scholarly journals The Influence of Tropical Pacific SST Anomaly on Surface Air Temperature in China

2014 ◽  
Vol 27 (4) ◽  
pp. 1425-1444 ◽  
Author(s):  
XiaoJing Jia ◽  
Hai Lin ◽  
Xia Yao
Keyword(s):  
Pacific Ocean ◽  
Air Temperature ◽  
Numerical Models ◽  
Surface Air Temperature ◽  
Tropical Pacific ◽  
The Arctic ◽  
Seasonal Forecasts ◽  
Climate Trend ◽  
Atmospheric Component ◽  
The Tropical Pacific

Abstract The influence of the tropical Pacific sea surface temperature (SST) on the wintertime surface air temperature (SAT) in China is investigated using both the observational data and the output of coupled ocean–atmosphere numerical models during the period from 1960 to 2006. A singular value decomposition analysis (SVD) is applied between 500-hPa geopotential height (Z500) in the Northern Hemisphere and SST in the tropical Pacific Ocean to get the tropical Pacific SST-forced atmospheric patterns. The association of the SAT over China and the tropical Pacific SST is measured by calculating the temporal correlation coefficient (TCC) between the SAT and the expansion coefficient of the atmospheric component of the leading two SVD modes. Results show that the SAT over China is significantly correlated to the second SVD mode (SVD2). The SST component of SVD2 is characterized by negative tropical Pacific SST anomalies centered over the midequatorial Pacific Ocean. The atmospheric component of SVD2 (ASVD2) shares many similarities in spatial structures to the Arctic Oscillation (AO). The time variation of ASVD2, however, is found more closely correlated to the variation of SAT over China than the AO. When SVD2 is in its positive phase, the SAT over China tends to be warmer than normal. Further analysis indicates that the TCC between the SAT in China and ASVD2 is largely decreased after the long-term climate trend is removed. The time variability of the tropical Pacific SST-forced large-scale atmospheric patterns and its relationship to SAT are reasonably captured by the multimodel ensemble (MME) seasonal forecasts. An examination of the MME forecast skill indicates that ASVD2 contributes significantly to the TCC skill of MME forecasts.

scholarly journals Influence of Forced Large-Scale Atmospheric Patterns on Surface Air Temperature in China

2011 ◽  
Vol 139 (3) ◽  
pp. 830-852 ◽  
Author(s):  
Xiaojing Jia ◽  
Hai Lin
Keyword(s):  
Air Temperature ◽  
General Circulation ◽  
Large Scale ◽  
Statistical Approach ◽  
Surface Air Temperature ◽  
Tropical Pacific ◽  
Second Phase ◽  
Seasonal Forecasts ◽  
The Relationship ◽  
The Tropical Pacific

Abstract The seasonality of the influence of the tropical Pacific sea surface temperature (SST)-forced large-scale atmospheric patterns on the surface air temperature (SAT) over China is investigated for the period from 1969 to 2001. Both observations and output from four atmospheric general circulation models (GCMs) involved in the second phase of the Canadian Historical Forecasting Project (HFP) are used. The large-scale atmospheric patterns are obtained by applying a singular value decomposition (SVD) analysis between 500-hPa geopotential height (Z500) in the Northern Hemisphere and SST in the tropical Pacific Ocean. Temporal correlations between the SAT over China and the expansion coefficients of the leading SVD modes show that SAT over China can be significantly influenced by these large-scale atmospheric patterns, especially by the second SVD mode. The relationship between the SAT over China and the leading atmospheric patterns in the observations is partly captured by the HFP models. Furthermore, seasonal forecasts of SAT over China are postprocessed using a statistical approach. This statistical approach is designed based on the relationship between the forecast Z500 and the observed SST to calibrate the SAT forecasts. Results show that the forecast skill of the postprocessed SAT over China can be improved in all seasons to some extent, with that in fall having the most significant improvement. Possible mechanisms behind the improvement of the forecast are investigated.

scholarly journals Impact of Model Physics on Seasonal Forecasts of Surface Air Temperature in the Arctic

2017 ◽  
Vol 145 (3) ◽  
pp. 773-782 ◽  
Author(s):  
Qiong Yang ◽  
Muyin Wang ◽  
James E. Overland ◽  
Wanqiu Wang ◽  
Thomas W. Collow
Keyword(s):  
Sea Ice ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Ice Thickness ◽  
Seasonal Forecasts ◽  
Forecast System ◽  
Climate Forecast System ◽  
Sea Ice Thickness ◽  
Forecast Bias

The impacts of model physics and initial sea ice thickness on seasonal forecasts of surface energy budget and air temperature in the Arctic during summer were investigated based on Climate Forecast System, version 2 (CFSv2), simulations. The model physics changes include the enabling of a marine stratus cloud scheme and the removal of the artificial upper limit on the bottom heat flux from ocean to sea ice. The impact of initial sea ice thickness was examined by initializing the model with relatively realistic sea ice thickness generated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS). Model outputs were compared to that from a control run that did not impose physics changes and used Climate Forecast System Reanalysis (CFSR) sea ice thickness. After applying the physics modification to either sea ice thickness initialization, the simulated total cloud cover more closely resembled the observed monthly variations of total cloud cover except for the midsummer reduction. Over the Chukchi–Bering Seas, the model physics modification reduced the seasonal forecast bias in surface air temperature by 24%. However, the use of initial PIOMAS sea ice thickness alone worsened the surface air temperature predictions. The experiment with physics modifications and initial PIOMAS sea ice thickness achieves the best surface air temperature improvement over the Chukchi–Bering Seas where the area-weighted forecast bias was reduced by 71% from 1.05 K down to −0.3 K compared with the control run. This study supports other results that surface temperatures and sea ice characteristics are highly sensitive to the Arctic cloud and radiation formulations in models and need priority in model formulation and validation.

