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Coastal upwelling that cools sea temperatures and nutrifies the euphotic layer is the focus of this research, motivated by how these processes benefit the marine ecosystem. Here, atmosphere–ocean reanalysis fields and satellite radiance data are employed to link South African coastal upwelling with nearshore winds and currents in the 2000–2021 period. Temporal behavior is quantified in three regimes—Benguela, transition, and Agulhas—to distinguish the influence of offshore transport, vertical pumping, and dynamic uplift. These three mechanisms of coastal upwelling are compared to reveal a leading role for cyclonic wind vorticity. Daily time series at west, south, and east coast sites exhibit pulsing of upwelling-favorable winds during summer. Over the western shelf, horizontal transport and vertical motion are in phase. The south and east shelf experience greater cyclonic wind vorticity in late winter, due to land breezes under the Mascarene high. Ekman transport and pumping are out of phase there, but dynamic uplift is sustained by cyclonic shear from the shelf-edge Agulhas current. Temporal analysis of longshore wind stress and cyclonic vorticity determined that vertical motion of ~5 m/day is pulsed at 4- to 11-day intervals due to passing marine high/coastal low-pressure cells. Height sections reveal that 15 m/s low-level wind jets diminish rapidly inshore due to topographic shearing by South Africa’s convex mountainous coastline. Mean maps of potential wind vorticity show a concentration around capes and at nighttime, due to land breezes. Air–land–sea coupling and frequent coastal lows leave a cyclonic footprint on the coast of South Africa that benefits marine productivity, especially during dry spells with a strengthened subtropical atmospheric ridge. This work has, for the first time, revealed that South Africa is uniquely endowed with three overlapping mechanisms that sustain upwelling along the entire coastline. Amongst those, cyclonic potential vorticity prevails due to the frequent passage of coastal lows that initiate downslope airflows. No other coastal upwelling zone exhibits such a persistent feature.

Soil moisture data is crucial for enhancing drought monitoring, optimizing water management, refining irrigation schedules, forecasting floods, and understanding climate change impacts. Despite the existence of long-term global satellite and reanalysis products, the performance of global satellite products in Ethiopia is underexplored, highlighting a need for comprehensive assessments to effectively utilize these resources and address critical environmental challenges. This research evaluates various operational satellites and reanalysis soil moisture datasets over the Gilgel Abay watershed. The datasets include the European Space Agency's Climate Change Initiative Soil Moisture (ESA-CCI SM), Soil Moisture and Ocean Salinity (SMOS), NASA's Soil Moisture Active Passive mission (SMAP Enhanced), the European Centre for Medium-Range Weather Forecasts Fifth Generation Reanalysis (ECMWF ERA5), Climate Forecast System reanalysis (CFSRv2), NASA's Short-term Prediction Research and Transition Center - Land Information System (SPoRT-LIS), and NASA's Global Land Data Assimilation System (GLDAS). After applying bias correction, the Kolmogorov-Smirnov two-sample t-tests, Bonferroni correction, and statistical error metrics, the evaluation reveals that all products, except NASA-GLDAS, effectively capture soil moisture dynamics. SMAP shows superior temporal dynamics, followed by SMOS, ESA-CCI, CFSRv2, LIS and ERA5. Using Spearman's rank correlation coefficient (rs), SMAP (rs = 0.68) and SMOS (rs = 0.67) identified as the most accurate soil moisture products, with SMOS excelling in spatial representation and closely aligning with the Topographic Wetness Index (TWI). However, the lack of sufficient in situ monitoring networks limits the ability to perform a thorough evaluation. Establishing these networks is essential for improving satellite retrievals and modelling in the upper Blue Nile Basin, Ethiopia.

