Warm Nights Research Articles

A Multiregion Assessment of Observed Changes in the Areal Extent of Temperature and Precipitation Extremes

Abstract This study examines trends in the area affected by temperature and precipitation extremes across five large-scale regions using the climate extremes index (CEI) framework. Analyzing changes in temperature and precipitation extremes in terms of areal fraction provides information from a different perspective and can be useful for climate monitoring. Trends in five temperature and precipitation components are analyzed, calculated using a new method based on standard extreme indices. These indices, derived from daily meteorological station data, are obtained from two global land-based gridded extreme indices datasets. The four continental-scale regions of Europe, North America, Asia, and Australia are analyzed over the period from 1951 to 2010, where sufficient data coverage is available. These components are also computed for the entire Northern Hemisphere, providing the first CEI results at the hemispheric scale. Results show statistically significant increases in the percentage area experiencing much-above-average warm days and nights and much-below-average cool days and nights for all regions, with the exception of North America for maximum temperature extremes. Increases in the area affected by precipitation extremes are also found for the Northern Hemisphere regions, particularly Europe and North America.

An overview of weather and climate extremes – Products and trends

Abstract This paper provides an overview of trends in weather and climate extremes as presented at a recent WMO Symposium on global food security and biodiversity. Analyses and conclusions about weather and climate extremes are best based on daily data, and an internationally agreed-upon set of daily extremes indices has been devised for this purpose. Characteristics of climate data sets which are necessary for an adequate analysis of changes or trends in extremes are identified. Analyses summarized in the Intergovernmental Panel on Climate Change Fifth Assessment Report indicate that, since the 1950s, there has been a trend toward fewer cold days and nights and more warm days and nights globally, increasing heavy precipitation events in many parts of the world, and regional trends (both increasing and decreasing) in drought and dryness extremes. A more detailed discussion of indices for the USA illustrates features of some of these trends, including a significant change in trends of extremes which occurred in the 1970s. There is considerable decadal variability in drought area in the contiguous USA, and the long-term trend depends on the beginning and ending years chosen, but there has generally been an increasing trend in drought area over the 20th to 21st centuries and over the last four decades. The annual percent area of the USA experiencing greater-than-normal number of days with (without) precipitation has increased (decreased) over the 20th to 21st centuries, but both indices have increased over the last four decades. There has been an increase in the occurrence of extreme 1-day precipitation events over the last hundred years, with the rate of increase accelerating in recent decades. Extremely warm maximum and minimum temperatures have shown an increasing trend over the 20th to 21st centuries and over the last four decades, while the occurrence of extremely cold maximum and minimum temperatures has decreased over these periods. The U.S. Climate Extremes Index, which integrates several extremes indices, indicates that the 1940s and 1960s were the decades of most stable (smallest occurrence of extremes) climate in the last 104 years, and that recent decades have become as unstable (variable) as, or more unstable than, the early decades of the 20th century but for different reasons.

Trends in extreme temperature over Nigeria from percentile‐based threshold indices

ABSTRACTThis study analyses spatial and temporal trends in extreme temperature indices over Nigeria. The percentile indices were calculated from newly homogenized daily minimum and maximum temperature data for the period 1971–2012 for 21 stations in Nigeria. Indices describing the characteristics of hot extremes and cold extremes are calculated with the RClimDex software. The annual and seasonal trends in these indices are obtained using the ordinary least square fit and the statistical significance tested using the R‐based modified Mann–Kendall test. We examine characteristics of these indices for the entire country and separately for the three geographical zones in Nigeria: Guinea, Savanna, and Sahel. The spatial and temporal patterns of trends in the indices indicate that Nigeria has experienced statistically significant increase in the frequency of hot extreme and decrease in cold extreme events. Although majority of the stations have significant trends in warm days and warm nights, the annual trend is greatest in warm nights. In addition, the rate of warming in minimum temperature (‘warm nights’) is stronger in June, July, August (JJA) and September, October, November (SON) compare with December, January, February (DJF) and March, April, May (MAM). As for the trends in cold days and cold nights, the trends in cold nights are larger than for cold days at both the annual and seasonal scales. The regional analysis indicates that trends in warm nights and cold nights are most pronounced in Guinea and Sahel regions.

High night temperatures during grain number determination reduce wheat and barley grain yield: a field study.

