Extreme temperatures detection and attribution related to external
forcing in Madagascar
Abstract
In this paper, we use standard extreme temperature indices to detect and
attribute external forcing in Madagascar. These indices are calculated
from observations and multi-model ensemble mean responses on
anthropogenic-plus-natural (ALL), greenhouse gases (GHG), natural (NAT)
and anthropogenic (ANT) which is subtracted from ALL and NAT forcings
over 1950-2018. Correlation analysis emphasizes that the observed
changes are more influenced by ENSO events especially in minimum
temperature. The observed changes are regressed or combined with model
simulations from sixth phase of the Coupled Model Inter-comparison
Project (CMIP6) to assess human impacts in indices. CMIP6 models with
ALL, GHG, ANT forcings correspond well with the observations for the
frequency indices that the intensity indices. Moreover, decadal trends
indicate the existence of anthropogenic warming according to
observations and multi-model ensembles with ALL, GHG, and ANT forcings.
Detection and attribution parties identify and justify the causes of the
observed changes. We do this by performing the single-signal and
two-signal analysis using the Regularized Optimal Fingerprinting (ROF)
method with Total Least Square (TLS) regression. We estimate internal
climate variability by means of control model simulations. As a result,
we note an inconsistency in the warming trend with the NAT forcing. The
influence of ALL, GHG and ANT forcings is detectable for standard
extreme temperature indices between 1950 and 2018. Nearly, observed
changes are attributed to GHG and ANT forcings except for coldest night
and warm nights in Madagascar.