Development and testing of the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) cm and mm wavelength occultation instrument

E R Kursinski,R Stickney,S Albanna,B Wheelwright,C Groppi,M Stovern,B Duffy,J Hainsworth,A Young,A C Otarola,D Ward

doi:10.5194/amt-5-439-2012

E R Kursinski, R Stickney + Show 9 more

Open Access

https://doi.org/10.5194/amt-5-439-2012

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Abstract

Abstract. We present initial results from testing a new remote sensing system called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS is designed as a satellite-to-satellite occultation system for monitoring climate. We are developing the prototype instrument for an aircraft to aircraft occultation demonstration. Here we focus on field testing of the ATOMMS instrument, in particular the remote sensing of water by measuring the attenuation caused by the 22 GHz and 183 GHz water absorption lines. Our measurements of the 183 GHz line spectrum along an 820 m path revealed that the AM 6.2 spectroscopic model provdes a much better match to the observed spectrum than the MPM93 model. These comparisons also indicate that errors in the ATOMMS amplitude measurements are about 0.3%. Pressure sensitivity bodes well for ATOMMS as a climate instrument. Comparisons with a hygrometer revealed consistency at the 0.05 mb level, which is about 1% of the absolute humidity. Initial measurements of absorption by the 22 GHz line made along a 5.4 km path between two mountaintops captured a large increase in water vapor similar to that measured by several nearby hygrometers. A storm passage between the two instruments yielded our first measurements of extinction by rain and cloud droplets. Comparisons of ATOMMS 1.5 mm opacity measurements with measured visible opacity and backscatter from a weather radar revealed features simultaneously evident in all three datasets confirming the ATOMMS measurements. The combined ATOMMS, radar and visible information revealed the evolution of rain and cloud amounts along the signal path during the passage of the storm. The derived average cloud water content reached typical continental cloud amounts. These results demonstrated a significant portion of the information content of ATOMMS and its ability to penetrate through clouds and rain which is critical to its all-weather, climate monitoring capability.

Highlights

Because the 820 m distance used on campus was too short to achieve significant optical depths at 22 GHz, we designed tests to run between Mt
The derived average cloud water content reached typical continental cloud amounts. These results demonstrated a significant portion of the information content of ATOMMS and its ability to penetrate through clouds and rain which is critical to its all-weather, climate monitoring capability
For the tests performed on 13 March 2010, our best observations were obtained when the reference frequency was set to 200.6 GHz, while the other transmit frequency was tuned over the range from 183.60 GHz to 187.50 GHz in steps of 0.15 GHz for a total of 27 frequencies

Summary

Introduction

Because the 820 m distance used on campus was too short to achieve significant optical depths at 22 GHz, we designed tests to run between Mt. Bigelow (2515 m) and Mt. Lemmon ridge (2752 m) separated by approximately 5.4 km just north of the University of Arizona (Fig. 8a). For cross comparisons we used three hygrometers located near the 5.4 km test path: the weather station in the town of Summerhaven at 2401 m (Fig. 8a); the Sustainability of semiArid Hydrology and Riparian Areas (SAHRA) eddy correlation tower on Mt. Bigelow approximately 400 m to the east of the ATOMMS instrument on Mt. Bigelow at an elevation of 2613 m; and a Buck Instruments CR4 laboratory-quality chilled mirror hygrometer located at the site of the 22 GHz transmitter on Mt. Bigelow at 2515 m.

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