Deficient Rainfall Research Articles

The influence of drought and anthropogenic effects on groundwater levels in Orissa, India

Summary Investigating the response of groundwater levels to the extreme weather events provides essential information for sustainable planning and management of water resources. The aim of this study was to identify and quantify the groundwater level trend of the state Orissa (India) to understand the forcing mechanism of droughts in conjunction with the anthropogenic pressure using the non-parametric Mann–Kendall statistical procedure. The pre- and post-monsoon groundwater level records of 1002 monitoring stations during the period 1994–2003 were analyzed. The results show that the drawdowns due to deficient rainfall during dry years, high temperatures, and anthropogenic pressure have not been recovered through the recharge in wet years. However, this study does not determine whether drought, high temperatures or anthropogenic effects have had largest influence on the groundwater levels decline. The cases of significant water table declines are higher in number than those expected to occur by chance. In the pre-monsoon season, 59% of the monitoring stations experienced groundwater declines as against 51% in the post-monsoon season for the study area as a whole. This could be interpreted that the fluctuation is not a part of noise, but that a signal is being identified. Further, the trend result showed wide spatial and seasonal differences. Irrespective of seasons, the consolidated rock formation that covers 80% of the geographical area experienced significant water table decline. However, the semi-consolidated and unconsolidated formations experienced water table decline in the pre-monsoon (summer) season only. The vulnerable sites where the groundwater-level declined significantly were identified so that recharge measures could be taken up.

On the El Niño‐Indian monsoon predictive relationships

Most of the severe droughts over India are associated with El Niño. However, only less than half of El Niño events are associated with deficient rainfall over India. In other El Niño years, Indian summer monsoon rainfall (ISMR) was either normal or excess. A recent study suggested that the El Niño events with the warmest SST anomalies in the central Pacific are more effective in focusing drought producing subsidence over India than events with the warmest SST anomalies in the eastern equatorial Pacific. They have further suggested that the incorporation of additional information on the spatial distribution of SST anomalies over the equatorial Pacific Ocean in the statistical models should improve monsoon forecast skill. The present study explores this hypothesis on the skill of monsoon forecasts by analyzing SST data for the period 1880–2004. The present study reveals that incorporation of information on the spatial pattern of SST anomalies (by incorporating the Trans Niño Index) does not improve the association between El Niño and Indian monsoon rainfall. Simply using the SST index over the central Pacific (Niño‐3.4) may be a better indicator for the association than the Combined Niño Index derived from Niño‐3 and Trans Niño Index (TNI).

Long range prediction of Indian summer monsoon rainfall

The search for new parameters for predicting the all India summer monsoon rainfall (AISMR) has been an important aspect of long range prediction of AISMR. In recent years NCEP/NCAR reanalysis has improved the geographical coverage and availability of the data and this can be easily updated. In this study using NCEP/NCAR reanalysis data on temperature, zonal and meridional wind at different pressure levels, few predictors are identified and a prediction scheme is developed for predicting AISMR. The regression coefficients are computed by stepwise multiple regression procedure. The final equation explained 87% of the variance with multiple correlation coefficient (MCC), 0.934. The estimated rainfall in the El-Niño year of 1997 was −1.7% as against actual of 4.4%. The estimated rainfall deficiency in both the recent deficient years of 2002 and 2004 were −19.5% and −8.5% as against observed −20.4% and −11.5% respectively.

