Mooney, P.A. and Mulligan, F.J. and Broderick, Ciaran
(2016)
Diurnal cycle of precipitation over the British Isles in a 0.44°
WRF multiphysics regional climate ensemble over the period
1990–1995.
Climate Dynamics.
ISSN 1432-0894
Abstract
The diurnal cycle of precipitation is an important
and fundamental cycle in Earth’s climate system, yet
many aspects of this cycle remain poorly understood. As
a result climate models have struggled to accurately simulate
the timing of the peak and the amplitude of the cycle.
This has led to a large number of modelling studies on the
diurnal cycle of precipitation which have focussed mainly
on the influence of grid spacing and/or convective parameterizations.
Results from these investigations have shown
that, while grid spacing and convective parameterizations
are important factors in the diurnal cycle, it cannot be fully
explained by these factors and it must also be subject to
other factors. In this study, we use the weather research and
forecasting (WRF) model to investigate four of these other
factors, namely the land surface model (LSM), microphysics,
longwave radiation and planetary boundary layer in
the case of the diurnal cycle of precipitation over the British
Isles. We also compare their impact with the effect of
two different convective schemes. We find that all simulations
have two main problems: (1) there is a large bias (too
much precipitation) in both summer and winter (+19 and
+38 % respectively for the ensemble averages), and (2)
WRF summer precipitation is dominated by a diurnal (24-h)
component (~28 % of the mean precipitation) whereas the
observations show a predominantly semidiurnal (12-h)
component with a much smaller amplitude (~10 % of mean
precipitation). The choice of LSM has a large influence on
the simulated diurnal cycle in summer with the remaining
physics schemes showing very little effect. The magnitude
of the LSM effect in summer is as large as 35 % on average
and up to 50 % at the peak of the cycle. While neither of the
two LSMs examined here capture the harmonic content of
the diurnal cycle of precipitation very well, we find that use
of the RUC LSM results in better agreement with the observations
compared with Noah.
| Item Type: |
Article
|
| Keywords: |
Physics parameterizations; Regional climate model; Diurnal cycle of precipitation; Temperate maritime climate; British Isles; Weather research and forecasting;
model |
| Academic Unit: |
Faculty of Science and Engineering > Experimental Physics |
| Item ID: |
6999 |
| Identification Number: |
https://doi.org/10.1007/s00382-016-3026-6 |
| Depositing User: |
Dr. Frank Mulligan
|
| Date Deposited: |
02 Mar 2016 09:30 |
| Journal or Publication Title: |
Climate Dynamics |
| Publisher: |
Springer Verlag |
| Refereed: |
Yes |
| URI: |
|
| Use Licence: |
This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available
here |
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