Warm nights are a widespread predicted feature of climate change. This study investigated the impact of high night temperatures during the critical period for grain yield determination in wheat and barley crops under field conditions, assessing the effects on development, growth and partitioning crop-level processes driving grain number per unit area (GN). Experiments combined: (i) two contrasting radiation and temperature environments: late sowing in 2011 and early sowing in 2013, (ii) two well-adapted crops with similar phenology: bread wheat and two-row malting barley and (iii) two temperature regimes: ambient and high night temperatures. The night temperature increase (ca. 3.9 °C in both crops and growing seasons) was achieved using purpose-built heating chambers placed on the crop at 19:000 hours and removed at 7:00 hours every day from the third detectable stem node to 10 days post-flowering. Across growing seasons and crops, the average minimum temperature during the critical period ranged from 11.2 to 17.2 °C. Wheat and barley grain yield were similarly reduced under warm nights (ca. 7% °C(-1) ), due to GN reductions (ca. 6% °C(-1) ) linked to a lower number of spikes per m(2) . An accelerated development under high night temperatures led to a shorter critical period duration, reducing solar radiation capture with negative consequences for biomass production, GN and therefore, grain yield. The information generated could be used as a starting point to design management and/or breeding strategies to improve crop adaptation facing climate change.

Análisis de las noches tropicales en la fachada atlántica de la Pení­nsula Ibérica. Una propuesta metodológica

Texto resumen.

Assessment of climate variations in temperature and precipitation extreme events over Iran

In this study, changes in the spatial and temporal patterns of climate extreme indices were analyzed. Daily maximum and minimum air temperature, precipitation, and their association with climate change were used as the basis for tracking changes at 50 meteorological stations in Iran over the period 1975–2010. Sixteen indices of extreme temperature and 11 indices of extreme precipitation, which have been quality controlled and tested for homogeneity and missing data, are examined. Temperature extremes show a warming trend, with a large proportion of stations having statistically significant trends for all temperature indices. Over the last 15 years (1995–2010), the annual frequency of warm days and nights has increased by 12 and 14 days/decade, respectively. The number of cold days and nights has decreased by 4 and 3 days/decade, respectively. The annual mean maximum and minimum temperatures averaged across Iran both increased by 0.031 and 0.059 °C/decade. The probability of cold nights has gradually decreased from more than 20 % in 1975–1986 to less than 15 % in 1999–2010, whereas the mean frequency of warm days has increased abruptly between the first 12-year period (1975–1986) and the recent 12-year period (1999–2010) from 18 to 40 %, respectively. There are no systematic regional trends over the study period in total precipitation or in the frequency and duration of extreme precipitation events. Statistically significant trends in extreme precipitation events are observed at less than 15 % of all weather stations, with no spatially coherent pattern of change, whereas statistically significant changes in extreme temperature events have occurred at more than 85 % of all weather stations, forming strongly coherent spatial patterns.

Climate changes in temperature and precipitation extremes in an alpine grassland of Central Asia

The natural ecosystem in Central Asia is sensitive and vulnerable to the arid and semiarid climate variations, especially the climate extreme events. However, the climate extreme events in this area are still unclear. Therefore, this study analyzed the climate variability in the temperature and precipitation extreme events in an alpine grassland (Bayanbuluk) of Central Asia based on the daily minimum temperature, daily maximum temperature, and daily precipitation from 1958 to 2012. Statistically significant (p < 0.01) increasing trends were found in the minimum temperature, maximum temperature at annual, and seasonal time scales except the winter maximum temperature. In the seasonal changes, the winter temperature had the largest contribution to the annual warming. Further, there appeared increasing trends for the warm nights and the warm days and decreasing trends for the cool nights and the cool days at a 99 % confidence level. These trends directly resulted in an increasing trend for the growing season length (GSL) which could have positively influence on the vegetation productivity. For the precipitation, it displayed an increasing trend for the annual precipitation although it was not significant. And the summer precipitation had the same variations as the annual precipitation which indicated that the precipitation in summer made the biggest contribution to the annual precipitation than the other three seasons. The winter precipitation had a significant increasing trend (1.49 mm/10a) and a decreasing trend was found in spring. We also found that the precipitation of the very wet days mainly contributes to the annual precipitation with the trend of 4.5 mm/10a. The maximum 1-day precipitation and the heavy precipitation days only had slight increasing trend. A sharp decreasing trend was found before the early 1980s, and then becoming increase for the above three precipitation indexes. The climate experienced a warm-wet abrupt climate change in the 1980s. Further, this tendency may be continuous into the future.

