Abstract. Water vapor measurements made by the Halogen Occultation Experiment (HALOE)fromwater vapor, thus contributing to the observed increase in water vapor. The increase in water vapor observed by both instruments is larger than that which would be expected from the sum of all of the above effects. We therefore conclude that there has been a significant increase in the amount of water vapor entering the middle atmosphere. A temperature increase of--0.1K/yr in regions of stratosphere-troposphere exchange could increase the saturation mixing ratio of water vapor by an amount consistent with the observed increase.

at most altitudes, there is no significant instrumental drift between the HALOE measurements and the measurements obtained from the two WVMS instruments over these time periods. We also find that at altitudes below $60 km, where the solar cycle effects are unimportant, there were no significant trends in either the HALOE or WVMS data sets over the periods of intercomparison. This is in marked contrast to the early 1990s where large trends (2%/year) were obtained from both HALOE and WVMS measurements. Similarly, we compare the HALOE data with the high-latitude 1998-2002 POAM data set at equivalent latitudes from 45N-55N. Again, the trends are small, and the instrumental trend differences are at most only slightly >1s. We also look at the HALOE water vapor and H 2 O + 2CH 4 data globally and find that, after a large increase from 1991-1995, there is almost no trend below $60 km from 1996-2002. The water vapor trend over the entire HALOE measurement period (1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002) is <1%/year. The unusual stratospheric dynamics at the beginning of the 1990s caused large changes in upper stratospheric and lower mesospheric water vapor that were unrelated to the amount of water vapor entering the stratosphere, hence in this region the less dynamically sensitive quantity H 2 O + 2CH 4 probably provides a better measure of water vapor entering the stratosphere during this period. The trend in H 2 O + 2CH 4 over the 1991-2002 HALOE measurements period is $0.5%/year.

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.

Table Mountain Facility in California (TMF). The main objectives of the campaign were to (1) validate the water vapor measurements of several instruments, including, three Raman lidars, two microwave radiometers, two Fourier-Transform spectrometers, and two GPS receivers (column water), (2) cover water vapor measurements from the ground to the mesopause without gaps, and (3) study upper tropospheric humidity variability at timescales varying from a few minutes to several days.Correspondence to: T. Leblanc (leblanc@tmf.jpl.nasa.gov) A total of 58 radiosondes and 20 Frost-Point hygrometer sondes were launched. Two types of radiosondes were used during the campaign. Non negligible differences in the readings between the two radiosonde types used (Vaisala RS92 and InterMet iMet-1) made a small, but measurable impact on the derivation of water vapor mixing ratio by the FrostPoint hygrometers. As observed in previous campaigns, the RS92 humidity measurements remained within 5 % of the Frost-point in the lower and mid-troposphere, but were too dry in the upper troposphere.Over 270 h of water vapor measurements from three Raman lidars (JPL and GSFC) were compared to RS92, CFH, and NOAA-FPH. The JPL lidar profiles reached 20 km when integrated all night, and 15 km when integrated for 1 h. Excellent agreement between this lidar and the frost-point hygrometers was found throughout the measurement range, Published by Copernicus Publications on behalf of the European Geosciences Union. T. Leblanc et al.: MOHAVE-2009: overview of campaign operations and resultswith only a 3 % (0.3 ppmv) mean wet bias for the lidar in the upper troposphere and lower stratosphere (UTLS). The other two lidars provided satisfactory results in the lower and midtroposphere (2-5 % wet bias over the range 3-10 km), but suffered from contamination by fluorescence (wet bias ranging from 5 to 50 % between 10 km and 15 km), preventing their use as an independent measurement in the UTLS.The comparison between all available stratospheric sounders allowed to identify only the largest biases, in particular a 10 % dry bias of the Water Vapor Millimeterwave Spectrometer compared to the Aura-Microwave Limb Sounder. No other large, or at least statistically significant, biases could be observed.Total Precipitable Water (TPW) measurements from six different co-located instruments were available. Several retrieval groups provided their own TPW retrievals, resulting in the comparison of 10 different datasets. Agreement within 7 % (0.7 mm) was found between all datasets. Such good agreement illustrates the maturity of these measurements and raises confidence levels for their use as an alternate or complementary source of calibration for the Raman lidars.Tropospheric and stratospheric ozone and temperature measurements were also available during the campaign. The water vapor and ozone lidar measurements, together with the advected potential vorticity results from the high-resolution transport model MIMOSA, allowed the identification and study of a deep stratospheri...

The Water Vapor Millimeter‐wave Spectrometer (WVMS) system has been making measurements from the Network for the Detection of Atmospheric Composition Change site at Mauna Loa, Hawaii (19.5°N, 204.4°E), since 1996, covering nearly the complete period of solar cycle 23. The WVMS measurements are compared with Halogen Occultation Experiment (HALOE) (1992–2005), Microwave Limb Sounder (MLS) (2004 to present), and Atmospheric Chemistry Experiment (ACE) Fourier transform spectrometer (2004 to present) measurements in the mesosphere. In the upper mesosphere Lyman α radiation photodissociates water vapor; hence, water vapor in the upper mesosphere varies with the solar cycle. We calculate fits to the WVMS and HALOE water vapor data in this region using the Lasp Interactive Solar Irradiance Datacenter Lyman α data set. This is, to our knowledge, the only published validation of the sensitivity of HALOE water vapor measurements to the solar cycle, and the HALOE and WVMS water vapor measurements show a very similar sensitivity to the solar cycle. Once the solar cycle variations are taken into account, the primary water vapor variations at all of these altitudes from 1992 to the present are an increase from 1992 to 1996, a maximum in water vapor in 1996, and small changes from 1997 to the present. Measurements from 2004 to 2008, which are available from WVMS, MLS, and ACE, show not only good agreement in interannual variations but also excellent agreement in their absolute measurements (to within better than 3%) of the water vapor mixing ratio from 50 to 80 km.