Lagrangian Dry Point data regarding the sensitivity of stratospheric water vapour to variability in tropical tropopause temperatures and large-scale transport

This dataset contains results in support of a publication that investigates processes affecting water vapour entry to the stratosphere. The back trajectories were calculated using the OFFLINE trajectory model. Past publications have shown the key processes are temperatures in the tropical tropopause layer and large-scale transport into the stratosphere using trajectory methods. Lagrangian Dry Points (LDPs) are normally calculated as the minimum water vapour saturation mixing ratio experienced along a back-trajectory that has traversed from troposphere to tropical lower stratosphere in its recorded history.

This study separated the two key processes by sampling alternative temperatures. These alternative temperatures are either time-shifted or averaged in time or longitude. This method is applied for two meteorological datasets: ERA-Interim (ERA-I) reanalysis for the period 1999-2009, and the UM-UKCA chemistry-climate model for eleven years of a repeat-year-2000 forcing scenario. The ERA-I trajectories were calculated by S Fueglistaler and S Liu for separate publications. The UM-UKCA climate model scenario was conducted by A Maycock. This dataset contains only the LDPs resulting from alternative-temperature sampling.

The directory UM-UKCA/LDP-original-T/ provides a simple view of the original unmodified method to calculate LDPs.

LDP-alt-T/ directories contain LDPs determined with time-shifted alternative temperature samplings. The time-shift is identified by the alternative initialisation date, denoted in the filename and file metadata.

LDP-ave-T/ directories contain LDPs determine with averaged alternative temperature samplings. The averaging is identified by the variable name and metadata. In the variable names, shorthand and full-name identifiers include 6h (6 hourly instantaneous), ZM (zonal mean), 30DZM (30-day rolling window mean and zonal mean), 120DM, 90DM, 60DM, 30DM, 15DM, 14DM, 8DM, 7DM, 4DM, 2DM, 1DM (rolling window 120 day mean, 90 day mean, etc.).

Note that various alternative temperatures are recorded at each LDP calculated from each alternative temperature.

For more information on the directory structure, file naming conventions, variable naming conventions and attribute conventions please see the README.txt.

Date (Publication): 2020-11-30T14:07:13

Date (Creation): 2020-11-30T14:07:13

Citation identifier: https://catalogue.ceda.ac.uk/uuid/c6b2f1ca5f8e4c5285fb4f69d1514a03

Citation identifier: Centre for Environmental Data Analysis (CEDA) / c6b2f1ca5f8e4c5285fb4f69d1514a03

Citation identifier: doi / 10.5285/c6b2f1ca5f8e4c5285fb4f69d1514a03

Point of contact

Organisation name	Individual name	Electronic mail address	Role
Unavailable	Smith, Jacob	Unavailable	Author
Unavailable	Haynes, Peter	Unavailable	Author
Unavailable	Maycock, Amanda	Unavailable	Author
Centre for Environmental Data Analysis (CEDA)		support@ceda.ac.uk	Custodian
Unavailable	Smith, Jacob	Unavailable	Owner
Centre for Environmental Data Analysis (CEDA)		support@ceda.ac.uk	Distributor
NERC EDS Centre for Environmental Data Analysis		support@ceda.ac.uk	pointofContact
Centre for Environmental Data Analysis (CEDA)		support@ceda.ac.uk	Publisher

Maintenance and update frequency: Unknown

Update scope: Dataset

Keywords

OFFLINE
stratospheric
ERA
UM-UKCA
trajectories

GEMET - INSPIRE themes, version 1.0

atmospheric conditions

Access constraints: Other restrictions

Other constraints: Public data: access to these data is available to both registered and non-registered users.

Use constraints: Other restrictions

Other constraints: Under the following licence http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/, appropriate use of these data may fall under any use. This message is intended as guidance, always read the full licence. When using these data you must cite them correctly using the citation given on the CEDA Data Catalogue record.

Spatial representation type: Grid

Language: English

Topic category

Climatology, meteorology, atmosphere

Begin date: 1999-01-01T00:00:00

End date: 2009-12-31T23:59:59

Unique resource identifier: WGS 84

Distribution format

Name	Version
Data are provided in NetCDF formats.

Distributor contact

Organisation name	Individual name	Electronic mail address	Role
Centre for Environmental Data Analysis (CEDA)		support@ceda.ac.uk	Distributor

OnLine resource

Protocol	Linkage	Name
	https://catalogue.ceda.ac.uk/uuid/c6b2f1ca5f8e4c5285fb4f69d1514a03	CEDA Data Catalogue Page

OnLine resource

Protocol	Linkage	Name
	http://data.ceda.ac.uk/badc/deposited2020/OFFLINE_h2o_strat_variability/	DOWNLOAD

OnLine resource

Protocol	Linkage	Name
	https://doi.org/10.5194/acp-2020-934	Smith, J. W., Haynes, P. H., Maycock, A. C., Butchart, N., and Bushell, A. C.: Sensitivity of stratospheric water vapour to variability in tropical tropopause temperatures and large-scale transport, Atmos. Chem. Phys. Discuss., https://doi.org/10.5194/acp-2020-934, in review, 2020.

Hierarchy level: Dataset

Conformance result

Title: Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services

Date (Publication): 2010-12-08

Statement: Diabatic trajectories subjected to ERA-I meteorology were obtained from S Liu and S Fueglistaler. Kinematic trajectories subjected to UM-UKCA meteorology were calculated using the OFFLINE trajectory model (Methven et al. 1997, Liu et al. 2009) in a from modified by S Liu and by the data provider. Trajectories are initialised every 2 degrees longitude and latitude between 30 N - 30 S on a surface above the tropical tropopause layer (83 hPa surface for ERA-I and 400K potential temperature surface for UM-UKCA). Alternative temperature sampling was also calculated using OFFLINE. Lagrangian Dry Points were calculated using python processing scripts by the data provider. Data has been converted to CF-netCDF using python processing scripts by the data provider, and then passed on to the Centre for Environmental Data Analysis (CEDA).

Metadata

File identifier: c6b2f1ca5f8e4c5285fb4f69d1514a03 XML

Metadata language: English

Character set: UTF8

Hierarchy level: Dataset

Date stamp: 2026-02-08T03:22:46

Metadata standard name: UK GEMINI

Metadata standard version: 2.3

Metadata author

Organisation name	Individual name	Electronic mail address	Role
Centre for Environmental Data Analysis (CEDA)		support@ceda.ac.uk	Point of contact

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