This study analyses climate variability on the north coast of Peru to understand how the local weather is coupled with anomalous ocean conditions. Using high-resolution satellite reanalysis, statistical outcomes are generated via composite analysis and point-to-field regression. Daily time series data for 1979–2023 for Moche area (8S, 79W) river discharge, rainfall, wind, sea surface temperature (SST) and potential evaporation are evaluated for departures from the average. During dry weather in early summer, the southeast Pacific anticyclone expands, an equatorward longshore wind jet ~10 m/s accelerates off northern Peru, and the equatorial trough retreats to 10N. However, most late summers exhibit increased river discharge as local sea temperatures climb above 27 °C, accompanied by 0.5 m/s poleward currents and low salinity. The wet spell composite featured an atmospheric zonal overturning circulation comprised of lower easterly and upper westerly winds > 3 m/s that bring humid air from the Amazon. Convection is aided by diurnal heating and sea breezes that increase the likelihood of rainfall ~ 1 mm/h near sunset. Wet spells in March 2023 were analyzed for synoptic weather forcing and the advection of warm seawater from Ecuador. Although statistical correlations with Moche River discharge indicate a broad zone of equatorial Pacific ENSO forcing (Nino3 R~0.5), the long-range forecast skill is rather modest for February–March rainfall (R2 < 0.2).

Study region: The eastern flank of the 4 km Rwenzori Mountains and the Mobuku catchment 0.25–0.4 N, 29.85–30.1E are the geographic area for detailed analysis. Research focus: Hydro-climate variability is studied using high resolution satellite- and model- assimilated products in the period 1980–2023. The Mobuku catchment receives rainfall of 3–6 mm/day which generates an eastward discharge of 100 m3/s that declines rapidly downstream, thereby limiting hydro-power availability. New insights: Long-term trends in cloud fraction and potential evaporation reveal a tendency for drying associated with increasing easterly winds, subsidence near the mountain top, and warming of +.04 C/year that is melting glaciers. These constrain runoff on the eastern flank of the Rwenzori Mountains. Low river flows in Dec-Mar correspond with dry air intrusions from the northeast. High river flows in Jul-Nov are modulated by sea temperatures in the Indian Ocean that oscillate east-west at ∼3 year interval. Improved understanding of climate variability will contribute to better management of Uganda’s hydro-power resources.

Southwestern Peru has an arid climate typical of subtropical west coasts bordering cold ocean currents. Mountain runoff is barely able to sustain urban needs and motivates this research. Using high-resolution satellite reanalysis products, the meso-scale climate and weather variability are explored via point-to-field regression. A time series spanning 1970–2022 of Tacna area (18 S, 70.2 W, 570 m) rainfall, potential evaporation, wind, and weather parameters were evaluated for thermodynamic and kinematic features. Although sea breezes draw marine air inland, they simultaneously generate low-level divergence and subsidence aloft. Potential evaporation in early summer causes water deficits that are rarely offset by late summer runoff from the Andes Mountains. Winter (May–September) showers from passing cold fronts are more frequent during El Niño. Warming of the tropical east Pacific accelerates subtropical westerly winds that lift over the coastal plains. Quasi-stationary Rossby wave patterns amplify transient troughs at 70 W, but the winter showers rarely exceed 4 mm/day due to low-level stability from negative heat fluxes over cool seawater offshore. Two winter wet spells were studied using satellite and surface data (July 2002, July 2009). Light showers were prominent in elevations from 400 to 900 m. An early summer dry spell was considered (November 2020), wherein southeast winds, coastal upwelling, and low dewpoint temperatures coincided with La Niña conditions. A rain-gauge transect showed that summer convection stays east of the Andes escarpment and seldom benefits the coastal plains. Thus, water resources in Tacna are strained beyond the carrying capacity.

This study analyzes fluctuations in the atmospheric boundary layer height (aBLH) over a Caribbean island using hourly measured and model-interpolated data from the 2019–2023 period. Our focus is the mean structure, diurnal cycle, and aBLH correlation with meteorological parameters on the leeward coast at Mayaguez (18.2 N, 67.1 W). The mean diurnal cycle of the aBLH increases from 300 m near sunrise (07:00) to 1200 m by 13:00 because of turbulent heating. Summer-time thermal circulations lead to a 3 °C increase in near-surface dewpoint temperature (Td) that propagates upward to 3000 m by 16:00. A case study demonstrates how mid-day trade winds turn onshore and generate significant rainfall and river discharge across the island. The context for this study is provided by a 24 yr cluster analysis that identifies rainfall over the island’s northwest interior driven by upstream heating. Analysis of linear trends from 1979 to 2023 shows that Td declined by −0.02 °C/yr above 1500 m because of large-scale subsidence. However, cool interior forests transpire humidity and instill contrasting trends that may amplify climate extremes. A better understanding of entrainment at the top of the atmospheric boundary layer could be critical for managing future water resources in Caribbean islands.

