Coastal Stations Research Articles

Картографирование и верификация сроков залегания снежного покрова Прибайкалья по дистанционным данным MODIS «снежный покров»

The mapping and analysis of the dates of onset and melting the snow cover in the Baikal region for 2000–2010 based on eight-day MODIS “snow cover” composites with a spatial resolution of 500 m, as well as their verification based on the data of 17 meteorological stations was carried out. For each year of the decennary under study, for each meteorological station, the difference in dates determined from the MODIS data and that of weather stations was calculated. Modulus of deviations vary from 0 to 36 days for onset dates and from 0 to 47 days – for those of stable snow cover melting, the average of the deviation modules for all meteorological stations and years is 9–10 days. It is assumed that 83 % of the cases for the onset dates can be considered admissible (with deviations up to 16 days), and 79 % of them for the end dates. Possible causes of deviations are analyzed. It was revealed that the largest deviations correspond to coastal meteorological stations and are associated with the inhomogeneity of the characteristics of the snow cover inside the pixels containing water and land. The dates of onset and melting of a stable snow cover from the images turned out to be later than those of weather stations for about 10 days. First of all (from the end of August to the middle of September), the snow is established on the tops of the ranges Barguzinsky, Baikalsky, Khamar-Daban, and later (in late November–December) a stable cover appears in the Barguzin valley, in the Selenga lowland, and in Priolkhonye. The predominant part of the Baikal region territory is covered with snow in October, and is released from it in the end of April till the middle of May.

Aeolian Dust Inputs in the Mediterranean and Black Sea Marine System

<p>The aim of this paper is to estimate the amount of aeolian dust, deposited by dry and wet processes, that is deposited to the eleven marine regions of the Mediterranean-Black Sea Marine System (MBMS) and to compare it to the riverine influxes (i.e. suspended and dissolved sediment loads). This research is based on information for aeolian dust deposition at several coastal stations, around the MBMS, following an extended research of the available literature. For data elaboration, processing, and visualization a G.I.S. environment was utilized. The total annual amount of dust input for the whole system has been estimated to 59.9 × 106 tonnes, of which 57.2 × 106 tonnes are deposited in the Mediterranean Sea and only 2.7 ×106 tonnes in the Black Sea. The contribution of dust input (load), corresponding to 6.2% and 0.8% of the total amount of suspended and dissolved load, for the Mediterranean and Black Sea respectively, reveals the significant role of the aeolian dust inputs to the MBMS marine environment, in particular, at its southern Mediterranean domain.</p>

Radon transport events associated with the impact of a NORM repository in the SW of Europe

Two radon measurement stations located to the north and south of a NORM (Naturally Occurring Radioactive Materials) repository of phosphogypsum (southwest of Europe) were used to monitor radon behavior during 2018. The stations are located at opposing sides of the repository, one in Huelva City to the north and other one in a rural area to the south. This setup aimed to identify the influence of the NORM repository on each station and use radon levels as a marker of atmospheric transport in the local area. To achieve this, a comparison was carried out with other coastal stations in the south of Spain, finding higher average concentrations in Huelva City, ~3.3 Bq m−3. Hierarchical clustering was applied to identify days with different radon patterns at each Huelva station, detecting possible local radon transport events from the repository. Three events were investigated with WRF (Weather Research and Forecasting) and FLEXPART-WRF (FLEXible PARTicle dispersion model). It was found that both sampling sites required atmospheric stagnant conditions to reach high radon concentration. However, under these conditions the urban station showed high radon regardless of wind direction while the rural station also required radon transport from the repository, either directly or indirectly.

Evaluation of global ocean tide models based on tidal gravity observations in China

Previous studies show that the calculated loading effects from global ocean tide models do not match actual measurements of gravity attraction and loading effects in Southeast Asia. In this paper, taking advantage of a unique network of gravity tidal stations all over the Chinese mainland, we compare the observed and modeled tidal loading effects on the basis of the most recent global ocean tide models. The results show that the average efficiencies of the ocean tidal loading correction for O1, K1, M2 are 77%, 73% and 59%, respectively. The loading correction efficiencies using recent ocean tidal models are better than the 40 years old Schwiderskis model at coastal stations, but relative worse at stations far from ocean.