Agroecological analysis and economic benefit of organic resources and fertiliser in till and no-till sorghum production after a 6-year fallow in semi-arid West Africa

A field experiment was conducted in Gampela (Burkina Faso) in 2000 and 2001 to assess the impact of organic and mineral sources of nutrients and combinations thereof in optimising crop production in till and no-till systems and to assess the economic benefit of these options. The study showed that under conditions of rainfall deficiency, the use of a single organic resource at an equivalent dose of 40 kg N ha−1 better secured crop yield than the application of an equivalent amount as urea-N, while a combination of organic resources and fertiliser was better in increasing crop yield than the application of the same N amount in the form of urea. In a year of rainfall deficiency, a mix of organic resources and fertiliser in both till and no-till systems increased crop water use efficiency, with the result that the farmer was able to purchase only half of the normal quantity of N fertiliser to obtain a higher yield that he would have done when all of the N was supplied in the form of urea. Under conditions where soil N is deficient, an economic benefit was achieved when urea was combined with easily decomposable organic material (e.g. sheep dung); mixing the urea at a dose of 40 kg N ha−1 with maize straw was not sufficient in alleviating the negative interaction due to the enhanced N immobilisation. The results demonstrate that the use of N fertiliser alone was risky and that a higher yield, with the accompanying economic benefit, was scarcely achieved under the prevailing rainfall conditions. The application of soil and water conservation measures can contribute greatly to increasing the economic benefit of mineral, organic or combined organic and mineral-derived nutrient application under semi-arid conditions.

The Indian summer monsoon drought of 2002 and its linkage with tropical convective activity over northwest Pacific

The Indian subcontinent witnessed a severe monsoon drought in 2002, which largely resulted from a major rainfall deficiency in the month of July. While moderate El Nino conditions prevailed during this period, the atmospheric convective activity was anomalously enhanced over northwest and north-central Pacific in the 10–20°N latitude belt; and heavy rainfall occurred over this region in association with a series of northward moving tropical cyclones. Similar out-of-phase rainfall variations over the Indian region and the northwest (NW) Pacific have been observed during other instances of El Nino/Southern Oscillation (ENSO). The dynamical linkage corresponding to this out-of-phase rainfall variability is explored in this study by conducting a set of numerical experiments using an atmospheric general circulation model. The results from the model simulations lend credence to the role of the tropical Pacific sea surface temperature anomalies in forcing the out-of-phase precipitation variability over the NW Pacific and the Indian monsoon region. It is seen that the ENSO induced circulation response reveals an anomalous pattern comprising of alternating highs and lows which extend meridionally from the equatorial region into the sub-tropic and mid-latitude regions of west-central Pacific. This meridional pattern is associated with an anomalous cyclonic circulation over NW Pacific, which is found to favor enhanced tropical cyclonic activity and intensified convection over the region. In turn, the intensified convection over NW Pacific induces subsidence and rainfall deficiency over the Indian landmass through anomalous east-west circulation in the 10–20°N latitude belt. Based on the present findings, it is suggested that the convective activity over NW Pacific is an important component in mediating the ENSO-monsoon teleconnection dynamics.

Dry season clouds and rainfall in northern Central America: Implications for the Mesoamerican Biological Corridor

The proposed Mesoamerican Biological Corridor (MBC) is an ambitious effort to stem the erosion of biodiversity in one of the world's biologically richest regions. The intent is to connect large existing parks and reserves with new protected areas by means of an extensive network of biological corridors within Mesoamerica/Central America to create an environment which provides better prospects for the long-term survival of native species while also addressing the region's socioeconomic needs. While the forest types in northern Central America generally receive some dry season rainfall, in the proposed protected regions, however, it is unclear whether current rainfall has been altered by regional land-use change. Based upon climatological rainfall records at 266 stations in Guatemala and adjacent areas, dry season rainfall in March is markedly lower in deforested areas than in forested areas of the same life zone for each of the widespread life zones. In general, dry season deforested habitats have higher daytime temperatures, are less cloudy, have lower estimated soil moisture and lower values of normalized difference vegetation index (NDVI) than do forested habitats in the same life zone. The result is hotter and drier air over deforested regions, with lower values of cloud formation and precipitation. Rainfall is predicted from the correlation of raingauge measurements and observed cloud cover; moreover, March rainfall deficiencies > 25 mm are found for several Holdridge life zones. The data suggest that deforestation is locally intensifying the dry season, increasing the risk of fire, especially for the long corridor connecting regions. In addition, forest regeneration in some parts of the MBC may not result in second-growth forest that is characteristic of that life zone but rather in forest regeneration more typical of drier conditions. The extent to which this would influence the conservation utility of any given corridor depends upon the ecological requirements of the organisms concerned.

