Interannual variability of annual streamflow and the Southern Oscillation in Costa Rica

AbstractThe Haines index (HI) is a fire-weather index that is widely used as an indicator of the potential for dry, low-static-stability air in the lower atmosphere to contribute to erratic fire behavior or large fire growth. This study examines the interannual variability of HI over North America and its relationship to indicators of large-scale circulation anomalies. The results show that the first three HI empirical orthogonal function modes are related respectively to El Niño–Southern Oscillation (ENSO), the Arctic Oscillation (AO), and the interdecadal sea surface temperature variation over the tropical Pacific Ocean. During the negative ENSO phase, an anomalous ridge (trough) is evident over the western (eastern) United States, with warm/dry weather and more days with high HI values in the western and southeastern United States. During the negative phase of the AO, an anomalous trough is found over the western United States, with wet/cool weather and fewer days with high HI, while an anomalous ridge occurs over the southern United States–northern Mexico, with an increase in the number of days with high HI. After the early 1990s, the subtropical high over the eastern Pacific Ocean and the Bermuda high were strengthened by a wave train that was excited over the tropical western Pacific Ocean and resulted in warm/dry conditions over the southwestern United States and western Mexico and wet weather in the southeastern United States. The above conditions are reversed during the positive phase of ENSO and AO and before the early 1990s.

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Phenology of myxomycetes in Turrialba, Costa Rica

Karstenia ◽

10.29203/ka.2021.506 ◽

2021 ◽

pp. 1-12

Author(s):

Carlos Rojas ◽

Pedro A. Rojas ◽

Steven L. Stephenson

Keyword(s):

Costa Rica ◽

Southern Oscillation ◽

Biological Data ◽

Species Level ◽

Ecological Effect ◽

Sampling Effort ◽

Ecosystem Structure ◽

Forest Patch ◽

Local Climate ◽

Substrate Quality

Long-term monitoring and phenological patterns of microbial communities are rare in the scientific literature. Myxomycetes have life cycle characteristics that allow both to be documented. The present study summarizes the integrated floristic and bioclimatic components of a 30-month assessment of myxomycete sporocarps in a premontane tropical forest in Turrialba, Costa Rica. Based on monthly visits and a standard sampling effort of 120 minutes per visit, myxomycetes were recorded on leaves, twigs, and logs on the ground by two to three people in 20-minute periods associated with six different collecting sites within a 34-hectare successional forest patch. Biological data were analyzed using three recorded climatic variables obtained in situ during the complete period of study. Also, the Oceanic Niño Index (ONI), provided by NOAA, an estimate of El Niño-Southern Oscillation (ENSO), was evaluated in the analyses. Overall, 54 species and 2245 records of myxomycetes were recorded, with an average of 14.5 species (range between 6-24) and 78.4 records (range between 20-110) detected each month. In general, neither the number of records nor the number of species were associated with individual climate variables, but multiple regression analyses showed that a combination of the accumulated precipitation of the four days before sampling and the average relative humidity can explain most of the fruiting dynamics (R2 = 0.56). When the ONI index was included in the analyses, the explained variability increased (R2 = 0.64), and when a categorization of months based on the same index was used, analyses showed that both the number of records and species evenness were affected by ENSO. At the species level, Hemitrichia calyculata was the only species observed during every month, closely followed by Arcyria cinerea, A. denudata, and Physarum compressum, recorded on most visits. Sporadic fruiting in some species such as Tubifera microsperma, P. tenerum, P. bogoriense, P. melleum, and Metatrichia vesparia could have been associated with local climate oscillations influenced by ENSO patterns. Phenological patterns were observed at the species level, indicating that in the Neotropics, under favorable conditions, myxomycete sporocarps are practically always present, but species assemblages vary temporally. These variations are primarily driven by local climate, but regional climate dynamics also affect fruiting patterns. Presumably, the remaining ecological effect on fruiting patterns in the Neotropics can be attributed to certain finer factors such as ecosystem structure, substrate quality/ availability, and biotic interactions. As such, phenomena such as climate change can have an important effect on the production of sporocarps by tropical myxomycetes, with subsequent effects of their ecological dynamics.

