Identification

Title

Seasonal variation of O/N2 on different pressure levels from GUVI limb measurements

Abstract

The ratio of O number density to N-2 number density (O/N-2) is an important parameter to describe thermospheric composition changes and its effects on the ionosphere. Based on Global Ultraviolet Imager (GUVI) limb measurements, we investigate the seasonal behaviors of O/N-2 volume density ratio on different constant pressure levels during geomagnetically quiet periods. The global O/N-2 shows the prominent annual and semiannual variations with solar activity dependence. An empirical model considering the solar activity and annual/semiannual variations can reasonably reproduce the original O/N-2. The modeled O/N-2 captures the hemispheric asymmetry of the annual variations in both length and magnitude. Global maps of the seasonal harmonic components of the modeled O/N-2 indicate the latitudinal and altitudinal dependence of O/N-2 seasonal variations. The annual component dominates over the semiannual component at mid-latitudes, but it is smaller than the semiannual component at low latitudes. In the Northern Hemisphere, and at low geomagnetic latitudes of the Southern Hemisphere, the annual component peaks around December solstice at all altitudes, whereas at middle geomagnetic latitudes of the Southern Hemisphere, it peaks around June solstice. The semiannual component peaks at the equinoxes in almost all regions over the globe at all altitudes. The annual and semiannual amplitudes both increase with altitude. In addition, O/N-2 annual variations and solar activity dependence are more influenced by the thermal expansion and contraction.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d72v2kdj

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2020-08-07T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact