2.5 Measurement versus Model Concentration Issues?
18.3 What Are the PM
Ambient measurements are needed to perform a model evaluation. Historically, ozone
model evaluations have used routinely measured ambient data (e.g. ozone) collected on a
continuous basis. The measurements tend to be of high frequency and quality. Conversely, PM2.5
and PM2.5 component measurements are (mostly) filter based measurements which have relatively
long sampling times (usually 24 hours) and aren't collected every day (usually once every three or
42For predicted/observed comparisons, organic carbon is preferred over organic carbon
mass to allow for transparency between model predictions and observed measurements. Organic
carbon mass may include hydrogen, oxygen, and other components.
43Other inorganic particulate matter can contribute up to 10% of PM2.5 mass in certain
locations. Unspeciated inorganic PM (sometimes referred to as “other PM”) is often used
interchangeably with “crustal” or “soil” PM. The term “soil” usually refers to the specific
definition of soil from the IMPROVE program. “Other primary (inorganic) PM” includes heavy
metals and other inorganic species in addition to those commonly found in soil.
six days). Speciated data play an especially important role, as the deterministic models predict
exact chemical components which can be compared to some of the corresponding measured
analytes. In addition, there are known positive and negative sampling artifacts as well as analysis
artifacts associated with FRM and speciation monitors. For example, FRM monitors do not
measure all of the PM2.5 in the air, and the speciation samplers don't measure PM2.5 in the same
way as the FRM monitors (Frank, 2006). Due to the complex nature of the measurements, a basic
understanding of the various PM2.5 and speciation monitoring technology and measurements are
needed before undertaking a model evaluation. This section attempts to address the range of
measurements and measurement issues associated with PM2.5 and its components.
Table 18.1 summarizes many of the PM2.5 species measurements and networks and lists
sampling time and measurement issues. This data will commonly be used as part of an
n851 - n852 - n853 - n854 - n855 - n856 - n857 - n858 - n859 - n860 - n861 - n862 - n863 - n864 - n865 - n866 - n867 - n868 - n869 - n870 - n871 - n872 - n873 - n874 - n875 - n876 - n877 - n878 - n879 - n880 - n881 - n882 - n883 - n884 - n885 - n886 - n887 - n888 - n889 - n890 - n891 - n892 - n893 - n894 - n895 - n896 - n897 - n898 - n899 - n900
castellano: DISPER CUSTIC DESCAR RADIA italiano:
deutsch: DIS CUS DES RAD
castellano: DIS CUS DES RAD english: DIS CUS DES RAD
português: DIS CUS DES RAD italiano: DIS CUS DES RAD
français: DIS CUS DES RAD