Past and projected climatic trends in Puerto Rico in the period 1950–2100 are evaluated by detection of slope and fit in smoothed time series and by the mapping of local and regional trends using 5- to 50-km resolution products. New outcomes include second-order upward trends for evaporation and sea surface height. At a regional scale, Hadley Cell overturning is drying the mid-troposphere, inducing a northerly tendency for trade winds. The past rainfall trend (1950–2020) has increased ∼10% on the Atlantic-facing seaboard. Warming seas (+.02 °C/year) and rising vegetation fraction induce more evaporation that is deepening the moist boundary layer and sustaining thermal orographic precipitation over the island. Historical trends and model projections show a decrease in rainfall in spring and an increase in autumn, attributable to the retreat of the jet stream and the influence of transpiration, respectively. Outcomes reveal competition between small- and large-scale processes, and an island-wide water balance sustained by diurnal cycling. Adapting to the rising sea level makes pro-active coastal management a necessity. HIGHLIGHTS Past and future climate changes are similar.; Dataset and model resolution of

Severe weather impacts in the central Caribbean are quantified by an objective index of daily maximum wind and rainfall (W•R) in the area 16–19°N, 63–69°W over the period 1970–2021. The index, based on ERA5 hindcast assimilation of satellite and in situ data, peaks from the July to October season as high sea temperatures and weak wind shear promote tropical cyclogenesis. Climate forcing is studied by reducing the W•R index to seasonal values and regressing the time series onto reanalysis fields 10°S–25°N, 180°W–20°E. The outcome reflects Jul–Oct warming in the tropical Atlantic, cooling in the tropical east Pacific (cold tongue), decreased/increased convection over the Pacific/Atlantic, and tropical upper easterly winds. New findings emerge in the Mar–Jun season preceding higher W•R: reduced SW-cloud bands in the northeast Pacific, a convective trough over the equatorial Atlantic, and Caribbean cold-air outbreaks. The multivariate El Niño Southern Oscillation index correlates with Jul–Oct Caribbean W•R at 2-month lead time and shows growing influence. Composite analysis of the top-10 years identifies an anomalous Pacific–Atlantic Walker Circulation favoring higher Caribbean W•R. Salinity is below normal and heat flux is downward across the Atlantic. Anomalous low-level airflow inhibits upwelling in the SW Caribbean, deepening atmospheric moisture. A leading case (TC Fiona 2022) demonstrates the environmental conditions underpinning storm intensification. The key drivers of severe weather impacts yield guidance in strategic planning, risk management and disaster preparedness. New insights are gained from a localized index of severe weather.

Study region: Tana basin is the origin of the Blue Nile Basin located in Ethiopia. The Lake Tana’s mean annual precipitation is approximately 1400 mm/yr and its outflow drains an area of about 15,096 km2. There is limited effort to apply nested hydrological models for flood prediction due to being poorly gauged for validation. Study focus: The objective of this study is to show how climate simulations can be used to generate reliable local predictions of flood and runoff for the Blue Nile in the Ethiopian highlands.In this study, outputs from the Coupled Model Intercomparison Project Phase 6 (CMIP6) were used to initialize a nested hydrological model to reveal long-term trends of runoff in flood-prone areas of the Lake Tana basin, Ethiopia. Available satellite and reanalysis datasets were used for selection of CMIP6 products and the five models with best validation were used to force a nested hydrological model: Known as Wflow_sbm. A model-independent multi-algorithm optimization estimation tool was implemented for calibration of Wflow with insitu observations. New hydrological insights for the region: In terms of simulating runoff and flood events, application of Wflow_sbm to the Lake Tana basin gave promising results. This study serves as a major step towards the development and implementation of global model-driven nested hydrological assessments of flood risk in future projections for Lake Tana basin.