Northwest Pacific tropical cyclone activity and July rainfall over India

In 2002, India had experienced one of the most severe droughts. The severe drought conditions were caused by the unprecedented deficient rainfall in July 2002, in which only 49% of the normal rainfall was received. One of the major circulation anomalies observed during July 2002, was the active monsoon trough over Northwest (NW) Pacific and enhanced typhoon activity over this region. The present study was designed to examine the long-term relationships between Tropical Cyclone (TC) activity over NW Pacific and monsoon rainfall over India in July.

Drought in Late Spring of South China in Recent Decades

Abstract Late spring (21 April–20 May) precipitation to the south of the Yangtze River in China along the East Asian front is a salient feature of the global climate. The present analysis reveals that during 1958–2000 South China (26°–31°N, 110°–122°E) has undergone a significant decrease in late spring precipitation since the late 1970s. The sudden reduction of the precipitation concurs with a notable cooling in the upper troposphere over the central China (30°–40°N, 95°–125°E). The upper-level cooling is associated with an anomalous meridional cell with descending motions in the latitudes 26°–35°N and low-level northerly winds over southeastern China (22°–30°N, 110°–125°E), causing deficient rainfall over South China. The late spring cooling in the upper troposphere over the central China is found to strongly link to the North Atlantic Oscillation (NAO) in the preceding winter. During winters with a positive NAO index, the upper-tropospheric cooling occurs first to the north of the Tibetan Plateau in early–middle spring, then propagates southeastward to central China in late spring. It is suggested that the interdecadal change of the winter NAO is the root cause for the late spring drought over South China in recent decades.

The role of the Madden–Julian Oscillation in the El Niño and Indian drought of 2002

AbstractIn 2002 India experienced a severe drought, one among the five worst droughts since records began in 1871, notable for its countrywide influence. The drought was primarily due to an unprecedented break in the monsoon during July, which persisted for almost the whole month and affected most of the sub‐continent. The failure of the monsoon in 2002 was not predicted and India was not prepared for the devastating impacts on, for example, agriculture. This paper documents the evolution of the 2002 Indian summer monsoon and considers the possible factors that contributed to the drought and the failure of the forecasts.The development of the 2002/2003 El Niño and the unusually high levels of Madden–Julian Oscillation (MJO) activity during the monsoon season are identified as the central players. The 2002/2003 El Niño was characterised by very high sea‐surface temperatures (SSTs) in the central Pacific that developed rapidly during the monsoon season. It is suggested that the unusual character of the developing El Niño was associated with the MJO and was a consequence of the eastward extension of the West Pacific Warm Pool, brought about primarily by a series of westerly wind events (WWEs) as part of the eastward movement of the active phase of the MJO.During the boreal summer, the MJO is usually characterised by northward movement, but in 2002 the northward component of the MJO was weak and the MJO was dominated by a strong eastward component, probably driven by the abnormally high SSTs in the central Pacific. It is suggested that a positive feedback existed between the developing El Niño and the eastward component of the MJO, which weakened the active phases of the monsoon. In particular, the unprecedented monsoon break in July could be associated with the juxtaposition of strong MJO activity with a developing El Niño, both of which interfered constructively with each other to produce major perturbations to the distribution of tropical heating. Subsequently, the main impact of the developing El Niño was a modulation of the Walker circulation that led to the overall suppression of the Indian monsoon during thess latter part of the season.It is argued that the unique combination of a rapidly developing El Niño and strong MJO activity, which was timed within the seasonal cycle to have maximum impact on the Indian summer monsoon, meant that prediction of the prolonged break in July and the seasonally deficient rainfall was a challenge for both the empirical and dynamical forecasting systems. Copyright © 2006 Royal Meteorological Society

