The University of Southampton
University of Southampton Institutional Repository

The effect of instrument exposure on marine air temperatures: an assessment using VOSClim data

The effect of instrument exposure on marine air temperatures: an assessment using VOSClim data
The effect of instrument exposure on marine air temperatures: an assessment using VOSClim data
Observations of marine air temperature (MAT) by Voluntary Observing Ships (VOS) are known to contain significant biases due to solar heating of the sensor environment. MAT and humidity observations are usually made using wet- and dry-bulb thermometers housed in Stevenson screens, or with psychrometers. These instruments are typically mounted in the bridge wings or on the wheel-house top. If not sited carefully then the instruments can be poorly exposed to the undisturbed environmental conditions and have inadequate ventilation, leading to biased observations of both MAT and humidity.

In this paper we use observations collected as part of the VOS Climate (VOSClim) project to investigate the relationship between instrument exposure and heating errors. The heating errors are estimated as the difference between the observed MAT and the collocated output of a numerical weather prediction model. The instrument exposures are assessed from hotographs of the instruments. Currently, photographs of the instruments and sufficient observations exist for 17 VOSClim ships.

Two methods of assessing the instrument exposure using the observations are presented. The first method is based on the skewness of the distribution of estimated heating errors for individual ships. The second method is based on a correction developed to correct the heating errors and uses the ratio of the heating to cooling terms in the correction. When ships are ranked both on the skewness and on the ratio of the heating to cooling terms, there is a statistically significant correspondence between the rankings and the visual assessments of instrument exposure. The skewness of the distribution of estimated errors in MAT is proposed as a simple indicator of instrument exposure.
VOSClim, ICOADS, ship, air temperature, humidity, exposure, skewness
1007-1022
Berry, D.I.
55ffc590-f459-49c8-aecf-842d65aeb0fb
Kent, E.C.
ea23f6f0-ccf6-4702-a5c9-184e9c5d4427
Berry, D.I.
55ffc590-f459-49c8-aecf-842d65aeb0fb
Kent, E.C.
ea23f6f0-ccf6-4702-a5c9-184e9c5d4427

Berry, D.I. and Kent, E.C. (2005) The effect of instrument exposure on marine air temperatures: an assessment using VOSClim data. International Journal of Climatology, 25 (7), 1007-1022. (doi:10.1002/joc.1178).

Record type: Article

Abstract

Observations of marine air temperature (MAT) by Voluntary Observing Ships (VOS) are known to contain significant biases due to solar heating of the sensor environment. MAT and humidity observations are usually made using wet- and dry-bulb thermometers housed in Stevenson screens, or with psychrometers. These instruments are typically mounted in the bridge wings or on the wheel-house top. If not sited carefully then the instruments can be poorly exposed to the undisturbed environmental conditions and have inadequate ventilation, leading to biased observations of both MAT and humidity.

In this paper we use observations collected as part of the VOS Climate (VOSClim) project to investigate the relationship between instrument exposure and heating errors. The heating errors are estimated as the difference between the observed MAT and the collocated output of a numerical weather prediction model. The instrument exposures are assessed from hotographs of the instruments. Currently, photographs of the instruments and sufficient observations exist for 17 VOSClim ships.

Two methods of assessing the instrument exposure using the observations are presented. The first method is based on the skewness of the distribution of estimated heating errors for individual ships. The second method is based on a correction developed to correct the heating errors and uses the ratio of the heating to cooling terms in the correction. When ships are ranked both on the skewness and on the ratio of the heating to cooling terms, there is a statistically significant correspondence between the rankings and the visual assessments of instrument exposure. The skewness of the distribution of estimated errors in MAT is proposed as a simple indicator of instrument exposure.

Full text not available from this repository.

More information

Published date: 2005
Keywords: VOSClim, ICOADS, ship, air temperature, humidity, exposure, skewness

Identifiers

Local EPrints ID: 16207
URI: https://eprints.soton.ac.uk/id/eprint/16207
PURE UUID: f223e349-39db-4889-ae66-3d203102f9e4

Catalogue record

Date deposited: 29 Jun 2005
Last modified: 17 Jul 2017 16:44

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×