Trials of a new relative humidity sensor

A new relative humidity and air temperature sensor, the Sensirion Model SHTl, has been thoroughly tested by the Upper Ocean Processes (UOP) group at the Woods Hole Oceanographic Institution. One-minute averages from two of the sensors, as well as a Väisälä HMP4SA, were recorded for over a year. A third Sensirion sensor was kept in the laboratory and calibrated at monthly intervals with the other three sensors. The standard deviation of the difference in relative humidity between the Sensirion sensors and the Väisälä was about 2% RH. The difference in air temperature was about 0.2°C. Drift rates in relative humidity for the two Sensirion sensors were 2.7% RH/yr and -0.3% RH/yr, and in air temperature, O.1°C/yr and 0/3°C/yr. Because one of the two Sensirion sensors deployed outside had significant variations in its calibration, the UOP group will not adopt these sensors. However, their very small size, low-cost, and low-power requirements may make them desirable for other uses.Funding was provided by the National Oceanic and Atmospheric Administration under Grant Number NA17RJ1223

Design and validation of a modified Eppley PSP pyranometer

A modified version of the Eppley PSP pyranometer has been designed for use on ships and moored buoys. Seventeen have been built by the Eppley Laboratory for the Upper Ocean Processes Group and deployed on buoys in the deep ocean. Six others have been incorporated into IMET systems mounted on U.S. research ships. A comparison study between four Improved METeorology (IMET) PSPs and one standard PSP shows that the two are completely equivalent in performance. The IMET PSP is more corrosion resistant, compact, robust, and is easier to mate to electronics modules. It is available from the Eppley Laboratory for about the same price as the standard PSP.Funding was provided by the National Science Foundation under Grant No. OCE-91-15000

An all-thermistor pyrgeometer

The design and testing of an all-thermistor (no thermopile) pyrgeometer (LWT) is descrbed. After calibration by comparison with a Kipp & Zonen CG4, 9.2 months of data show mean differences of order 1-2 W m-2 with standard deviations of order 7-8 W m-2. Approximately half of the mean difference and the standard deviation derived from 40 occasions when the LWT readings were anomalously high for periods of 2-l4 hours, principally at night. No reason has been found for the anomalous behavior. During the 9.2 months, of data, there were also 11 periods of a few hours each when the Eppley PIR indicated noticeably higher flux values than did the Kipp & Zonen CG4. The conclusion reached is that contemporary thermistors allow temperature measurements of suffcient accuracy, and the thermopile can be eliminated from pyrgeometers. The differences seen between the Kipp & Zonen and the Epply raise doubts about their absolute accuracies on time scales of hours, although their long-term averages are quite comparable.Funding was provided by the National Science Foundation under Contract Number OCE98-l8470

Long-term tests of some inexpensive barometers and results of pressure cycling of an AIR-DB-1A

For approximately 1.5 year, daily observations of barometrc pressure were made with a varety of sensors and compared to readings from a Paroscientific Model 760-16B while all sensors were maintained at a temperature of 20°C±2°C. The results of two samples from each of three inexpensive (strain gauge integral to a silicon chip) pressure sensors are reported on. The SenSym Model SCXI5AN, Nova PI and the Microswitch Model 134PC15A1 had standard deviations of 0.2, 2.6, and 5.6 mb, respectively. The SenSym and Nova sensors had drift rates of 0.5 and 0.9 mb per year, respectively. A fourth sensor, the Microswitch, had output that was too noisy for a meaningful computation of drift rate. Neither of the Omega Model PX93-015GV samples operated properly. The excellent results indicate that strain gauge sensors are worth considering for measuring barometrc pressure in situations where the highest accuracy is not required. Temperature effects, which can be substantial in strain gauge sensors, were not investigated. Pressure cycling tests of an AIR Model DB-1A show that cycles of 3-10 psi above ambient pressure do not affect the accuracy of the sensor, even after millions of cycles. Therefore, rough weather conditions at sea, i.e., waves washing over the barometer port on a drifting buoy, are unlikely to cause inaccuracy in an AIR sensor.Funding was provided by the National Science Foundation under Grant No. OCE-91-15000

