Boulder Environmental Sciences and Technology (BEST) is developing several new radiometers for environmental monitoring: a Profiling Radiometer for Atmospheric and Cloud Observation (PRACO), a Marine Profiling Radiometer (MPR), and an Autonomous Profiling Radiometer (APR). These instruments use novel design approaches that aim to remove the user completely from supervision and allow all-weather operation, data collection, and retrievals.
In cooperation with the Atmospheric and Environmental Research (AER) we are working on a design of a Hyperspectral Microwave Sensor.
Boulder Environmental Sciences and Technology was founded in 2006 with the goal of producing radiometers that are practical, user friendly, reliable, and easy to use. The founders of BEST have decades of experience working in various field applications of passive microwave remote sensing. Ours is a comprehensive experience: from theoretical channels selections, to radiometer hardware design, assembly, control and data acquisition software, field deployment, operations, calibrations, and data analysis. We believe these sensors, the radiometers, can be and should be designed to be Reliable, Autonomous, Integrated, Simple, Easy to use, and Sturdy. In our designs, we strive for RAISES Radiometers. We use innovative approaches to radiometer receiver designs, modes of operation, environmental protection, calibration, and data retrievals, while striving to make it easy for our customer by removing him/her from instrument supervision and minimizing maintenance requirements. Our goal is to provide customers with the reliable measurements of environmental variables they desire while aiming for an economical instrument, not only with respect to initial costs, but also to operational expenses.
Microwave Radiometry Today:
The microwave absorption spectrum from 0.3 GHz to 1000 GHz covers a number of water vapor and oxygen absorption lines that allow temperature and water vapor profiling. The spectrum wavelengths are from 1 m to 0.3 mm and thus one part of spectrum allows clouds penetration while other part is very sensitive to cloud particles.
Thus, the microwave spectrum is sensitive to atmospheric temperature, water within the atmosphere in any phase (vapor, liquid, ice, snow, groupel) and also to surface properties. Passive microwave remote sensing – radiometry – has been developed during the past half century into an operational status. Today’s weather forecasts are heavily based on data from space borne microwave radiometers on board of several satellites. These data provide a number of rigorous and valuable constraints on environmental variables to numerical weather prediction models. Examples of the microwave instruments on various satellites include AMSU-A/B, MHS, SSMIS, CMIS (Conical Microwave Imager Sounder), ATMS, SMOS, and others. These instruments provide crucial inputs for numerical weather prediction (NWP) models initialization and thus are contributing significantly to accuracy and improvements of weather forecasts and climate observations. The variables derived from microwave instruments include: temperature and humidity profiles, precipitation rate, snow cover & depth, sea ice edge, sea ice age, cloud liquid water, cloud ice water path, surface temperature, sea surface wind, soil moisture, and others.
Because of such satellite data there has been a revolution in the accuracy and utility of weather forecasts in the past several decades. Weather forecasts at all temporal ranges have improved remarkably as a direct outgrowth of technological developments (in addition to coverage from satellites, these include: advances in computer technologies and communication systems-Internet), basic and applied research, and increased forecaster understanding of how the atmosphere works. It really took two or three decades before satellite data made such a positive impact on forecasts. However, there is no meteorologist today that can imagine a weather forecast without microwave radiometer data.
The situation on ground-based techniques is very different. Ground based microwave radiometry is still more of a curiosity than operational instrumentation. The data that can be potentially provided by microwave radiometers are sought for, but are not used operationally. These data include temperature and humidity profiles of the lower atmosphere (troposphere and especially up to the boundary layer), integrated water vapor and integrated cloud liquid. Experts agree these data are very important for improving the accuracy of the short term (0-48 hours) mesoscale (~county area) weather forecasts. A report by National Research Council titled “Observing weather and climate from the ground up” indicates that most hazardous weather events that need to be detected, monitored, and predicted would benefit greatly from more timely observations of temperature, moisture and wind. These extremely significant events include flooding, large scale storms, Nor-easters, snowstorms, hurricanes, tropical storms, thunderstorms, as well as fire, air pollution, and aviation-related weather risks. Of the three, moisture represents, by far, the biggest opportunity, because its measurement is poor or non-existent, particularly in the boundary layer or lower atmosphere (up to 5km).
Ground based radiometers can provide moisture and temperature measurements in the most economical way. They are already less expensive than any other technology, and they still can get more economical if their wide spread applications are realized. The experts of the recent “Thermodynamic Profiling Technologies Workshop” consider microwave radiometers as a very viable and economical technology for much needed thermodynamic profiling. They also indicate the shortcomings of currently available technology – calibration and optical surface protection from hydrometeors. We believe calibration and all weather operations (radome protection) are the main reasons inhibiting a wider use of the radiometers in operational networks.
Commercially available radiometers are still in a very nascent state. They require a sophisticated user who constantly monitors radiometer operations and it is capable to identify and correct problems before they make data unusable. Such problems can be a dirty optical surface (radome) or drift in calibration. Operating a network of such instruments gets quite expensive quickly if operator intervention is required. However, it is still more economical than any other method that provides comparable data. Click here to read about cost of radiosondes compared to radiometer. Cost of other technologies are estimated in the report from “Thermodynamic Profiling Technologies Workshop”.