The eastward shift of semi-arid climate across South Africa is studied using satellite assimilated cloud cover, vegetation temperature and potential evaporation 1981–2019, and 21st century coupled model projections. Semi-arid thresholds over the plateau have shifted hundreds of kilometers eastward in the Vaal River catchment for potential evaporation, cloud fraction, and vegetation temperature. Coastal cloudiness has also changed due to sea breezes modified by shelf zone sea temperatures. Processes underlying the spread of semi-arid conditions across South Africa are quantified. Desiccation is related to greater westerly airflow, as the atmospheric boundary layer over the Kalahari preferentially links with the upper-level circulation. Warm dry spells and climate change enhance the meridional temperature gradient and accelerate the sub-tropical jet at both short- and long timescales. According to observations and reanalysis, dry westerlies prevail during the afternoon and induce +0.2 °C/year trends in vegetation temperature over the Highveld during the study period. Coupled model projections show that semi-arid conditions expand eastward from Bloemhof (25.5°E) by 50,000 km2, altering future adaptation strategies. HIGHLIGHTS The semi-arid climate of South Africa is studied using high-resolution satellite datasets 1981–2019 and 21st century coupled model projections.; Semi-arid thresholds over the plateau have shifted hundreds of kilometers southeastward.; A westerly airflow over the Kalahari joins with the sub-tropical jet to export warm dry air to the escarpment, particularly in the afternoon.;

Modulation of the marine environment in the Natal Bight (~29.1°S, 31.6°E) was studied using daily high-resolution climate reanalysis products and monthly satellite green- and red-band reflectance in the period 2002–2022. The KwaZulu-Natal shelf edge is characterized by a narrow band of upwelling next to the warm Agulhas Current. Strong, reversing longshore winds ~7 m/s and meandering poleward flow ~1 m/s pulse the system, but along the leeward coast that forms the Natal Bight, environmental conditions are buffered by a weak cyclonic gyre. Wind and current shear create a shadow zone that aggregates plankton, recycles nutrients, and sustains marine resources. The seasonal cycle is of high amplitude: the surface heat balance reaches +70 W/m2 in December, followed by river discharges ~3 M m3/yr of fresh nutrient-rich water that peak in February. This induces a buoyant surface layer that inhibits wind wave turbulence during summer. By contrast, winter (June–August) cooling −95 W/m2 and frequent cyclonic storminess deepen the mixed layer from 25 to 65 m, enabling wind wave turbulence to reach the seafloor (Tugela Bank). Red-band reflectance increases 3-fold from summer to winter and is significantly correlated with net heat balance −0.54, daily wave heights > 2.5 m +0.51, mixed layer depth +0.47, sea surface temp −0.41, and wind vorticity −0.39. Daily longshore winds from the northeast and southwest were, unexpectedly, most amplified in spring (August–October). The seasonality exhibits sequential effects that supports year-round marine nutrification in the Natal Bight. Intra-seasonal fluctuations were related to meandering of the Agulhas Current and changes in longshore winds and shelf waves that impart significant pulsing of near-shore currents at 4–9-day periods. Although the cyclonic gyre in the Natal Bight spins up and down, SST variance was found to be relatively low in its center, where external influences are buffered. Considering linear trends for winds and runoff and surface temperature over the period 1950–2021, we found that northeasterlies increased, runoff decreased, and inshore sea surface temperatures have warmed slowly relative to the adjacent land surface temperature. New insights derive from the use of monthly satellite red-band reflectance and daily 10 km climate reanalysis fields to understand how air–land–sea fluxes modulate the marine environment in the Natal Bight.

Near-surface currents entering the northern Caribbean from the Atlantic are described using ocean reanalysis at monthly to daily timescales, underpinned by satellite data assimilation. Statistical analyses involved spatial clustering into current vector modes with associated time scores for quantifying spectral power and regression onto atmospheric fields. Inflow across the Anegada, Mona, Windward (AMW) Passages peaks at ~100 m depth at ~0.2 m/s during summer and pulses at periods of 45, 100, and 365 days, and at 3, 6.5 years. The intra-seasonal periods may relate to Madden–Julian Oscillations and westward ocean Rossby waves, while inter-annual periods associate with regional climate anomalies. An empirical orthogonal function analysis demonstrates that AMW inflow varies across multiple timescales and is enhanced when the subtropical high-pressure ridge penetrates into the western Caribbean. A case study reveals key features during a surge of inflow to the northern Caribbean. Marine climate change involves heat advected poleward by currents along the western edge of the tropical Atlantic, fed through the Caribbean Sea. Consequently, the study of inflows garners wide interest.

