Net biome productivity (NBP) dominates the observed large variation of atmospheric CO annual incr... more Net biome productivity (NBP) dominates the observed large variation of atmospheric CO annual increase over the last five decades. However, the dominant regions controlling inter-annual to multi-decadal variability of global NBP are still controversial (semi-arid regions vs. temperate or tropical forests). By developing a theory for partitioning the variance of NBP into the contributions of net primary production (NPP) and heterotrophic respiration (R ) at different timescales, and using both observation-based atmospheric CO inversion product and the outputs of 10 process-based terrestrial ecosystem models forced by 110-year observational climate, we tried to reconcile the controversy by showing that semi-arid lands dominate the variability of global NBP at inter-annual (<10 years) and tropical forests dominate at multi-decadal scales (>30 years). Results further indicate that global NBP variability is dominated by the NPP component at inter-annual timescales, and is progressiv...
IOP Conference Series: Earth and Environmental Science, 2010
The atmospheric circulation acts as a bridge between large-scale sources of climate variability, ... more The atmospheric circulation acts as a bridge between large-scale sources of climate variability, and climate variability on regional scales. Here a statistical method is applied to monthly mean Southern Hemisphere 500hPa geopotential height to separate the interannual variability of the seasonal mean into intraseasonal and slowly varying (time scales of a season or longer) components. Intraseasonal and slow modes of variability are estimated from realisations of models from the Coupled Model Intercomparison Project Phase 3 (CMIP3) twentieth century coupled climate simulation (20c3m) and are evaluated against those estimated from reanalysis data. The intraseasonal modes of variability are generally well reproduced across all CMIP3 20c3m models for both Southern Hemisphere summer and winter. The slow modes are in general less well reproduced than the intraseasonal modes, and there are larger differences between realisations than for the intraseasonal modes. New diagnostics are proposed to evaluate model variability. It is found that differences between realisations from each model are generally less than inter-model differences. Differences between model-mean diagnostics are found. The results obtained are applicable to assessing the reliability of changes in atmospheric circulation variability in CMIP3 models and for their suitability for further studies of regional climate variability.
2012 2nd International Conference on Remote Sensing, Environment and Transportation Engineering, 2012
ABSTRACT Precipitation is an important part of hydrologic cycle in global scale or regional scale... more ABSTRACT Precipitation is an important part of hydrologic cycle in global scale or regional scale. Although satellite-based observation is able to provide spatial and temporal distribution of precipitation, the satellite measurements tend to show systematic bias. A fusion method for mapping precipitation is introduced in this paper. The thin plate smoothing spline interpolation method is introduced to combine rainfall gauge and TRMM Multisatellite Precipitation Analysis (TMPA) data and map daily precipitation over china mainland region. With combined gauge data, the new daily precipitation provide more reliable high temporal/spatial resolution precipitation estimates.
ABSTRACT The interannual variability of seasonal precipitation in eastern China from fall to foll... more ABSTRACT The interannual variability of seasonal precipitation in eastern China from fall to following spring is examined for the period of 1951–2004 based on observations at 106 stations. The temporal variability of seasonal mean values is decomposed into intraseasonal (fast) and slow (potentially predictable) components. EOF analysis is then applied to both the fast and predictable components. We find that (1) the most predictable signal migrates in a north–south direction along with the annual cycle of the monsoon in east China, while spatial patterns of the leading fast modes does not change much; (2) the predictable signal of precipitation in eastern China is associated with anomalous atmospheric circulation patterns having more zonally symmetric structures while the fast time-varying precipitation components are accompanied by wavy anomalous atmospheric circulation patterns; (3) the most predictable signal has an apparent 1-season lagged correlation with the interannual variation of sea surface temperature associated with El Niño/Southern Oscillation; (4) The fast rainfall component is largely attributed to the intraseasonal variabilities of the Siberian High over the Eurasian continent and the subtropical high associated with the Western-Pacific-Oscillation-like variabilities over the North Pacific; and (5) The ENSO signal in the fall seasonal precipitation persisted throughout the entire 54-year period while the signal in winter intensified significantly after the mid-1970s. This is attributed to the weaker/stronger intensification of ENSO anomalies in the tropical Pacific during the fall/winter.
