:

Abstract:

The data presented here are the record of subjectively identified areas of large-scale organized convection over the global tropics on the daily daytime Mercator projection mosaics for a 15-year period from 1971 to 1988. These convection areas appear as highly reflective clouds in the visible-range mosaics and as white areas in the infrared (IR) range. Highly reflective cloud (HRC) is defined here as a deep, organized tropical convection system extending at least 200 km horizontally. HRCs are composed of many individual convective cells embedded within a common cirrostratus canopy. These cloud systems, commonly known as cloud clusters, have been extensively studied in recent years (e.g., Houze, 1982); they are responsible for most tropical rainfall and are important components in the general circulation of the atmosphere. These data originally appeared in the Atlas of Highly Reflective Clouds for the Global Tropics: 1971-1985. Until now, the most widely used indicator of large-scale convection over the global tropics has been the outgoing longwave radiation (OLR) data set (Gruber and Krueger, 1984). OLR data for 9 years were recently summarized in NOAA Atlas No. 6 (Janowiak et al., 1985). In the tropics, low values of OLR are found over areas covered by high clouds with low cloud-top temperatures. In most cases, such clouds are convective. However, low OLR values are also associated with nonconvective clouds such as cirrostratus plumes. In contrast to the OLR data, the HRC data presented here deliberately exclude nonconvective cold clouds. The original idea for the creation of the HRC data set came from a study conducted at the University of Hawaii by Kilonsky and Ramage (1976). The study was based on the assumption that most tropical rainfall occurs in organized convective systems (cloud clusters), which appear as HRC in the polar-orbiting satellite picture mosaics. Kilonsky and Ramage (KR) obtained monthly rainfall data for Pacific atoll stations assumed to be representative of open ocean conditions. They correlated these data with the number of days per month having HRC. The presence of HRC was noted in grid squares of the satellite picture mosaics. KR assumed a linear relationship between the number of days with HRC at a particular location and the amount of rainfall recorded there; a linear regression equation was thus derived, linking the number of days with HRC cover (the independent variable) to the observed rainfall (the dependent variable). The correlation coefficient between the two variables was 0.75. Both the regression relationship and the correlation between the two variables were found to be significant at the 1% level. Subsequent to the original work of Kilonsky and Ramage, Garcia (1981) used HRC data and the KR technique to produce rainfall estimates for the tropical Atlantic Ocean. The estimates proved to be reasonably close to those obtained by using more sophisticated geostationary satellite techniques and to those estimated from shipboard radar data. These results provided the impetus for extending the HRC data set to the entire tropical belt, including land areas, and for updating the HRC data continually. Note that the validity of using HRC data from the daytime visible and IR Mercator projection mosaics as a means of estimating monthly rainfall amounts is greatly affected by the mean diurnal cycle of convection over different regions of the tropics. There is some evidence (e.g., Griffith et al., 1980) that convection over land areas has a fairly pronounced maximum during the late evening hours, whereas convection over oceans is more evenly distributed throughout the 24-hour cycle. Thus, a rainfall estimation scheme (such as the KR technique) that samples conditions only once a day during daylight hours will tend to underestimate rainfall over land areas. In addition, changes in the time of passage of polar-orbiting satellites can significantly change cumulative amounts of convection observed in a given area. NOAAServer Codes: [POL 25 -25 180 -180] ; nodateline preview obtain Scientific research.

Purpose:

Not Available

Supplemental_Information:

Not Available

Time_Period_of_Content:

Time_Period_Information:

Range_of_Dates/Times:

Beginning_Date: 19710101

Ending_Date: 19880131

Currentness_Reference:Unknown

Status:

Progress: Complete

Maintenance_and_Update_Frequency: As needed

Spatial_Domain:

Description_of_Geographic_Extent:

Bounding_Coordinates:

West_Bounding_Coordinate: -180.0

East_Bounding_Coordinate: 180.0

North_Bounding_Coordinate: 25.0

South_Bounding_Coordinate: -25.0

Keywords:

Theme:

Theme_Keyword_Thesaurus: GCMD SCIENCE PARAMETERS

Theme_Keyword_Thesaurus: PROJECT

Theme_Keyword_Thesaurus: ANCILLARY KEYWORDS

Theme_Keyword_Thesaurus: ISO TOPIC CATEGORY

Theme_Keyword: EARTH SCIENCE > ATMOSPHERE > CLOUDS > CLOUD RADIATIVE TRANSFER > CLOUD REFLECTANCE > HIGHLY REFLECTIVE CLOUDS

Theme_Keyword: DODS > DISTRIBUTED OCEANOGRAPHIC DATA SYSTEM

Theme_Keyword: ESIP > EARTH SCIENCE INFORMATION PARTNERS PROGRAM

Theme_Keyword: OPENDAP > OPEN-SOURCE PROJECT FOR A NETWORK DATA ACCESS PROTOCOL

Theme_Keyword: Noaa Highly Reflective Clouds [pol 25.00 -25.00 180 -180]

Theme_Keyword: CLIMATOLOGY/METEOROLOGY/ATMOSPHERE

Place:

Place_Keyword_Thesaurus: GCMD

Place_Keyword: GEOGRAPHIC REGION > EQUATORIAL

Access_Constraints: None.

Use_Constraints:

None. Acknowledgement of CDC would appreciated in products derived from these data.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: ESRL/PSD DATA INQUIRIES

Contact_Position: TECHNICAL CONTACT

Contact_Position: DIF AUTHOR

Contact_Address:

Address_Type: Mailing and Physical Address

Contact_Electronic_Mail_Address: esrl.psd.data@noaa.gov

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report:

Not Available

Logical_Consistency_Report:

Not Available

Completeness_Report:

Not Available

Lineage:

Process_Step:

Process_Description:

Not Available

Process_Date: Unknown

Spatial_Reference_Information:

Distribution_Information:

Distributor:

Contact_Information:

Contact_Organization_Primary:

Contact_Organization: DOC/NOAA/OAR/ESRL/PSD/CAB > Climate Analysis Branch, Physical Sciences Division, Earth System Research Laboratory, OAR, NOAA, U.S. Department of Commerce

Contact_Person: ESRL/PSD DATA INQUIRIES

Contact_Position: DATA CENTER CONTACT

Contact_Address:

Address_Type: Mailing and Physical Address

Contact_Electronic_Mail_Address: esrl.psd.data@noaa.gov

Resource_Description: CDC043

Distribution_Liability:

Not Available

Standard_Order_Process:

Digital_Form:

Digital_Transfer_Information:

Format_Name: Not Available

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

http://www.esrl.noaa.gov/psd/psd1/

Access_Instructions:

DATA CENTER URL

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

http://www.cdc.noaa.gov/data/gridded/data.noaa.hrc...

Access_Instructions:

Obtain this data set via HTML.

Digital_Transfer_Option:

Online_Option:

Computer_Contact_Information:

Network_Address:

Network_Resource_Name:

ftp://ftp.cdc.noaa.gov/Datasets/noaa_hrc/

Access_Instructions:

Obtain this data set via FTP.

Fees: Not Available

Metadata_Reference_Information:

Metadata_Date: 20020322

Metadata_Review_Date: 20090715

Metadata_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: ESRL/PSD DATA INQUIRIES

Contact_Position: TECHNICAL CONTACT

Contact_Position: DIF AUTHOR

Contact_Address:

Address_Type: Mailing and Physical Address

Contact_Electronic_Mail_Address: esrl.psd.data@noaa.gov

Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata

Metadata_Standard_Version: FGDC-STD-001-1998

Metadata_Time_Convention: local time