A remarkably quick habituation and high use of a rope bridge by an endangered marsupial, the western ringtail possum

Rope bridges are being increasingly installed worldwide to mitigate the negative impacts of roads on arboreal animals. However, monitoring of these structures is still limited and an assessment of factors influencing the crossing behaviours is lacking. We monitored the use of a rope bridge near Busselton, Western Australia by the endangered western ringtail possums (Pseudocheirus occidentalis) in order to identify the patterns of use and factors influencing the crossings. We installed motion sensor cameras and microchip readers on the bridge to record the crossings made by individual animals, and analysed these crossing data using generalised linear models that included factors such as days since the installation of the bridge, breeding season, wind speed, minimum temperature and moonlight. Possums started investigating the bridge even before the installation was completed, and the first complete crossing was recorded only 36 days after the installation, which is remarkably sooner than arboreal species studied in other parts of Australia. The possums crossed the bridge increasingly over 270 days of monitoring at a much higher rate than we expected (8.87 ± 0.59 complete crossings per night). Possums crossed the bridge less on windy nights and warm nights probably due to the risk of being blown away and heat stress on warmer days. Crossings also decreased slightly on brighter nights probably due to the higher risk of predation. Breeding season did not influence the crossings. Pseudocheirus occidentalis habituated to the bridge very quickly, and our results demonstrate that rope bridges have a potential as an effective mitigation measure against the negative impacts of roads on this species. More studies and longer monitoring, as well as investigating whether crossing results in the restoration of gene flow are then needed in order to further assess the true conservation value of these crossing structures.

Changes in temperature and precipitation extreme indices over China: analysis of a high‐resolution grid dataset

ABSTRACTBased on the high‐resolution gridding data (CN05) from 2416 station observations, a grid dataset of temperature and precipitation extreme indices with the resolution of 0.5° × 0.5° for China region was developed using the approach recommended by the Expert Team on Climate Change Detection and Indices. This article comprehensively presents temporal and spatial changes of these indices for the time period 1961–2010. Results showed widespread significant changes in temperature extremes consistent with warming, for instance, decreases in cold extremes and increases in warm extremes over China. The warming in the coldest day and night is larger than the warmest day and night, respectively, which is concurrent with the coldest night larger than the coldest day and the warmest night larger than the warmest day. Changes in the number of the cold and warm nights are more remarkable than the cold and warm days. Changes in precipitation extremes are, in general, spatially more complex and exhibit a less widespread spatial coverage than the temperature indices, for instance, the patterns of annual total precipitation amount, average daily precipitation rate, and the proportion of heavy precipitation in total annual precipitation are similar with negative trends in a southwest–northeast belt from Southwest China to Northeast China while positive trends in eastern China and northwestern China. The consistency of changes in climate extremes from the CN05 with other datasets based on the stations and reanalyses is also analysed.

Transient high-resolution regional climate simulation for Greece over the period 1960-2100: evaluation and future projections