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Stratospheric ozone interannual variability (1995–2011) as observed by Lidar and Satellite at Mauna Loa Observatory, HI and Table Mountain Facility, CA

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-12-30825-2012 ◽

2012 ◽

Vol 12 (11) ◽

pp. 30825-30867

Author(s):

G. Kirgis ◽

T. Leblanc ◽

I. S. McDermid ◽

T. D. Walsh

Keyword(s):

Time Series ◽

Solar Cycle ◽

Interannual Variability ◽

Southern Oscillation ◽

Stratospheric Ozone ◽

Montreal Protocol ◽

Quasi Biennial Oscillation ◽

Mauna Loa ◽

Table Mountain ◽

Biennial Oscillation

Abstract. The Jet Propulsion Laboratory (JPL) lidars, at the Mauna Loa Observatory, Hawaii (MLO, 19.5° N, 155.6° W) and the JPL Table Mountain Facility (TMF, California, 34.5° N, 117.7° W), have been measuring vertical profiles of stratospheric ozone routinely since the early 1990's and late-1980s respectively. Interannual variability of ozone above these two sites was investigated using a multi-linear regression analysis on the deseasonalized monthly mean lidar and satellite time-series at 1 km intervals between 20 and 45 km from January 1995 to April 2011, a period of low volcanic aerosol loading. Explanatory variables representing the 11-yr solar cycle, the El Niño Southern Oscillation, the Quasi-Biennial Oscillation, the Eliassen–Palm flux, and horizontal and vertical transport were used. A new proxy, the mid-latitude ozone depleting gas index, which shows a decrease with time as an outcome of the Montreal Protocol, was introduced and compared to the more commonly used linear trend method. The analysis also compares the lidar time-series and a merged time-series obtained from the space-borne stratospheric aerosol and gas experiment II, halogen occultation experiment, and Aura-microwave limb sounder instruments. The results from both lidar and satellite measurements are consistent with recent model simulations which propose changes in tropical upwelling. Additionally, at TMF the ozone depleting gas index explains as much variance as the Quasi-Biennial Oscillation in the upper stratosphere. Over the past 17 yr a diminishing downward trend in ozone was observed before 2000 and a net increase, and sign of ozone recovery, is observed after 2005. Our results which include dynamical proxies suggest possible coupling between horizontal transport and the 11-yr solar cycle response, although a dataset spanning a period longer than one solar cycle is needed to confirm this result.

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Oceanography of the New Zealand subantarctic region

10.26686/wgtn.17009291 ◽

2021 ◽

Author(s):

◽

Aitana Forcén-Vázquez

Keyword(s):

New Zealand ◽

Interannual Variability ◽

Water Column ◽

Large Scale ◽

Southern Oscillation ◽

Complex Structure ◽

Positive Trend ◽

Intermediate Water ◽

Subantarctic Region

Subantarctic New Zealand is an oceanographycally dynamic region with the Subtropical Front (STF) to the north and the Subantarctic Front (SAF) to the south. This thesis investigates the ocean structure of the Campbell Plateau and the surrounding New Zealand subantarctic, including the spatial, seasonal, interannual and longer term variability over the ocean properties, and their connection to atmospheric variability using a combination of in-situ oceanographic measurements and remote sensing data. The spatial and seasonal oceanographic structure in the New Zealand subantarctic region was investigated by analysing ten high resolution Conductivity Temperature and Depth (CTD) datasets, sampled during oceanographic cruises from May 1998 to February 2013. Position of fronts, water mass structure and changes over the seasons show a complex structure around the Campbell Plateau combining the influence of subtropical and subantarctic waters. The spatial and interannual variability on the Campbell Plateau was described by analysing approximately 70 low resolution CTD profiles collected each year in December between 2002 and 2009. Conservative temperature and absolute salinity profiles reveal high variability in the upper 200m of the water column and a homogeneous water column from 200 to 600m depth. Temperature variability of about 0.7 °C, on occasions between consecutive years, is observed down to 900m depth. The presence of Subantarctic Mode Water (SAMW) on the Campbell Plateau is confirmed and Antarctic Intermediate Water (AAIW) reported for the first time in the deeper regions around the edges of the plateau. Long-term trends and variability over the Campbell Plateau were investigated by analysing satellite derived Sea Level Anomalies (SLA) and Sea Surface Temperature (SST) time series. Links to large scale atmospheric processes are also explored through correlation with the Southern Oscillation Index (SOI) and Southern Annular Mode (SAM). SST shows a strong seasonality and interannual variability which is linked to local winds, but no significant trend is found. The SLA over the Campbell Plateau has increased at a rate of 5.2 cm decade⁻¹ in the last two decades. The strong positive trend in SLA appears to be a combination of the response of the ocean to wind stress curl (Ekman pumping), thermal expansion and ocean mass redistribution via advection amongst others. These results suggest that the variability on the Campbell Plateau is influenced by the interaction of the STF and the SAF. The STF influence reaches the limit of the SAF over the western Campbell Plateau and the SAF influence extends all around the plateau. Results also suggest different connections between the plateau with the surrounding oceans, e.g., along the northern edge with the Bounty Trough and via the southwest edge with the SAF. A significant correlation with SOI and little correlation with SAM suggest a stronger response to tropically driven processes in the long-term variability on the Campbell Plateau. The results of this thesis provide a new definitive assessment of the circulation, water masses and variability of the Campbell Plateau on mean, annual, and interannual time scales which will support research in other disciplines such as palaeoceanography, fisheries management and climate.