Effect of town microclimate on the Queensland fruit fly Bactrocera tryoni

Weekly data from the urban and rural environments of numerous Australian inland towns were used to assess the impact of urban environments on the potential growth rate of the Queensland fruit fly. The urban environments were warmer and more moist than adjacent rural environments, making rural landscapes less attractive for fruit fly. Further analysis of climatic data revealed an acute negative water balance during the summer season. Under this harsh environment, the health and greenness of urban backyards and parks is maintained with frequent use of urban irrigation. This study aims to quantify the impact of urban hydrology on environmental conditions for the population potential of Queensland fruit fly in south-eastern New South Wales. CLIMEX, a climate-driven simulation model, was used in this study. Results indicated that throughout the winter season, low temperatures kept the Queensland fruit fly under control, irrespective of any other factor, including favourable moisture conditions. During summer, moisture was the major limiting factor. Even partial irrigation reduced the limiting effects of the deficiency of rainfall often experienced during midsummer. Irrigation also resulted in a large increase in the duration of the favourable period for the potential growth of fruit fly and an almost complete removal of unfavourable periods. When irrigation water was applied at optimal or excessive levels, the duration of favourable conditions for the Queensland fruit fly extended beyond the summer season. For the Queensland fruit fly, towns appear to be oases compared with the surrounding rural desert. Queensland fruit fly is unlikely to travel freely between towns, minimising chances of reinvasion once a resident population has been eliminated.

A study on the role of synoptic and semi-permanent features of Indian summer monsoon on it’s rainfall variations during different phases of El-Nino

Characteristics of different synoptic and semi-permanent features of Indian Summer Monsoon Rainfall (ISMR), such as monsoon disturbances (lows and depressions), monsoon trough and Tibetan anticyclone and duration of monsoon, are studied individually for different phases of El-Nino during the period 1960-98 to understand why during some El-Nino single events, ISMR was deficient while during other years, ISMR was on the positive side of normal or normal. This study examines cases of El-Nino double events with deficient and near deficient ISMR in one of the two years and in both the years respectively. The cases of deficient ISMR without any El-Nino are also discussed. Emphasis has been given on the effects of the synoptic and semi-permanent features on spatial variations of ISMR.
 Results show that characteristics of synoptic and semi-permanent features were important for ISMR and these were responsible for producing normal or above normal ISMR during some years in spite of El-Nino such as 1997. Also in the absence of El-Nino, ISMR was deficient because of less number of days of monsoon trough, lows and depressions, and weak Tibetan anticyclone. The reverse happened during flood years when there was no La-Nina. Statistical analysis indicates very high correlation coefficients (CCs) of these synoptic and semi-permanent features with ISMR than those of SST of Nino-3 region. India received highest monsoon rainfall during 1961 because total number of days of intense monsoon disturbances and monsoon trough and the total duration of monsoon over India during the year was the highest. This study shows that monsoon disturbances and monsoon trough are the most important components of synoptic and semi-permanent features, which affected spatial variation of ISMR in 1965 and 1966 with deficient rainfall and in 1961 and 1994 with excess rainfall over a large part of India.

EFFECT OF NITROGEN AND GYPSUM ON THE ESTABLISHMENT AND EARLY GROWTH OF SALVADORA PERSICA (L.) ON SALT AFFECTED SOILS UNDER HOT ARID CONDITIONS IN INDIA

ABSTRACT An experiment was laid out in a hot, arid part of Rajasthan, India to study the effect of nitrogen and gypsum applications on the establishment and growth of Salvadora persica on a sandy loam, saline alkali soil—waterlogged during the monsoon. Four different doses of nitrogen (0, 9, 18 and 27 g) in the form of urea were applied with two levels of gypsum (0 and 100% soil GR), with an application of farmyard manure (FYM) and drainage a common treatment at the time of planting only. Despite deficient rainfall—including a severe drought—survival ranged from 67 to 85% in different treatments after 60 months. The application of nitrogen in combination with gypsum (gypsum + 9g N) gave the best results—41% for height and 35% for crown diameter more than the untreated plants. Crescent shaped drainage trenches for individual plants helped in plant establishment and growth, serving the dual purpose of harvesting water and leaching salts. The site has shown substantial reduction in soil pH and electrical conductivity and improvement in percent organic carbon content during the study period. Protection and plantation activities promoted colonisation and the number of plant species increased gradually. Weed mass was influenced by the rainfall.