Drought is a slow onset, recurring and inevitable feature of South Africa's climate. This research deconstructs the meteorological processes underlying drought and its impacts on surface temperature and vegetation in the more productive eastern half of South Africa. We use an index area 22–31°S, 22–32°E and extract monthly satellite and reanalysis data in the period 1979–2019. Drought intensity is determined by i) vegetation color, ii) soil moisture, iii) maximum air temperature and iv) net outgoing longwave radiation. Global drivers are represented by tropical Pacific and Indian Ocean sea temperatures. Composite and regression analysis of drought reveals a mid-tropospheric anticyclone over Namibia induces equatorward flow and subsidence that drives away atmospheric moisture. This feature is associated with the Pacific El Niño, positive Indian Ocean Dipole and an accelerated westerly jet stream. Ocean warming east of Madagascar draws NW-cloud bands there. The advection of anticyclonic vorticity from the South Atlantic and standing atmospheric Rossby wave-trains are key features of South African drought. Dry spells in the summers of 2015, 2016 and 2019 were more intense than 1983 and 1992, as reflected by S-pan potential evaporation measurements >14 mm/day. Despite water deficits, maize yields and river discharge appear stable, due to the uptake of scientific advice and innovative engineering.

Air pollution dispersion over Durban is studied using satellite, reanalysis and in situ measurements. This coastal city of 4 million people located on the east coast of South Africa contributes 29 million T/yr of trace gases, mostly from transport and industry. Terrestrial and agricultural particulates derive from the Kalahari Desert, Zambezi Valley and Mozambique. Surface air pollutants accumulate during winter (May–August) and provide a focus for statistical analysis of monthly, daily and hourly time series since 2001. The mean diurnal cycle has wind speed minima during the land−sea breeze transitions that follow morning and evening traffic emissions. Daily air pollution concentrations (CO, NO2, O3, PM2.5 and SO2) vary inversely with dewpoint temperature and tend to peak during winter prefrontal weather conditions. Descending airflow from the interior highlands induces warming, drying and poor air quality, bringing dust and smoke plumes from distant sources. Spatial regression patterns indicate that winters with less dispersion are preceded by warm sea surface temperatures in the tropical West Indian Ocean that promote a standing trough near Durban. Statistical outcomes enable the short- and long-range prediction of atmospheric dispersion and risk of exposure to unhealthy trace gases and particulates. The rapid inland decrease of mean wind speed from 8 to 2 m/s suggests that emissions near the coast will disperse readily compared with in interior valleys.

Using ozone data from model-assimilated satellite measurements in the eastern Caribbean 15–20N, 60–68W, cases were studied when upper tropospheric O3 values declined below 60 ppb. Secondary criteria on convection and circulation isolated two hurricanes for analysis (Irma and Maria 2017). Winds at 150 hPa (14 km) show divergence over the vortex characterized by ozone 100 ppb appear west of hurricanes, where sinking motions interact with vortex outflow. Past work suggests that high values are important, but here low ozone concentrations near the core are more conspicuous. The low O3 layer formed over the ocean and lifted by the hurricane circulation and convection, indicates vortex – environment interaction, vertical motion and storm intensity. Upper tropospheric O3 concentrations 10 mm/h, appearing as a protective envelope around the core.

Region: Upper Zambezi catchment and the river flow gauge at Kafue Hook (13.4S, 27.8E), typified by gentle topography and a strong seasonal cycle. Focus: Evaluation of satellite and model estimates of hydro-meteorology conditions using data in the period 1998–2015, to supplement the very limited operational reports coming from the region. Insights: Satellite soil moisture and model run-off track the Kafue Hook gauge with correlation values of 84% and 68%, respectively. Satellite river flow estimates achieve a logarithmic fit to monthly and daily gauge of 92% and 65%, respectively. Discrepancies are related to inadequate (calibration) reporting and to under-estimation of evaporation in the dry season. Statistical analyses of satellite rainfall and model evaporation are used to suggest improvements to hydro-meteorology network coverage in the upper Zambezi. An automated online network of ∼20 weather stations and river flow gauges appears sufficient, given satellite-model ability to interpolate between observations.