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A Hydroclimatological Analysis of Precipitation in the Ganges–Brahmaputra–Meghna River Basin

Water ◽

10.3390/w10101359 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1359 ◽

Cited By ~ 3

Author(s):

Scott Curtis ◽

Thomas Crawford ◽

Munshi Rahman ◽

Bimal Paul ◽

M. Miah ◽

...

Keyword(s):

Interannual Variability ◽

River Basin ◽

Significant Relationship ◽

Large Scale ◽

Monsoon Rainfall ◽

Southern Oscillation ◽

Wave Train ◽

Principal Component ◽

South Atlantic ◽

The Ganges

Understanding seasonal precipitation input into river basins is important for linking large-scale climate drivers with societal water resources and the occurrence of hydrologic hazards such as floods and riverbank erosion. Using satellite data at 0.25-degree resolution, spatial patterns of monsoon (June-July-August-September) precipitation variability between 1983 and 2015 within the Ganges–Brahmaputra–Meghna (GBM) river basin are analyzed with Principal Component (PC) analysis and the first three modes (PC1, PC2 and PC3) are related to global atmospheric-oceanic fields. PC1 explains 88.7% of the variance in monsoonal precipitation and resembles climatology with the center of action over Bangladesh. The eigenvector coefficients show a downward trend consistent with studies reporting a recent decline in monsoon rainfall, but little interannual variability. PC2 explains 2.9% of the variance and shows rainfall maxima to the far western and eastern portions of the basin. PC2 has an apparent decadal cycle and surface and upper-air atmospheric height fields suggest the pattern could be forced by tropical South Atlantic heating and a Rossby wave train stemming from the North Atlantic, consistent with previous studies. Finally, PC3 explains 1.5% of the variance and has high spatial variability. The distribution of precipitation is somewhat zonal, with highest values at the southern border and at the Himalayan ridge. There is strong interannual variability associated with PC3, related to the El Nino/Southern Oscillation (ENSO). Next, we perform a hydroclimatological downscaling, as precipitation attributed to the three PCs was averaged over the Pfafstetter level-04 sub-basins obtained from the World Wildlife Fund (Gland, Switzerland). While PC1 was the principal contributor of rainfall for all sub-basins, PC2 contributed the most to rainfall in the western Ganges sub-basin (4524) and PC3 contributed the most to the rainfall in the northern Brahmaputra (4529). Monsoon rainfall within these two sub-basins were the only ones to show a significant relationship (negative) with ENSO, whereas four of the eight sub-basins had a significant relationship (positive) with sea surface temperature (SST) anomalies in the tropical South Atlantic. This work demonstrates a geographic dependence on climate teleconnections in the GBM that deserves further study.

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Impact of El Niño Southern Oscillation on the interannual variability of methane and tropospheric ozone

10.5194/acp-2019-222 ◽

2019 ◽

Author(s):

Matthew J. Rowlinson ◽

Alexandru Rap ◽

Stephen R. Arnold ◽

Richard J. Pope ◽

Martyn P. Chipperfield ◽

...

