# Evaluating Uncertainties in Marine Biogeochemical Models: Benchmarking Aerosol Precursors
## 2 Methods  
Sea-air ventilation and the vertical transfer of trace greenhouse gases or marine aerosol precursors are closely associated with the dynamics of marine food webs, along with shifts in regional ecosystems [4; 53; 54; 55; 56]. Thus, any shift in nutrient availability within the euphotic layer--coupled to changes in ambient conditions that could influence biomass production in a less direct manner--can affect gas or aerosol loadings in the lower troposphere. The core of our effort is thus focused necessarily upon the uppermost, sunlit layers of the ocean. However, remineralization injects inorganics into the water column at depth, and the associated recycling patterns reflect central ocean distributions, so that the sectional analysis approaches cannot be ignored. Our International Ocean Model Benchmarking (IOMB) package constitutes open source software built on the Python programming language, and it is both currently and continually under development to benchmark the most relevant marine biogeochemical variables and processes. Our strategy is to aid in investigating the numerous, complex ocean biogeochemical feedbacks of the Earth system residing within the international suite of climate models. In some cases, we anticipate that large sections of important biogeochemical interactions will be entirely missing from computational representations. This is the essence of structural uncertainty, and it is part of our responsibility to identify such omissions. The goal is most easily accomplished by cross-comparing biogeochemical capabilities among modeling groups, and this will be a key component of the project. The essential goal of our effort is to constrain future model developments by bringing available observational datasets to bear. Detailed documentation and a tutorial regarding the most recently released version 2.2 of the ILAMB/IOMB package are now readily available to the potential user from [PERSON] et al. [57]. The two tools can be downloaded and installed simultaneously. This marine biogeochemistry validation package contains metrics that we continue to adapt to satisfy diagnostic and benchmarking needs for almost all of the simulation scientists who are currently engaged in the study of ocean processes within ESMs. For example, tools at the user's disposal for comparison include simple regional and global distribution maps for either model output or data, then, differencing capabilities, and also Taylor diagrams. Mapping can be focused on a particular region such as the Arctic or Southern Ocean. This feature should prove especially useful in the current era of rapid polar environmental change [58]. Plots can be extended downward in semi-arbitrary sections anywhere on the planet. The freedom to use spatial and temporal coverage of choice is accommodated in the system, with the intent to give users some level of flexibility when working with regional and global models. The only requirement is that input files are compliant with standard climate and forecast (CF) specifications ([[http://cfconventions.org/](http://cfconventions.org/)]([http://cfconventions.org/](http://cfconventions.org/))). At this point, IOMB works best with monthly mean files. Data on other temporal scales will have to be preprocessed to comply with this mode of comparison. The package calculates a one-dimensional variable score for each quantity with respect to a range of independent benchmark data. The overall variable score (S), which is generated from an arbitrary combination of the relative error (\(\epsilon\)) in bias, rootmeansquare error (RMSE), and spatial distribution, is scaled from zero to unity. Zero errors are mapped to a score of one, and the score reduces as the error grows, but it never reaches exactly zero. This ranking system gives a high level pictorial representation of how well a model represents the particular variable of interest within a given time frame.