Tropospheric water vapour above Switzerland over the last 12 years

Integrated Water vapour (IWV) has been measured since 1994 by the TROWARA microwave radiometer in Bern, Switzerland. Homogenization techniques were used to identify and correct step changes in IWV related to instrument problems. IWV from radiosonde, GPS and sun photometer (SPM) was used in the homogenisation process as well as partial IWV columns between valley and mountain weather stations. The average IWV of the homogenised TROWARA time series was 14.4 mm over the 1996–2007 period, with maximum and minimum monthly average values of 22.4 mm and 8 mm occurring in August and January, respectively. A weak diurnal cycle in TROWARA IWV was detected with an amplitude of 0.32 mm, a maximum at 21:00 UT and a minimum at 11:00 UT. For 1996–2007, TROWARA trends were compared with those calculated from the Payerne radiosonde and the closest ECMWF grid point to Bern. Using least squares analysis, the IWV time series of radiosondes at Payerne, ECMWF, and TROWARA showed consistent positive trends from 1996 to 2007. The radiosondes measured an IWV trend of 0.45±0.29%/y, the TROWARA radiometer observed a trend of 0.39±0.44%/y, and ECMWF operational analysis gave a trend of 0.25±0.34%/y. Since IWV has a strong and variable annual cycle, a seasonal trend analysis (Mann-Kendall analysis) was also performed. The seasonal trends are stronger by a factor 10 or so compared to the full year trends above. The positive IWV trends of the summer months are partly compensated by the negative trends of the winter months. The strong seasonal trends of IWV on regional scale underline the necessity of long-term monitoring of IWV for detection,understanding, and forecast of climate change effects in the Alpine region.

[1]  P. Sen.  Estimates of the Regression Coefficient Based on Kendall's Tau , 1968 .

[2]  Sien-Chong Wu,et al.  Optimum frequencies of a passive microwave radiometer for tropospheric path-length correction , 1979 .

[3]  E. Matthews.  Global Vegetation and Land Use: New High-Resolution Data Bases for Climate Studies , 1983 .

[4]  R. Hirsch,et al.  A Nonparametric Trend Test for Seasonal Data With Serial Dependence , 1984 .

[5]  H. Alexandersson.  A homogeneity test applied to precipitation data , 1986 .

[6]  T. Herring,et al.  GPS Meteorology: Remote Sensing of Atmospheric Water Vapor Using the Global Positioning System , 1992 .

[7]  N. Kämpfer,et al.  Radiometric determination of water vapor and liquid water and its validation with other techniques , 1992 .

[8]  Joab R Winkler,et al.  Numerical recipes in C: The art of scientific computing, second edition , 1993 .

[9]  P. Crill,et al.  Rapid degradation of atmospheric methyl bromide in soils , 1995, Nature.

[10]  W. Elliott,et al.  Tropospheric Water Vapor Climatology and Trends over North America: 1973–93 , 1996 .

[11]  R. Cicerone,et al.  Bromine emissions from leaded gasoline , 1997 .

[12]  J. Butler,et al.  The potential effect of oceanic biological degradation on the lifetime of atmospheric CH3Br , 1997 .

[13]  Lucie A. Vincent,et al.  A Technique for the Identification of Inhomogeneities in Canadian Temperature Series , 1998 .

[14]  S. Yates,et al.  Production of methyl bromide by terrestrial higher plants , 1998 .

[15]  Khaled H. Hamed,et al.  A modified Mann-Kendall trend test for autocorrelated data , 1998 .

[16]  J. Güldner,et al.  Results of Year-Round Remotely Sensed Integrated Water Vapor by Ground-Based Microwave Radiometry , 1999 .

[17]  S. Manabe,et al.  The Role of Water Vapor Feedback in Unperturbed Climate Variability and Global Warming , 1999 .

[18]  P. Crill,et al.  Wetlands: A potentially significant source of atmospheric methyl bromide and methyl chloride , 1999 .

[19]  E. Holland,et al.  Litter decomposition as a potential natural source of methyl bromide , 2000 .

[20]  Beat Schmid,et al.  Modeled and empirical approaches for retrieving columnar water vapor from solar transmittance measurements in the 0.72, 0.82, and 0.94 μm absorption bands , 2000 .

[21]  R. Cicerone,et al.  Emissions of methyl halides and methane from rice paddies. , 2000, Science.

[22]  Michael B. McElroy,et al.  Three-dimensional climatological distribution of tropospheric OH: Update and evaluation , 2000 .

[23]  James B. Kerr,et al.  Detecting the recovery of total column ozone , 2000 .

[24]  R. Weiss,et al.  Natural methyl bromide and methyl chloride emissions from coastal salt marshes , 2000, Nature.

[25]  R. Weiss,et al.  Shrubland fluxes of methyl bromide and methyl chloride , 2001 .

[26]  G. Nickless,et al.  Biogenic fluxes of halomethanes from Irish peatland ecosystems , 2001 .

[27]  F. Woodward,et al.  Global response of terrestrial ecosystem structure and function to CO2 and climate change: results from six dynamic global vegetation models , 2001 .

