to be written in plain language, avoiding atmospheric-science jargon as much as possible. In the synthesis of key issues, the objectives of the assessment and its limitations and assumptions need to be clearly described. The committee recommends that the charge, goals and specific objectives, and assumptions set forth by NARSTO for the assessment (see Box 1–1) be included in their entirety in the synthesis. At present, that information appears nowhere in the document. Without such material, the reader is uncertain why this assessment was written and what its intended audience is.
Of particular importance is an explicit definition of the “PM problem” in the context of NARSTO’s first assumption for the assessment (see Box 3–1 in the present report). At no point in the current executive summary is it clearly and explicitly stated how the PM problem is defined. When the committee queried the assessment cochairs, they indicated that they considered the PM problem to be exceedance of existing or proposed mass-based standards. The committee appreciates why the authors focused on providing scientific and technical guidance toward meeting the standards, but this substantial limitation of the scope needs to be made clear.
In addition to clearly stating the objectives of the assessment, the synthesis of key issues should provide a crosswalk between the objectives and the main body of the assessment. One way to accomplish that would be to align the discussion in the synthesis with the objectives. The committee has developed an outline that shows how this could be done (see Box 3–1). According to the suggested outline, the synthesis of key issues would begin with a discussion of why the assessment was written and a presentation of the charge, goal, objectives, and assumptions that guided and limited the preparation of the document. The second section of the synthesis would explain the PM problem in terms of a framework for informing airborne-PM management, thereby addressing NARSTO objectives 2 and 3. As discussed in more detail previously (in Chapter 2 of this report), the framework should enable a reader to understand what PM is, how the various processes that influence it interact, and what is involved in assessing and managing the PM problem. The third section would describe how the task was approached, with a focus on explaining the interactions with the policy community, which is NARSTO objective 1. The fourth section would step through the eight PQs, providing answers that would be useful to research managers (NARSTO objective 4) and linking the answers to specific atmospheric-science research accomplishments and needs (NARSTO objective 5). The last section of the synthesis would address NARSTO objective 6 by providing a context for researchers in related fields.
The committee commends NARSTO for taking the time to query decision-makers about their scientific and technical needs. Efforts to identify what information would be useful to the intended audience before writing a scientific assessment of this sort are rare. A document providing the information that decision-makers expressly request is certainly valuable, and presenting this information as responses to specific PQs is a useful format.