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Weather types (WTs) are often used to assess the relationships between synoptic‐scale atmospheric dynamics and local scale climate anomalies. We focus here on Aotearoa New Zealand (ANZ) where pre‐existing WTs have recently been characterized using a set of descriptors monitoring the daily location and intensity of their main atmospheric centres of action (ACAs). We show here that the precipitation and temperature anomalies associated with the WTs in ANZ are more complex than previously thought. They do not solely depend on type occurrence, but are also strongly modulated by within‐type changes in the location and intensity of ACAs, and their interaction with surface terrain. Thus, the mere analysis of WT occurrence is not sufficient to explain climate variability over ANZ. The magnitude and sign of daily minimum and maximum temperature anomalies are strongly driven by meridional advection of temperature, which is also driven by within‐type changes in ACAs. The amplitude of precipitation anomalies is likewise strongly variable within WTs. Associated mechanisms involve interactions between the underlying terrain and atmospheric fluxes modulated by ACAs, modifying the strength and location of orographic uplift. Finally, daily extreme precipitation can occur under several cyclonic WTs, more particularly when their low‐pressure ACAs are significantly more intense than normal. This situation is associated with more intense moisture transport towards ANZ, promoting heavy precipitation there. These results provide a detailed assessment of within‐type variability in temperature and precipitation patterns at both synoptic and local scales. They also help to improve understanding of local effects of larger scale synoptic patterns, thereby allowing for more accurate use of analogues in forecasting. [ABSTRACT FROM AUTHOR]

Central southwest Asia (CSWA; 20°-47°N, 40°-85°E) is a water-stressed region prone to significant variations in precipitation during its winter precipitation season of November-April. Wintertime precipitation is crucial for regional water resources, agriculture, and livelihood; however, in recent years droughts have been a notable feature of CSWA interannual variability. Here, the predictability of CSWA wintertime precipitation is explored based on its time-lagged relationship with the preceding months' (September-October) sea surface temperature (SST), using a canonical correlation analysis (CCA) approach. For both periods, results indicate that for CSWA much of the seasonal predictability arises from SST variations in the Pacific related to El Niño-Southern Oscillation (ENSO) and the Pacific decadal oscillation (PDO). Additional sources of skill that play a weaker predictive role include long-term SST trends, North Atlantic variability, and regional teleconnections. CCA cross-validation skill shows that the regional potential predictability has a strong dependency on the ENSO phenomenon, and the strengthening (weakening) of this relationship yields forecasts with higher (lower) predictive skill. This finding is validated by the mean cross-validated correlation skill of 0.71 and 0.38 obtained for the 1980/81-2014/15 and 1950/51-2014/15 CCA analyses, respectively. The development of cold (warm) ENSO conditions during September-October, in combination with cold (warm) PDO conditions, is associated with a northward (southward) shift of the jet stream and a strong tendency of negative (positive) winter precipitation anomalies; other sources of predictability influence the regional precipitation directly during non-ENSO years or by modulating the impact of ENSO teleconnection based on their relative strengths. [ABSTRACT FROM AUTHOR]

Palaeoclimate-proxy data provide an invaluable source of evidence for past climatic conditions, which can be compared with data from climate model simulations. This study illustrates how high-resolution regional climate model simulations can be used to estimate the difference in the climate of New Zealand between 6000 years before present (yr BP) and the pre-industrial era (c. ad 1750). Four pairs (pre-industrial and 6000 yr BP) of atmosphere-only global and regional climate model simulations were run with prescribed sea surface temperatures (SST). The SSTs are derived from four different fully coupled ocean–atmosphere general circulation model simulations, resulting in a different lower-boundary forcing in each of the atmosphere-only simulations. We find evidence for generally cooler conditions and for wetter (drier) conditions over eastern (western) New Zealand 6000 yr BP. The work compares well with model and proxy estimates of temperature and precipitation in the New Zealand region between 7000 and 6000 yr BP. The results also highlight the added value of regional model studies in regions with such complex terrain as New Zealand. This study also shows the limitations of applying uniformitarian principles when downscaling global model fields (and ‘up-scaling’ palaeo-proxy data) to infer past climatic conditions. [ABSTRACT FROM AUTHOR]

The article reports on the use of a high-resolution nested regional climate model (RCM) in the simulation of New Zealand's climate. The relation of RCM with GCM is presented, both are run under pre-industrial condition. Also, the comparison of RCM's seasonal mean output against the country's national climate database and the National Centers for Environmental Prediction (NCEP) data is mentioned. It shows that the seasonal and regional aspects of the modelled surface precipitation and temperature, which main difference are relative to the difficulty of incorporating the country's orography appropriately and to the initial and lateral limit conditions. An overview of the NCEP data on the correlation patterns of precipitation and temperature with mean sea-level pressure is offered.