Water vapour flux divergence over the Arabian Sea during 1987 summer monsoon using satellite data

1990 ◽  
Vol 51 (1-2) ◽  
pp. 199-209 ◽  
Author(s):  
P. N. Vinayachandran ◽  
M. R. Ramesh Kumar
2000 ◽  
Vol 80 (2) ◽  
pp. 367-373 ◽  
Author(s):  
R. L. Raddatz

Water vapour from regional evapotranspiration that falls again as rain within the same region is referred to as recycled rainfall. This study estimated the summer rainfall recycling ratios (i.e., the relative contribution of recycled rain to total rain) for an agricultural region of the Canadian Prairies by examining the soil water balance component of the land surface branch of the water cycle along with the atmospheric branch of the cycle for June-July-August of 1997, 1998 and 1999. Recycled rain accounted for 24 to 35% of the total rainfall. For these three summers, this study also estimated the horizontal water vapour flux divergence for the region, and compared the areal average summer evapotranspiration totals determined from land-use weighted soil water balance modelling and as residuals in the atmospheric water balance equation. The horizontal water vapour flux divergence per unit area averaged 36 mm. The mean difference between the evapotranspiration estimates was about 15%. It can be concluded, for the summers of 1997, 1998 and 1999, that: (1) regional evapotranspiration was secondary to advection, yet significant, as a source of water vapour for rainfall on the Canadian Prairies, (2) the agricultural area of the Canadian Prairies was a source region of water vapour – consistent with the arid character of the climate, and (3) the land-use weighted soil water balance estimates of areal average evapotranspiration were reasonably accurate. Key words: Water cycle, horizontal water vapour flux, evapotranspiration, atmospheric water balance, soil water balance


2016 ◽  
Vol 37 (9) ◽  
pp. 3660-3673 ◽  
Author(s):  
Weili Duan ◽  
Bin He ◽  
Netrananda Sahu ◽  
Pingping Luo ◽  
Daniel Nover ◽  
...  

2003 ◽  
Vol 23 (13) ◽  
pp. 1663-1675 ◽  
Author(s):  
Adrie F. G. Jacobs ◽  
Bert G. Heusinkveld ◽  
Albert A. M. Holtslag

2006 ◽  
Vol 6 (3) ◽  
pp. 5329-5355 ◽  
Author(s):  
C. Ammann ◽  
A. Brunner ◽  
C. Spirig ◽  
A. Neftel

Abstract. The most direct approach for measuring the exchange of biogenic volatile organic compounds between terrestrial ecosystems and the atmosphere is the eddy covariance technique. It has been applied several times in the last few years using fast response proton-transfer-reaction mass spectrometry (PTR-MS). We present an independent validation of this technique by applying it to measure the water vapour flux in comparison to a common reference system comprising an infra-red gas analyser (IRGA). Water vapour was detected in the PTR-MS at mass 37 (atomic mass units) corresponding to the cluster ion H3O+·H2O. During a five-week field campaign at a grassland site, we obtained a non-linear but stable calibration function between the mass 37 signal and the reference water vapour concentration. With a correction of the high-frequency damping loss based on empirical ogive analysis, the eddy covariance water vapour flux obtained with the PTR-MS showed a very good agreement with the flux of the reference system. The application of the empirical ogive method for high-frequency correction led to significantly better results than using a correction based on theoretical spectral transfer functions. This finding is attributed to adsorption effects on the tube walls that are presently not included in the theoretical correction approach.


2007 ◽  
Vol 4 (3) ◽  
pp. 395-410 ◽  
Author(s):  
A. Brunner ◽  
C. Ammann ◽  
A. Neftel ◽  
C. Spirig

Abstract. Concentrations and fluxes of methanol were measured above two differently managed grassland fields (intensive and extensive) in central Switzerland during summer 2004. The measurements were performed with a proton-transfer-reaction mass-spectrometer and fluxes were determined by the eddy covariance method. The observed methanol emission showed a distinct diurnal cycle and was strongly correlated with global radiation and water vapour flux. Mean and maximum daily emissions were found to depend on grassland species composition and, for the intensive field, also on the growing state. The extensive field with a more complex species composition had higher emissions than the graminoid-dominated intensive field, both on an area and on a biomass basis. A simple parameterisation depending on the water vapour flux and the leaf area index allowed a satisfying simulation of the temporal variation of methanol emissions over the growing phase. Accumulated carbon losses due to methanol emissions accounted for 0.024 and 0.048% of net primary productivity for the intensive and extensive field, respectively. The integral methanol emissions over the growing periods were more than one order of magnitude higher than the emissions related to cut and drying events.


2007 ◽  
Vol 147 (3-4) ◽  
pp. 140-156 ◽  
Author(s):  
Andreas Ibrom ◽  
Ebba Dellwik ◽  
Henrik Flyvbjerg ◽  
Niels Otto Jensen ◽  
Kim Pilegaard

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