Eighth Symposium on the Urban Environment
11th Conference on Atmospheric Chemistry
Timothy R. Oke Symposium
Special Symposium on Measurements in the Urban Environment and Observations
Eighth Conference on Coastal Atmospheric and Oceanic Prediction and Processes
16th Conference on Satellite Meteorology and Oceanography
Fourth Conference on the Meteorological Applications of Lightning Data


Development of a NYC Meteorological Network with emphasis on vertical wind profiles in support of meteorological and dispersion models

Mark Arend, City College of New York, New York, NY; and D. Santoro, B. Gross, F. Moshary, S. Ahmed, and S. Abdelazim

The Urban Dispersion Program (UDP) first developed by PNNL is a multi-year program that began during early 2004, is aimed at investigating air flow and atmospheric dispersion through the heavily urbanized Manhattan borough of New York City (NYC) and explore the performance of a variety of air dispersion modeling strategies at both street level and urban level. Preliminary deployment of tracer gases were performed in local sites where some key meteorological instruments were used in and around Manhattan to provide wind, temperature, pressure, humidity and rainfall rate measurements. The usefulness of these measurements in assessing emergency management capabilities were sufficient to begin the task of obtaining continuous measurements  and thereby establish a permanent meteorological network in NYC (NYC MetNet) based on the equipment used in the field studies and the addition to a variety of ancillary measurements obtained from research grade instruments including a radar wind profiler (RWP) to provide a profile of winds routinely up to 2.5 km, a Doppler lidar for simultaneous aerosol and wind measurements.

An example of the RWP systems being deployed are shown in figure 1 on top of the Liberty Science Center. Data Processing of this data showing a frontal passage is illustrated in figure 2.

Figure 1. View of the Radar Wind Profiler from the LSC Observation Tower



<>Figure 2. Radar Wind Profiler Sample Case Study December 16th, 2007

<>Here, the arrows indicate horizontal, two-dimensional winds (vector pointing upward indicates a southerly wind). The exhibited behavior is consistent with approaching warm front as observed based on MODIS satellite imagery observing a cloud line. (vertical line indicates time of the plots [0700 EST]). Low-altitude winds measured are northeasterly, while the winds aloft between 1.5 and 2.0 km above ground are southerly.

<>Besides using the wind profiles for dispersion for hazard management purposes,  a variety of meteorological applications can benefit from a combination of radar profilers and lidar-aerosol wind profilers. Perhaps most important, convective mixing height has been a relevant parameter for climate studies, urban heat island as well as conventional dispersion models, and becomes even more important in advanced models where the intensity of turbulence under convective conditions is assumed to be strongly related to CBL height. For example, SODAR profiles can be very useful for obtaining SODAR Boundary Layers (SBL). However, the SBL mixing height determination is plagued by different problems. On one hand, turbulence in the outer SBL often is intermittent and patchy, so that it is very difficult to measure the height up to which turbulence extends. The other problem is that the backscatter intensity, on which mixing height estimation from sodar data in the SBL usually relies, depends not only on turbulent fluctuations of the refractive index but also on its mean gradient. In this case,  the mixing height determined from the sodar output maybe the top of the stable layer which has developed due to radiative cooling rather than the top of the mixing layer.

On the other hand, aerosol lidars whose backscatter profiles indicate the aerosol concentration profiles, have also been used in the determination of mixing height. This correspondence is usually very good during daytime where convective heating is dominant. However, the problem with this approach is that the height where a significant decrease of the aerosol concentration is observed does not need to coincide with the current mixing height. Instead, it may often represent the top of a reservoir layer, built up on a previous day. An example of this phenomenon is exhibited in figure 3.

Figure 3. a)  Aerosol Lidar Observations b) CBL Height from CMAQ model compared to both growing and residual layer.

In particular, we note that the convective boundary layer height follows the growth mode of the aerosol layer fairy well but a significant residual layer is present. Care must be made to isolate these multiple layers.

The purpose of this presentation is to provide an update on installation upgrades and operations of the New York City Meteorological Network (NYC MetNet).  Beside providing  an important service to the New York City Metropolitan Area by supplying useful and timely air transport information, the network may act as a test bed for advanced studies of the dispersion of air particles under complex conditions with applications ranging from social concerns to military operations and government planning.  To enhance the networks reach and performance, we have made a number of upgrades and preliminary tests for new installations.  A description of the network will be given which includes operations, upgrades and the dissemination of quality assured data.


This work was partially supported by the NOAA  Interdisciplinary Scientific Environmental Technology (ISET) Cooperative SCIENCE Center  under grant # NA06OAR4810187

extended abstract  Extended Abstract (272K)

wrf recording  Recorded presentation

Joint Session 1, Measurements in the Urban Environment
Tuesday, 13 January 2009, 8:30 AM-9:45 AM, Room 124A

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