Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperature
A Climate Pattern-Scaling Model (CPSM) that simulates global patterns of climate change, for a prescribed emissions scenario, is described. A CPSM works by quantitatively establishing the statistical relationship between a climate variable at a specific location (e.g. daily maximum surface temperatu...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2014-01-01
|
| Series: | Geoscientific Model Development |
| Online Access: | http://www.geosci-model-dev.net/7/249/2014/gmd-7-249-2014.pdf |
| _version_ | 1818265963399741440 |
|---|---|
| author | S. Kremser G. E. Bodeker J. Lewis |
| author_facet | S. Kremser G. E. Bodeker J. Lewis |
| author_sort | S. Kremser |
| collection | DOAJ |
| description | A Climate Pattern-Scaling Model (CPSM) that simulates global patterns of
climate change, for a prescribed emissions scenario, is described. A CPSM
works by quantitatively establishing the statistical relationship between a
climate variable at a specific location (e.g. daily maximum surface
temperature, <i>T</i><sub>max</sub>) and one or more predictor time series (e.g. global
mean surface temperature, <i>T</i><sub>global</sub>) – referred to as the
"training" of the CPSM. This training uses a regression model to derive fit
coefficients that describe the statistical relationship between the predictor
time series and the target climate variable time series. Once that
relationship has been determined, and given the predictor time series for any
greenhouse gas (GHG) emissions scenario, the change in the climate variable
of interest can be reconstructed – referred to as the "application" of the
CPSM. The advantage of using a CPSM rather than a typical atmosphere–ocean
global climate model (AOGCM) is that the predictor time series required by
the CPSM can usually be generated quickly using a simple climate model (SCM)
for any prescribed GHG emissions scenario and then applied to generate global
fields of the climate variable of interest. The training can be performed
either on historical measurements or on output from an AOGCM. Using model
output from 21st century simulations has the advantage that the climate
change signal is more pronounced than in historical data and therefore a more
robust statistical relationship is obtained. The disadvantage of using AOGCM
output is that the CPSM training might be compromised by any AOGCM
inadequacies. For the purposes of exploring the various methodological
aspects of the CPSM approach, AOGCM output was used in this study to train
the CPSM. These investigations of the CPSM methodology focus on monthly mean
fields of daily temperature extremes (<i>T</i><sub>max</sub> and <i>T</i><sub>min</sub>). The
methodological aspects of the CPSM explored in this study include
(1) investigation of the advantage gained in having five predictor time
series over having only one predictor time series, (2) investigation of the
time dependence of the fit coefficients and (3) investigation of the
dependence of the fit coefficients on GHG emissions scenario. Key conclusions
are (1) overall, the CPSM trained on simulations based on the Representative
Concentration Pathway (RCP) 8.5 emissions scenario is able to reproduce AOGCM
simulations of <i>T</i><sub>max</sub> and <i>T</i><sub>min</sub> based on predictor time series from
an RCP 4.5 emissions scenario; (2) access to hemisphere average land and
ocean temperatures as predictors improves the variance that can be explained,
particularly over the oceans; (3) regression model fit coefficients derived
from individual simulations based on the RCP 2.6, 4.5 and 8.5 emissions
scenarios agree well over most regions of the globe (the Arctic is the
exception); (4) training the CPSM on concatenated time series from an
ensemble of simulations does not result in fit coefficients that explain
significantly more of the variance than an approach that weights results
based on single simulation fits; and (5) the inclusion of a linear time
dependence in the regression model fit coefficients improves the variance
explained, primarily over the oceans. |
| first_indexed | 2024-12-12T19:59:09Z |
| format | Article |
| id | doaj.art-71767091b76444a28ff918cd2c02452a |
| institution | Directory Open Access Journal |
| issn | 1991-959X 1991-9603 |
| language | English |
| last_indexed | 2024-12-12T19:59:09Z |