ABSTRACT A new approach is presented to construct daily gridded precipitation fields with high sp... more ABSTRACT A new approach is presented to construct daily gridded precipitation fields with high spatial resolution by fusing gauge precipitation observations and existing gridded precipitation, including remote sensing precipitation products and reanalysis data. The approach comprises of the following two steps: first, gauge observations are used as the response variable, and a bivariate thin-plate smoothing spline and an existing gridded precipitation field are used as explanatory variables, to estimate the precipitation trend surface which is better than using the gridded precipitation field only; then the Cressman weight is modified and applied to correct the correlated residual field to ensure the interpolated precipitation is close to observations. An approach for estimating the error covariance matrix of the interpolated precipitation field is also provided. An observed daily precipitation dataset from New Zealand is then applied to validate the proposed approach. The results suggest that the proposed interpolation approach can produce precipitation surfaces with high spatial resolution and smaller interpolation errors in both data sparse and data dense areas.
2011 International Conference on Electrical and Control Engineering, 2011
ABSTRACT This paper used the methods of thin-plate spline multisource data fusion, generating Chi... more ABSTRACT This paper used the methods of thin-plate spline multisource data fusion, generating China area precipitation for 3 hours time resolution and spatial resolution of 5 × 5 km. The comparison with general interpolation, Kriging interpolation and remote sensing data inversion method through the actual data illustrates the superiority of the proposed method.
... Zheng, Xiaogu, Reid E. Basher, 1999: Structural Time Series Models and Trend Detection in Glo... more ... Zheng, Xiaogu, Reid E. Basher, 1999: Structural Time Series Models and Trend Detection in Global and Regional Temperature Series. J. Climate, 12, 23472358. doi: 10.1175/1520-0442( 1999)012<2347:STSMAT>2.0.CO;2. ... Xiaogu Zheng and Reid E. Basher ...
Net biome productivity (NBP) dominates the observed large variation of atmospheric CO annual incr... more Net biome productivity (NBP) dominates the observed large variation of atmospheric CO annual increase over the last five decades. However, the dominant regions controlling inter-annual to multi-decadal variability of global NBP are still controversial (semi-arid regions vs. temperate or tropical forests). By developing a theory for partitioning the variance of NBP into the contributions of net primary production (NPP) and heterotrophic respiration (R ) at different timescales, and using both observation-based atmospheric CO inversion product and the outputs of 10 process-based terrestrial ecosystem models forced by 110-year observational climate, we tried to reconcile the controversy by showing that semi-arid lands dominate the variability of global NBP at inter-annual (<10 years) and tropical forests dominate at multi-decadal scales (>30 years). Results further indicate that global NBP variability is dominated by the NPP component at inter-annual timescales, and is progressiv...
IOP Conference Series: Earth and Environmental Science, 2010
The atmospheric circulation acts as a bridge between large-scale sources of climate variability, ... more The atmospheric circulation acts as a bridge between large-scale sources of climate variability, and climate variability on regional scales. Here a statistical method is applied to monthly mean Southern Hemisphere 500hPa geopotential height to separate the interannual variability of the seasonal mean into intraseasonal and slowly varying (time scales of a season or longer) components. Intraseasonal and slow modes of variability are estimated from realisations of models from the Coupled Model Intercomparison Project Phase 3 (CMIP3) twentieth century coupled climate simulation (20c3m) and are evaluated against those estimated from reanalysis data. The intraseasonal modes of variability are generally well reproduced across all CMIP3 20c3m models for both Southern Hemisphere summer and winter. The slow modes are in general less well reproduced than the intraseasonal modes, and there are larger differences between realisations than for the intraseasonal modes. New diagnostics are proposed to evaluate model variability. It is found that differences between realisations from each model are generally less than inter-model differences. Differences between model-mean diagnostics are found. The results obtained are applicable to assessing the reliability of changes in atmospheric circulation variability in CMIP3 models and for their suitability for further studies of regional climate variability.
