Paroscientific’s MET3A Benefits to Satellite Laser Ranging

by
John Mooseles
Paroscientific, Inc.

Figure 1. Satellite Laser Ranging Network

Introduction

Paroscientific’s MET3A Broadband Meteorological Measurement Systems has been chosen as the leading system by the International Laser Ranging Service to provide Met data to help minimize the adverse effect of Meteorological errors on the quality of SLR (Satellite Laser Ranging) data. For these applications, precision, accuracy, reliability, and long-term stability of the MET3A station equates to reliability and low total cost-of-ownership for the life of the program. The broadband feature of these instruments also enables scientists to measure other atmospheric and geophysical signals with a network of GPS receivers co-located with Digiquartz® MET3A Meteorological Measurement System.

Satellite Laser Ranging

Figure 2. Satellite Laser Ranging

In Satellite Laser Ranging (SLR) a global network of stations measures the instantaneous round-trip time of flight of ultra-short pulses of light to satellites equipped with special reflectors. This provides instantaneous range measurements of millimeter level precision, which can be accumulated to provide accurate orbits and a host of important science products.

• Satellite Laser Ranging is a proven geodetic technique with significant potential for important contributions to scientific studies of the Earth/Atmosphere/Oceans system.

• SLR is the most accurate technique currently available to determine the geocentric position of an Earth satellite, allowing for the precise calibration of radar altimeters and separation of long-term instrumentation drift from secular changes in ocean topography.

• SLR’s ability to measure the temporal variations in the Earth’s gravity field and to monitor motion of the station network with respect to the geocenter, together with the capability to monitor vertical motion in an absolute system, makes it unique for modeling and evaluating long-term climate change by providing a reference system for post-glacial rebound, sea level and ice volume change.

• Determining the temporal mass redistribution of the solid Earth, ocean, and atmosphere system monitoring the response of the atmosphere to seasonal variations in solar heating.

• SLR provides a unique capability for verification of the predictions of the Theory of General Relativity.

• SLR stations form an important part of the international network of space geodetic observatories, which include VLBI (Very Long Baseline Interferometry), GPS (Global Positioning Systems), DORIS (Doppler Orbitography and Radiopositioning) and PRARE (Precise Rang and Range-Rate Equipment) systems. 

• On several critical missions, SLR has provided failsafe redundancy when other radiometric tracking systems have failed.

• The cost effectiveness of SLR operations are improving through increased standardization, configuration control, and automation. NASA is vigorously pursuing the development of SLR 2000, a stand-alone, low-cost, sub centimeter SLR system.

• The International Laser Ranging Service has been formed by the global SLR community to enhance geophysical and geodetic research activities.

The Paroscientific MET3 is the most widely used model within the ILRS. Accurate measurements of barometric pressure require an environmentally rugged pressure port design that minimizes pressure errors under dynamic wind conditions. Wind tunnel and field tests of the high-performance pressure port (DigiPort) used on the Paroscientific MET3A Meteorological System show superior performance over all other ports. Barometric readings with the MET3A pressure port system easily meet the requirements of Satellite Laser Ranging, GPS Meteorology, Weather Stations, Digital Altimeter Setting Indicators, High-Resolution Measurements of Atmospheric Waves, and Aircraft Wake-Turbulence Detection.

The Digiquartz® barometer used in the MET3A has a 3 year stability warranty of better than 0.1 hPa per year. It includes a market leading limited 5-year warranty with the first 2 years covered at 100%.
The purchase and proper installation/care of a state-of-the-art meteorological device coupled with periodic calibrations should significantly improve the quality of the data.

©2005 Paroscientific, Inc.