Characteristics and spatio-temporal variability of the Amazon River Basin Water Budget

The spatio-temporal variations of the water budget components in the Amazon region are investi- gated by using a combination of hydrometeorological observations and moisture fluxes derived from the NCEP/NCAR reanalyses, for the period 1970-1999. The key new finding of this study identifies the major dif- ferences in the water balance characteristics and vari- ability between the northern and southern parts of the basin. Our results show that there is a seasonality and interannual variability of the water balance that varies across the basin. At interannual time scales, anomalies in the water balance components in the northern Ama- zon region show relatively stronger links with tropical Pacific interannual variability. Over the entire region, precipitation exceeds evaporation and the basin acts as a sink of moisture (P>E). However, on some occasions the basin can act as a source for moisture (P<E) under extreme conditions, such as those related to deficient rainfall in northern Amazonia during the strong El Nino of 1983. Our estimates of the Amazon region's water balance do not show a closure of the budget, with an average imbalance of almost 50%, suggesting that some of the moisture that converges in the Amazon region is not accounted for. The imbalance is larger over the southern Amazon region than over the northern region, and it also exhibits interannual variability. Large uncertainties are detected in the evaporation and mois- ture-convergence fields derived from the reanalyses, and in the case of evaporation it can be as large as 10-20% when compared with the few field observations across the basin. Observed precipitation fields derived from station data and from grid-box products also show some discrepancies due to sampling problems and interpola- tion techniques. The streamflow observed at the mouth of the river is obtained after corrections on the series observed taken at a gauging site almost 200 km inland. However, variability in the evaporation, moisture con- vergence, and observed rainfall and runoff matches quite well.

Distinct synoptic patterns associated with pre-break onset phase and revival of normal monsoon phase

In the present study, an attempt has been made to synoptically classify the intraseasonal variation of Indian summer monsoon into two new monsoon conditions except already existing active and break monsoon conditions. These are transitional phases found prior to occurrence of break monsoon (here after “Pre-break onset phase”) and during revival of normal monsoon after the culmination of break monsoon phase (here after “Revival of normal monsoon phase”) and they have distinct synoptic patterns differing from patterns that are associated with active/break monsoon conditions. The distinct circulation, rainfall and pressure distribution associated with pre-break onset and revival of normal monsoon phases are also discussed.&#x0D; The study shows that strong negative pressure anomaly and excess rainfall over north India and strong positive pressure anomaly and deficient rainfall over Peninsular India are associated with pre-break onset phase and vice-versa with revival of normal monsoon.

Past monsoon rainfall variations in peninsular India recorded in a 331-year-old speleothem

An actively growing stalagmite collected from a cave located in the hills of the Western Ghats in the Uttar Kannada District of Karnataka, India, has been studied for stable isotope ratios of oxygen and carbon, width of growth layers and grey-level changes. Distinct carbonate layers, alternate coarse and compact, are seen in cross-section. Each couplet of compact and coarse layer is found to represent a single year. A total of 331 such couplets has been counted, indicating that the stalagmite started growing in AD 1666 and continued until it was sampled. Stable isotope ratios of oxygen (δ18O) and carbon (δ13C) show variations ranging from-13.6 to-7.9%° and from-2.7 to 1.6%°, respectively. We have reconstructed past rainfall changes of the cave site using the‘amount effect’ in &amp;δ18O of rain. Speleothemδ18O and instrumental rainfall data from the associated climate subdivision show a significant correlation (r =-0.62, decadal average). Several sharp spikes of enrichment and depletion in 18O are indicative of the past deficiency and excess in rainfall. Most of the severe drought years recorded independently by meteorological observations are found registered in the stalagmite layers. During the 331-year-period, rainfall was highest at Añ 1666 and lowest around AD 1900. The stalagmite-generated past rainfall record can serve as a reasonable proxy for testing monsoon models.

