We compare water vapor measurements from the Naval Research Laboratory ground‐based Water Vapor Millimeter‐wave Spectrometer (WVMS) instruments with measurements taken by five space‐based instruments. For coincident measurements the retrievals from all of the instruments show qualitatively similar altitude profiles. The retrieved mixing ratios from most instruments generally differ from an average calculated using retrievals from all of the instruments by <1 ppmv at most altitudes from 40 km to 80 km. Comparisons with the Microwave Limb Sounder (MLS) and the Halogen Occultation Experiment (HALOE) allow for the validation of observed temporal variations. The observed variations show similar annual and semiannual cycles. A comparison of several years of data from HALOE and WVMS also shows that the instruments are detecting similar interannual variations. A regression analysis of the WVMS and HALOE data sets shows that the observed variability is consistent within the estimated errors in the mesosphere and that in the upper stratosphere, where the natural variability is small, there is a positive correlation between the WVMS and the HALOE data.

We present data obtained during more than 3 years of nearly continuous measurements of middle atmospheric water vapor. The data are obtained from ground‐based measurements at 22 GHz taken at two sites, one in each hemisphere, using the Naval Research Laboratory water vapor millimeter‐wave spectrometer (WVMS). With the construction of a second instrument, it has been possible to maintain continuous monitoring from both sites since January 1994. The measurements from both instruments show significant seasonal variability. There is a clear annual cycle, with the water vapor above ∼60 km increasing in summer and decreasing in winter. The observed amplitude of the annual oscillation is larger at 45.0°S than at 34.4°N, a result which is qualitatively consistent with the higher latitude of the southern hemisphere site. There is also an indication of a semiannual cycle, particularly at altitudes near 80 km. The annual cycle is consistent with transport due primarily to advection, while the weaker semiannual cycle may be indicative of the effect of gravity waves on diffusive transport.

We present measurements of the middle atmospheric water vapor mixing ratio profile obtained using the ground‐based Naval Research Laboratory water vapor millimeter‐wave spectrometer (WVMS) instrument at the Jet Propulsion Laboratory Table Mountain Observatory. The measurements cover a period of 262 days from January 23, 1992, to October 13, 1992. During this campaign it was possible to retrieve useful daily mixing ratio profiles for 186 days. We thus have a nearly continuous record of water vapor mixing ratios for altitudes from ≈35 to 75 km. The retrievals are obtained using the optimal estimation method. Details of the error analysis are presented, and a technique is introduced that reduces baseline effects and helps to estimate the baseline error. The high‐altitude (≳65 km) data show a sharp rise prior to the expected maximum near the summer solstice and a gradual decline in the following months. The mixing ratios generally peak between 55 and 65 km, at which point the mixing ratios are 6–7 parts per million by volume. The highest peaks occur in January, May, and October.

We report on new developments of the WVMS instrument that provide extended altitude coverage (25-75 km) and precision that have not been achieved before with ground based microwave remote sensing of water vapor. This paper emphasizes the technical details of the instrument, experimental techniques, and especially accuracy and calibration issues.

The water vapor monitoring system (WVMS) is a ground based broad band microwave (22.235 GHz) radiometer that analyzes emission spectra from the mesosphere to determine water vapor mixing ratios. This paper emphasizes the technical details of the instrument, experimental techniques, comparison of alternate techniques, and especially accuracy and calibration issues.<>

Journal of Geophysical Research: AtmospheresVolume 90, Issue D1 p. 2438-2440 Commentaries Reply [to “Eddy diffusion coefficients in the mesosphere: Comment on ‘An observational study of water vapor in the mid-latitude mesosphere using ground-based microwave techniques’ by R. M. Bevilacqua et al.”] R. M. Bevilacqua, R. M. BevilacquaSearch for more papers by this authorJ. J. Olivero, J. J. OliveroSearch for more papers by this authorP. R. Schwartz, P. R. SchwartzSearch for more papers by this authorC. J. Gibbins, C. J. GibbinsSearch for more papers by this authorJ. M. Bologna, J. M. BolognaSearch for more papers by this authorD. L. Thacker, D. L. ThackerSearch for more papers by this author R. M. Bevilacqua, R. M. BevilacquaSearch for more papers by this authorJ. J. Olivero, J. J. OliveroSearch for more papers by this authorP. R. Schwartz, P. R. SchwartzSearch for more papers by this authorC. J. Gibbins, C. J. GibbinsSearch for more papers by this authorJ. M. Bologna, J. M. BolognaSearch for more papers by this authorD. L. Thacker, D. L. ThackerSearch for more papers by this author First published: 20 February 1985 https://doi.org/10.1029/JD090iD01p02438Citations: 4AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume90, IssueD120 February 1985Pages 2438-2440 RelatedInformation

A search for molecular absorption redshifted to the same degree as the observed 21-cm hydrogen line in the directions of several Seyfert galaxies and quasars has been conducted to determine whether the observed absorption could be due to an intervening molecularly enriched object such as a galaxy. Observations were made with the NRAO 11-m antenna at Kitt Peak, the NRAO 42-m antenna at Green Bank, and the NRL 26-m antenna at Maryland Point Observatory. For the Seyfert galaxy 3C 84, the object with the greatest radio brightness in the survey, and for 3C 120, a CH2O opacity of 0.0001 is found which is less than that observed in all edge-on spiral galaxies. An H2O opacity limit of 0.014 excludes the possibility of any water masers between 0.13 and 4 kpc in front of 3C 84, and the opacity limit for CO implies an upper limit to its column density an order of magnitude less than predicted from the galactic CO/hydrogen ratio. The possible detection of the 118 GHz line of O2 in 3C 84 is, however, obtained.

Measurements of the H2O emission line at 22.2 GHz show that the concentration in the mesosphere of water vapor molecules can be highly variable, ranging from nearly constant mixing ratios of 2‐4 ppmv, up to a layer near 65 km altitude with peak values around 12 ppmv. Results above 70 km altitude have been used to deduce a value for the vertical eddy diffusion coefficient of (4.4 ± 0.7)×105 cm²sec−1.

The 616−523 rotational transition at 22.2 GHz has been used to measure the H2O vertical profile in the upper stratosphere and mesosphere. Observations were made during January, April, July, and September 1980 and, except in April, the average profile was characterized by a 10 ppmv layer between 60 and 70 km and a decrease in concentration to less than 1 ppmv above 80 km.

view Abstract Citations (94) References (79) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Very long baseline interferometric observations of the H2O sources in W49N, W3(OH), Orion A, and VY Canis Majoris. Moran, J. M. ; Papadopoulos, G. D. ; Burke, B. F. ; Lo, K. Y. ; Schwartz, P. R. ; Thacker, D. L. ; Johnston, K. J. ; Knowles, S. H. ; Reisz, A. C. ; Shapiro, I. I. Abstract Observations of four galactic H20 sources were made in 1970 June and 1971 February and March at 1.35-cm wavelength with interferometers having fringe spacings between 00008 and 001. The features in the spectrum of W49 N between -16 and + 12 km -1 were all unresolved and apparently smaller than 0.0005 (1.1 x 1014 cm) in diameter (uniform disk model). The feature at -1.8 km 1 was less than 0.0003 (0.7 x 1014 cm) in diameter. The features were distributed over an area of about 1" >c 1" (2 x 2 x 1017 cm) and clumped into three regions. Differences in the spatial distribution were observed among the three measurement periods. The H20 emission regions were coincident, within 5", with the OH emission source. The five features in the spectrum of W3(OH) between -52 and -47 km s - were all unresolved, with upper limits of 0'!002 (0.7 x 1014 cm) in diameter. The emission region had dimensions 2" >c 0"2 (0.8 x 0.08 >c 1017 cm). The features in the Ori A source had apparent sizes between 00008 (0.6 x 1014 cm) and 001 (8 x 1014 cm) and were spread over an area of 30" >c 30" (2 x 2 >c 1017 cm). Changes in the spatial distribution occurred between observations. The two strongest features in VY CMa were unresolved and smaller than 0'.'002 (3 x 1013 cm) and were separated by 015 (0.2 x 1016 cm). The emission region in VY CMa was an order of magnitude smaller in linear dimension than were those of the other three sources and probably has significantly different physical conditions. Some of the interferometric spectra of W49 N and Ori A seem consistent with the presence of hyperfine structure. Subject headings: molecules nebulae - radio sources Publication: The Astrophysical Journal Pub Date: October 1973 DOI: 10.1086/152437 Bibcode: 1973ApJ...185..535M full text sources ADS | data products SIMBAD (5)

view Abstract Citations (34) References (6) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Observations of the ^{2}Π_{1/2}, J = 1/2 State of OH Thacker, D. L. ; Wilson, W. J. ; Barrett, A. H. Abstract Observations of the 211112, J = T1 excited-state emission of OH have been made which resulted in the first detection of emission from the F = 0 .1 transition at 4660 MHz in the source Sgr B2. Emission from the F = 1 .0 transition at 4765 MHz was also detected from the sources Sgr B2 and NGC 6334N. A correlation between the excited-state -MHz and the ground-state 1720MHz emission was noted which supports the far-infrared/ultraviolet pumping models for Type I OH sources. A search for 211112, J = emission was made in thirty-one other OH and H2O sources, with negative results. Publication: The Astrophysical Journal Pub Date: September 1970 DOI: 10.1086/180601 Bibcode: 1970ApJ...161L.191T full text sources ADS | data products SIMBAD (10)