| publishDate | 2014-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj.art-71767091b76444a28ff918cd2c02452a2022-12-22T00:13:48ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032014-01-017124926610.5194/gmd-7-249-2014Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperatureS. Kremser0G. E. Bodeker1J. Lewis2Bodeker Scientific, Alexandra, New ZealandBodeker Scientific, Alexandra, New ZealandBodeker Scientific, Alexandra, New ZealandA Climate Pattern-Scaling Model (CPSM) that simulates global patterns of climate change, for a prescribed emissions scenario, is described. A CPSM works by quantitatively establishing the statistical relationship between a climate variable at a specific location (e.g. daily maximum surface temperature, <i>T</i><sub>max</sub>) and one or more predictor time series (e.g. global mean surface temperature, <i>T</i><sub>global</sub>) – referred to as the "training" of the CPSM. This training uses a regression model to derive fit coefficients that describe the statistical relationship between the predictor time series and the target climate variable time series. Once that relationship has been determined, and given the predictor time series for any greenhouse gas (GHG) emissions scenario, the change in the climate variable of interest can be reconstructed – referred to as the "application" of the CPSM. The advantage of using a CPSM rather than a typical atmosphere–ocean global climate model (AOGCM) is that the predictor time series required by the CPSM can usually be generated quickly using a simple climate model (SCM) for any prescribed GHG emissions scenario and then applied to generate global fields of the climate variable of interest. The training can be performed either on historical measurements or on output from an AOGCM. Using model output from 21st century simulations has the advantage that the climate change signal is more pronounced than in historical data and therefore a more robust statistical relationship is obtained. The disadvantage of using AOGCM output is that the CPSM training might be compromised by any AOGCM inadequacies. For the purposes of exploring the various methodological aspects of the CPSM approach, AOGCM output was used in this study to train the CPSM. These investigations of the CPSM methodology focus on monthly mean fields of daily temperature extremes (<i>T</i><sub>max</sub> and <i>T</i><sub>min</sub>). The methodological aspects of the CPSM explored in this study include (1) investigation of the advantage gained in having five predictor time series over having only one predictor time series, (2) investigation of the time dependence of the fit coefficients and (3) investigation of the dependence of the fit coefficients on GHG emissions scenario. Key conclusions are (1) overall, the CPSM trained on simulations based on the Representative Concentration Pathway (RCP) 8.5 emissions scenario is able to reproduce AOGCM simulations of <i>T</i><sub>max</sub> and <i>T</i><sub>min</sub> based on predictor time series from an RCP 4.5 emissions scenario; (2) access to hemisphere average land and ocean temperatures as predictors improves the variance that can be explained, particularly over the oceans; (3) regression model fit coefficients derived from individual simulations based on the RCP 2.6, 4.5 and 8.5 emissions scenarios agree well over most regions of the globe (the Arctic is the exception); (4) training the CPSM on concatenated time series from an ensemble of simulations does not result in fit coefficients that explain significantly more of the variance than an approach that weights results based on single simulation fits; and (5) the inclusion of a linear time dependence in the regression model fit coefficients improves the variance explained, primarily over the oceans.http://www.geosci-model-dev.net/7/249/2014/gmd-7-249-2014.pdf |
| spellingShingle | S. Kremser G. E. Bodeker J. Lewis Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperature Geoscientific Model Development |
| title | Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperature |
| title_full | Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperature |
| title_fullStr | Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperature |
| title_full_unstemmed | Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperature |
| title_short | Methodological aspects of a pattern-scaling approach to produce global fields of monthly means of daily maximum and minimum temperature |
| title_sort | methodological aspects of a pattern scaling approach to produce global fields of monthly means of daily maximum and minimum temperature |
| url | http://www.geosci-model-dev.net/7/249/2014/gmd-7-249-2014.pdf |
| work_keys_str_mv | AT skremser methodologicalaspectsofapatternscalingapproachtoproduceglobalfieldsofmonthlymeansofdailymaximumandminimumtemperature AT gebodeker methodologicalaspectsofapatternscalingapproachtoproduceglobalfieldsofmonthlymeansofdailymaximumandminimumtemperature AT jlewis methodologicalaspectsofapatternscalingapproachtoproduceglobalfieldsofmonthlymeansofdailymaximumandminimumtemperature |