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Precipitation-Based ENSO Indices

Federal Geographic Data Committee (FGDC) Metadata:


Identification_Information:
Citation:
Citation_Information:
Originator: Unknown
Publication_Date: Unknown
Title: Precipitation-Based ENSO Indices
Description:
Abstract:
The goal in constructing a precipitation-based measure of ENSO was to estimate the gradient of rainfall anomalies across the Pacific basin and ensure a good relationship with SST- and pressure-based indices. Areas were selected that represent the Maritime Continent (MC) (100 N - 100S; 900 E - 1500 E) and central to eastern Pacific (P) (100 N - 100 S; 1600 E - 1000 W). These regions capture the largest precipitation anomalies associated with the interannual variations of the Walker circulation and contain the largest correlations between GPCP and Nino 3.4 and SOI. Within P and MC the absolute magnitude of the largest correlation is over +0.6. Because of the spatially varying nature of rainfall, it was decided to use a moving block average which would capture the strongest zonal gradients within the equatorial Pacific. This procedure is unlike many fixed area average indices, and allows for a realistic meridional component of the precipitation gradient and migration of the ascending and descending branches of the Walker circulation. A 100 latitude by 500 longitude box is moved in 2.50 increments (grid block by grid block) throughout the P and MC domains. The maximum and minimum average precipitation anomalies are found for P (Ap+ and Ap- respectively) and MC (Amc+ and Amc- respectively). To create a homogeneous record, Ap+, Ap-, Amc+, and Amc- were separately averaged over 1991-97 for GPCP and GPROF. Then, the GPROF values were subtracted from the GPCP values to create adjustments that were applied to the GPROF part of the record (usually the last few months). Significant adjustments are made to Ap+, and especially in the winter and spring months. However, it is planned to replace GPROF values with the more accurate GPCP analyses as they become available, about three months after the observation time. Amc- is subtracted from Ap+ and normalized to create the El Nino Index (EI). Ap- is subtracted from Amc+ and normalized to create the La Nina Index (LI). Normalization is achieved for each month by subtracting off the 1979-98 means and dividing by the standard deviations as shown in Eq. 1: where i = (January, February, ... , December). Positive EI (LI) values would indicate that the ENSO cycle was in its warm (cold) phase. There are advantages to quantifying the evolution of the warm and cold phases of ENSO through separate indices. However, there is also an advantage to having one index describe the ENSO cycle. This was accomplished by taking the difference and normalizing to create the ENSO Precipitation Index (ESPI): ESPI = normalized EI - LI (2) Positive (negative) values indicate the warm (cold) phase of the ENSO cycle. Applying a two month running mean to the ESPI data reduces the effect of the 30-60 day oscillation signal. View the Precipitation-Based ENSO Indices on-line: "http://precip.gsfc.nasa.gov/" [Summary Extracted from the NASA/GSFC/MAPB Home Page]
Purpose:
Not Available
Supplemental_Information:
REFERENCE: Curtis, S. and R. Adler, 2000: ENSO indexes based on patterns of satellite-derived precipitation. J. Climate, 13, 2786-2793.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19790101
Ending_Date: Unknown
Currentness_Reference:Unknown
Status:
Progress: In Work
Maintenance_and_Update_Frequency: As needed
Spatial_Domain:
Description_of_Geographic_Extent:
Bounding_Coordinates:
West_Bounding_Coordinate: 160.0
East_Bounding_Coordinate: -100.0
North_Bounding_Coordinate: 10.0
South_Bounding_Coordinate: -10.0
Spatial_Domain:
Description_of_Geographic_Extent:
Bounding_Coordinates:
West_Bounding_Coordinate: 90.0
East_Bounding_Coordinate: 150.0
North_Bounding_Coordinate: 10.0
South_Bounding_Coordinate: -10.0
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_Thesaurus: DATA SET LANGUAGE
Theme_Keyword: EARTH SCIENCE > ATMOSPHERE > PRECIPITATION > PRECIPITATION AMOUNT
Theme_Keyword: EARTH SCIENCE > ATMOSPHERE > PRECIPITATION > PRECIPITATION ANOMALIES
Theme_Keyword: EARTH SCIENCE > ATMOSPHERE > PRECIPITATION > PRECIPITATION RATE
Theme_Keyword: EARTH SCIENCE > CLIMATE INDICATORS > ATMOSPHERIC/OCEAN INDICATORS > TELECONNECTIONS > EL NINO SOUTHERN OSCILLATION (ENSO) > ENSO
Theme_Keyword: GPCP > GLOBAL PRECIPITATION CLIMATOLOGY PROJECT
Theme_Keyword: El Nino
Theme_Keyword: El Nino Southern Oscillation
Theme_Keyword: Enso
Theme_Keyword: La Nina
Theme_Keyword: Soi
Theme_Keyword: Southern Oscillation Index
Theme_Keyword: CLIMATOLOGY/METEOROLOGY/ATMOSPHERE
Theme_Keyword: ENGLISH
Place:
Place_Keyword_Thesaurus: GCMD
Place_Keyword: OCEAN > PACIFIC OCEAN
Access_Constraints: Not Available
Use_Constraints:
Not Available
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: SCOTT CURTIS
Contact_Position: INVESTIGATOR
Contact_Address:
Address_Type: Mailing and Physical Address
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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
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Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 2.5 degree
Longitude_Resolution: 2.5 degree
Geographic_Coordinate_Units: Decimal degrees
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: NASA/GSFC/SED/ESD/LA/MAPB > Mesoscale Atmospheric Processes Branch, Laboratory for Atmospheres, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA
Contact_Person: DAVID T. BOLVIN
Contact_Position: DATA CENTER CONTACT
Contact_Address:
Address_Type: Mailing and Physical Address
Address: NASA
Address: Goddard Space Flight Center
Address: Mailstop 613.1
City: Greenbelt
State_or_Province: MD
Postal_Code: 20771
Country: USA
Contact_Voice_Telephone: 301-614-6323
Contact_Facsimile_Telephone: 301-614-5492
Contact_Electronic_Mail_Address: david.t.bolvin@nasa.gov
Resource_Description: GPCP_PRECIP_ENSO_INDIC
Distribution_Liability:
Not Available
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://atmospheres.gsfc.nasa.gov/meso/
Access_Instructions:
DATA CENTER URL
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://precip.gsfc.nasa.gov/
Access_Instructions:
ENSO Precipitation Index Data
Fees: None
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Metadata_Reference_Information:
Metadata_Date: 20000817
Metadata_Review_Date: 20050705
Metadata_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person: SCOTT A. RITZ
Contact_Position: DIF AUTHOR
Contact_Address:
Address_Type: Mailing and Physical Address
Address: NASA Goddard Space Flight Center
Address: Global Change Master Directory
City: Greenbelt
State_or_Province: Maryland
Postal_Code: 20771
Country: USA
Contact_Voice_Telephone: 301-614-5126
Contact_Facsimile_Telephone: 301-614-5268
Contact_Electronic_Mail_Address: Scott.A.Ritz@nasa.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998
Metadata_Time_Convention: local time
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