kimmo_ruosteenoja@fmi_fi
New Member
Dear colleagues
Within this inquiry, we would like to obtain information about the
processing of near-surface relative humidity (variable "hurs" in the
monthly and "rhs" in the daily CMIP5 output) in the CCSM4, CESM1-CAM5
and CESM1-BGC models.
In our study we have explored the existence of supersaturation (hurs >
100 %) in the published output files of 29 CMIP5 climate models. In
the majority of the models (17 out of 29), supersaturated states
occur, mainly at high latitudes in winter. Fortunately, it is likely
that this is basically a diagnostic problem that does not degrade
other aspects of the model output, e.g., temperature and precipitation
simulations.
All three models belong to the 17 models in which supersaturations
occur. The problem is only moderate in CCSM4 and CESM1-BGC but quite
severe in CESM1-CAM5.
Our manuscript dealing with the supersaturation issue has been
submitted to Journal of Geophysical Research and is under revision
now. A central review comment was that we should consult the
modelling groups to learn their insight on why the supersaturations
occur. Accordingly, we would greatly appreciate if you would have
time to respond to the following questions:
(1) Are you already aware of the occurrence of the near-surface
supersaturations in the output of your models?
(2) Can you suggest any explanation for how the supersaturations have
arisen?
(3) Could you briefly explain how near-surface RH (variable "hurs"/"rhs")
has been calculated in your models? Is it a prognostic model variable
or only determined diagnostically in the post-processing phase? How
does the algorithm creating the hurs data function?
Even partial responses may help us.
Sincerely
Kimmo Ruosteenoja
Finnish Meteorological Institute
Co-authors: Kirsti Jylhä, Jouni Räisänen and Antti Mäkelä
PS: Further information will be given by request. Please contact
kimmo.ruosteenoja@fmi.fi.
Within this inquiry, we would like to obtain information about the
processing of near-surface relative humidity (variable "hurs" in the
monthly and "rhs" in the daily CMIP5 output) in the CCSM4, CESM1-CAM5
and CESM1-BGC models.
In our study we have explored the existence of supersaturation (hurs >
100 %) in the published output files of 29 CMIP5 climate models. In
the majority of the models (17 out of 29), supersaturated states
occur, mainly at high latitudes in winter. Fortunately, it is likely
that this is basically a diagnostic problem that does not degrade
other aspects of the model output, e.g., temperature and precipitation
simulations.
All three models belong to the 17 models in which supersaturations
occur. The problem is only moderate in CCSM4 and CESM1-BGC but quite
severe in CESM1-CAM5.
Our manuscript dealing with the supersaturation issue has been
submitted to Journal of Geophysical Research and is under revision
now. A central review comment was that we should consult the
modelling groups to learn their insight on why the supersaturations
occur. Accordingly, we would greatly appreciate if you would have
time to respond to the following questions:
(1) Are you already aware of the occurrence of the near-surface
supersaturations in the output of your models?
(2) Can you suggest any explanation for how the supersaturations have
arisen?
(3) Could you briefly explain how near-surface RH (variable "hurs"/"rhs")
has been calculated in your models? Is it a prognostic model variable
or only determined diagnostically in the post-processing phase? How
does the algorithm creating the hurs data function?
Even partial responses may help us.
Sincerely
Kimmo Ruosteenoja
Finnish Meteorological Institute
Co-authors: Kirsti Jylhä, Jouni Räisänen and Antti Mäkelä
PS: Further information will be given by request. Please contact
kimmo.ruosteenoja@fmi.fi.