Identification

Title

Sensing climate change using the Global Positioning System

Abstract

Using simulated atmospheric data from the National Center for Atmospheric Research (NCAR) community climate model (CCM), we test the hypothesis that the global positioning system (GPS) can be used to detect global and regional climate change. We examine how the fundamental GPS variables (wet and total delays and vertical profiles of refractivity) as well as precipitable water as estimated by ground-based GPS receivers would change in a climate with 2 times the present concentration of carbon dioxide (CO₂). Because of the higher water vapor content in the doubled CO₂ simulation the wet delay and the precipitable water show a significant increase in the tropics and middle latitudes. Refractivity also shows an increase in the lower troposphere. We also simulate the changes in the GPS signal delay in a doubled CO₂ climate as would be measured by a radio occultation technique using low Earthorbiting (LEO) satellites equipped with GPS receivers. Increases in temperature and water vapor in the lower troposphere of the model atmosphere produce opposite effects on the occultation delay. Increased temperature tends to decrease the delay, while increased water vapor increases the delay. Amplified by the long "lever arms" of the LEO-atmosphere-GPS link, a strong "greenhouse warming" signal is simulated, with increases in occultation delay of nearly 100 m using the globally averaged data. This increase indicates that globally the effect of increased water vapor dominates. However, significant regional differences are present in the occultation delay response. In the tropics, where the temperature increase is smallest and the water vapor increases are largest, increases in delay of about 300 m are simulated. In contrast, in the polar regions where the increased temperatures are greatest and the increases in water vapor are smallest, the temperature effect dominates and a decrease in occultation delay of nearly 70 m is simulated. When compared to expected errors in measuring the occultation delay of about 1 m, these results indicate that monitoring trends in occultation delays would be a practical way to detect global and regional climate change.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7988892

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

1993-08-20T00:00:00Z

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