Recognizing problems in shipboard logging meteorology systems

This report is to assist shipboard technicians whose responsibilities are maintaining digital logging meteorological systems. Examples of good and bad data recorded on ships by IMET (Improved METeorology) systems are given, as well as general comments on how various parameters should appear when plotted against time. Parameters included are: wind speed and direction, air temperature, relative humidity, barometric pressure, short- and long-wave radiation, and precipitation (R. M. Young gauges).Funding provided by the National Science Foundation under Grant No. OCE-9806381

Calibration history of some Rotronic MP-100 and Vaisala Humicap relative humidity sensors

An analysis has been made of the calibrations done during 1990 through 1994 on Rotronic MP- 100 relative humidity sensors (used in the Improved METeorological (IMET) system and sensors built at the Woods Hole Oceanographic Institution (WHOI) with the Vaisala Humicap sensing element (used in the Vector Averaging Wind Recorder (VAWR)). The shift from one calibration to the next is, typically, 2-3% RH which represents the major uncertainty in relative humidity with either of these sensors. The direction of each shift appears to be random; thus, there does not appear to be any long-term drifts.Funding was provided by the National Science Foundation, under Grant No. OCE-91-15000

An improved long-wave radiometer

May also be cited as: WHOI-00-13This report describes the development of an improved long-wave radiometer (pyrgeometer) for deployment on ships and buoys. Standard pyrgeometers use a thermopile to measure the temperature gradient between the receiver surface and the instrument case, and thus infer the receiver temperature and incident radiation. The key design change employed in the new radiometer is to remove the thermopile and replace it with a small, glass-encapsulated thermistor to measure the receiver temperature directly. To prove the concept, a prototype radiometer was built and calibrated. It was then deployed outside for a period of a week on the roof of the Clark Laboratory (Quissett Campus, Woods Hole Oceanographic Institution) to demonstrate the feasability of the new concept. Data from the prototype were compared to those from a pair of standard radiometers. The intercomparison shows that the prototype performed surprisingly well. It was able to capture all the variability observed by the standards with only a small bias. The next step in the design process, which has been funded by the National Science Foundation, is to build a rugged version of the prototype that can be deployed in the field.Funding was provided by the Cecil H. and Ida M. Green Technology Innovations Awards Program and the National Science Foundation, Grant OCE98-18470

Performance characteristics of some wind sensors

Summaries of performance data on three wind recorder sensor sets are presented a W.H.O.I.-built vane and cup set mounted on a vector averaging current meter (VAWR), a set of standard orthogonal propellers from the vector measuring current meter (VMWR), and an R. M. Young Company utility cup and vane set (Gill). Data were recorded in a wind tunnel and on a dock. Cup or propeller distance constants were 14.5 m (VAWR), 11m (VMWR), and 3.5 m {Gill). The VMWR propeller distance constant varied little with azimuth. The VPWR cups had the least sensitivity to tilt, less than 5% at 30° compared to 5% and 10% at 20° for the Gill and VMWR. The Gill and VAWR vanes had delay constants of 1.4 m and 2.6 m, damping factors of .67 and .58, and natural wavelengths of 5.9 m and 10 m, respectively, with some doubt of the VPWR vane figures due to experimental uncertainties. That the Gill cups had the least overspeeding was apparent even in the vector averaged wind speeds from the dock intercomparisons. In general, the Gill set is capable of recording vector averaged winds on a buoy more accurately than the VAWR or VMWR set although it is not as rugged mechanically.Prepared for the Office of Naval Research under Contract N00014-76-C-0197; NR 083-400 and for the National Science Foundation under Grant OCE 80-14941

Community Corrections Professionals\u27 Views of Sex Offenders, Sex Offender Registration and Community Notification and Residency Restrictions

The article discusses a study which explained the views of corrections professionals on sex offender registration and community notification (SORN) policies. The researchers focused on the examination of attitudes of criminal justice officials who are charged with enforcing such policies by forty three-item survey questionnaire. They found that these professionals are moderately supportive of residency restrictions and believe that both with SORN are effective in preventing sex offenses