[28]  W. Elliott,et al.  Radiosonde-Based Northern Hemisphere Tropospheric Water Vapor Trends , 2001 .

[29]  M. Andreae,et al.  Emission of trace gases and aerosols from biomass burning , 2001 .

[30]  Y. Yokouchi,et al.  Recent decline of methyl bromide in the troposphere , 2002 .

[31]  J. Butler,et al.  Effect of oceanic uptake on atmospheric lifetimes of selected trace gases , 2002 .

[32]  J. Butler,et al.  Predicting oceanic methyl bromide saturation from SST , 2002 .

[33]  Junhong Wang,et al.  Diurnal variation in water vapor over North America and its implications for sampling errors in radiosonde humidity , 2002 .

[34]  C. Reeves.  Atmospheric budget implications of the temporal and spatial trends in methyl bromide concentration , 2003 .

[35]  S. Montzka,et al.  A decline in tropospheric organic bromine , 2003 .

[36]  Jennifer A. Logan,et al.  An assessment of biofuel use and burning of agricultural waste in the developing world , 2003 .

[37]  Shepard A. Clough,et al.  The ARM program's water vapor intensive observation periods - Overview, initial accomplishments, and future challenges , 2003 .

[38]  Gerd Gendt,et al.  On the determination of atmospheric water vapor from GPS measurements , 2003 .

[39]  Guergana Guerova,et al.  Validation of NWP Mesoscale Models with Swiss GPS Network AGNES , 2003 .

[40]  C. Tucker,et al.  Climate-Driven Increases in Global Terrestrial Net Primary Production from 1982 to 1999 , 2003, Science.

[41]  S. Yvon-Lewis,et al.  Methyl Bromide In Preindustrial Air: Measurements From an Antarctic Ice Core , 2003 .

[42]  J. Randerson,et al.  Continental-Scale Partitioning of Fire Emissions During the 1997 to 2001 El Niño/La Niña Period , 2003, Science.

[43]  Christian Mätzler,et al.  The STARTWAVE atmospheric water database , 2005 .

[44]  N. Kämpfer,et al.  A 10‐year integrated atmospheric water vapor record using precision filter radiometers at two high‐alpine sites , 2005 .

[45]  M. Begert,et al.  Homogeneous temperature and precipitation series of Switzerland from 1864 to 2000 , 2005 .

[46]  Derek M. Cunnold,et al.  Evidence for variability of atmospheric hydroxyl radicals over the past quarter century , 2005 .

[47]  Russell S. Vose,et al.  Maximum and minimum temperature trends for the globe: An update through 2004 , 2005 .

[48]  Junhong Wang,et al.  Global estimates of water‐vapor‐weighted mean temperature of the atmosphere for GPS applications , 2005 .

[49]  N. Kämpfer,et al.  Deriving the tropospheric integrated water vapor from tipping curve–derived opacity near 22 GHz , 2005 .

[50]  E. Brockmann,et al.  An Integrated Assessment of Measured and Modeled Integrated Water Vapor in Switzerland for the Period 2001–03 , 2005 .

[51]  Kevin E. Trenberth,et al.  Trends and variability in column-integrated atmospheric water vapor , 2005 .

[52]  David N. Whiteman,et al.  Absolute accuracy of water vapor measurements from six operational radiosonde types launched during AWEX-G and implications for AIRS validation , 2006 .

[53]  J. Pyle,et al.  Global Modelling of the Atmospheric Methyl Bromide Budget , 2006 .

[54]  Wolfgang Lucht,et al.  Carbon Balance and Management , 2006 .

[55]  M. Liniger,et al.  Comparison of GPS and ERA40 IWV in the Alpine region, including correction of GPS observations at Jungfraujoch (3584 m) , 2006 .

[56]  J. Lelieveld,et al.  New Directions: Watching over tropospheric hydroxyl (OH) , 2006 .

[57]  J. Randerson,et al.  Interannual variability in global biomass burning emissions from 1997 to 2004 , 2006 .

[58]  R. Gehrig,et al.  Long‐term trend analysis of aerosol variables at the high‐alpine site Jungfraujoch , 2007 .

[59]  C. Mätzler,et al.  Spatial interpolation of GPS integrated water vapour measurements made in the Swiss Alps , 2007 .

[60]  Tobias Nilsson,et al.  Long-term trends in the atmospheric water vapor content estimated from ground-based GPS data , 2008 .

[61]  S. Bekki,et al.  Diurnal changes in middle atmospheric H2O and O3: Observations in the Alpine region and climate models , 2008 .

[62]  Junhong Wang,et al.  Systematic Errors in Global Radiosonde Precipitable Water Data from Comparisons with Ground-Based GPS Measurements , 2008 .

[63]  Christian Mätzler,et al.  Refined Physical Retrieval of Integrated Water Vapor and Cloud Liquid for Microwave Radiometer Data , 2009, IEEE Transactions on Geoscience and Remote Sensing.

[64]  P. Steigenberger,et al.  On the homogeneity and interpretation of precipitable water time series derived from global GPS observations , 2009 .