Episodic variations in stream water chemistry associated with acid rainfall and run-off and the effect on aquatic ecosystem, with particular reference to fish populations in N.W. England

This is the episodic variations in stream water chemistry associated with acid rainfall and run-off and the effect on aquatic ecosystems, with particular reference to fish populations in North West England produced by the North West Water Authority in 1985. This report looks at the biological, physical and chemical information collected over a five year period from over 100 sites on upland streams in the North West Region of which drained rocks of low buffering capacity. In both Lake District and South Pennine sites striking differences were found between the composition of invertebrate communities inhabiting acid-stressed and less acid-stressed streams. Electric fishing surveys showed that acidic streams (geometric mean pH <5.5) generally had abnormally low densities of salmonids ( < 0 .2m2) and that 0+ fish were very few or absent. The latter indicates recruitment failure. Salmon were more sensitive than trout to low pH.

Relationships between ENSO events and San Francisco rainfall, 1949-1991

As California entered its sixth consecutive year of drought, the onset of a positive sea surface temperature anomaly in the equatorial Pacific and other indicators of a developing ENSO event were observed. This brought the following question from the media, water officials, and the public: What effect will El Niño have on the current rainfall season in general and on the intraseasonal distribution of rain in particular? To answer the question, the historical San Francisco rainfall record was examined in relationship to previous ENSO events.

Pacific sea surface temperature associations with southwestern United States summer rainfall and atmospheric circulation

Pacific sea surface temperatures (SSTs) are examined for their associations with (1) summer rainfall, and (2) the latitude location of the mid-tropospheric subtropical high pressure ridge (STR) in the southwestern United States during 1945 to 1986. Extreme northward (southward) displacements of STR are associated with wet (dry) summers over Arizona and an enhanced (weakened) gradient of SST off the California and Baja coasts. These tend to follow winters marked by positive (negative) phases of the PNA, Pacific/North America, teleconnection pattern. Recent decadal variations of Arizona summer rainfall (1950s wet; 1970s dry) appear similarly related to southwestern United States synoptic circulation and eastern Pacific SSTs.

One hundred years of rainfall trends in California

This paper is an examination of precipitation trends in California for 100 years based on 96 rain records. The study resulted from an attempt to develop a wetness index for the San Francisco Bay area, where declining rainfall trends indicated a lot more rainfall in the first 50 years of the study period. A regular pattern of decline was found in California coastal stations, concurrent with an increasing trend at inland stations.

Case studies of two contrasting rainfall episodes in Hawaii

This case study, utilizing surface and upper-air data, has attempted to shed light on the mechanisms that exerted control on two contrasting rainfall episodes in Hawaii [in the dry winter of 1981 and wet winter of 1982].

Some effects of Earth's surface on winter jet stream positions in the Northern Hemisphere and rainfall patterns in northern and central California

EXTRACT (SEE PDF FOR FULL ABSTRACT): This report shows that the mean wintertime polar-front jet stream structure consists of three long waves. Prominent ridges in the jet stream flow occur near the longitudes of India, eastern Pacific/west coast of North America, and eastern Atlantic/British Isles; prominent troughs occur near the longitudes of the Middle East, western Pacific, and western Atlantic/east coast of North America. ... One of the climatological ridges occurs along the west coast of North America ... just off the central Oregon coast. The position of the jet stream at this location appears to be the main reason most Pacific storms pass to the north of California. Sustained rainfall in northern and central California occurs only when the storm track is displaced southward of this climatological position.

Influence of climatography on rainfall thresholds for initiation of debris-flows on the California coast [abstract]

EXTRACT (SEE PDF FOR FULL ABSTRACT): Since 1986, the U.S. Geological Survey and National Weather Service have operated a warning system for debris flows triggered by severe rainstorms in the San Francisco Bay region. The NWS tracks storm systems as they approach the region, forecasts precipitation, and observes rainfall with a network of radiotelemetered rain gauges (ALERT). The USGS also monitors ALERT data and compares the observed and forecast rainfall to thresholds for debris-flow initiation. Both groups jointly assess debris-flow hazards and issue public advisories when rainfall conditions reach or approach critical levels.

Daily rainfall along the United States Pacific Coast appears to conform to a square-root normal probability distribution

EXTRACT (SEE PDF FOR FULL ABSTRACT): As part of a study of climatic influences on landslide initiation, a statistical analysis of long-term (>40 years) records of daily rainfall from 24 Pacific coastal stations, from San Diego to Cape Flattery, disclosed an unexpected result - the square root of the daily rainfall closely approximates a normal distribution function. ... This paper illustrates the use of the square-root-normal distribution to analyze variations in precipitation along the mainland United States Pacific Coast with examples of orographic enhancement, rain shadows, and increase in precipitation frequency with geographic latitude.

Role of rainfall in the breeding of Labeo rohita (Ham.), Cirrhinus mrigala (Ham.), Catla catla (Ham.), at Damdama (Haryana), a semi-arid zone

The role of several environmental factors on the breeding and hatching of fish has been studied by many earlier investigators. Perfection in the hypophysation technique has helped to some extent in by-passing the environmental variables such as temperature, light and rain. With the use of a modern fish hatchery, it is possible to attain maximum success in breeding and hatching, even without rains; reference is given to studies carried out regarding the role of rainfall in the breeding of Labeo rohita, Cirrhinus mrigala, Catla catla.

Relationship between El Nino and summer monsoon rainfall over Pakistan

The present paper deals with the influence of El Nino event on the summer monsoon rainfall over Pakistan. The correlation between monthly rainfall of summer monsoon season and bi-Monthly Multivariate ENSO Index (MEI) has been calculated to see the influence of El Nino on the summer monsoon rainfall. MEI is bimonthly ENSO Index pertaining to the period from first week of previous month to first week of the month under consideration. While study the correlation's with the ENSO events out side the Pacific Ocean MEI is more appropriate than other indices like Southern Oscillation Index (SOI) as MEI integrates complete information on ENSO viz. six oceanic and meteorological variables over the tropical Pacific. The results of the study show that there is a tendency of reduction in summer monsoon rainfall over Pakistan during El Nino years. The deficiency in % rainfall is statistically significant up to 90% level during July and September months. It is interesting to note that Pakistan receives more than normal rainfall during summer monsoon season in the immediate following year after the El Nino event. The correlation analysis is also performed on the summer monsoon months for individual provinces of Pakistan. All provinces receive deficient rainfall during monsoon months. The deficiency in rainfall over Punjab during all monsoon months is significant, whereas the deficiency in rainfall is significant during July and August over NWFP and Sindh respectively. No significant impact of El Nino on the summer monsoon rainfall over Baluchistan is observed.