Seasonal Precipitation Data Research Articles

Wavelet based periodical analysis of the precipitation data of the Mediterranean Region and its relation to atmospheric indices

Main aim of this study finds out multi annual variability of the precipitation data in the Mediterranean Region of Turkey. For this aim, continuous wavelet transformation and global wavelet spectrum was applied on the annual and seasonal precipitation data. The results show that there are strong periodic events at 1–4 scale years in the precipitation data. These periodicities may be related to the El Nino and La Nina phenomenon. Besides, nearly 8–10 year periodicity has the highest magnitudes for the both annual and winter precipitation. The global wavelet spectrum of precipitation data shows that the main multi-annual periodicities are at 16 year scale level for Burdur station while the main multi-annual periodicities are at 8 year scale level for Adana and Alanya stations. Besides, the results indicate that the precipitation data of the Mediterranean Region has high negative correlations with the North Atlantic Oscillation.

Trends in observed mean and extreme precipitation within the Yellow River Basin, China

We analyzed spatiotemporal precipitation trends within the Yellow River Basin (YRB) in China and examined the connection between the changes in average and extreme precipitation indices. Data from 423 weather stations recorded from 1961 to 2016 were analyzed using the Mann-Kendall test to explore the linear trends of relationships between various indices, along with a simple linear regression used to detect monotonic positive or negative trends in the annual and seasonal precipitation data. Moreover, we divided the YRB into three distinct topographic regions to better understand the effect of regional geography on precipitation patterns. Our results demonstrated that mean precipitation and extreme precipitation days in different areas of the YRB had different variation trends. Precipitation in the YRB overall showed a negative trend, as did extreme precipitation days in the lower YRB. Mean and extreme precipitation indices were significantly correlated both annually and seasonally. These results may be helpful in preparing for both drought and flood events.

Spatio-Temporal Variation in Rainfall Erosivity over Jordan Using Annual and Seasonal Precipitation

The objective of this research is to estimate the annual and seasonal rainfall erosivity over Jordan based on three different regression models. Readily available annual and seasonal precipitation data with long records (40 - 53 years) pertaining to 40 weather stations were utilized to estimate rainfall erosivity. The spatial distribution of rainfall erosivity over Jordan is controlled largely by morphological (relief) and climatic factors. The lowest R-values (28 MJ mm.ha-1.h-1.yr-1) are found in the arid zone, where the average annual rainfall is below 100 mm, whereas the highest R-values are found in the northern highlands (505 MJ mm.ha-1.h-1.yr-1) where the average annual rainfall approaches 650 mm. The correlation between annual and seasonal precipitation (mm) and annual erosivity exhibits a very strong relationship (R varies from 0.964 to 1.0, and all correlations are significant at 0.01 level [2-tailed test]). Moderate positive correlations were achieved between latitude (N) and the mean annual/seasonal precipitation (R ranges from 0.407 to 0.642, and all correlations are significant at 0.01 level [2-tailed test]). Spatial differences observed in erosivity, afforded a substantial source of information and maps for predicting erosion in Jordan. According to the present analysis, two parameters proved to be useful to predict rainfall erosivity on a national level. These parameters are the average annual precipitation, and latitude.

Trend and Cycle Analysis of Annual and Seasonal Precipitation in Liaoning, China

Annual and seasonal precipitation data for 49 meteorological stations over the period of 1960–2006 in Liaoning province were analyzed. Liaoning experienced province-wide decreases in precipitation over the 47-year period, with annual precipitation decreasing by 96% of the stations, followed by 92, 84, 63, and 27%, respectively, for summer, autumn, spring, and winter precipitation. Regional trend analysis confirmed the province-wide decrease, which was detected by the site-specific analysis, but a greater number of significant declines were found for annual, summer, and autumn precipitation for Liaoning province and for three of its four subregions. Four significant cycles with alternation patterns were detected mainly at the time scales of 3–5, 10-11, 20–23, and 31.2 years for each of the four subregions (Liaodong Peninsula, Northeastern Mountain, Western Highland, and Central Plain) and the entire Liaoning province, with the dominant periodicities being 10-11 years. The 10-11-year periodic variation of Liaoning annual precipitation was negatively associated with sunspot activity and positively associated with the East Asian Summer Monsoon (EASM) at the same time scale, while the 31.2-year periodic variation of Liaoning annual precipitation was positively correlated with both the EASM and ENSO activities at the 30–33-year time scale.