Over the past three decades, marine resource management has shifted conceptually from top-down sectoral approaches towards the more systems-oriented multi-stakeholder frameworks of integrated coastal management and ecosystem-based conservation. However, the successful implementation of such frameworks is commonly hindered by a lack of cross-disciplinary knowledge transfer, especially between natural and social sciences. This review represents a holistic synthesis of three decades of change in the oceanography, biology and human dimension of False Bay, South Africa. The productivity of marine life in this bay and its close vicinity to the steadily growing metropolis of Cape Town have led to its socio-economic significance throughout history. Considerable research has highlighted shifts driven by climate change, human population growth, serial overfishing, and coastal development. Upwelling-inducing winds have increased in the region, leading to cooling and likely to nutrient enrichment of the bay. Subsequently the distributions of key components of the marine ecosystem have shifted eastward, including kelp, rock lobsters, seabirds, pelagic fish, and several alien invasive species. Increasing sea level and exposure to storm surges contribute to coastal erosion of the sandy shorelines in the bay, causing losses in coastal infrastructure and posing risk to coastal developments. Since the 1980s, the human population of Cape Town has doubled, and with it pollution has amplified. Overfishing has led to drastic declines in the catches of numerous commercially and recreationally targeted fish, and illegal fishing is widespread. The tourism value of the bay contributes substantially to the country’s economy, and whale watching, shark-cage diving and water sports have become important sources of revenue. Compliance with fisheries and environmental regulations would benefit from a systems- oriented approach whereby coastal systems are managed holistically, embracing both social and ecological goals. In this context, we synthesize knowledge and provide recommendations for multidisciplinary research and monitoring to achieve a better balance between developmental and environmental agendas.

Near-surface winds around the mountainous Caribbean islands contribute to orographic lifting and thermal diurnal rainfall that requires mesoscale analysis. Here, a new perspective is presented via high-resolution satellite and reanalysis products. Singular value decomposition is applied to 5 km cold-cloud duration satellite data to understand the leading mode of seasonal hydro-climate variability and its regional controls. The spatial loadings reflect wet islands in a dry marine climate, while temporal amplitude is modulated by the large-scale zonal circulation. When summer-time trade winds weaken, daytime confluence around Caribbean islands enlarges, gathering and lifting more moisture. In addition to the static geographic forcing, transient easterly waves impart the majority of marine rainfall between June and September. Higher resolution products capture the thermal orographic effect and reveal upward trends in island rainfall and soil moisture over the satellite era, while lower resolution products miss this effect. The climate of mountainous Caribbean islands is trending toward increased runoff and soil moisture.

Rain-fed agriculture in North-West (NW) Ethiopia is seasonally modulated, and our objective is to isolate past and future trends that influence crop growth. Statistical methods are applied to gauge-interpolated, reanalysis, and satellite data to evaluate changes in the annual cycle and long-term trends. The June to September wet season has lengthened due to the earlier arrival and later departure of rains. Meteorological composites relate this spreading to local southerly winds and a dry-south/wet-north humidity dipole. At the regional scale, an axis of convection over the Rift Valley (35E) is formed by westerly waves on 15S and an anticyclone over Asia 30N. Coupled Model Intercomparsion Project (CMIP5) Hadley2 data assimilated by the Inter-Sectoral Impact Model Intercomparision Project (ISIMIP) hydrological models are used to evaluate projected soil moisture and potential evaporation over the 21st century. May and October soil moisture is predicted to increase in the future, but trends are weak. In contrast, the potential evaporation is rising and may put stress on the land and water resources. A lengthening of the growing season could benefit crop yields across the NW Ethiopian highlands.

Environmental influences on Hurricane Maria in the Antilles Islands are analyzed at the large-scale (1−25 September) and at the meso-scale (17−20 September 2017). The storm intensified rapidly prior to landfall in Dominica, going from category 1 to 5 in 15 h. As the storm progressed toward Puerto Rico (PR), its NE flank entrained air from seas cooled by the earlier passage of two hurricanes, and strengthened on its SW flank. Operational model forecasts tended to delay intensification until west of the Antilles Islands, thus motivating two independent weather research and forecasting (WRF) simulations. These gave minimal track errors at 1- to 3-day lead time. The simulation for landfall at Dominica on 19 September 2017 showed that a static nest with 0.8 km resolution using a Holland-type synthetic vortex and Yonsei University (YSU)/Kain-Fritsch schemes performed better; with a track error of 8 km and intensity error of 10 m/s. Our PR-area simulation of central pressure lagged 30 hPa behind observation; and caught up with reality by landfall in PR. The simulated rainband structure corresponded with Cloudsat observations over PR. Maria’s intensification occurred in an area of thermodynamic gradients included cooler SST in the right side of the track, so operational models with right-track bias were late in predicting intensification. Category-2 forecasts prior to 18 September 2017 left many Antilles islanders unprepared for the disaster that ensued.

