Richard E. Payne

The IMET (Improved Meteorology) Ship and Buoy Systems

Abstract The recently developed IMET (improved meteorology) system for ships and buoys and the key elements of the program that led to its development are described. The system improves the ability to measure mean meteorological variables, including wind velocity, barometric pressure, incoming shortwave and longwave radiation, air temperature, sea surface temperature, humidity, and precipitation, from both types of platforms. Extensive laboratory and field tests of a variety of sensors were conducted to investigate and document their stability, accuracy, and reliability. Modular electronics were developed so that each sensor in the system communicated digitally, returning calibrated values to a central data recorder. IMET systems have been deployed on buoys in the Atlantic and Pacific Oceans and on research vessels. The history of the program, reasons for the choice of the present sensor suite, the design of the sensor modules, a description of the data acquisition system, and examples of data collected w...

Measuring Near-Surface Meteorology over the Ocean from an Array of Surface Moorings in the Subtropical Convergence Zone

Abstract An array of five surface moorings was set in the subtropical convergence zone southwest of Bermuda with spacings of 16 to 53 km. Meteorological instrumentation on each of the surface buoys recorded wind velocity, barometric pressure, solar radiation, air temperature, sea temperature, and relative humidity. One objective of the deployment was to look for horizontal variability in the meteorological fields on the scale of the array. In support of that objective, both a high data return from the instruments and a quantitative evaluation of the quality of the measurements were sought. To maximize data return rates, two meteorological instruments were placed on each buoy. To determine the accuracy of the measurements, careful predeployment and post-deployment calibrations of all instruments were carried out, and, during the experiment, meteorological data were collected from ships stationed near the buoys. From the two redundant instruments it was possible to construct one complete dataset for each mo...

Transfer processes at the air-sea interface and discussion

Near-surface data from ships, buoys, aircraft and a microwave remote-sensing satellite have been used to estimate the fluxes of momentum, heat and water vapour at the sea surface over a 200 km x 200 km area during the Joint Air-Sea Interaction Experiment of 1978. In particular, daily means of the surface heat balance and the wind stress are presented. Generally, the sensible heat flux was found to be less than 25 % of the latent heat flux. Over periods of a day the total upward heat flux was about a third of the net radiation, implying that a significant proportion of the available energy went into heating the ocean. The Ekman pumping accounted for most of the divergence in the atmospheric boundary layer but only 10 % at most of that in the upper ocean. Some case studies of the horizontal variation of the fluxes in relation to larger scales are also discussed and it is suggested that the fluxes are modulated by mesoscale patterns in sea-surface temperature.

A New Look at Calibration and Use of Eppley Precision Infrared Radiometers. Part II: Calibration and Use of the Woods Hole Oceanographic Institution Improved Meteorology Precision Infrared Radiometer*

Abstract For some years, investigators have made measurements of downwelling longwave irradiance with the Eppley Precision Infrared Radiometer (PIR), recording the values of thermopile voltage and body and dome thermistor resistances and combining them in data processing. Part I of this paper reviews previous work on the processing equation and presents an improved equation. It establishes that the standard single-output Eppley has an inherent uncertainty of 5%. By measuring the three possible outputs separately and comparing them in the improved equation, the inherent accuracy can be improved to 1.5%. Part II presents a method of calibrating the Eppley PIR for the three-output equation using an easily constructed blackbody cavity in a temperature bath capable of a 0°–50°C temperature range. Calibration of PIR thermistors is recommended since occasionally one is found out of specifications. An outdoor comparison of 15 PIRs calibrated with the technique was carried out in groups of four, with one PIR used ...

A comparison of buoy meteorological systems

Funding was provided by the National Oceanic and Atmospheric Administration under Grant Number NA96GPO429.

Accuracy of temperature measurements with the VACM

Abstract : The report describes temperature measurement techniques with the Vector Averaging Current Meter (VACM) designed at WHOI and manufactured at AMF. Included are descriptions of circuitry, calibration techniques and calibration results. Precision calibrations of VACM thermistors began in 1971 at WHOI. Of the thermistors in our pool, 70 have had at least 3 calibrations over a period no shorter than 2 years. Of these 70 thermistors the results described show that 51 are stable.

Improved meteorological measurements from buoys and ships (IMET) : preliminary comparison of solar radiation air temperature shields

Several different types of solar radiation air temperature shields are evaluated for use at sea on ships and buoys. They include three types of static or Thaller shields, two vane oriented shields, and two fan ventilated shields. A preliminary data analysis is presented and

Improved meteorological measurements from buoys and ships (IMET) : preliminary comparison of precipitation sensors

Rainfall data obtained from an optical rain gauge and a capacitive siphon rain gauge are analyzed and discussed. These sensors were developed for unattended use and are being considered for use at sea on ships and buoys.

Long-Term Stability of Some Barometric Pressure Sensors

Abstract A variety of Pressure sensors have been tested in the laboratory for accuracy and long-term stability. The Paroscientific 215-AT, Rosemount 1201 FIB, and Setra 270 were found to be the most accurate, maintaining 0.1-mb accuracy over long periods. These were followed by the AIR DB-1A with 0.5 mb in most units tested. The Paroscientific and AIR sensors require the least power and are the most suitable for remote deployments. Results on several inexpensive sensors show that some are worthy of consideration if accuracy requirements can be relaxed somewhat. The AIR DB-1A was selected for use in the barometric pressure module for the IMET (improved meteorology) system.

Improved meteorological measurements from buoys and ships (IMET) : preliminary comparison of pyranometers

Three different types of pyranometers (two of each) are tested and evaluated. The sensors include the Eppley Precision Spectral Pyranometer (PSP) which meets the World Meteorological Organization (1965) criteria for a first class pyranometer, the Eppley 8-48 Black and White Pyranometer (second class) and the Hollis MR-5 Silicon Photovoltaic Pyranometer (third class).