Sea surface temperatures (SSTs) in the North Atlantic Ocean show multidecadal fluctuations known ... more Sea surface temperatures (SSTs) in the North Atlantic Ocean show multidecadal fluctuations known as the Atlantic Multidecadal Oscillation (AMO) . The AMO has been related to the thermohaline circulation, which implies a strong association to large-scale climate variability. Indeed, the variability of a wide range of climate parameters in the North Atlantic region has been related to the AMO, e.g. temperatures, precipitation, drought and hurricanes. Moreover, the AMO seems to influence the Asian summer monsoon, and South American precipitation. Most of these relationships have been established analyzing the short observational records or from experiments with climate models. In order to establish the stability of the multidecadal oscillation in the AMO as well as the association with climate, it is necessary to extend the record further back in time. Using tree-ring data from the Northern Hemisphere a reconstruction of the AMO, spanning AD 800 to 2000 is presented. The reconstruction suggests anomalously warm North Atlantic SSTs from ca. AD 900 to 1050, coinciding with the "Medieval Warm Period", as well as a phase between 1100 and 1400 with relatively little interdecadal variability. There is a prolonged negative phase of AMO from ca. 1600-1860, i.e. during the "Little Ice Age" (LIA). The multidecadal variability of approximately 40-80 years remains constant throughout the record, except around ca 1500-1700, i.e. during the LIA, when it breaks down.
The Journal of bone and joint surgery. American volume, 2003
Recent reports on internal fixation of acute fractures of the scaphoid waist have demonstrated hi... more Recent reports on internal fixation of acute fractures of the scaphoid waist have demonstrated higher rates of central placement of the screw when cannulated screws were used than when noncannulated screws were used. This cadaveric study was designed to determine whether central placement in the proximal fragment of the scaphoid offers a biomechanical advantage. Eleven matched pairs of scaphoids were removed from fresh cadaveric wrists. Each scaphoid was placed in a custom manufactured jig that was used to create reproducible central and eccentric positioning of the guidewire. Then a linear osteotomy was made followed by placement of a Herbert-Whipple cannulated screw to fix the osteotomy. The specimen was then potted in a holder with use of polymethylmethacrylate with a Kirschner wire passed through the proximal end of the scaphoid and placed into a fixture with a pneumatically driven plunger resting on the surface of the distal pole. The load acting through the plunger was measure...
International journal of pediatric otorhinolaryngology, 2003
Children have traditionally been kept in hospital overnight after mastoid surgery, but evidence f... more Children have traditionally been kept in hospital overnight after mastoid surgery, but evidence from the US in adults suggests that a substantial number of patients may be suitable for discharge on the day of surgery. We sought to ascertain the proportion of our children having mastoid operations between February 1994 and December 2000 who were suitable for same-day discharge. We also evaluated some of the factors that prevented discharge the same day. A standard proforma was used to record relevant data in 35 children (mean age 10 years 6 months) undergoing consecutive mastoid operations at Mayday University Hospital, London, UK. Operative findings, duration of anaesthesia and time back on ward were recorded as well as details regarding admission, follow-up findings and complications. A bed was booked preoperatively but there was intent to discharge the patient if feasible. Nine out of twelve patients (75%) operated between 1998 and 2000 were suitable for discharge on the day of su...