The meteorological influences on Caribbean air chemistry are studied using in-situ, satellite and model data. Although African dust plumes join locally generated pollutants, concentrations are relatively low in the eastern Caribbean due to geographic remoteness and steady oceanic trade winds. Urban-industrial emissions from big cities (e.g., Kingston, Santo Domingo, San Juan), agricultural emissions from the south, and volcanic emissions from Montserrat contribute a noticeable burden. Conditions over Puerto Rico in the dry season (December–May) provide a focus for statistical analysis of air chemistry constituents and weather variables that describe dispersion conditions. Monthly and daily air indices are formed by summing the normalized values of fine aerosols and particulates, long- and short-lived trace gases from in-situ, satellite and model sources. The spatial correlation of a daily Puerto Rico air index onto regional dewpoint temperature, air pressure and outgoing longwave radiation fields in December–May 2005–2015 reveals the northward movement of a dry tongue and trough. At the climate timescale, Pacific El Nino conditions favor an increase of spring-time air pollution corresponding to anomalous inflow from Africa and the southern Caribbean coast. Composite weather patterns for a group of high air index values reflect divergent trade winds and a strong jet stream that imparts anticyclonic vorticity, subsidence and low humidity. This new understanding will underpin better air quality forecasts for Puerto Rico and the wider Caribbean.

Year-to-year fluctuations of Ethiopia climate are investigated to develop statistical predictions at one-season lead time. Satellite vegetation data from NASA and rainfall from ARC2 are the basis for analysis. The “target” seasons are May–July and August–October, while “predictors” are December–February and March–May, respectively. Global fields of surface temperature, sea level air pressure, and upper and lower level zonal winds are employed in point-to-field correlations. After step-wise multivariate regression, the leading predictors are: surface temperature across Europe (cold-favourable), 850 mb zonal winds over the tropical Atlantic (easterly-favourable), and surface temperature in the tropical Indian Ocean (cold-favourable). Predictive algorithms for early and late rainfall exhibit a consistent r2 fit of ~0.50, while those for vegetation reach ~0.65 in late summer, indicating that fluctuations in food resources could be forewarned.

This study evaluates seasonal forecasts of rainfall and maximum temperature across the Ethiopian highlands from coupled ensemble models in the period 1981–2006, by comparison with gridded observational products (NMA + GPCC/CRU3). Early season forecasts from the coupled forecast system (CFS) are steadier than European community medium range forecast (ECMWF). CFS and ECMWF April forecasts of June–August (JJA) rainfall achieve significant fit (r2=0.27, 0.25, resp.), but ECMWF forecasts tend to have a narrow range with drought underpredicted. Early season forecasts of JJA maximum temperature are weak in both models; hence ability to predict water resource gains may be better than losses. One aim of seasonal climate forecasting is to ensure that crop yields keep pace with Ethiopia’s growing population. Farmers using prediction technology are better informed to avoid risk in dry years and generate surplus in wet years.

Weather forecast and reanalysis models exhibit different performance in daily rainfall estimation over the Ethiopian highlands, 2000–2012, with ECMWF closer to observations than other models. Background is given to illustrate the Hadley circulation and easterly jets over Ethiopia, using sections on 37°E in July–August 2011. ECMWF reanalysis has a narrow band of rainfall >15 mm/day on 10°N, consistent with TRMM satellite estimates, associated with a steep gradient in meridional wind. MERRA and GFS models have a wider band of rainfall and weaker gradients in meridional winds. The contrasting background states influence a nested WRF model simulation of heavy rain in the upper Nile Valley on 29 July, 2011. The GFS (ECMWF) initialization yields stronger northerly (southerly) winds north (south) of Ethiopia, while aircraft observations are southerly at 850 mb and northerly at 700 mb. ECMWF produces heavy and widespread rainfall consistent with observations, with a potentially more realistic simulation of the Hadley circulation.