CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Seasonality and variability of stratospheric water vapour
Stockholm University, Faculty of Science, Department of Meteorology .ORCID iD: 0000-0002-2557-8541
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Stratospheric water vapour (SWV) plays a critical role in the climate system by modulating the radiation budget and influencing the stratospheric chemistry. Studying changes of SWV on global scale is helpful for our understanding of climate change. This thesis aims to gain an improved understanding of the stratospheric processes and dynamic mechanisms that determine the seasonality and variability of SWV. 

Water vapour is characterized by its compound, which leaves an isotopic fingerprint in relevant atmospheric and hydrologic processes. The thesis starts with analyzing the global features of three stable water isotopes (SWIs) in the stratosphere by using satellite retrievals from Odin/SMR. The spatial pattern of SWI indicates clear effects of methane oxidation in the upper stratosphere, dehydration at the tropopause and stratospheric transport via the Brewer-Dobson circulation (BDC). In addition to the tropical tape recorder in the lower stratosphere, a pronounced downward propagation of the seasonal signal from the upper to the lower stratosphere is observed in high-latitudes. These observed features are further compared to model outputs to identify possible causes of model deficiencies in reproducing the distribution of SWV.

The downward propagation signal of zonal wind has been demonstrated in the high-latitude stratosphere in spring seasonal transition in the Southern Hemisphere, but not in the Northern Hemisphere. This inter-hemispheric difference is due to the stronger stratospheric planetary wave activity in austral spring than in boreal spring. With strong wave activity in spring, the transition is inclined to occur first at the stratopause followed by a downward propagation to the lower stratosphere. In particular, the stronger the upward propagation of planetary waves in high-latitudes in spring the earlier the stratospheric seasonal transition. 

The new generation reanalysis ERA5 represents climatological distribution and seasonal cycle of SWV better than its predecessor ERA-Interim by assimilating more satellite observations. The variability of SWV in ERA5 is highly consistent with SDI MIM observation. The interannual variability of water vapour in the lower stratosphere is found to be closely linked to the tropical Quasi-Biennial Oscillation (QBO) and QBO-induced residual circulation. On decadal scale, the deficit of SWV in boreal winter is associated with a warm sea surface temperature (SST) anomaly in the North Atlantic, which leads to stronger upward propagation of planetary waves, resulting in a warmer pole in the lower stratosphere, colder tropical tropopause and stronger BDC, hence less water vapour enters the stratosphere through the tropopause and the anomaly extends to the entire stratosphere. 

Sensitivity experiments for a CO2 doubling scenario are performed with the model WACCM to investigate the SWV response to climate change. The response of SWV is dominated by the warm SST, which is induced by CO2 doubling in a coupled ocean-atmosphere system. The enhanced SST leads to a moist troposphere and warmer tropical and subtropical tropopause, resulting in more water vapour entering the stratosphere from below. A large increase of SWV in the lower stratosphere, in turn, affects stratospheric temperature. It results in a warming in the tropical and subtropical lower stratosphere, offsetting the cooling caused by CO2 doubling in general.

Place, publisher, year, edition, pages
Stockholm: Department of Meteorology, Stockholm University , 2019. , p. 32
Keywords [en]
stratospheric water vapour, seasonality, variability
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
URN: urn:nbn:se:su:diva-173284ISBN: 978-91-7797-853-4 (print)ISBN: 978-91-7797-854-1 (electronic)OAI: oai:DiVA.org:su-173284DiVA, id: diva2:1360305
Public defence
2019-11-29, Högbomsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2019-11-06 Created: 2019-10-11 Last updated: 2019-10-28Bibliographically approved
List of papers
1. Stable Water Isotopologues in the Stratosphere Retrieved from Odin/SMR Measurements
Open this publication in new window or tab >>Stable Water Isotopologues in the Stratosphere Retrieved from Odin/SMR Measurements
Show others...
2018 (English)In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 10, no 2, article id 166Article in journal (Refereed) Published
Abstract [en]

Stable Water Isotopologues (SWIs) are important diagnostic tracers for understanding processes in the atmosphere and the global hydrological cycle. Using eight years (2002-2009) of retrievals from Odin/SMR (Sub-Millimetre Radiometer), the global climatological features of three SWIs, (H2O)-O-16, HDO and (H2O)-O-18, the isotopic composition D and O-18 in the stratosphere are analysed for the first time. Spatially, SWIs are found to increase with altitude due to stratospheric methane oxidation. In the tropics, highly depleted SWIs in the lower stratosphere indicate the effect of dehydration when the air comes through the cold tropopause, while, at higher latitudes, more enriched SWIs in the upper stratosphere during summer are produced and transported to the other hemisphere via the Brewer-Dobson circulation. Furthermore, we found that more (H2O)-O-16 is produced over summer Northern Hemisphere and more HDO is produced over summer Southern Hemisphere. Temporally, a tape recorder in (H2O)-O-16 is observed in the lower tropical stratosphere, in addition to a pronounced downward propagating seasonal signal in SWIs from the upper to the lower stratosphere over the polar regions. These observed features in SWIs are further compared to SWI-enabled model outputs. This helped to identify possible causes of model deficiencies in reproducing main stratospheric features. For instance, choosing a better advection scheme and including methane oxidation process in a specific model immediately capture the main features of stratospheric water vapor. The representation of other features, such as the observed inter-hemispheric difference of isotopic component, is also discussed.

