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Regional Model Simulations of the South-Asian Summer Monsoon
Reference
Syed, F.S., Iqbal, W., Syed, A.A.B. and Rasul, G. 2014. Uncertainties in the regional climate models simulations of South-Asian summer monsoon and climate change. Climate Dynamics 42: 2079-2097.

Background
The authors write that "South-Asian summer monsoon (SASM) rainfall is the backbone of the agriculture-based economies of the region," noting that it directly affects the livelihood of more than one billion people. Hence, they say it is important to be able to project how the SASM may respond to anthropogenic-induced climate change. However, they note that "climate models generally have difficulties in reproducing both the position and variation of the monsoon rain bands of the SASM, because of their inability to resolve the monsoon convective processes and the complex regional heterogeneity," citing Sabin (2013).

What was done
In further exploring this issue, Syed et al. assessed a number of uncertainties in regional climate models (RCMs) by analyzing the driving global data of ERA40 reanalysis and the output of ECHAM5 general circulation models in conjunction with the downscaled output of two RCMs (RegCM4 and PRECIS) over South-Asia for present-day simulations (1971-2000) of the SASM.

What was learned
The four Pakistani scientists determined that (1) "the RCMs have systematic biases" that (2) "seem to come from the physics parameterization of the RCMs," and that as a result, (3) "the RCMs are not able to capture the inter-annual variability," that (4) "RegCM4 has a cold bias over the whole domain," that (5) "this cold bias is more than 5°C over the high mountains in the north of Pakistan and India," that (6) "PRECIS has a warm bias of more than 2°C over the central parts of Pakistan," but that (7) "the cold bias over the northern high mountains is similar to that of RegCM4,"that (8) "the RegCM4 has a dry bias over central India," that (9) its penetration "into Pakistan is not very well simulated," that (10) "both the RCMs have poorly captured the inter-annual variability" of both temperature and rainfall, that (11) "both the RCMs show very low values of correlations, <0.5 over most of the selected regions," such that (12) "both the RCMs have systematic biases in simulating the SASM."

What it means
In light of their several findings, Syed et al. conclude that "further research is required to further understand the uncertainties in the RCMs and the driving GCMs." So in answer to the eternal child-to-parent question - Are we there yet? - we would have to answer with a resounding NO!

Reference
Sabin, T.P., Krishnan, R., Ghattas, J., Denvil, S., Dufresne, J.-L., Hourdin, F. and Pascal, T. 2013. High resolution simulation of the South Asian monsoon using a variable resolution global climate model. Climate Dynamics: 10.1007/s00382-012-1658-8.

Reviewed 9 July 2014