Journal cover Journal topic
Earth System Dynamics An interactive open-access journal of the European Geosciences Union

Journal metrics

  • IF value: 3.635 IF 3.635
  • IF 5-year<br/> value: 3.869 IF 5-year
    3.869
  • CiteScore<br/> value: 4.15 CiteScore
    4.15
  • SNIP value: 0.995 SNIP 0.995
  • SJR value: 2.742 SJR 2.742
  • IPP value: 3.679 IPP 3.679
  • h5-index value: 21 h5-index 21
https://doi.org/10.5194/esd-2017-9
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
01 Feb 2017
Review status
A revision of this discussion paper is under review for the journal Earth System Dynamics (ESD).
Comparison of land–surface humidity between observations and CMIP5 models
Robert J. H. Dunn, Kate M. Willett, Andrew Ciavarella, and Peter A. Stott Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB, UK
Abstract. We compare the latest observational land-surface humidity dataset, HadISDH, with the latest generation of climate models extracted from the CMIP5 archive and the ERA-Interim reanalysis over the period 1973 to present. The globally averaged behaviour of HadISDH and ERA-Interim are very similar in both humidity measures and air temperature, at decadal and interannual timescales.

The global average relative humidity shows a gradual increase from 1973 to 2000, followed by a steep decline in recent years. The observed specific humidity shows a steady increase in the global average during the early period but in the later period it remains approximately constant. None of the CMIP5 models or experiments capture the observed behaviour of the relative or specific humidity over the entire study period. When using an atmosphere-only model, driven by observed sea-surface temperatures and radiative forcing changes, the behaviour of regional average temperature and specific humidity are better captured, but there is little improvement in the relative humidity.

Comparing the observed and historical model climatologies show that the models are generally cooler everywhere, are drier and less saturated in the tropics and extra tropics, and have comparable moisture levels but are more saturated in the high latitudes. The spatial pattern of linear trends are relatively similar between the models and HadISDH for temperature and specific humidity, but there are large differences for relative humidity, with less moistening shown in the models over the Tropics, and very little at high latitudes. The observed drying in mid-latitudes is present at a much lower magnitudes. Relationships between temperature and humidity anomalies (Tq and Trh) show good agreement for specific humidity between models and observations, and between the models themselves, but much poorer for relative humidity. The Tq correlation from the models is more steeply positive in all regions than the observations, and this over-correlation may be due to missing processes in the models.

The observed temporal behaviour appears to be a robust climate feature rather than observational error. It has been previously documented and is theoretically consistent with faster warming rates over land compared to oceans. Thus, the poor replication in the models, especially in the atmosphere only model, leads to questions over future projections of impacts related to changes in surface relative humidity. It also precludes any formal detection and attribution assessment.


Citation: Dunn, R. J. H., Willett, K. M., Ciavarella, A., and Stott, P. A.: Comparison of land–surface humidity between observations and CMIP5 models, Earth Syst. Dynam. Discuss., https://doi.org/10.5194/esd-2017-9, in review, 2017.
Robert J. H. Dunn et al.
Robert J. H. Dunn et al.
Robert J. H. Dunn et al.

Viewed

Total article views: 516 (including HTML, PDF, and XML)

HTML PDF XML Total Supplement BibTeX EndNote
290 198 28 516 12 4 27

Views and downloads (calculated since 01 Feb 2017)

Cumulative views and downloads (calculated since 01 Feb 2017)

Viewed (geographical distribution)

Total article views: 516 (including HTML, PDF, and XML)

Thereof 514 with geography defined and 2 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 24 Jun 2017
Publications Copernicus
Download
Short summary
We compare the latest observations of relative and specific humidity with those from climate models. The climate models do not accurately reproduce the observed humidity behaviour for the last 15–20 years. We use the temporal, spatial and trend information to contrast the patterns exhibited by the observations and models. The temporal behaviour of the observations has previously been documented, and is consistent with faster warming rates over land compared to oceans.
We compare the latest observations of relative and specific humidity with those from climate...
Share