Keywords
stable water isotopologues, stratosphere, climatology, Odin, SMR satellite data
National Category
Earth and Related Environmental Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
urn:nbn:se:su:diva-156014 (URN)10.3390/rs10020166 (DOI)000427542100013 ()
Available from: 2018-05-08 Created: 2018-05-08 Last updated: 2019-12-09Bibliographically approved
2. On the dynamics of the spring seasonal transition in the two hemispheric high-latitude stratosphere
Open this publication in new window or tab >>On the dynamics of the spring seasonal transition in the two hemispheric high-latitude stratosphere
Show others...
2019 (English)In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 71, no 1, article id 1634949Article in journal (Refereed) Published
Abstract [en]

The seasonal transition is one of the main features of the atmospheric general circulation and is particularly manifest in the high-latitude stratosphere. To explore the dynamics of stratospheric seasonal transition in both hemispheres, the observational features of the annual cycle and seasonal transition in high-latitude stratosphere are investigated using the 38-year ERA-interim reanalysis. Climatological analysis shows that tropospheric planetary waves propagate to the stratosphere and affect significantly the winter-to-summer stratospheric seasonal transition over both hemispheres, but with a much stronger wave activity in austral spring than its boreal counterpart. The austral spring seasonal transition occurs first at the stratopause then propagates down to the lower stratosphere due to enhanced planetary wave breaking, weakening the westerlies. In boreal spring, the seasonal transition occurs simultaneously across the depth of the stratosphere, mainly due to the solar radiation and weaker planetary wave activity. Interannual variability analysis shows that the timing of stratospheric seasonal transition is closely linked to the intensity of upward propagation of planetary wave activity, i.e. the stronger the upward propagation of planetary wave activity in high-latitudes in spring the earlier the stratospheric seasonal transition. Transition indexes are defined and the probability distributions of the indexes show that there are two types of transition in both hemispheres: synchronous/asynchronous in the Northern Hemisphere (NH), and steep/moderate transitions in the Southern Hemisphere (SH). A composite analysis shows that before the transition, stronger wave activity leads to asynchronous rather than synchronous transition in the NH, which propagates downward from the stratopause. In the SH, a moderate rather than steep transition is obtained, which occurs earlier and takes longer to propagate from the upper to lower stratosphere.

Keywords
seasonal transition, stratosphere, planetary wave propagation
National Category
Earth and Related Environmental Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
urn:nbn:se:su:diva-171765 (URN)10.1080/16000870.2019.1634949 (DOI)000475356600001 ()
Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-12-09Bibliographically approved
3. Tropical water vapour in the lower stratosphere in ERA5 and its relationship to tropical/extra-tropical dynamic processes
Open this publication in new window or tab >>Tropical water vapour in the lower stratosphere in ERA5 and its relationship to tropical/extra-tropical dynamic processes
Show others...
(English)Manuscript (preprint) (Other academic)
Keywords
Stratospheric water vapour, ERA5, Planetary wave activity, Stratospheric dynamic processes
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
urn:nbn:se:su:diva-174799 (URN)
Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-12-09Bibliographically approved
4. Response of stratospheric water vapour to CO2 doubling in WACCM
Open this publication in new window or tab >>Response of stratospheric water vapour to CO2 doubling in WACCM
(English)Manuscript (preprint) (Other academic)
Keywords
Stratospheric water vapour, response, CO2 doubling
National Category
Meteorology and Atmospheric Sciences
Research subject
Atmospheric Sciences and Oceanography
Identifiers
urn:nbn:se:su:diva-174800 (URN)
Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-12-09Bibliographically approved

Open Access in DiVA

Seasonality and variability of stratospheric water vapour(5863 kB)25 downloads
File information
File name FULLTEXT01.pdfFile size 5863 kBChecksum SHA-512
6146dce530716762fc1de141d7cf89cb8bb03d7b96017a176c01c1e41326c03975fc28d2fd78a45c8f27b74b2b3d6111e6698d7cfc427174f748c922c11c649a
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Wang, Tongmei
By organisation
Department of Meteorology
Meteorology and Atmospheric Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 25 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 227 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf