Latitudinal survey of water vapor in the middle atmosphere using an airborne millimeter wave sensor

Noctilucent clouds are often cited as potential indicators of climate change in the middle atmosphere. They owe their existence to the very cold summer mesopause region (~130K) at mid and high latitudes. We analyze trends derived from the Leibniz-Institute Middle Atmosphere Model (LIMA) and the MIMAS ice particle model (Mesospheric Ice Microphysics And tranSport model) for the years 1871-2008 and for middle, high and arctic latitudes, respectively. Model runs with and without an increase of carbon dioxide and water vapor (from methane oxidation) concentration are performed. Trends are most prominent after ~1960 when the increase of both carbon dioxide and water vapor accelerates. Negative trends of (geometric) NLC altitudes are primarily due to cooling below NLC altitudes caused by carbon dioxide increase. Increases of ice particle radii and NLC brightness with time are mainly caused by an enhancement of water vapor. Several ice layer and background parameter trends are similar at high and arctic latitudes but are substantially different at middle latitudes. This concerns, for example, occurrence rates, ice water content (IWC), and number of ice particles in a column. Considering the time period after 1960, geometric altitudes of NLC decrease by approximately 260m per decade, and brightness increases by roughly 50% (1960-2008), independent of latitude. NLC altitudes decrease by approximately 15-20m per increase of carbon dioxide by 1ppmv. The number of ice particles in a column and also at the altitude of maximum backscatter is nearly constant with time. At all latitudes, yearly mean NLC appear at altitudes where temperatures are close to 145+/-1K. Ice particles are present nearly all the time at high and arctic latitudes, but are much less common at middle latitudes. Ice water content and maximum backscatter are highly correlated, where the slope depends on latitude. This allows to combine data sets from satellites and lidars. Furthermore, IWC and the concentration of water vapor at the altitude of maximum backscatter are also strongly correlated. Results from LIMA/MIMAS agree nicely with observations.

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The Effect of Clouds on Water Vapor Profiling from the Millimeter-Wave Radiometric Measurements

Journal of Applied Meteorology ◽

10.1175/1520-0450(1997)036<1232:teocow>2.0.co;2 ◽

1997 ◽

Vol 36 (9) ◽

pp. 1232-1244 ◽

Cited By ~ 8

Author(s):

J. R. Wang ◽

J. D. Spinhirne ◽

P. Racette ◽

L. A. Chang ◽

W. Hart

Keyword(s):

Water Vapor ◽

Millimeter Wave ◽

Radiometric Measurements

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Middle atmosphere abundances of water vapor and ozone during MAP/WINE

Journal of Atmospheric and Terrestrial Physics ◽

10.1016/0021-9169(87)90022-5 ◽

1987 ◽

Vol 49 (7-8) ◽

pp. 827-841 ◽

Cited By ~ 18

Author(s):

K.U. Grossmann ◽

H.G. Brückelmann ◽

D. Offermann ◽

P. Schwabbauer ◽

R. Gyger ◽

...

Keyword(s):

Water Vapor ◽

Middle Atmosphere

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MIAWARA-C, a new ground based water vapor radiometer for measurement campaigns

Atmospheric Measurement Techniques Discussions ◽

10.5194/amtd-3-2389-2010 ◽

2010 ◽

Vol 3 (3) ◽

pp. 2389-2432

Author(s):

C. Straub ◽

A. Murk ◽

N. Kaempfer

Keyword(s):

Water Vapor ◽

Middle Atmosphere ◽

Horn Antenna ◽

Profile Measurement ◽

Correlation Receiver ◽

Water Vapor Radiometer ◽

Set Up ◽

Compact Design ◽

Crucial Parameter ◽

Measurement Campaigns

Abstract. In this paper a new 22 GHz water vapor spectro-radiometer which has been specifically designed for profile measurement campaigns of the middle atmosphere is presented. The instrument is of a compact design and has a simple set up procedure. It can be operated as a standalone instrument as it maintains its own weather station and a calibration scheme that does not rely on other instruments or the use of liquid nitrogen. The optical system of MIAWARA-C combines a choked gaussian horn antenna with a parabolic mirror which reduces the size of the instrument in comparison with currently existing radiometers. For the data acquisition a correlation receiver is used together with a digital cross correlating spectrometer. The complete backend section, including the computer, is located in the same housing as the instrument. The receiver section is temperature stabilized to avoid gain fluctuations. Calibration of the instrument is achieved through a balancing scheme with the sky used as the cold load and the tropospheric properties are determined by performing regular tipping curves. Since MIAWARA-C is used in measurement campaigns it is important to be able to determine the elevation pointing in a simple manner as this is a crucial parameter in the calibration process. Here we present two different methods; scanning the sky and the Sun. Finally, we report on the first spectra and retrieved water vapor profiles acquired during the Lapbiat campaign at Sodankylä Geophysical Observatory. The performance of MIAWARA-C is validated here by comparison of the presented profiles against the equivalent profiles from the Microwave Limb Sounder on the EOS/Aura satellite.

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