An ensemble of simulations of 20th Century climate using the HadCM3 coupled climate model forced ... more An ensemble of simulations of 20th Century climate using the HadCM3 coupled climate model forced with estimates of natural and anthropogenic forcings is compared with instrumental temperature data sets. The results show that while external climate forcing can account for most of 20th century climate change, there are also significant multidecadal climate fluctuations that are not produced by forcings. A major part of this variability corresponds to the `Atlantic Multidecadal Oscillation' (AMO), which has been identified in observations, and represents coherent fluctuations in temperature throughout most of the Northern Hemisphere. Using a 1400 year calculation with HadCM3 without external forcings, we show the model produces a quasi-periodic internal mode with a pattern, amplitude and characteristic time scale similar to that of the observed AMO. Further, the model implies the AMO is a genuine long-lived quasi-cyclical climate phenomenon related to large-scale oceanic heat transport variations associated with changes in the strength of the thermohaline circulation (THC) of about 2 Sv (10%). In the simulation, stronger cross-equatorial temperature gradients are associated with the anomalous northward ocean heat transport during a warm AMO phase. This causes a northward displacement of the mean ITCZ, leading to more rainfall and the development of anomalously fresh water in the tropical North Atlantic. These sustained anomalies slowly propagate to the subpolar North Atlantic in about 5 decades, where they act to slow the THC. The results also confirm observed links between the AMO and multidecadal variability in north-east Brazil and Sahel precipitation, and Atlantic hurricane formation. In addition, the simulated link between temperature and the THC allows an estimate of possible past changes in THC strength. Our results imply that the THC has undergone distinct strong and weak phases in the 20th century and has strengthened over recent decades. We also produce a forecast of the natural component of future THC change that shows a likely decline in the next 35 years to levels similar to the lowest levels reconstructed in the 20th century. This would accelerate anthropogenic THC weakening and the associated change in the AMO would offset Northern Hemisphere warming.
An improved operational Global Seasonal Forecast System (GloSea5) was introduced by the Met Offic... more An improved operational Global Seasonal Forecast System (GloSea5) was introduced by the Met Office in Spring 2013. The new system has an atmospheric resolution of approximately 40km in mid latitudes and 0.25 degree in the ocean. Hindcast simulations of past years show GloSea5 possesses unprecedented skill in predicting the winter North Atlantic Oscillation (NAO), with an anomaly correlation of 0.6 for the hindcast period. This represents a dramatic improvement over the current generation of seasonal prediction systems, which lack any significant skill in predicting the NAO (anomaly correlations less than 0.2). It suggests that slowly changing components in the climate system (e.g. ocean heat content anomalies) do indeed play an important role in the variability of extratropical atmospheric circulation in winter, as opposed to being predominantly unpredictable weather noise. Importantly, NAO predictability provides predictability of surface winter climate in Europe and the United Sta...
ABSTRACT The Met Office Hadley Centre Decadal Prediction System (DePreSys) produced the first ini... more ABSTRACT The Met Office Hadley Centre Decadal Prediction System (DePreSys) produced the first initialised short-term climate prediction in 2007. It showed, for the first time, that climate prediction up to a decade ahead was improved by including an accurate representation of the initial state of the ocean and atmosphere. Decadal predictions have subsequently been produced by a wide range of climate modelling centres, and this activity is an important new feature of IPCC AR5. Here, results from a comprehensively revised version of the Decadal Prediction System (DePreSys version 2) will be presented. The key enhancement is the use of the Met Office's latest climate model HadGEM3 within the forecast system (as opposed to the HadCM3 model used in the original system). This has approximately doubled the horizonal resolution of HadCM3, and quadrupled the number of vertical levels, in both atmospheric and oceanic components. In addition, the atmospheric component has an improved dynamical core, fully revised parameterisations, and is coupled to a different ocean model (NEMO). The initialisation methodology is essentially the same as for DePreSys version 1. Taking a global overview, indices of local predictive skill show significant improvements for key surface variables across a range of timescales relative to the previous system. In particular, there appears to be more skill in predicting multiannual to decadal variability in the Pacific Ocean and regions with which it has teleconnections. A forecast for global climate over the next few years produced by DePreSys version 2 will also be presented.
2011 IEEE 61st Electronic Components and Technology Conference (ECTC), 2011
... 6. CH Yu, HS Kang, KS Kim, SW Han, and KC Yang, Effects of Postbake on the Microstructure an... more ... 6. CH Yu, HS Kang, KS Kim, SW Han, and KC Yang, Effects of Postbake on the Microstructure and Whisker Growth of Matte Sn Finish, Proceedings of the 12th International Symposium on Advanced Packaging Materials: Processes, Properties, and Interfaces, APM 2007, pp. ...
