Surface air relative humidities spuriously exceeding 100% in CMIP5 model output and their impact on future projections

Show simple item record Ruosteenoja, Kimmo Jylha, Kirsti Räisänen, Jouni Mäkelä, Antti 2019-12-12T10:42:04Z 2019-12-12T10:42:04Z 2017-09-27
dc.identifier.citation Ruosteenoja , K , Jylha , K , Räisänen , J & Mäkelä , A 2017 , ' Surface air relative humidities spuriously exceeding 100% in CMIP5 model output and their impact on future projections ' , Journal of Geophysical Research : Atmospheres , vol. 122 , no. 18 , pp. 9557-9568 .
dc.identifier.other PURE: 95493503
dc.identifier.other PURE UUID: 39bf03aa-5d03-410b-8245-2f39ebe2b03c
dc.identifier.other WOS: 000416388000001
dc.identifier.other Scopus: 85031105270
dc.identifier.other ORCID: /0000-0003-3657-1588/work/39925472
dc.description.abstract In 17 out of the 29 Phase 5 of Coupled Model Intercomparison Project (CMIP5) climate models examined in this work, near-surface air relative humidity (RH) frequently exceeded 100% with respect to ice in polar areas in winter. The degree of supersaturation varied considerably across the models, and the same evidently applies to the causes of the phenomenon. Consultations with the modeling groups revealed three categories of explanations for supersaturation occurrence: specification of RH with respect to ice rather than liquid water; inconsistencies in the determination of specific humidity and air temperature for the near-surface level; and the nonlinearity of saturated specific humidity as a function of temperature. Modeled global warming tended to reduce the artificial supersaturations, inducing a spurious negative trend in the future RH change. For example, over East Antarctica under Representative Concentration Pathway 8.5, the multimodel mean RH would decrease by about 10% by the end of the ongoing century. Truncation of overly high RHs to a maximum value of 100% cut the RH response close to zero. In Siberia and northern North America, truncation even reversed the sign of the response. The institutes responsible for the CMIP6 model experiments should be aware of the supersaturation issue, and the algorithms used to produce near-surface RH should be developed to eliminate the problem before publishing the RH output data. Plain Language Summary In the atmosphere, observed relative humidity is between 0% and 100%. However, some climate models produce spurious higher than 100% humidities. The problem only concerns polar areas in winter. As temperatures rise in the future, such model-produced excessively high relative humidities partially vanish. Unfortunately, this induces a spurious negative trend in the future humidity projections. Such a spurious component in the simulated trend complicates discerning the real physically based trend. The spurious trend could be eliminated by truncating the portion of relative humidity that exceeds 100% in the model output data. Even so, this may not be fully adequate for elaborating reliable humidity projections for polar areas. Therefore, it is highly desirable that the relative humidity calculations in the climate models would be developed so that unrealistic relative humidities would not occur in future model generations. We emphasize that this issue only concerns humidity projections and does not affect model-based predictions of temperature and precipitation change. en
dc.format.extent 12
dc.language.iso eng
dc.relation.ispartof Journal of Geophysical Research : Atmospheres
dc.rights cc_by_nc_sa
dc.rights.uri info:eu-repo/semantics/openAccess
dc.subject ANTARCTICA
dc.subject LAND
dc.subject RISK
dc.subject ICE
dc.subject 114 Physical sciences
dc.title Surface air relative humidities spuriously exceeding 100% in CMIP5 model output and their impact on future projections en
dc.type Article
dc.contributor.organization Department of Physics
dc.description.reviewstatus Peer reviewed
dc.relation.issn 2169-897X
dc.rights.accesslevel openAccess
dc.type.version publishedVersion

Files in this item

Total number of downloads: Loading...

Files Size Format View
Ruosteenoja_et_ ... l_Research_Atmospheres.pdf 4.487Mb PDF View/Open

This item appears in the following Collection(s)

Show simple item record