Paragraph d states that when these advisories are in effect ATC will issue the latest braking action report to each arriving and departing aircraft, essentially giving pilots real-time NOTAM information.
When things get bad enough to halt operations, we go back to AC 150/5200-30C, Section 5-6: "A NIL pilot braking action report (PIREP), or NIL braking action assessment by the airport operator, requires that the runway be closed before the next flight operation.
Braking action reports extend not just to runways, but also to other movement areas, such as taxiways.
The most prominent reference most pilots use for information about braking action reports and runway friction is in AIM 4-3-8 "Braking Action Reports and Advisories" and 4-3-9 "Runway Friction Reports and Advisories."
AIM 4-3-8 gives us all the guidance we're going to get in an FAA pilot reference on braking action reports. The guidance begins "When available, ATC furnishes pilots the quality of braking action received from pilots or airport management," and restates the four qualitative descriptors, adding that a combination of terms can be used if necessary ("fair to poor," for example).
Paragraph b covers situations where numerous subjective reports may come in, and states that NOTAMs regarding braking action reports are published using the most critical--worst--condition reported.
Beyond braking action reports, runway friction reports quantify runway friction with values obtained from special ground-based measuring equipment.
The FAA is clear in treating friction readings and braking action reports as entirely separate and unrelated reports: "No correlation has been established between MU values and the descriptive terms 'good,' 'fair,' 'poor,' and 'nil' used in braking action reports."
Well, in this case, when the sun came up at this particular airport, the contamination would often sublimate, and braking action reports would come in noting the conditions improving as the sun angle grew.