排序方式： 共有5条查询结果，搜索用时 15 毫秒
1
1.
Dragutin T. Mihailovic Jelena Lazic Jacek Leśny Janusz Olejnik Branislava Lalic Darko Kapor Ana Cirisan 《Theoretical and Applied Climatology》2010,100(3-4):299-323
Numerical simulations and tests with the recently redesigned land–air parameterization scheme (LAPS) are presented. In all experiments, supported either by one-point micrometeorological, 1D or 3D simulations, the attention has been directed to: (1) comparison of simulation outputs, expressing the energy transfer over and through heterogeneous and non-heterogeneous surfaces, versus observations and (2) analysis of uncertainties occurring in the solution of the energy balance equation at the land–air interface. To check the proposed method for aggregation of albedo, “propagating hole” sensitivity tests with LAPS over a sandstone rock grid cell have been performed with the forcing meteorological data for July 17, 1999 in Baxter site, Philadelphia (USA). Micrometeorological and biophysical measurements from the surface experiments conducted over crops and apple orchard in Serbia, Poland, Austria and France were used to test the operation of LAPS in calculating surface fluxes and canopy environment temperatures within and above plant covers of different densities. In addition, sensitivity tests with single canopy covers over the Central Europe region and comparison against the observations taken from SYNOP data using 3D simulations were made. Validation of LAPS performances over a solid surface has been done by comparison of 2 m air temperature observations against 5-day simulations over the Sahara Desert rocky ground using 3D model. To examine how realistically the LAPS simulates surface processes over a heterogeneous surface, we compared the air temperature measured at 2 m and that predicted by the 1D model with the LAPS as the surface scheme. Finally, the scheme behaviour over urban surface was tested by runs over different parts of a hypothetical urban area. The corresponding 1D simulations were carried out with an imposed meteorological dataset collected during HAPEX-MOBILHY experiment at Caumont (France). The quantities predicted by the LAPS compare well with the observations and the various subcomponents of the scheme appear to operate realistically. 相似文献
2.
3.
A high-quality monthly pan evaporation dataset of 60 stations has been developed for monitoring long-term pan evaporation
trends over Australia. The quality control process involved examination of historical station metadata together with an objective
test comparing candidate series with neighboring stations. Identified points of discontinuity were located, including installations
of bird guards, site relocations and changes in exposure. Appropriate inhomogeneity adjustments have been applied using established
methods to produce the first homogeneous pan evaporation dataset for Australia. Analysis of these data reveals that Australian
annual mean pan-evaporation shows large interannual variability with no trend over the 1970–2005 period. Previous studies
using unadjusted data have shown a decline in pan evaporation, highlighting the importance of checking data for homogeneity
before drawing conclusions about long-term trends. A strong inverse correlation is evident between all-Australian means of
pan evaporation and rainfall, while a moderate positive correlation is found between pan evaporation and mean temperature.
The positive correlations between mean temperature and pan evaporation that exist on the interannual time scales are not reflected
in the long-term trends, highlighting that the mechanisms that are responsible for variations on the short and longer time
scales are different. This result cautions against the expectation that large changes in potential evaporation are a natural
consequence of global warming. 相似文献
4.
A Roughness Sublayer Wind Profile Above A Non-Uniform Surface 总被引：2，自引：0，他引：2
D. T. Mihailović Branislava Lalić B. Rajković I. Arsenić 《Boundary-Layer Meteorology》1999,93(3):425-451
In atmospheric models for different scales the underlying surface consists of patches of bare soil and plant communities with different morphological parameters. Experimental evidence indicates that there is a significant departure of the wind profile above a vegetative surface from that predicted by the logarithmic relationship, which gives values that are greater than those observed. This situation can seriously disturb the physical picture concerning the transfers of momentum, heat and water vapour from the surface into the atmosphere.The intention of this paper is to generalise the calculation of exchange of momentum between the atmosphere and a non-homogenous vegetative surface, and to derive a general equation for the wind speed profile in a roughness sublayer under neutral conditions. Furthermore, these results are extended to non-neutral cases. The suggested expression for the wind profile is compared with some earlier approaches and the observations obtained above a broad range of plant communities. 相似文献
5.
Branislava Jovanovic Dean Collins Karl Braganza Doerte Jakob David A. Jones 《Climatic change》2011,108(3):485-517
A high-quality monthly total cloud amount dataset for 165 stations has been developed for monitoring and assessing long-term
trends in cloud cover over Australia. The dataset is based on visual 9 a.m. and 3 p.m. observations of total cloud amount,
with most records starting around 1957. The quality control process involved examination of historical station metadata, together
with an objective statistical test comparing candidate and reference cloud series. Individual cloud series were also compared
against rainfall and diurnal temperature range series from the same site, and individual cloud series from neighboring sites.
Adjustments for inhomogeneities caused by relocations and changes in observers were applied, as well as adjustments for biases
caused by the shift to daylight saving time in the summer months. Analysis of these data reveals that the Australian mean
annual total cloud amount is characterised by high year-to-year variability and shows a weak, statistically non-significant
increase over the 1957–2007 period. A more pronounced, but also non-significant, decrease from 1977 to 2007 is evident. A
strong positive correlation is found between all-Australian averages of cloud amount and rainfall, while a strong negative
correlation is found between mean cloud amount and diurnal temperature range. Patterns of annual and seasonal trends in cloud
amount are in general agreement with rainfall changes across Australia, however the high-quality cloud network is too coarse
to fully capture topographic influences. Nevertheless, the broadscale consistency between patterns of cloud and rainfall variations
indicates that the new total cloud amount dataset is able to adequately describe the broadscale patterns of change over Australia.
Favourable simple comparisons between surface and satellite measures of cloudiness suggest that satellites may ultimately
provide the means for monitoring long-term changes in cloud over Australia. However, due to the relative shortness and homogeneity
problems of the satellite record, a robust network of surface cloud observations will be required for many years to come. 相似文献
1