Monsoon

About: Monsoon is a research topic. Over the lifetime, 16087 publications have been published within this topic receiving 599888 citations.

Uncertainties in monsoon precipitation projections over China: results from two high-resolution RCM simulations

Abstract: A high-resolution climate change simulation at a grid spacing of 25 km was conducted over East Asia with the Abdus Salam International Centre for Theoretical Physics’ (ICTP) regional climate model RegCM3, for the period 1951−2100. The model is driven at the lateral boundaries by the global model CCSR/NIES/FRCGC MIROC3.2_hires. Two time slices, 1961− 1990 for present-day and 2071−2100 for future climate conditions were analyzed and compared with a previous high-resolution simulation of RegCM3 driven by the NASA/NCAR global model FvGCM. The focus of the present paper is on mean temperature and precipitation and their changes during the monsoon season (May−September). Overall, for present-day conditions, the regional model improves the simulation of both temperature and precipitation patterns compared to the driving global climate models, with greater agreement between the RegCM3 simulations than with the corresponding driving models. When driven by the 2 global models, RegCM3 simulates a consistent precipitation change pattern over western China, characterized by an increase over the northwest and a decrease over the Tibetan Plateau and Southwest China. These latter precipitation decreases have opposite signs compared those from the driving global models, and the causes of these differences (mostly associated with the different topographic representations) are discussed in the paper. This implies that over these regions the internal model physics and processes can be dominant factors. On the other hand, warming patterns are essentially driven by the large-scale boundary forcing. Our results show that precipitation change projections by current global models need to be considered cautiously and that the use of nested regional models adds an element of uncertainty which needs to be properly characterized.

Surface air temperature variability over India during 1901–2007, and its association with ENSO

Abstract: Seasonal and annual trends in surface air temperature over India and 7 homogeneous regions (western Himalaya, northwest, north-central, northeast, east coast, west coast and interior peninsula) were assessed during 3 periods: 1901–2007, 1971–2007 and 1998–2007 Indian annual mean (average of maximum and minimum), maximum and minimum temperatures showed significant warming trends of 051, 072 and 027°C 100 yr–1, respectively, during the period 1901–2007 However, accelerated warming was observed in the recent period 1971–2007, mainly due to intense warming in the recent decade 1998–2007 Temperatures (mean, maximum and minimum) increased by about 02°C per decade for the period 1971–2007, with a much steeper increase in minimum temperature than maximum temperature In the most recent decade, maximum temperature was significantly higher compared to the long-term (1901–2007) mean, with a stagnated trend during this period, whereas minimum temperature showed an increasing trend, almost equal to that observed during 1971–2007 On a seasonal scale, pronounced warming trends in mean temperature were observed in winter and monsoon seasons, and a significant influence of El Nino Southern Oscillation events on temperature anomalies during certain seasons across India was observed The composites of maximum and minimum temperatures of El Nino years showed positive anomalies during monsoon, post-monsoon and subsequent year winter and pre-monsoon seasons However, statistically significant positive anomalies were observed only during monsoon and post-monsoon seasons over large areas of the country The composite temperature anomalies of La Nina years were almost opposite to El Nino composites: the negative temperature anomalies associated with La Nina events persisted from the current monsoon season to the subsequent year pre-monsoon season

Trends in Peninsular Malaysia rainfall data during the Southwest monsoon and Northeast monsoon seasons: 1975-2004

Abstract: This study investigated the spatial pattern and trends of the daily rainfall data in Peninsular Malaysia based on seasonal rainfall indices. Five rainfall indices which describe the main characteristics of rainfall, the total amount of rainfall, frequency of wet days, rainfall intensity, extreme frequency, and extreme intensity, were employed in this study. The statistics of rainfall indices were calculated in terms of their means for four regions in Peninsular Malaysia for the period 1975 to 2004. The findings indicate that the southwest monsoon had the greatest impact on the western part of the Peninsula, particularly in characterizing the rainfall pattern of the northwest region. During this season, the northwest region could be considered as the wettest region since all rainfall indices tested are higher than in other regions of the Peninsula. Otherwise, the northwest region is denoted as the driest part of the Peninsula during the northeast monsoon period. The northwest region is less influenced by the northeast monsoon because of the existence of the Titiwangsa Range, which blocks the region from receiving heavy rainfall. On the other hand, it is found that the lowlands areas such as the eastern part of the Peninsula are strongly characterized by the northeast monsoonal flow. Based on the results of the Mann-Kendall test, as the trend of the total amount of rainfall and the frequency of wet days during the southwest monsoon decrease at most of the stations, the rainfall intensity increases. In contrast, increasing trends in both the total amount of rainfall and the frequency of wet days were observed at several stations during the northeast monsoon, which give rise to the increasing trend of rainfall intensity. The results for both seasons indicate that there are significantly decreasing trends in the frequency of wet days during the extreme events for most of the stations on the peninsula. However, a smaller number of significant trends was found for extreme intensity.