Trends in the southern oscillation phenomenon and Australian rainfall and changes in their relationship

AbstractAn attempt has been made to investigate decadal‐scale trends in Australian rainfall and in the southern oscillation index (SOI) and their influence on the relationship between them. Monthly rainfall data from high‐quality stations in Australia (from 1900 to 1995), India, Sri Lanka and Tahiti are used. The relationship between the SOI and Australian rainfall is positive, but shows decadal‐scale variations during the past century. Although there were extended and severe El Niño events in the early 1990s and in 1997, Australia did not experience the expected severe rainfall deficiencies characteristic of previous events. However, severe drought conditions over eastern Australia were associated with a moderate El Niño event during 2002–03.Long‐term fluctuations of March–May (MAM) rainfall show high‐frequency variations, but trends during June–August (JJA), September–November (SON) and December–February (DJF) show low‐frequency or decadal‐scale variations. Trends and multi‐decadal fluctuations in all‐Australian spring (SON) and summer (DJF) rainfall are strongly dominated by rainfall trend fluctuations in northern and eastern Australia. Austral summer rainfall shows an increasing trend during the 1980s and 1990s, particularly in Queensland and New South Wales, despite the occurrence of extended and severe El Niños. However, some parts of New South Wales and Queensland experienced severe rainfall deficiencies during 2002–03 in conjunction with an El Niño event.The relationship between the SOI and rainfall on the interannual time scale is strong when the SOI and rainfall follow the same direction, but it is weak when they follow opposite directions on a decadal‐time scale. The poor correlation during the 1920s and 1930s was due to a slightly increasing trend in the SOI and a stronger decreasing trend in rainfall. A weakening in the relationship between the SOI and rainfall in recent years, after the mid‐1970s, is due to a small increase in rainfall in the 1980s and 1990s and a strong decrease in the SOI. Rainfall trends were enhanced (stronger decreases or increases) when the influence of the SOI (or El Niño‐southern oscillation (ENSO)) was removed. Enhanced increases and decreases are particularly strong during SON and DJF, when the ENSO phenomenon is at the mature stage and also the influence on Australian rainfall is strong. The increasing trend in rainfall during the 1980s and 1990s in some parts of eastern Australia and the decreasing trend in the SOI result in more rainfall for a given SOI compared with the same SOI during the previous period, i.e. before the mid‐1970s. A similar analysis was carried out for two periods, before and after 1972, for Tahiti, India and Sri Lanka. The upward or downward shift in regression lines is very clear during the season, that shows a strong relationship between rainfall and the SOI. Moreover, strengthening or weakening of the relationship between rainfall and the SOI is largely dependent on their multi‐decadal variations and trends during the past century.Increases in rainfall during the 1980s and the 1990s and decreases in the SOI have weakened their relationship, both in Australia and India. Such a relationship gives more rainfall for a given SOI after 1973. The pattern was reversed for Sri Lanka, where rainfall during the second intermonsoon season has decreased. Analyses of trends in temperature at Darwin and Tahiti and of rainfall over Australia, India, Tahiti and Sri Lanka suggest a regional‐scale change in climate, whereas the SOI reflects a change in the large‐scale circulation pattern over the Indo‐Pacific region after the mid‐1970s. Copyright © 2004 Royal Meteorological Society

Anomalies of the South American summer monsoon associated with the 1997–99 El Niño–southern oscillation

