Summer precipitation anomalies over eastern China axe characterized spatially by meridionally banded structnres fluctu- ating on interannual and interdecadal timescales, leading to regional droughts and floods. In add...Summer precipitation anomalies over eastern China axe characterized spatially by meridionally banded structnres fluctu- ating on interannual and interdecadal timescales, leading to regional droughts and floods. In addition to long-term trends, how these patterns may change under global warming has important implications for agricultural planning and water resources over this densely populated area. Using the latest Hadley Centre climate model, HadGEM3-GC2, this paper investigates the potential response of summer precipitation patterns over this region, by comparing the leading modes between a 4×CQ simulation and the model＇s pre-industrial control simulation. Empirical Orthogonal Function （EOF） analyses show that the first two leading modes account for about 20% of summer rainfall variability. EOF1 is a monopole mode associated with the developing phase of ENSO events and EOF2 is a dipole mode associated with the decaying phase of ENSO. Under 4×CO2 forcing, the dipole mode with a south-north orientation becomes dominant because of a strengthened influence from exces- sive warming of the Indian Ocean. On interdecadal time scales, the first EOF looks very different from the control simulation, showing a dipole mode of east-west contrast with enhanced influence from high latitudes.展开更多
Previous studies have revealed a combination mode （C-mode） occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates ...Previous studies have revealed a combination mode （C-mode） occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates the simulation of this C-mode and its asymmetric SST response in HadGEM3 and its resolution sensitivity using three sets of simulations at horizontal resolutions of N96, N216 and N512. The results show that HadGEM3 can capture well the spatial pattern of the C-mode associated surface wind anomalies, as well as the asymmetric response of SST in the tropical Pacific, but it strongly overestimates the explained variability of the C-mode compared to the ENSO mode. The model with the three resolutions is able to reproduce the distinct spectral peaks of the C-mode at the near annual combination frequencies, but the performance in simulating the longer periods is not satisfactory, presumably due to the unrealistic simulation of the ENSO mode. Increasing the horizontal resolution can improve the consistency between atmospheric and oceanic representations of the C-mode, but not necessarily enhance the accuracy of C-mode simulation compared with observation.展开更多
基金jointly sponsored by the National Key R&D Program of China(Grant No.2016YFA0600404)the National Natural Science Foundation of China(Grant Nos.41530532 and 41605057)+1 种基金the China Special Fund for Meteorological Research in the Public Interest(Grant No.GYHY201506001-1)the Jiangsu Collaborative Innovation Center for Climate Change,and the UK-China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP) China as part of the Newton Fund
文摘Summer precipitation anomalies over eastern China axe characterized spatially by meridionally banded structnres fluctu- ating on interannual and interdecadal timescales, leading to regional droughts and floods. In addition to long-term trends, how these patterns may change under global warming has important implications for agricultural planning and water resources over this densely populated area. Using the latest Hadley Centre climate model, HadGEM3-GC2, this paper investigates the potential response of summer precipitation patterns over this region, by comparing the leading modes between a 4×CQ simulation and the model＇s pre-industrial control simulation. Empirical Orthogonal Function （EOF） analyses show that the first two leading modes account for about 20% of summer rainfall variability. EOF1 is a monopole mode associated with the developing phase of ENSO events and EOF2 is a dipole mode associated with the decaying phase of ENSO. Under 4×CO2 forcing, the dipole mode with a south-north orientation becomes dominant because of a strengthened influence from exces- sive warming of the Indian Ocean. On interdecadal time scales, the first EOF looks very different from the control simulation, showing a dipole mode of east-west contrast with enhanced influence from high latitudes.
基金jointly supported by the China Meteorological Administration Special Public Welfare Research Fund(Grant No.GYHY201506013)the China National Science Foundation(Grant No.41606019)the UK-China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership(CSSP) China as part of the Newton Fund
文摘Previous studies have revealed a combination mode （C-mode） occurring in the Indo-Pacific region, arising from nonlinear interactions between ENSO and the western Pacific warm pool annual cycle. This paper evaluates the simulation of this C-mode and its asymmetric SST response in HadGEM3 and its resolution sensitivity using three sets of simulations at horizontal resolutions of N96, N216 and N512. The results show that HadGEM3 can capture well the spatial pattern of the C-mode associated surface wind anomalies, as well as the asymmetric response of SST in the tropical Pacific, but it strongly overestimates the explained variability of the C-mode compared to the ENSO mode. The model with the three resolutions is able to reproduce the distinct spectral peaks of the C-mode at the near annual combination frequencies, but the performance in simulating the longer periods is not satisfactory, presumably due to the unrealistic simulation of the ENSO mode. Increasing the horizontal resolution can improve the consistency between atmospheric and oceanic representations of the C-mode, but not necessarily enhance the accuracy of C-mode simulation compared with observation.