Raindrop Size Distributions of North Indian Ocean Tropical Cyclones Observed at the Coastal and Inland Stations in South India

The current study summarizes the raindrop size distributions (RSDs) characteristic of the North Indian Ocean (NIO) tropical cyclones (TCs) measured with ground-based disdrometers installed at the coastal (Thiruvananthapuram, 8.5335°N, 76.9047°E) and inland (Kadapa, 14.4742°N, 78.7098°E) stations in south India. The NIO TCs observed at the coastal station showed more mid- and large-size drops (>1 mm) than the inland station. On the other hand, for both inland and coastal stations, small and mid-size drops (<3 mm) primarily contributed to the total number concentration and rainfall rate. The RSDs of the NIO TCs segregated into precipitation types (stratiform and convective) demonstrated the presence of more mid- and large-size drops at the coastal station. The RSD relations of the NIO TCs, which are used in rain retrieval algorithms of remote sensing (global precipitation measurement) radars, exhibited contrasts between the coastal and inland station. Further, the NIO TCs’ rainfall kinetic energy relations, which are crucial in rainfall erosivity studies, estimated for the coastal station revealed dissimilar characteristics to that of the inland station. The conceivable thermo-dynamical and microphysical processes that are accountable for the disparities in the NIO TCs RSDs measured at the coastal and inland stations are also elucidated in this work.

Ozone chemistry and dynamics at a tropical coastal site impacted by the COVID-19 lockdown

The nationwide lockdown in India to curb the spread of Coronavirus disease 2019 (COVID-19) led to colossal reduction in anthropogenic emissions. Here, we investigated the impact of lockdown on surface ozone (O3) and nitrogen dioxide (NO2) over a tropical coastal station – Thumba, Thiruvananthapuram (8.5°N, 76.9°E). Daytime as well as night-time NO2 showed reduction by 0.8 (40%) and 2.3 (35%) ppbv, respectively during the lockdown period of 25–30 March 2020 as compared with the same period of previous 3 years. Unlike many urban locations, daytime surface O3 is found to be dramatically reduced by 15 ppbv (36%) with O3 production rate being lower by a factor of 3 during the lockdown. Interestingly, a feature of O3-hump during the onset of land breeze typically observed during 1997–1998 has reappeared with magnitude of 5–10 ppbv. A photochemical box model, capturing this feature, revealed that significant O3 sustained till onset of land breeze over the land due to weaker titration with NOx during lockdown. It is suggested that the transport of this O3 rich air with onset of land breeze led to the observed hump. Our measurements unravel a remarkable impact of the COVID-19 lockdown on the chemistry and dynamics of O3 over this tropical coastal environment.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12040-021-01666-3.

Quarantine supervision of Wood Packaging Materials (WPM) at Chinese ports of entry from 2003 to 2016.

Exotic pests have caused huge losses to agriculture, forestry, and human health. Analyzing information on all concerned pest species and their origin will help to improve the inspection procedures and will help to clarify the relative risks of imported cargo and formulate international trade policies. Records of intercepted pests from wood packaging materials (WPM) from 2003 to 2016 in the China Port Information Network (CPIN) database were analyzed. Results showed that the number of intercepted pests from WPM was lowest in the first quarter and highest in the fourth one. The total number of interceptions increased each year, with 53.33% of intercepted insects followed by nematodes (31.54%). The original continent of most intercepted pests was Asia (49.29%). Xylophagous insects were primarily intercepted from Southeast Asian countries, whereas nematodes were primarily intercepted from Korea, Australia, Mexico, and other countries. WPM interception records were mainly concentrated in China's coastal inspection stations (98.7%), with the largest number of interceptions documented in Shanghai, followed by the inspection stations of Jiangsu Province. The proportion of pest taxa intercepted by the Chinese provinces' stations each year is becoming increasingly balanced. The number of pest disposal treatment measures for intercepted cargoes with dead non-quarantine pests increased significantly from 2012 to 2016. This reflects the fact that Chinese customs inspection stations are becoming increasingly scientific and standardizing the interception and treatment of WPM pests. The issues reflected in the database, with a view to providing a reference for future work by customs officers and researchers.