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 64:123-140 (2015) - DOI: https://doi.org/10.3354/cr01304 Transient high-resolution regional climate simulation for Greece over the period 1960-2100: evaluation and future projections P. Zanis1,*, E. Katragkou1, C. Ntogras1, G. Marougianni2, A. Tsikerdekis1, H. Feidas1, E. Anadranistakis3, D. Melas2 1Department of Meteorology and Climatology, School of Geology, Aristotle University of Thessaloniki, Thessaloniki, Greece 2Laboratory of Atmospheric Physics, School of Physics, Aristotle University of Thessaloniki, Thessaloniki, Greece 3Hellenic National Meteorological Service, Ellinikon, Greece *Corresponding author: zanis@geo.auth.gr ABSTRACT: A transient regional climate model simulation with a spatial grid resolution of 10 km (RCM10), nested to a regional simulation with 25 km resolution (RCM25), was carried out over Greece with RegCM3 for the period 1960-2100 under the IPCC A1B scenario. RCM10 precipitation and temperature fields depict the finer regional characteristics over the complex Greek terrain compared to RCM25, but a station-based evaluation for the period 1975-2000 does not reveal a considerable improvement in RCM10 compared to RCM25. Future projections for the early-future period 2021-2050 indicate small changes, with annual temperature increasing mostly over land by less than 1.8°C and precipitation changing by ±15%, being mostly negative in the southern part of the domain. At the end of the century (2071-2100), the projected changes become larger, with mean annual temperature increasing by about 3.4 to 4.2°C over land and by 2.6 to 3.4°C over the sea and precipitation decreasing by 10 to 40%, with a positive gradient from the north to the south. Summer presents the largest future increase in mean near-surface temperature over the Greek mainland, while winter and spring show the largest decreases in precipitation rate. The number of hot days, warm nights, night frosts and continuous dry spell days and length of the growing season are projected to increase slightly in the near-future period, but markedly and consistently in the late 21st century future period in accordance with the generally warmer and drier climate projected from the RCM10 simulation. KEY WORDS: Regional climate models · Greece · High resolution · Evaluation · Future projections Full text in pdf format Supplementary material PreviousNextCite this article as: Zanis P, Katragkou E, Ntogras C, Marougianni G and others (2015) Transient high-resolution regional climate simulation for Greece over the period 1960-2100: evaluation and future projections. Clim Res 64:123-140. https://doi.org/10.3354/cr01304 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 64, No. 2. Online publication date: July 07, 2015 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2015 Inter-Research.

Quantile Trends in Temperature Extremes in China

AbstractA number of recent studies have examined trends in extreme temperature indices using a linear regression model based on ordinary least-squares. In this study, quantile regression was, for the first time, applied to examine the trends not only in the mean but also in all parts of the distribution of several extreme temperature indices in China for the period 1960–2008. For China as a whole, the slopes in almost all the quantiles of the distribution showed a notable increase in the numbers of warm days and warm nights, and a significant decrease in the number of cool nights. These changes became much faster as the quantile increased. However, although the number of cool days exhibited a significant decrease in the mean trend estimated by classical linear regression, there was no obvious trend in the upper and lower quantiles. This finding suggests that examining the trends in different parts of the distribution of the time-series is of great importance. The spatial distribution of the trend in the 9...

Trends in the temperature and rainfall extremes during recent past in Gujarat

In the present study, an attempt has been made to analyze the temperature and rainfall extremes observed in Gujarat during the recent past. Observed daily data of maximum and minimum temperature and rainfall for 32 geographically well distributed locations in Gujarat for the available time series during year 1958 to 2011 has been used to calculate various extreme climate indices and their trends. Results revealed signature of warming in Gujarat as indicated by statewide uniform increase in numbers of warm nights (TR25), decrease in cold days (FD10), decrease in frequency cool nights (TN10p), increase in minimum of minimum temperature (TNn) and increase in frequency of warm nights (TN90p). The results also indicated an increase in total amount of precipitation (PRCPTOT) and extremely wet days (R99p) over more numbers of stations of the state. However, most temperature and rainfall extremes showed mixed over the state.

Attribution of extreme temperature changes during 1951–2010

An attribution analysis of extreme temperature changes is conducted using updated observations (HadEX2) and multi-model climate simulation (CMIP5) datasets for an extended period of 1951–2010. Compared to previous HadEX/CMIP3-based results, which identified human contributions to the observed warming of extreme temperatures on global and regional scales, the current results provide better agreement with observations, particularly for the intensification of warm extremes. Removing the influence of two major modes of natural internal variability (the Arctic Oscillation and Pacific Decadal Oscillation) from observations further improves attribution results, reducing the model-observation discrepancy in cold extremes. An optimal fingerprinting technique is used to compare observed changes in annual extreme temperature indices of coldest night and day (TNn, TXn) and warmest night and day (TNx, TXx) with multi-model simulated changes that were simulated under natural-plus-anthropogenic and natural-only (NAT) forcings. Extreme indices are standardized for better intercomparisons between datasets and locations prior to analysis and averaged over spatial domains from global to continental regions following a previous study. Results confirm previous HadEX/CMIP3-based results in which anthropogenic (ANT) signals are robustly detected in the increase in global mean and northern continental regional means of the four indices of extreme temperatures. The detected ANT signals are also clearly separable from the response to NAT forcing, and results are generally insensitive to the use of different model samples as well as different data availability.