Sea surface temperatures (SSTs) in the North Atlantic Ocean show multidecadal fluctuations known ... more Sea surface temperatures (SSTs) in the North Atlantic Ocean show multidecadal fluctuations known as the Atlantic Multidecadal Oscillation (AMO) . The AMO has been related to the thermohaline circulation, which implies a strong association to large-scale climate variability. Indeed, the variability of a wide range of climate parameters in the North Atlantic region has been related to the AMO, e.g. temperatures, precipitation, drought and hurricanes. Moreover, the AMO seems to influence the Asian summer monsoon, and South American precipitation. Most of these relationships have been established analyzing the short observational records or from experiments with climate models. In order to establish the stability of the multidecadal oscillation in the AMO as well as the association with climate, it is necessary to extend the record further back in time. Using tree-ring data from the Northern Hemisphere a reconstruction of the AMO, spanning AD 800 to 2000 is presented. The reconstruction suggests anomalously warm North Atlantic SSTs from ca. AD 900 to 1050, coinciding with the "Medieval Warm Period", as well as a phase between 1100 and 1400 with relatively little interdecadal variability. There is a prolonged negative phase of AMO from ca. 1600-1860, i.e. during the "Little Ice Age" (LIA). The multidecadal variability of approximately 40-80 years remains constant throughout the record, except around ca 1500-1700, i.e. during the LIA, when it breaks down.
The Journal of bone and joint surgery. American volume, 2003
Recent reports on internal fixation of acute fractures of the scaphoid waist have demonstrated hi... more Recent reports on internal fixation of acute fractures of the scaphoid waist have demonstrated higher rates of central placement of the screw when cannulated screws were used than when noncannulated screws were used. This cadaveric study was designed to determine whether central placement in the proximal fragment of the scaphoid offers a biomechanical advantage. Eleven matched pairs of scaphoids were removed from fresh cadaveric wrists. Each scaphoid was placed in a custom manufactured jig that was used to create reproducible central and eccentric positioning of the guidewire. Then a linear osteotomy was made followed by placement of a Herbert-Whipple cannulated screw to fix the osteotomy. The specimen was then potted in a holder with use of polymethylmethacrylate with a Kirschner wire passed through the proximal end of the scaphoid and placed into a fixture with a pneumatically driven plunger resting on the surface of the distal pole. The load acting through the plunger was measure...
International journal of pediatric otorhinolaryngology, 2003
Children have traditionally been kept in hospital overnight after mastoid surgery, but evidence f... more Children have traditionally been kept in hospital overnight after mastoid surgery, but evidence from the US in adults suggests that a substantial number of patients may be suitable for discharge on the day of surgery. We sought to ascertain the proportion of our children having mastoid operations between February 1994 and December 2000 who were suitable for same-day discharge. We also evaluated some of the factors that prevented discharge the same day. A standard proforma was used to record relevant data in 35 children (mean age 10 years 6 months) undergoing consecutive mastoid operations at Mayday University Hospital, London, UK. Operative findings, duration of anaesthesia and time back on ward were recorded as well as details regarding admission, follow-up findings and complications. A bed was booked preoperatively but there was intent to discharge the patient if feasible. Nine out of twelve patients (75%) operated between 1998 and 2000 were suitable for discharge on the day of su...