Precipitation in west and northwestern Iran associated to PDO and ENSO signals and relevance to drought

The temporal relationship between El Nino-Southern Oscillation (ENSO), the Pacific Decadal Oscillation (PDO) and precipitation in the west and northwestern regions of Iran is explored through the use of multichannel singular spectrum analysis (MSSA), using monthly and seasonal precipitation data (in the form of Standard Precipitation Index, SPI), and the bivariate ENSO time series (BEST) and PDO from 1957 to 2008. Three SPI time aggregations: annual (from October to September), cold (from October to April) and warm (from May to September) seasons were chosen. To assess spatial and temporal patterns of droughts, a principal component analysis (PCA) and MSSA were applied to the SPI series. MSSA shows significant oscillations (with variance explained between 20 and 50%) around four and seven years among the SPI-PDO and SPI-BEST channels. The results show an in-phase influence of ENSO and PDO on precipitation during the cold season, contrasting the off-phase relationship during the warm season. An increased variability in precipitation regime, noticeable after 1990, was also detected in the reconstructions. These results are relevant in determining the likelihood of droughts in this part of Iran (mainly due to critically dry cold seasons during negative PDO and ENSO phases), which may be helpful for water management and agriculture planning in the region.

Spatiotemporal trends and change point of precipitation in Iran

The analyses of the spatial and temporal trends of precipitation are pertinent for the future development and sustainable management of water resources of a given region. Annual and seasonal precipitation data from 28 synoptic stations of Iran (1967–2006) were analyzed to determine the spatial and temporal trends and approximate year of the beginning of the significant trends by using the Mann–Kendall and Mann–Kendall rank statistic tests, respectively. The trend free pre-whitening (TFPW) method was applied to eliminate the influence of serial correlation on the Mann–Kendall test, and the magnitude of the precipitation trends was obtained from the Theil–Sen's slope estimator. Over the 40-year period, negative trend in annual precipitation occurred at 22 sites (79%), while just three sites had statistically significant (α=0.05) negative trend in precipitation. The magnitude of the significant negative trends of annual precipitation at the 95% confidence level varied from (−)2.53±0.69mm/year at Tabriz station to (−)3.43±0.81mm/year at Khoy station. The change points of the annual precipitation at Khoy, Oroomieh and Tabriz stations were 1982, 1994 and 1981, respectively. In the seasonal series, the negative trends in spring and winter precipitation were larger compared with those in the other seasonal series, so that, five significant negative trends were detected in the winter time series. A noticeable decrease in the winter precipitation series was observed mostly in northern Iran, as well as along the coasts of the Caspian Sea. In summer precipitation, two significant positive trends were found at Mashhad and Torbateheydarieh stations, whereas no significant positive or negative trends were detected by the trend tests in autumn precipitation.

Biophysical and Agroeconomic Influences on Pasture Quality in Da'erhanmaoming'an Union Banner, Inner Mongolian Autonomous Region, China

Since the economic reforms of the late 1970s, China has implemented a number of initiatives designed to stimulate local economies and protect environmental conditions in its rural western provinces. An area of particular concern is the Inner Mongolian steppes, which lie northwest of Beijing and are both economically depressed and a major source of dust storms. This work combines Advanced Very High Resolution Radiometer (AVHRR) imagery from 1985 to 2005 with annual and seasonal precipitation data and socioeconomic parameters collected at the township scale to investigate the relationships among husbandry activities, grassland health, as indicated by imagery-derived Normalized Difference Vegetation Indices (NDVI), and price data for wool and cashmere, the two major products in this area. Da'erhanmaoming'an Union Banner in southwestern Inner Mongolia was used as a study site. As expected for this arid steppe region, the results indicate a strong dependence on seasonal precipitation. The shift from sheep to goat production had a negative impact on grassland quality over time, but positive effects on income. Herd composition and size, along with market prices for wool and cashmere, were also correlated with per capita incomes. These results point toward a need to regulate the number of grazing animals in general, with restrictions on the number of goats being of primary importance.

Bi-site Analysis of Meteorological Drought Duration: Theoretical Modeling and Application

Droughts are regional incidents that threat the environment and limit most of the socio-economic activities. Given the dry and wet state sequences for two sites, \(X_t^{\left( 1 \right)} \) and \(X_t^{\left( 2 \right)} \), this paper presents a procedure to reduce the two sequences \(X_t^{\left( 1 \right)} \) and \(X_t^{\left( 2 \right)} \) to one sequence Z t for the purpose of simplifying the analysis of drought duration at two sites jointly. Theoretical models to evaluate the expected value and the variance of the process Z t and the occurrence probability of the dry state at two sites jointly are presented and verified using simulation experiments. Historical data for the period 1939–2005 and generated rainy season precipitation data for two gauging sites in Central Jordan, namely Amman Airport and Madaba, is used in the present study to investigate the occurrence of droughts. The joint analysis of drought duration obtained using the historical precipitation at the two sites appears to be inconsistent especially for droughts of duration longer than 3 years. On the other hand, the joint analysis of drought duration obtained theoretically by employing the characteristics of the process Z t are found to match well with the more reliable drought statistics obtained empirically by analyzing the long generated precipitation. Considering 25 years planning horizon, droughts of 1, 2, and 3 years duration are the most frequent droughts in the region of Central Jordan. The return period of such regional droughts ranges from 8–30 years.