Keyword(s):

Growth Rate ◽

Interannual Variability ◽

Biomass Burning ◽

El Niño ◽

Atmospheric Transport ◽

El Nino ◽

Southern Oscillation ◽

Fire Emissions ◽

Tropospheric O3 ◽

Global Mean

Abstract. The growth rate of global methane (CH4) concentrations has a strong interannual variability which is believed to be driven largely by fluctuations in CH4 emissions from wetlands and wildfires, as well as changes to the atmospheric sink. The El Niño Southern Oscillation (ENSO) is known to influence fire occurrence, wetland emission and atmospheric transport, but there are still important uncertainties associated with the exact mechanism and magnitude of this influence. Here we use a modelling approach to investigate how fires and meteorology control the interannual variability of global carbon monoxide (CO), CH4 and ozone (O3) concentrations, particularly during large El Niño events. Using a three-dimensional chemical transport model (TOMCAT) coupled to a sophisticated aerosol microphysics scheme (GLOMAP) we simulate changes to CO, hydroxyl radical (OH) and O3 for the period 1997–2014. We then use an offline radiative transfer model to quantify the impact of changes to atmospheric composition as a result of specific drivers. During the El Niño event of 1997–1998, there were increased emissions from biomass burning globally. As a result, global CO concentrations increased by more than 40 %. This resulted in decreased global mass-weighted tropospheric OH concentrations of up to 9 % and a resulting 4 % increase in the CH4 atmospheric lifetime. The change in CH4 lifetime led to a 7.5 ppb yr−1 increase in global mean CH4 growth rate in 1998. Therefore biomass burning emission of CO could account for 72 % of the total effect of fire emissions on CH4 growth rate in 1998. Our simulations indicate variations in fire emissions and meteorology associated with El Niño have opposing impacts on tropospheric O3 burden. El Niño-related atmospheric transport changes decrease global tropospheric O3 concentrations leading to a −0.03 Wm−2 change in O3 radiative effect (RE). However, enhanced fire emission of precursors such as nitrous oxides (NOx) and CO increase O3 RE by 0.03 Wm−2. While globally the two mechanisms nearly cancel out, causing only a small change in global mean O3 RE, the regional changes are large up to −0.33 Wm−2 with potentially important consequences for atmospheric heating and dynamics.

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Interannual variability of NDVI over Africa and its relation to El Niño/Southern Oscillation

International Journal of Remote Sensing ◽

10.1080/01431169608949091 ◽

1996 ◽

Vol 17 (13) ◽

pp. 2533-2548 ◽

Cited By ~ 148

Author(s):

A. ANYAMBA ◽

J. R. EASTMAN

Keyword(s):

Interannual Variability ◽

El Niño ◽

El Nino ◽

Southern Oscillation ◽

El Niño Southern Oscillation ◽

El Nino Southern Oscillation

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Interannual Modality of Upper-Ocean Temperature: 4D Structure Revealed by Argo Data

Journal of Climate ◽

10.1175/jcli-d-14-00351.1 ◽

2015 ◽

Vol 28 (9) ◽

pp. 3441-3452 ◽

Cited By ~ 2

Author(s):

Ge Chen ◽

Hanou Chen

Keyword(s):

Interannual Variability ◽

Southern Oscillation ◽

Hadley Circulation ◽

Walker Circulation ◽

Upper Ocean ◽

Kelvin Wave ◽

Argo Data ◽

Sea Temperature ◽

Equatorial Undercurrent ◽

The Pacific

Abstract Using the newly available decade-long Argo data for the period 2004–13, a detailed study is carried out on deriving four-dimensional (4D) modality of sea temperature in the upper ocean with emphasis on its interannual variability in terms of amplitude, phase, and periodicity. Three principal modes with central periodicities at 19.2, 33.8, and 50.3 months have been identified, and their relationship with El Niño–Southern Oscillation (ENSO) is investigated, yielding a number of useful results and conclusions: 1) A striking tick-shaped pipe-like feature of interannual variability maxima, which is named the “Niño pipe” in this paper, has been revealed within the 10°S–10°N upper Pacific Ocean. 2) The pipe core extends downward from ~50 m at 130°E to ~250 m near the date line before tilting upward to the sea surface at about 275°E, coinciding nicely with the pathway of the Pacific equatorial undercurrent (EUC). 3) The double-peak zonal modality pattern of the Niño pipe in the upper Pacific is echoed in the subsurface Atlantic and Indian Oceans through Walker circulation, while its single-peak meridional modality pattern is mirrored in the subsurface North and South Pacific through Hadley circulation. 4) A coherent three-peak modal structure implies a strong coupling between sea level variability at the surface and sea temperature variability around the thermocline. Accumulating evidence suggests that Rossby/Kelvin wave dynamics in tandem with EUC-based thermocline dynamics are the main mechanisms of the three-mode Niño pipe in ENSO cycles.

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