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Comparison between two statistical downscaling methods for summer daily rainfall in Chongqing, China

Fan, Lijun; Yan, Z.; Chen, Deliang and Fu, C. (2014) In International Journal of Climatology Epub ahead of print.
Abstract
Two circulation index-based methods were applied to downscale summer daily rainfall at four meteorological stations in Chongqing, China. One is a regression method (CIM) and the other a hybrid circulation classification plus regression method (CPM). Both methods used the same three circulation indices and surface specific humidity as predictors. In the first method (CIM), the indices and humidity were used directly as predictors and only one model was developed at each station. In the second method (CPM), the indices were further used to define circulation patterns using the objective Lamb-Jenkinson classification scheme, and one model was built using humidity as the sole predictor for each pattern. Logistic regression was used to define... (More)
Two circulation index-based methods were applied to downscale summer daily rainfall at four meteorological stations in Chongqing, China. One is a regression method (CIM) and the other a hybrid circulation classification plus regression method (CPM). Both methods used the same three circulation indices and surface specific humidity as predictors. In the first method (CIM), the indices and humidity were used directly as predictors and only one model was developed at each station. In the second method (CPM), the indices were further used to define circulation patterns using the objective Lamb-Jenkinson classification scheme, and one model was built using humidity as the sole predictor for each pattern. Logistic regression was used to define rainfall probability, and a gamma distribution was fit using observations to randomly generate daily rainfall amounts. The two downscaling methods were validated and compared. The results suggest that (1) both methods yield consistently reasonable results with respect to occurrence and amount of daily rainfall, although they perform poorly in reproducing interannual and interdecadal variability, (2) specific humidity should be used as a predictor. Both methods were forced by two future scenarios of a global climate model (GCM) to demonstrate the added value with two methods. The downscaled scenarios show a shift towards larger rainfall values, accompanied by more frequent dry days. This shift is mainly attributed to a change in specific humidity. Despite the similar performances of the two methods, CPM gives a higher frequency of dry days than CIM, whereas CIM produces stronger intensity of rainfall than CPM. This provides additional information about the uncertainty in the projections. (Less)
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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
statistical downscaling, circulation patterns, circulation indices, daily rainfall, Chongqing, China
in
International Journal of Climatology
volume
Epub ahead of print
publisher
John Wiley & Sons
external identifiers
  • scopus:84945315383
ISSN
1097-0088
DOI
10.1002/joc.4246
project
MERGE
language
English
LU publication?
no
id
d465a6ba-fc7e-4bca-9c26-dcc9be1738e0 (old id 7515360)
date added to LUP
2015-07-08 14:56:01
date last changed
2017-09-10 04:47:37
@article{d465a6ba-fc7e-4bca-9c26-dcc9be1738e0,
  abstract     = {Two circulation index-based methods were applied to downscale summer daily rainfall at four meteorological stations in Chongqing, China. One is a regression method (CIM) and the other a hybrid circulation classification plus regression method (CPM). Both methods used the same three circulation indices and surface specific humidity as predictors. In the first method (CIM), the indices and humidity were used directly as predictors and only one model was developed at each station. In the second method (CPM), the indices were further used to define circulation patterns using the objective Lamb-Jenkinson classification scheme, and one model was built using humidity as the sole predictor for each pattern. Logistic regression was used to define rainfall probability, and a gamma distribution was fit using observations to randomly generate daily rainfall amounts. The two downscaling methods were validated and compared. The results suggest that (1) both methods yield consistently reasonable results with respect to occurrence and amount of daily rainfall, although they perform poorly in reproducing interannual and interdecadal variability, (2) specific humidity should be used as a predictor. Both methods were forced by two future scenarios of a global climate model (GCM) to demonstrate the added value with two methods. The downscaled scenarios show a shift towards larger rainfall values, accompanied by more frequent dry days. This shift is mainly attributed to a change in specific humidity. Despite the similar performances of the two methods, CPM gives a higher frequency of dry days than CIM, whereas CIM produces stronger intensity of rainfall than CPM. This provides additional information about the uncertainty in the projections.},
  author       = {Fan, Lijun and Yan, Z. and Chen, Deliang and Fu, C.},
  issn         = {1097-0088},
  keyword      = {statistical downscaling,circulation patterns,circulation indices,daily rainfall,Chongqing,China},
  language     = {eng},
  publisher    = {John Wiley & Sons},
  series       = {International Journal of Climatology},
  title        = {Comparison between two statistical downscaling methods for summer daily rainfall in Chongqing, China},
  url          = {http://dx.doi.org/10.1002/joc.4246},
  volume       = {Epub ahead of print},
  year         = {2014},
}