Trends (1961Trends ( -2003 in daily maximum and minimum temperatures, extremes and variance were found to be spatially coherent across the Asia-Pacific region. The majority of stations exhibited significant trends: increases in mean maximum and mean minimum temperature, decreases in cold nights and cool days, and increases in warm nights. No station showed a significant increase in cold days or cold nights, but a few sites showed significant decreases in hot days and warm nights. Significant decreases were observed in both maximum and minimum temperature standard deviation in China, Korea and some stations in Japan (probably reflecting urbanization effects), but also for some Thailand and coastal Australian sites. The South Pacific convergence zone (SPCZ) region between Fiji and the Solomon Islands showed a significant increase in maximum temperature variability.Correlations between mean temperature and the frequency of extreme temperatures were strongest in the tropical Pacific Ocean from French Polynesia to Papua New Guinea, Malaysia, the Philippines, Thailand and southern Japan. Correlations were weaker at continental or higher latitude locations, which may partly reflect urbanization.For non-urban stations, the dominant distribution change for both maximum and minimum temperature involved a change in the mean, impacting on one or both extremes, with no change in standard deviation. This occurred from French Polynesia to Papua New Guinea (except for maximum temperature changes near the SPCZ), in Malaysia, the Philippines, and several outlying Japanese islands. For urbanized stations the dominant change was a change in the mean and variance, impacting on one or both extremes. This result was particularly evident for minimum temperature.The results presented here, for non-urban tropical and maritime locations in the Asia-Pacific region, support the hypothesis that changes in mean temperature may be used to predict changes in extreme temperatures. At urbanized or higher latitude locations, changes in variance should be incorporated.
[1] A climatology of the thermodynamic phase of the clouds over the Southern Ocean (40-65 S,100-160 E) has been constructed with the A-Train merged data product DARDAR-MASK for the four-year period 2006-2009 during Austral winter and summer. Low-elevation clouds with little seasonal cycle dominate this climatology, with the cloud tops commonly found at heights less than 1 km. Such clouds are problematic for the DARDAR-MASK in that the Cloud Profiling Radar (CPR) of CloudSat is unable to distinguish returns from the lowest four bins (heights up to 720-960 m), and the CALIOP lidar of CALIPSO may suffer from heavy extinction. The CPR is further limited for all of the low-altitude clouds (tops below 3 km) as they are predominantly in the temperature range from 0 C to À20 C, where understanding the CPR reflectivity becomes difficult due to the unknown thermodynamic phase. These shortcomings are seen to flow through to the merged CloudSat-CALIPSO product. A cloud top phase climatology comparison has been made between CALIPSO, the DARDAR-MASK and MODIS. All three products highlight the extensive presence of supercooled liquid water over the Southern Ocean, particularly during summer. The DARDAR-MASK recorded substantially more ice at cloud tops as well as mixed-phase in the low-elevation cloud tops in comparison to CALIPSO and MODIS. Below the cloud top through the body of the cloud, the DARDAR-MASK finds ice to be dominant at heights greater than 1 km, especially once the lidar signal is attenuated. The limitations demonstrated in this study highlight the continuing challenge that remains in better defining the energy and water budget over the Southern Ocean.
Data from a precipitation gauge network in the Snowy Mountains of southeastern Australia have been analyzed to produce a new climatology of wintertime precipitation and airmass history for the region in the period 1990-2009. Precipitation amounts on the western slopes and in the high elevations (.1000 m) of the Snowy Mountains region have experienced a decline in precipitation in excess of the general decline in southeastern Australia. The contrast in the decline east and west of the ranges suggests that factors influencing orographic precipitation are of particular importance. A synoptic decomposition of precipitation events has been performed, which demonstrates that about 57% of the wintertime precipitation may be attributed to storms associated with ''cutoff lows'' (equatorward of 458S). A further 40% was found to be due to ''embedded lows,'' with the remainder due to Australian east coast lows and several other sporadically occurring events. The declining trend in wintertime precipitation over the past two decades is most clearly seen in the intensity of precipitation due to cutoff lows and coincides with a decline in the number of systems associated with a cold frontal passage. Airmass history during precipitation events was represented by back trajectories calculated from ECMWF Interim Reanalysis data, and statistics of air parcel position were related to observations of precipitation intensity. This approach gives insight into sources of moisture during wintertime storms, identifying ''moisture corridors,'' which are typically important for transport of water vapor from remote sources to the Snowy Mountains region. The prevalence of these moisture corridors is associated with the southern annular mode, which corresponds to fluctuations in the strength of the westerly winds in southeastern Australia.
[1] Clouds over the Southern Ocean exist in a pristine environment that results in unique microphysical properties. However, in situ observations of these clouds are rare, and the dominant precipitation processes are unknown. Uncertainties in their life cycles and radiative properties make them interesting from a weather and climate perspective. Data from the standard cloud physics payload during the High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations global transects provide a unique snapshot the nature of low-level clouds in the Southern Ocean. High quantities of supercooled liquid water (up to 0.47 gm -3 ) were observed in clouds as cold as -22 ı C during two flights in different seasons and different meteorological conditions, supporting climatologies inferred from satellite observations. Cloud droplet concentrations were calculated from mean droplet size and liquid water concentrations, and were in the range of 30-120 cm -3 , which is fairly typical for the pristine Southern Ocean environment. Ice in nonprecipitating or lightly precipitating clouds was found to be rare, while drizzle drops with diameter greater than 100 m formed through warm rain processes were widespread. Large, pristine crystals were commonly seen in very low concentrations below cloud base. Citation: Chubb, T. H., J. B. Jensen, S. T. Siems, and M. J. Manton (2013), In situ observations of supercooled liquid clouds over the Southern Ocean during the HIAPER Poleto-Pole Observation (HIPPO) campaigns, Geophys. Res. Lett., 40,[5280][5281][5282][5283][5284][5285]
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