Variability and changes in Pearl River Delta water level: oceanic and atmospheric forcing perspectives

AbstractUnderstanding water level (WL) fluctuations in river deltas is of importance for managing water resources and minimizing the impacts of floods and droughts. Here, we demonstrate the competing effects of atmospheric and oceanic forcing on multi-timescale variability and changes in the Pearl River Delta (PRD) WLs in southern China, using 52 years (1961–2012) of in-situ observations at 13 hydrological stations. PRD WL presents significant seasonal to decadal variations, with large amplitudes upstream related to strong variability of southern China rainfall, and with relatively small amplitudes at the coastal stations determined by sea level (SL) fluctuations of the northern South China Sea. We find that the strengths of atmospheric and oceanic forcing in PRD are not mutually independent, leading to a distinct contrast of WL–forcing relationships at upstream and coastal stations. In the transition zone, because of counteracts of atmospheric and oceanic forcing, no robust relationships are identified between WL and either of the forcing. We further show that in the drought season of the warm ENSO and PDO epochs, the effect of atmospheric (oceanic) forcing on PRD WL is largely enhanced (weakened), due to increased southern China rainfall and negative SL anomalies. Over the observation period, WL significantly decreased at upstream stations, by up to 28–42 mm/year for flood season, contrasting with the upward trends of <4.3 mm/year at coastal stations across all seasons. Southern China rainfall explains little of the observed WL trends, whilst SL rise is mostly responsible for the WL trends at coastal stations.

High-resolution numerical survey of potential sites for tidal energy extraction along coastline of China under sea-level-rise condition

Many coastal countries are concerned with sustainable energy generation to meet their current and future energy needs. Tidal energy is an attractive resource as in-stream turbines can generate electricity even at moderate flow velocities. However, not all coastal areas are equally well-suited for tidal energy development. The survey of potential locations and their power densities is a crucial step in evaluating the potential cost-benefit of tidal energy. This research surveys the intensity and distribution of offshore tidal energy along whole coastline of China based on a high-resolution numerical simulation with a minimum mesh spacing of 80 m. The Finite Volume Community Ocean Model (FVCOM) has been used to carry out the numerical simulation work. Since FVCOM uses an unstructured mesh, it can accurately identify complex coastlines, such as those along islands, waterways, and estuaries. The simulation period for this numerical survey is 30 days. The accuracy of the simulation results is validated using 8-days in-situ measurements obtained at 17 coastal stations in the region of study. Research results indicate that the total mean tidal energy is 1.19 × 1014 J along the coastline of China. The tidal energy is mainly distributed in the south and southeast of the coastline of China. This study also identifies 45, 23 and 9 top sites, where the averaged tidal energy density is greater than 500, 1000, and 1500 W/m2, respectively, suitable for tidal energy extraction and utilization. Considering the long development cycle of tidal energy and global climate change, this study also investigates the impact of sea-level rise (SLR) on tidal energy distribution in the region of study using a 50-year (0.5 m) and 100-year (1.0 m) SLR scenarios. It is found that the total mean tidal energy increases by 3.0% and 6.5% for 50-year and 100-year SLR scenarios, respectively. It is believed that the findings drawn from this study could be instructive for future utilization of tidal energy along the coastline of China.

Seasonal niche differentiation among closely related marine bacteria

Bacteria display dynamic abundance fluctuations over time in marine environments, where they play key biogeochemical roles. Here, we characterized the seasonal dynamics of marine bacteria in a coastal oligotrophic time series station, tested how similar the temporal niche of closely related taxa is, and what are the environmental parameters modulating their seasonal abundance patterns. We further explored how conserved the niche is at higher taxonomic levels. The community presented recurrent patterns of seasonality for 297 out of 6825 amplicon sequence variants (ASVs), which constituted almost half of the total relative abundance (47%). For certain genera, niche similarity decreased as nucleotide divergence in the 16S rRNA gene increased, a pattern compatible with the selection of similar taxa through environmental filtering. Additionally, we observed evidence of seasonal differentiation within various genera as seen by the distinct seasonal patterns of closely related taxa. At broader taxonomic levels, coherent seasonal trends did not exist at the class level, while the order and family ranks depended on the patterns that existed at the genus level. This study identifies the coexistence of closely related taxa for some bacterial groups and seasonal differentiation for others in a coastal marine environment subjected to a strong seasonality.

