Identification

Title

Hurrell Wintertime SLP-based Northern Annular Mode (NAM) Index

Abstract

The NAM (or Arctic Oscillation) is defined as the first EOF of NH (20°-90°N) winter SLP data. It explains 23% of the extended winter mean (December-March) variance, and it is clearly dominated by the NAO structure in the Atlantic sector. Although there are some subtle differences from the NAO regional pattern over the Atlantic and Arctic, the main difference is larger amplitude anomalies over the North Pacific of the same sign as those over the Atlantic. This feature gives the NAM a more annular (or zonally-symmetric) structure. Positive values of the NAM are associated with lower-than-normal sea level pressures over the Arctic and westerly wind anomalies along ~55º-60ºN.

Resource type

dataset

Resource locator

Unique resource identifier

code

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

climatologyMeteorologyAtmosphere

Keywords

Keyword set

keyword value

Dataset

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2017-05-10

Keyword set

keyword value

EARTH SCIENCE > CLIMATE INDICATORS > ATMOSPHERIC/OCEAN INDICATORS > TELECONNECTIONS > ARCTIC OSCILLATION > AO

originating controlled vocabulary

title

GCMD

reference date

date type

revision

effective date

2017-07-18

Geographic location

West bounding longitude

-180

East bounding longitude

180

North bounding latitude

90

South bounding latitude

20

Temporal reference

Temporal extent

Begin position

1899-01-01

End position

2016-03-31

Dataset reference date

date type

publication

effective date

1995-01-01

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

TXT

version of format

Constraints related to access and use

Constraint set

Use constraints

Dash and its services comply with policies set by UCAR and NCAR.

Limitations on public access

citation: NAM Index Data provided by the Climate Analysis Section, NCAR, Boulder, USA. Updated regularly. Accessed DD Month YYYY [list date you accessed the data].

Responsible organisations

Responsible party

contact position

Associate Scientist

organisation name

UCAR/NCAR - Climate and Global Dynamics Laboratory

email address

asphilli@ucar.edu

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact

contact position

organisation name

UCAR/NCAR - Climate and Global Dynamics Laboratory

email address

asphilli@ucar.edu

responsible party role

pointOfContact

Metadata date

2023-11-12T10:05:02

Metadata language

eng