AbstractWe describe the rainfall and circulation anomalies of the South American summer monsoon (SASM) during December–January–February (DJF) of 1997–98 (El Niño) and 1998–99 (La Niña). The most pronounced rainfall signals in DJF 1997–98 include (a) excessive rainfall over northern Peru and Ecuador, (b) deficient rainfall over northern and central Brazil, and (c) above‐normal rainfall over southeastern subtropical South America. The rainfall anomalies in (a) and (b) are associated with the excitation of an anomalous east–west overturning cell with rising motion and low‐level westerlies over the equatorial eastern Pacific, coupled to sinking motion and low‐level easterlies over northern Brazil. The easterlies turn sharply southeastward on encountering the steep topography of the Andes, enhancing the summertime low‐level jet (LLJ) along the eastern foothills of the Andes near 15–20° S, possibly contributing to the increased rainfall in (c).During DJF 1997–98, the sea‐surface temperature‐induced warming spreads and expands over the entire tropical troposphere. The eastward expansion of a warm upper tropospheric geopotential and temperature ridge from the Niño‐3 region, across subtropical South America to the southeast Atlantic, enhances warming over the Altiplano Plateau, hydrostatically strengthening the Bolivia high. Similar to previous warming events, the South Pacific high is weakened, and the South Atlantic high is strengthened. During DJF 1998–99, as cold water develops over the equatorial central Pacific, the SASM anomalies in the tropics are weaker and less organized and appear to be in transition to the opposite phase to those found in DJF 97–98. In the subtropics, notable features include a weakening of the LLJ, a rainfall pattern associated with a poleward shift of the South Atlantic convergence zone, and development of the Pacific–South America teleconnection pattern. Published in 2003 by John Wiley &amp; Sons, Ltd.

Persistence, intensification and recession of meteorological drought over India during 1987

The persistence, intensification and recession of districtwise meteorological drought over India during 1987 have been studied using cumulative weekly rainfall deficiencies (%) from the normal during the southwest monsoon season (June-September) for 355 districts of India. These features have been analysed in northeast, North and Peninsular India during three distinct phases of southwest monsoon, viz., progress ( 9 weeks), active ( 6 weeks) and retreat phase ( 3 weeks). &#x0D; &#x0D; A prolonged dry spell emerged over a vast region of northwest India up to mid August due to the absence of major weather systems, leading to intense drought conditions. Mixed mode persistence prevailed throughout monsoon season over 65 districts. Unimode persistence of severe intensity occurred in 209 districts over different parts of India. Intensification of drought was more prominent in north India affecting 67% districts. Recession of drought occurred in 40% and more districts in northeast and Peninsular India respectively.

The Maritime Continent and Its Role in the Global Climate: A GCM Study

Abstract The Maritime Continent, with its complex system of islands and shallow seas, presents a major challenge to models, which tend to systematically underestimate the precipitation in this region. Experiments with a climate version of the Met Office model (HadAM3) show that even with a threefold increase in horizontal resolution there is no improvement in the dry bias. It is argued that the diurnal cycle over the islands and the complex circulation patterns generated by land–sea contrasts are crucial for the energy and hydrological cycles of the Maritime Continent and for determining the mean climate. It is shown that the model has substantial errors in its simulation of the diurnal cycle over the islands, which can rectify onto the seasonal mean climate. It is further argued that deficient rainfall over the Maritime Continent could be a driver for other systematic errors, such as the excess precipitation over the western Indian Ocean. To demonstrate the sensitivity of global systematic model errors t...

Uncertain Climate: The Recent History of Drought Policy in Australia

In 2002 Australia experienced widespread drought, with over 70 per cent of the country experiencing serious to severe rainfall deficiencies for the period April to October. During this period images of parched landscapes were frequently shown on television, and the Farm Hand drought appeal launched, with the backing of business, to raise funds to assist drought–affected farmers. Since 1992, Australia has had in place a National Drought Policy based on principles of self–reliance and risk management. This policy reflects the neo–liberal economic policy approach, which has dominated Australian policy since the 1980s. Severe drought tests the will of policy makers to hold to this policy line as agrarian sentiments are stirred and political pressure is brought to bear to change policy settings. This article describes the history of drought policy in Australia and the challenges facing policy makers.