scholarly journals Infrared Interferometric Measurements of the Near-Surface Air Temperature over the Oceans

2005 ◽  
Vol 22 (7) ◽  
pp. 1019-1032 ◽  
Author(s):  
P. J. Minnett ◽  
K. A. Maillet ◽  
J. A. Hanafin ◽  
B. J. Osborne
Keyword(s):  
Air Temperature ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Heat Island ◽  
Radiometric Measurement ◽  
Near Surface ◽  
Air Temperatures ◽  
Wide Range ◽  
Marine Air ◽  
The Tropical Pacific

Abstract The radiometric measurement of the marine air temperature using a Fourier transform infrared spectroradiometer is described. The measurements are taken by the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) that has been deployed on many research ships in a wide range of conditions. This approach is inherently more accurate than conventional techniques and can be used to determine some of the error characteristics of the standard measurements. Examples are given from several cruises ranging from the Arctic to the equatorial Pacific Oceans. It is shown that the diurnal heating signal in radiometric air temperatures in the tropical Pacific can typically reach an amplitude of ∼15% of that measured by conventional sensors. Conventional data have long been recognized as being contaminated by direct solar heating and heat island effects of the ships or buoys on which they are mounted, but here this effect is quantified by comparisons with radiometric measurements.

Thorium-derived dust fluxes to the tropical Pacific Ocean, 58Ma

2012 ◽  
Vol 87 ◽  
pp. 194-209 ◽  
Author(s):  
Stella C. Woodard ◽  
Deborah J. Thomas ◽  
Franco Marcantonio
Keyword(s):  
Pacific Ocean ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
The Tropical Pacific

scholarly journals Eddy-mean flow decomposition and eddy-diffusivity estimates in the tropical Pacific Ocean: 1. Methodology

1998 ◽  
Vol 103 (C13) ◽  
pp. 30855-30871 ◽  
Author(s):  
Sonia Bauer ◽  
Mark S. Swenson ◽  
Annalisa Griffa ◽  
Arthur J. Mariano ◽  
Ken Owens
Keyword(s):  
Pacific Ocean ◽  
Eddy Diffusivity ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
Mean Flow ◽  
The Tropical Pacific ◽  
Flow Decomposition

Isolation of sea surface salinity maps on various timescales in the tropical Pacific Ocean

2012 ◽  
Vol 68 (5) ◽  
pp. 687-701 ◽  
Author(s):  
Jian Chen ◽  
Ren Zhang ◽  
Huizan Wang ◽  
Yuzhu An ◽  
Peng Peng ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Tropical Pacific ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Tropical Pacific Ocean ◽  
Surface Salinity ◽  
The Tropical Pacific

scholarly journals Mechanism of Seasonal Arctic Sea Ice Evolution and Arctic Amplification

2016 ◽  
Author(s):  
Kwang-Yul Kim ◽  
Benjamin D. Hamlington ◽  
Hanna Na ◽  
Jinju Kim
Keyword(s):  
Heat Flux ◽  
Sea Ice ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Longwave Radiation ◽  
The Arctic ◽  
Turbulent Heat ◽  
Arctic Amplification ◽  
Ice Melting ◽  
Downward Longwave Radiation

Abstract. Sea ice melting is proposed as a primary reason for the Artic amplification, although physical mechanism of the Arctic amplification and its connection with sea ice melting is still in debate. In the present study, monthly ERA-interim reanalysis data are analyzed via cyclostationary empirical orthogonal function analysis to understand the seasonal mechanism of sea ice melting in the Arctic Ocean and the Arctic amplification. While sea ice melting is widespread over much of the perimeter of the Arctic Ocean in summer, sea ice remains to be thin in winter only in the Barents-Kara Seas. Excessive turbulent heat flux through the sea surface exposed to air due to sea ice melting warms the atmospheric column. Warmer air increases the downward longwave radiation and subsequently surface air temperature, which facilitates sea surface remains to be ice free. A 1 % reduction in sea ice concentration in winter leads to ~ 0.76 W m−2 increase in upward heat flux, ~ 0.07 K increase in 850 hPa air temperature, ~ 0.97 W m−2 increase in downward longwave radiation, and ~ 0.26 K increase in surface air temperature. This positive feedback mechanism is not clearly observed in the Laptev, East Siberian, Chukchi, and Beaufort Seas, since sea ice refreezes in late fall (November) before excessive turbulent heat flux is available for warming the atmospheric column in winter. A detailed seasonal heat budget is presented in order to understand specific differences between the Barents-Kara Seas and Laptev, East Siberian, Chukchi, and Beaufort Seas.

scholarly journals Tropopause height at 78° N 16° E: average seasonal variation 2007–2010

2011 ◽  
Vol 11 (1) ◽  
pp. 39-52
Author(s):  
C. M. Hall ◽  
G. Hansen ◽  
F. Sigernes ◽  
K. M. Kuyeng Ruiz
Keyword(s):  
Climate Change ◽  
Seasonal Variation ◽  
Air Temperature ◽  
High Latitude ◽  
Column Density ◽  
Surface Air Temperature ◽  
The Arctic ◽  
Tropopause Height ◽  
Vhf Radar ◽  
Ozone Column

Abstract. We present a seasonal climatology of tropopause altitude for 78° N 16° E derived from observations 2007–2010 by the SOUSY VHF radar on Svalbard. The spring minimum occurs one month later than that of surface air temperature and instead coincides with the maximum in ozone column density. This confirms similar studies based on radiosonde measurements in the arctic and demonstrates downward control by the stratosphere. If one is to exploit the potential of tropopause height as a metric for climate change at high latitude and elsewhere, it is imperative to observe and understand the processes which establish the tropopause – an understanding to which this study contributes.

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