A History of Gila Monster (Heloderma suspectum cinctum) Records from California with Comments on Factors Affecting their Distribution

The Gila monster (Heloderma suspectum), widely distributed in parts of the Mojave, Sonoran and Chihuahuan Deserts of the southwestern United States and northwestern Mexico, is rare in California. However, during the last 153 years, as many as 26 credible records have been documented from four California counties. Habitat in which the species has been observed in California is characterized by rocky, deeply incised topography, in most cases, associated with large and relatively high mountain ranges. Most localities are associated with riparian areas (including the lower Colorado River) and range from near sea level to over 1,200 m. All records except one (Mojave River) occur east of about 116° longitude. Records documented with photographs or museum specimens generally show color patterns diagnostic of the geographically expected subspecies H. s. cinctum. The distribution of the species in California suggests an invasion into the high mountain ranges of the northeastern Mojave during the last interglacial via the Colorado River corridor. We explored the hypothesis that climate patterns shaped the current distribution of the Gila monster in California. Precipitation is decidedly biphasic east of 116° longitude, with over 24 percent falling in the warm season. Warm season precipitation data from recording stations closest to Gila monster localities are almost identical for those in western Arizona where the species is more common. Summer precipitation may be important in the foraging ecology of the species. Gila monsters were probably already rare in California long before the arrival of Europeans due to changes in climate and landform that delimited the marginal location of California in the range of this species. Fortunately, most of the habitat for this species in California is protected or relatively free from human disturbance.

Frequency and severity of drought in the Lake Victoria region (Kenya) and its effects on food security

Using monthly and seasonal precipitation data for the period 1961-1999, we established drought frequency and severity in relation to food security in the Lake Victoria region in Kenya. We used percentiles together with time series analysis for a 40 yr period, with the lower 25% of the quar- tile designated as the threshold values that indicate drought years. We then used percentiles and Drought Severity Index (DSI) to ascertain the physical conditions and severity of the drought years. The 1980s and 1990s were drier decades (the 1980s had more drought events than any other decade considered in this study), with lower negative anomalies in comparison to the 1960s and 1970s, and the number of drought events and their severity have been increasing in recent years (especially during the 1990s). In general, drought affects the crop planting seasons of March to May (MAM) and September to November (SON), and leads to increased food imports in the years following the drought. If the present trends persist, the Lake Victoria region will face not only more severe drought events, but also significant reductions in food security.

Frequency Modes of Monsoon Precipitation in Arizona and New Mexico

Abstract The interannual and intraseasonal variability of the North American monsoon is of great interest because a large proportion of the annual precipitation for Arizona and New Mexico arrives during the summer monsoon. Forty-one years of daily monsoon season precipitation data for Arizona and New Mexico were studied using wavelet analysis. This time-localized spectral analysis method reveals that periodicities of less than 8 days are positively correlated with mean daily precipitation during the 1 July–15 September monsoon period. Roughly 17% of the years indicate no significant periodicity during the monsoon period for either region and are associated with low monsoon precipitation. High- and low-frequency modes explain an equivalent percentage of the variance in monsoon precipitation in both Arizona and New Mexico, and in many years concurrent multiple periodicities occur. Wavelet analysis was effective in identifying the contribution of high-frequency modes that had not been discerned in previous studies. These results suggest that precipitation processes during the monsoon season are modulated by phenomena operating at synoptic (2–8 days) and longer (>8 days) time scales and point to the need for further studies to better understand the associated atmospheric processes.

On the Application of Cluster Analysis to Growing Season Precipitation Data in North America East of the Rockies

Abstract Cluster analysis (CA) has been applied to geophysical research for over two decades although its popularity has increased dramatically over the past few years. To date, systematic methodological reviews have not appeared in geophysical literature. In this paper, after a review of a large number of applications on cluster analysis, an intercomparison of various cluster techniques was carried out on a well-studied dataset (7-day precipitation data from 1949 to 1987 in central and eastern North America). The cluster methods tested were single linkage, complete linkage, average linkage between groups, average linkage within a new group, Ward's method, k means, the nucleated agglomerative method, and the rotated principal component analysis. Three different dissimilarity measures (Euclidean distance, inverse correlation, and theta angle) and three initial partition methods were also tested on the hierarchical and nonhierarchical methods, respectively. Twenty-two of the 23 cluster algorithms yielded na...

Evidence of Climatic Change in United States Seasonal Precipitation Data, 1948–76

Abstract A method for determining climatic change in precipitation data is applied to seasonal data for the United States. This method is an analysis of variance procedure with a Markov chain model used to estimate the within-groups variance. A comparison of the within-groups variance computed with an allowance for dependence to the estimate of the variance computed under the assumption of independence shows that the model with dependence is superior. The statistic which is calculated in the test for climatic change may be significantly inflated if dependence in the data is not modeled. A consequence of this is that climatic change may be inferred when, in fact, it has not occurred. The greatest possibility of this error is in the fall season, and at West Coast stations in all seasons, for the period studied.

Spectral Analysis of Seasonal Precipitation Data from North America and Europe

Spectral analysis of 64-year time series (1897–1960) of seasonal precipitation data from 71 North American and 27 European meteorological stations has been performed. There is little evidence for statistically significant differences from the white noise spectrum.