Temperature and precipitation changes over the Loess Plateau between 1961 and 2011, based on high-density gauge observations

The Loess Plateau has the most serious soil erosion in China and is the main source of sediment in the Yellow River. In this study, we systematically analyzed the changes in the mean and extreme values for temperature and precipitation over the Loess Plateau between 1961 and 2011, using a gridded dataset with high-density gauge data. Statistically significant positive trends (p<0.05) in the mean, maximum, and minimum temperature values (TM, TX, and TN) were identified in almost all regions. Warming rates increased from the southeast to the northwest of the Loess Plateau for both TM and TN; however, for TX, the greatest warming increases were observed in the southeast region. We also found general decreases in the diurnal temperature range and the number of cold nights and cold days, and increases in the length of the growing season and the number of warm days and warm nights. Moreover, relatively intense changes occurred in the high percentile ranges for both TX and TN. The total amount of precipitation on wet days decreased over a large area of the Loess Plateau, particularly in the southeast region. The inequality in the spread of precipitation over the year (temporal inequality) increased extensively over the past fifty years in the wet region. Approximately 37.60% of the total area with a reduced amount of precipitation had concurrent decreases in both the frequency and intensity of rainfall. However, approximately 37.20% of the area with a reduced amount of precipitation had decreases in the frequency but increases in the intensity of rainfall. The proportion of days with light or moderate precipitation was decreased in the wet region which mainly located in the southwest of the Loess Plateau, but there were only minor changes in extreme precipitation events. Overall, when both temperature and precipitation changes were combined, we observed that the southwest of the Loess Plateau has undergone the largest degree of climate change. Consequently, both the ecological environment and local agriculture on the Loess Plateau will suffer increased challenges: the decline in water availability will lead to more frequent droughts, yet the risk of flood and soil erosion from extreme precipitation events will not be reduced.

Study of Daily Extreme Temperature Indices over Sutlej Basin, N-W Himalayan Region, India

&lt;div&gt; &lt;p&gt;A detailed analysis of extreme temperature indices for the period of 1970-2005 is conducted over Sutlej river basin located in North-West Himalayan region. For this purpose, daily records of maximum and minimum temperature data were procured from Bhakara Beas Management Board, India for four stations. These stations are installed at varying height from 518m to 976m under different physiographic and climatic conditions. Fourteen extreme indices for temperature as specified by the World Meteorological Organization (WMO) Commission for Climatology (CCL)/Climate Variability and Predictability (CLIVAR) Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI) are derived with the aid of RClimDex software. &amp;nbsp;Linear Regression (LR) method is employed for detecting annual as well as monthly trends in extreme indices of temperature over the period of thirty six years (1970-2005). Large spatial and inter-annual variability in trends of extreme indices is observed. However, a rise in diurnal temperature range is observed for the basin as a whole. This may be attributed to the decrease observed in maximum T&lt;sub&gt;Min&lt;/sub&gt; (TXn) and warm nights (TN90p) coupled with the increase in maximum T&lt;sub&gt;Max&lt;/sub&gt; (TXx).&lt;/p&gt; &lt;/div&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

Trends in indices of daily temperature and precipitations extremes in Morocco

The purpose of this paper is to provide a summary of Morocco’s climate extreme trends during the last four decades. Indices were computed based on a daily temperature and precipitation using a consistent approach recommended by the ETCCDI. Trends in these indices were calculated at 20 stations from 1970 to 2012. Twelve indices were considered to detect trends in temperature. A large number of stations have significant trends and confirm an increase in temperature, showing increased warming during spring and summer seasons. The results also show a decrease in the number of cold days and nights and an increase in the number of warm days and nights. Increasing trends have also been found in the absolute warmest and coldest temperatures of the year. A clear increase is detected for warm nights and diurnal temperature range. Eight indices for precipitation were also analyzed, but the trends for these precipitation indices are much less significant than for temperature indices and show more mixed spatial patterns of change. Heavy precipitation events do not exhibit significant trends except at a few locations, in the north and central parts of Morocco, with a general tendency towards drier conditions. The correlation between these climate indices and the large-scale atmospheric circulations indices such as the NAO, MO, and WEMO were also analyzed. Results show a stronger relationship with these climatic indices for the precipitation indices compared to the temperature indices. The correlations are more significant in the Atlantic regions, but they remain moderate at the whole country scale.