2012 2nd International Conference on Remote Sensing, Environment and Transportation Engineering, 2012
ABSTRACT Precipitation is an important part of hydrologic cycle in global scale or regional scale... more ABSTRACT Precipitation is an important part of hydrologic cycle in global scale or regional scale. Although satellite-based observation is able to provide spatial and temporal distribution of precipitation, the satellite measurements tend to show systematic bias. A fusion method for mapping precipitation is introduced in this paper. The thin plate smoothing spline interpolation method is introduced to combine rainfall gauge and TRMM Multisatellite Precipitation Analysis (TMPA) data and map daily precipitation over china mainland region. With combined gauge data, the new daily precipitation provide more reliable high temporal/spatial resolution precipitation estimates.
ABSTRACT The interannual variability of seasonal precipitation in eastern China from fall to foll... more ABSTRACT The interannual variability of seasonal precipitation in eastern China from fall to following spring is examined for the period of 1951–2004 based on observations at 106 stations. The temporal variability of seasonal mean values is decomposed into intraseasonal (fast) and slow (potentially predictable) components. EOF analysis is then applied to both the fast and predictable components. We find that (1) the most predictable signal migrates in a north–south direction along with the annual cycle of the monsoon in east China, while spatial patterns of the leading fast modes does not change much; (2) the predictable signal of precipitation in eastern China is associated with anomalous atmospheric circulation patterns having more zonally symmetric structures while the fast time-varying precipitation components are accompanied by wavy anomalous atmospheric circulation patterns; (3) the most predictable signal has an apparent 1-season lagged correlation with the interannual variation of sea surface temperature associated with El Niño/Southern Oscillation; (4) The fast rainfall component is largely attributed to the intraseasonal variabilities of the Siberian High over the Eurasian continent and the subtropical high associated with the Western-Pacific-Oscillation-like variabilities over the North Pacific; and (5) The ENSO signal in the fall seasonal precipitation persisted throughout the entire 54-year period while the signal in winter intensified significantly after the mid-1970s. This is attributed to the weaker/stronger intensification of ENSO anomalies in the tropical Pacific during the fall/winter.
ABSTRACT A new approach is presented to construct daily gridded precipitation fields with high sp... more ABSTRACT A new approach is presented to construct daily gridded precipitation fields with high spatial resolution by fusing gauge precipitation observations and existing gridded precipitation, including remote sensing precipitation products and reanalysis data. The approach comprises of the following two steps: first, gauge observations are used as the response variable, and a bivariate thin-plate smoothing spline and an existing gridded precipitation field are used as explanatory variables, to estimate the precipitation trend surface which is better than using the gridded precipitation field only; then the Cressman weight is modified and applied to correct the correlated residual field to ensure the interpolated precipitation is close to observations. An approach for estimating the error covariance matrix of the interpolated precipitation field is also provided. An observed daily precipitation dataset from New Zealand is then applied to validate the proposed approach. The results suggest that the proposed interpolation approach can produce precipitation surfaces with high spatial resolution and smaller interpolation errors in both data sparse and data dense areas.
2011 International Conference on Electrical and Control Engineering, 2011
ABSTRACT This paper used the methods of thin-plate spline multisource data fusion, generating Chi... more ABSTRACT This paper used the methods of thin-plate spline multisource data fusion, generating China area precipitation for 3 hours time resolution and spatial resolution of 5 × 5 km. The comparison with general interpolation, Kriging interpolation and remote sensing data inversion method through the actual data illustrates the superiority of the proposed method.
... Zheng, Xiaogu, Reid E. Basher, 1999: Structural Time Series Models and Trend Detection in Glo... more ... Zheng, Xiaogu, Reid E. Basher, 1999: Structural Time Series Models and Trend Detection in Global and Regional Temperature Series. J. Climate, 12, 23472358. doi: 10.1175/1520-0442( 1999)012<2347:STSMAT>2.0.CO;2. ... Xiaogu Zheng and Reid E. Basher ...
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