3.5.2 Data needs for wind field development

The development of a wind field for each modeling episode

depends upon ground-level and elevated wind observation data. It

is preferred that a surface-based monitoring network report wind

speed and direction as hourly averages, because an hour is the time

period commensurate with most UAM concentration output analyses.

The surface monitoring network should be broad and dense so that

diagnostic models (if that is the technique chosen) can depict

major features of the wind field. Data representing vertical

profiles of wind speed and direction are required in order to

establish upper-level wind fields. Preferably, data should provide

adequate spatial (horizontal) and temporal resolution. Results of

UAM applications are often criticized because of inadequate

meteorological data, and lack of sufficient meteorological data

often prevents definitive diagnostic analyses. Thus, the need for

adequate meteorological data cannot be overstated.

Time constraints imposed by the 1990 CAAA will probably

preclude consideration of new meteorological monitoring stations.

Thus, it is likely that the base case to be used in the attainment

demonstration will be from an historical episode for which model

performance has been deemed acceptable.


Meteorological data routinely available for a UAM modeling

demonstration usually consist of National Weather Service

(NWS) hourly surface and upper-air observations (for winds

aloft). If these data are the only data available for use in

a modeling demonstration, they may have to suffice. However,

the NWS data consist of observations made over very short

periods rather than hourly averaged values. An assumption

that wind velocity measured over a very short period persists

unaltered over an hour may lead to an overestimate of

transport. Therefore, whenever possible, hourly averaged

meteorological data (e.g., from an intensive field study)

should be used. Additional meteorological data may be

available from other sources in the domain (e.g., an on-site

meteorological monitoring program at an industrial facility).

These data may be used to supplement the NWS data, provided



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