An ensemble of simulations of 20th Century climate using the HadCM3 coupled climate model forced ... more An ensemble of simulations of 20th Century climate using the HadCM3 coupled climate model forced with estimates of natural and anthropogenic forcings is compared with instrumental temperature data sets. The results show that while external climate forcing can account for most of 20th century climate change, there are also significant multidecadal climate fluctuations that are not produced by forcings. A major part of this variability corresponds to the `Atlantic Multidecadal Oscillation' (AMO), which has been identified in observations, and represents coherent fluctuations in temperature throughout most of the Northern Hemisphere. Using a 1400 year calculation with HadCM3 without external forcings, we show the model produces a quasi-periodic internal mode with a pattern, amplitude and characteristic time scale similar to that of the observed AMO. Further, the model implies the AMO is a genuine long-lived quasi-cyclical climate phenomenon related to large-scale oceanic heat transport variations associated with changes in the strength of the thermohaline circulation (THC) of about 2 Sv (10%). In the simulation, stronger cross-equatorial temperature gradients are associated with the anomalous northward ocean heat transport during a warm AMO phase. This causes a northward displacement of the mean ITCZ, leading to more rainfall and the development of anomalously fresh water in the tropical North Atlantic. These sustained anomalies slowly propagate to the subpolar North Atlantic in about 5 decades, where they act to slow the THC. The results also confirm observed links between the AMO and multidecadal variability in north-east Brazil and Sahel precipitation, and Atlantic hurricane formation. In addition, the simulated link between temperature and the THC allows an estimate of possible past changes in THC strength. Our results imply that the THC has undergone distinct strong and weak phases in the 20th century and has strengthened over recent decades. We also produce a forecast of the natural component of future THC change that shows a likely decline in the next 35 years to levels similar to the lowest levels reconstructed in the 20th century. This would accelerate anthropogenic THC weakening and the associated change in the AMO would offset Northern Hemisphere warming.
An improved operational Global Seasonal Forecast System (GloSea5) was introduced by the Met Offic... more An improved operational Global Seasonal Forecast System (GloSea5) was introduced by the Met Office in Spring 2013. The new system has an atmospheric resolution of approximately 40km in mid latitudes and 0.25 degree in the ocean. Hindcast simulations of past years show GloSea5 possesses unprecedented skill in predicting the winter North Atlantic Oscillation (NAO), with an anomaly correlation of 0.6 for the hindcast period. This represents a dramatic improvement over the current generation of seasonal prediction systems, which lack any significant skill in predicting the NAO (anomaly correlations less than 0.2). It suggests that slowly changing components in the climate system (e.g. ocean heat content anomalies) do indeed play an important role in the variability of extratropical atmospheric circulation in winter, as opposed to being predominantly unpredictable weather noise. Importantly, NAO predictability provides predictability of surface winter climate in Europe and the United Sta...
ABSTRACT The Met Office Hadley Centre Decadal Prediction System (DePreSys) produced the first ini... more ABSTRACT The Met Office Hadley Centre Decadal Prediction System (DePreSys) produced the first initialised short-term climate prediction in 2007. It showed, for the first time, that climate prediction up to a decade ahead was improved by including an accurate representation of the initial state of the ocean and atmosphere. Decadal predictions have subsequently been produced by a wide range of climate modelling centres, and this activity is an important new feature of IPCC AR5. Here, results from a comprehensively revised version of the Decadal Prediction System (DePreSys version 2) will be presented. The key enhancement is the use of the Met Office's latest climate model HadGEM3 within the forecast system (as opposed to the HadCM3 model used in the original system). This has approximately doubled the horizonal resolution of HadCM3, and quadrupled the number of vertical levels, in both atmospheric and oceanic components. In addition, the atmospheric component has an improved dynamical core, fully revised parameterisations, and is coupled to a different ocean model (NEMO). The initialisation methodology is essentially the same as for DePreSys version 1. Taking a global overview, indices of local predictive skill show significant improvements for key surface variables across a range of timescales relative to the previous system. In particular, there appears to be more skill in predicting multiannual to decadal variability in the Pacific Ocean and regions with which it has teleconnections. A forecast for global climate over the next few years produced by DePreSys version 2 will also be presented.
2011 IEEE 61st Electronic Components and Technology Conference (ECTC), 2011
... 6. CH Yu, HS Kang, KS Kim, SW Han, and KC Yang, Effects of Postbake on the Microstructure an... more ... 6. CH Yu, HS Kang, KS Kim, SW Han, and KC Yang, Effects of Postbake on the Microstructure and Whisker Growth of Matte Sn Finish, Proceedings of the 12th International Symposium on Advanced Packaging Materials: Processes, Properties, and Interfaces, APM 2007, pp. ...
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