Hello, A change in allocation has been requested: Requester: jkim (Jong Kim) Project: POPAD Title: Adjoint Development of POP Ocean Model for Climate Modeling Applications Description: In realizing the importance of the meridional overturning circulation (MOC) to the global climate variations, an essential element is to fully understand the MOC sensitivity to various forcing variables and modeling parameters. However, there are significant uncertainties in the model configurations such as mixing parameter values and initial and boundary conditions. More systematic computational tools are desirable for robust and efficient modeling experiments. Unfortunately, the computational costs to run large-scale sensitivity studies with conventional approaches such as ensemble approaches or perturbed numerical difference are prohibitively high. As an alternative to the conventional approaches, automatic differentiation (AD) has been applied to enhance the POP ocean model with the derivative computations of the TLM/ADM methods. In the previous year, major source codes of the AD-based POP TLM/ADM methods were successfully implemented and optimized for shor t runs of a low resolution model. We plan to continue further applications of the new codes for the sensitivity studies of POP modeling variables with regard to global ocean circulations. In FY2013, the experiments for longer run simulations of the POP ocean models will be mainly performed with 1 degree resolution for the MPI-based parallel run test. It requires to run various types of the CCSM coupled and TLM/ADM simulations. Generally, the multi-decadal integrations of a coupled CCSM system for low resolution problems require a single computational time on the 8 cores of the fusion. The POP TLM/ADM runs take about 10 times of the computational cost compared to the forward POP integrations. Mainly written in Fortran 90, each of modeling component of the CCSM modeling system requires a C compiler and the MPI library to run with a link with Perl script. Current: undetermined amount Justification: Requested: 80000 A specific reason has been given: Current account for POPAD project has a negative allocation balance. There are still a couple months left for the fiscal year of the project and more development test of the POP adjoint code is needed to be exercised. This needs to be approved and the final allocation amount decided upon. Thank You, The LCRC Accounts System