| 1. |
- Cho, J. Y. N., et al.
(författare)
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Horizontal velocity structure functions in the upper troposphere and lower stratosphere 1. Observations
- 2001
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Ingår i: Journal of Geophysical Research-Atmospheres. - 0747-7309. ; 106:D10, s. 10223-10232
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Tidskriftsartikel (refereegranskat)abstract
- We compute horizontal velocity structure functions using quasiglobal data accumulated by specially equipped commercial aircraft on 7630 flights from August 1994 to December 1997. Using the ozone concentration measurements, we classify the results as tropospheric or stratospheric. We further divide the results into four absolute latitude bands. For separation distance r between 10 and 100 km, the lower stratospheric diagonal third-order structure functions are proportional to negative r. This implies a downscale energy cascade, and we estimate the mean energy dissipation rate to be (E) approximate to 6 x 10(-5) m(2) s(-3). For r between 300 and 1500 km a positive r(3) dependence was visible for the polar stratospheric data. This may be the result of a two-dimensional (2D) turbulence downscale enstrophy cascade, and we estimate the average enstrophy flux to be IIomega approximate to 2 x 10(-15) s(-3) and the energy spectral constant to be K approximate to 2. The negative sign of these third-order functions at mesoscales in both the upper troposphere and lower stratosphere provide no support for an inverse energy cascade 2D turbulence. At scales above similar to 100 km, the second-order structure functions increase with latitude in the troposphere and decrease with latitude in the stratosphere. The off-diagonal third-order functions in the stratosphere show a remarkably clean negative r(2) dependency from 10 to 1000 km in scale.
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| 2. |
- Lindborg, Erik, et al.
(författare)
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Horizontal velocity structure functions in the upper troposphere and lower stratosphere 2. Theoretical considerations
- 2001
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Ingår i: Journal of Geophysical Research-Atmospheres. - 0747-7309. ; 106:D10, s. 10233-10241
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Tidskriftsartikel (refereegranskat)abstract
- The Kolmogorov equation for the third-order velocity structure function is derived for atmospheric mesoscale motions on an f plane. A possible solution is a negative third-order structure function, varying linearly with separation distance and mean dissipation, just as in three-dimensional turbulence, but with another scaling constant. On the basis of the analysis and the observed stratospheric third-order structure function, it is argued that there is a forward energy cascade in the mesoscale range of atmospheric motions. The off-diagonal part of the general tenser equation is also studied. In this equation there is an explicit Coriolis term that may be crucial for the understanding of the kinetic energy spectrum at scales larger than 100km.
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| 3. |
- Moberg, A, et al.
(författare)
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Day-to-day temperature variability trends in 160-to 275-year-long European instrumental records
- 2000
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. - : AMER GEOPHYSICAL UNION. - 0747-7309. ; 105:D18, s. 22849-22868
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Tidskriftsartikel (refereegranskat)abstract
- Day-to-day temperature variability is investigated in eight European series of daily mean temperatures beginning between 1722 and 1833. Eight statistical measures of day-to-day temperature variability are compared. The intramonthly standard deviation of d
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| 4. |
- Peichl, Matthias, et al.
(författare)
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Energy exchange and water budget partitioning in a boreal minerogenic mire
- 2013
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Ingår i: Journal of Geophysical Research. - 2156-2202. ; 118, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated patterns and controls of the seasonal and inter-annual variations in energy fluxes (i.e., sensible heat, H, and latent heat, lambda E) and partitioning of the water budget (i.e., precipitation, P; evapotranspiration, ET; discharge, Q; and soil water storage, Delta S) over five years (2001-2005) in a boreal oligotrophic fen in northern Sweden based on continuous eddy covariance, water table level (WTL), and weir measurements. For the growing season (May 1 to September 31), the 5 year averages (+/- standard deviation) of the midday (10:00 to 14:00 h) Bowen ratio (beta, i.e., H/lambda E) was 0.86 +/- 0.08. Seasonal and inter-annual variability of beta was mainly driven by lambda E which itself was strongly controlled by both weather (i.e., vapor pressure deficit, D, and net radiation, R-n) and physiological parameters (i.e., surface resistance). During the growing season, surface resistance largely exceeded aerodynamic resistance, which together with low mean values of the actual ET to potential ET ratio (0.55 +/- 0.05) and Priestley-Taylor alpha (0.89) suggests significant physiological constrains on ET in this well-watered fen. Among the water budget components, the inter-annual variability of ET was lower (199 to 298 mm) compared to Q (225 to 752 mm), with each accounting on average for 34 and 65% of the ecosystem water loss, respectively. The fraction of P expended into ET was negatively correlated to P and positively to R-n. Although a decrease in WTL caused a reduction of the surface conductance, the overall effect of WTL on ET was limited. Non-growing season (October 1 to April 30) fluxes of H, lambda E, and Q were significant representing on average -67%, 13%, and 61%, respectively, of their growing season sums (negative sign indicates opposite flux direction between the two seasons). Overall, our findings suggest that plant functional type composition, P and R-n dynamics (i.e., amount and timing) were the major controls on the partitioning of the mire energy and water budgets. This has important implications for the regional climate as well as for ecosystem development, nutrient, and carbon dynamics. Citation: Peichl, M., J. Sagerfors, A. Lindroth, I. Buffam, A. Grelle, L. Klemedtsson, H. Laudon, and M. B. Nilsson (2013), Energy exchange and water budget partitioning in a boreal minerogenic mire, J. Geophys. Res. Biogeosci., 118, 1-13, doi:10.1029/2012JG002073.
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| 5. |
- Rakov, VA, et al.
(författare)
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New insights into lightning processes gained from triggered-lightning experiments in Florida and Alabama
- 1998
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. - : AMER GEOPHYSICAL UNION. - 0747-7309. ; 103:D12, s. 14117-14130
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Tidskriftsartikel (refereegranskat)abstract
- Analyses of electric and magnetic fields measured at distances from tens to hundreds of meters from the ground strike point of triggered lightning at Camp Blanding, Florida, and at 10 and 20 m at Fort McClellan, Alabama, in conjunction with currents measu
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| 6. |
- Schulz, A, et al.
(författare)
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Arctic ozone loss in threshold conditions: Match observations in 1997/1998 and 1998/1999
- 2001
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. - : AMER GEOPHYSICAL UNION. - 0747-7309. ; 106:D7, s. 7495-7503
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Tidskriftsartikel (refereegranskat)abstract
- Chemical ozone loss rates inside the Arctic polar vortex were determined in early 1998 and early 1999 by using the Match technique based on coordinated ozonesonde measurements. These two winters provide the only opportunities in recent years to investigat
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| 7. |
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| 8. |
- Yan, ZW, et al.
(författare)
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Recent trends in weather and seasonal cycles: An analysis of daily data from Europe and China
- 2001
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Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. - 0747-7309. ; 106:D6, s. 5123-5138
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Tidskriftsartikel (refereegranskat)abstract
- A wavelet analysis is conducted to investigate daily variability (DV, timescales of less than 3 days), weekly (weather) variability (WV, timescales of 5 days up to 2 months), and seasonal variability (SV, timescales of 8 to 17 months) in five temperature
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