New Jersey Precipitation Chemistry Monitoring Program

This summary of the precipitation monitoring chemistry program was developed from personal correspondence from Luther Smith, Ph.D., to Richard Artz, NOAA Air Resources Laboratory, Silver Spring, MD, 23 December 1997. Recently, New Jersey expanded the atmospheric deposition monitoring program to include organic constituents and trace metals in precipitation, aerosols, and air. A more comprehensive discussion of both the precipitation chemistry and atmospheric measurements collected from 1997 to 2003 in New Jersey may be found in the related document "The New Jersey Atmospheric Deposition Network (NJADN) Final Report"

Monitoring Sites

Precipitation samples were collected at the following sites:

Data Analysis and Processing

Approach

The New Jersey Precipitation Chemistry Monitoring Network data were treated in a manner as close to NADP data and data sets as possible. Though the data were at least nominally similar to NADP, the network had a somewhat different protocol and provided a somewhat different data set than NADP. The process of data "clean-up" included eliminating duplicate observations, checking observations for suspicious or erroneous information, converting codes to "NADP-like" form, and checking agreement between the documentation and the data sets themselves. Where possible, incorrect entries in an observation were changed based on a consideration of all information in the observation and, if appropriate, observations near it in time from the same site. Changes involving the raw data were limited to correcting dates when buckets were either removed or placed on a collector.

Very little changing of chemistry values was done. One change was to invalidate data for sample periods longer than eight days. Note that the New Jersey network supplied neither detection limits, per se, nor indicators that values were below detection.

Quality assurance type codes or comments for each individual sample were obtained for the New Jersey data. No data were changed based on such codes for the following reasons. The database contained instances of samples coded as contaminated (in one way or another) that had chemistry values missing and other such samples that had chemistry values present; such a scenario is consistent with NADP treatment of samples.

Results

The following data files are available for the New Jersey network: a site file including latitudes and longitudes; weekly data file; file of annual precipitation-weighted means and deposition totals; file of quarterly precipitation-weighted means and deposition totals. Latitude and longitude coordinates for the New Jersey sites are based on best estimates from a road atlas. The first quarter was defined as January-March, the second as April-June, and so on.

Although each monitoring site was equipped with a separate rain gauge, New Jersey supplied only one precipitation amount for each sample. (There was no indication as to whether this was based on sample volume or rain gauge amount.) Thus, the standard NADP collection efficiency criterion was not applied to the New Jersey data. The summary files contain data completeness measures. (Note that since New Jersey did not add water to samples for chemical analysis, but simply measured until no sample was left, data completeness criteria were separately calculated for each ion.)

A note of caution is in order about some of the ions reported. Fluoride, bromide, and phosphate may have been frequently reported as below the detection limit. Verification of this is not possible since New Jersey did not report below detection limit cases. Therefore, no adjustment to the data for these ions was done.

The years and quarters meeting the data completeness criteria were somewhat sparser than one might have hoped. The final results are summarized below.

Comments

Data provided by the State of New Jersey for 1997 through 2000 were not evaluated for completeness, but rather provided in the form that they were provided.

While it appears that the New Jersey network is not of the same quality as NADP, it is believed that it may be useful to CADM. The New Jersey database is documented well enough that one can locate the data gaps. The reported summary numbers are probably fairly good.

The New Jersey network is an ongoing concern. Some additional information from the State would allow more confidence in their numbers. Continued communication could help them improve their database, leading to mutual benefits for CADM and New Jersey.

Additional investigation was conducted to determine why sites failed to meet the data completeness criteria. There were several instances where the only criterion that was not met was the requirement that precipitation be monitored 90% of the time. If a rain gauge could be found that was near enough to each site, one could substitute the values from these gauges for some of the missing time periods. This approach holds out the possibility of "filling in" the following missing years in the above table:

• Ancora, NJ: 1984, 1985, 1991, 1992, and 1994
• Lebanon, NJ: 1995
• Millville, NJ: 1984, 1985, and 1986.

If successful, one would then have reasonable deposition estimates (in addition to those from the other networks) for at least two and as many as nine years.

Additional data are available at New Jersey DEP's Bureau of Air Monitoring.

Related Document

"The New Jersey Atmospheric Deposition Network (NJADN) Final Report"

Go to New Jersey Precipitation Chemistry Monitoring Program-Precipitation Chemistry Data