Analysis of temperature projections in the Koshi River Basin, Nepal

This study analyzes temperature projections in the Koshi River Basin in Nepal using data obtained from ten General Circulation Models (GCMs) for three IPCC Special Range of Emission Scenarios (SRES): B1, A1B and A2. Low resolution data of minimum and maximum temperature obtained from the selected GCMs was downscaled using the statistical downscaling model Long Ashton Research Station Weather Generator (LARS-WG) for ten stations located in two physiographic regions of the study area: the Middle Mountains (1500–2700 m) and the Siwalik Hills (700–1500 m). The projected temperature and differences in projections among individual GCM projections for changes in the mean value of seasonal and annual Tmin and Tmax are presented for three future periods: 2011–2030 (2020s), 2046–2065 (2055s) and 2080–2099 (2090s). We also analyzed the baseline period and future Tmin and Tmax data through seven indices, as recommended by the Expert Team on Climate Change Detection, Monitoring and Indices (ETCCDMI). Results show that the LARS-WG model performs well when downscaling Tmin and Tmax. An increase in seasonal as well as mean annual minimum and maximum temperature is projected for all three future periods. Projected warming, as well as the differences among projections from different GCMs, increases with time for each of the three scenarios. The cold years during the 2055s and 2090s are expected to be hotter than the hot years during the baseline period. The increase in temperature, as well as the range of uncertainty, is expected to be higher in the Mountains than in the Hills. The number of summer days and tropical nights is expected to increase during all three future periods. The temperature of the coldest day, coldest night, warmest day and warmest night is also expected to increase in both the regions during all three future periods.

Subtropical mouse-tailed bats use geothermally heated caves for winter hibernation.

We report that two species of mouse-tailed bats (Rhinopoma microphyllum and R. cystops) hibernate for five months during winter in geothermally heated caves with stable high temperature (20°C). While hibernating, these bats do not feed or drink, even on warm nights when other bat species are active. We used thermo-sensitive transmitters to measure the bats' skin temperature in the natural hibernacula and open flow respirometry to measure torpid metabolic rate at different ambient temperatures (Ta, 16-35°C) and evaporative water loss (EWL) in the laboratory. Bats average skin temperature at the natural hibernacula was 21.7 ± 0.8°C, and no arousals were recorded. Both species reached the lowest metabolic rates around natural hibernacula temperatures (20°C, average of 0.14 ± 0.01 and 0.16 ± 0.04 ml O2 g(-1) h(-1) for R. microphyllum and R. cystops, respectively) and aroused from torpor when Ta fell below 16°C. During torpor the bats performed long apnoeas (14 ± 1.6 and 16 ± 1.5 min, respectively) and had a very low EWL. We hypothesize that the particular diet of these bats is an adaptation to hibernation at high temperatures and that caves featuring high temperature and humidity during winter enable these species to survive this season on the northern edge of their world distribution.

Influence of eastern Pacific and central Pacific El Niño events on winter climate extremes over the eastern and central United States

ABSTRACTDifferent influences of the eastern‐Pacific (EP) El Niño and central‐Pacific (CP) El Niño on nine winter extreme indices over the eastern and central United States are examined through composite analysis of high‐resolution daily maximum temperature, minimum temperature, and precipitation for the period 1950–2010. During EP El Niño winters, there are usually more warm days and warm nights, fewer frost days, cold days, and cold nights over the eastern and central United States than in winters with a CP El Niño, especially for the Ohio Valley, around the Great Lakes, and southern New England. For precipitation extremes, compared with CP El Niño, EP El Niño usually brings more extreme precipitation amounts, more days with large precipitation amounts, larger amounts of maximum consecutive 5‐day total precipitation, and a shorter duration of consecutive dry days around the Great Lakes and Ohio Valley. The 500 hPa geopotential height anomalies show that wave train patterns differ when the maximum tropical sea surface heating locations are displaced. The corresponding wind field and moisture convergence anomalies are examined to analyse the mechanisms that drive the anomaly fields associated with the two types of El Niño events.

The Robes Project

More than 400 volunteers support the Robes Project in 22 host churches across south London. The charity supports homeless people, providing a safe and warm night shelter between November and April each year.