Phytoplankton assemblages and optical properties in a coastal region of the South Brazil Bight

Phytoplankton assemblages in the inner portion of the South Brazil Bight are studied at a coastal time-series station (2012–2017). Diagnostic pigment analysis (DPA) coupled with a hierarchical cluster analysis were applied to generate and evaluate a locally tuned model to retrieve phytoplankton groups. These results are intercompared with phytoplankton taxonomy (microscopy analysis) and phytoplankton bio-optical properties (i.e., specific absorption coefficient aph∗(λ),package effect index Qa∗(440) and size indices Sfand SI). Overall, phytoplankton bio-optical properties were well related to the DPA phytoplankton groups and size fractions. Samples with high proportions of diatoms, dinoflagellates, and cryptophytes usually presented low or intermediate values of aph∗(λ),Qa∗(440),Sf, and SI. When cyanobacteria and green algae proportions were high, the values of these indices were also higher. The locally-tuned model overestimated the chlorophyll-a fraction in diatoms and underestimated that in nanophytoplankton and dinoflagellates, compared with the biomass estimated from microscopic size measurements. The area is characterized mainly by oligo-mesotrophic conditions, with a mixed assemblage, and episodic events of phytoplankton blooms. Dominance of diatoms were associated with low sea surface temperature and high total chlorophyll-a under the influence of nutrient-enriched waters mixed within the Coastal Water, especially in upwelling events during spring-summer. On the other hand, cyanobacteria were associated with high sea surface temperature and low total chlorophyll-a. Surface waters were dominated by the Coastal Water. Episodic events with the intrusion of low salinity and temperature waters suggested the presence of the Río de La Plata River Plume Water in autumn-winter. High salinity and low-temperature waters indicated surface intrusions of the South Atlantic Central Water, in spring-summer, either by local upwelling or the Cape Frio Upwelling Front, characterizing a highly dynamic environment influencing the phytoplankton assemblages.

Decadal Dynamics of the CO2 System and Associated Ocean Acidification in Coastal Ecosystems of the North East Atlantic Ocean

Weekly and bi-monthly carbonate system parameters and ancillary data were collected from 2008 to 2020 in three coastal ecosystems of the southern Western English Channel (sWEC) (SOMLIT-pier and SOMLIT-offshore) and Bay of Brest (SOMLIT-Brest) located in the North East Atlantic Ocean. The main drivers of seasonal and interannual partial pressure of CO2 (pCO2) and dissolved inorganic carbon (DIC) variabilities were the net ecosystem production (NEP) and thermodynamics. Differences were observed between stations, with a higher biological influence on pCO2 and DIC in the near-shore ecosystems, driven by both benthic and pelagic communities. The impact of riverine inputs on DIC dynamics was more pronounced at SOMLIT-Brest (7%) than at SOMLIT-pier (3%) and SOMLIT-offshore (<1%). These three ecosystems acted as a weak source of CO2 to the atmosphere of 0.18 ± 0.10, 0.11 ± 0.12, and 0.39 ± 0.08 mol m–2 year–1, respectively. Interannually, air-sea CO2 fluxes (FCO2) variability was low at SOMLIT-offshore and SOMLIT-pier, whereas SOMLIT-Brest occasionally switched to weak annual sinks of atmospheric CO2, driven by enhanced spring NEP compared to annual means. Over the 2008–2018 period, monthly total alkalinity (TA) and DIC anomalies were characterized by significant positive trends (p-values < 0.001), from 0.49 ± 0.20 to 2.21 ± 0.39 μmol kg−1 year−1 for TA, and from 1.93 ± 0.28 to 2.98 ± 0.39 μmol kg–1 year–1 for DIC. These trends were associated with significant increases of calculated seawater pCO2, ranging from +2.95 ± 1.04 to 3.52 ± 0.47 μatm year–1, and strong reductions of calculated pHin situ, with a mean pHin situ decrease of 0.0028 year–1. This ocean acidification (OA) was driven by atmospheric CO2 forcing (57–66%), Sea surface temperature (SST) increase (31–37%), and changes in salinity (2–5%). Additional pHin situ data extended these observed trends to the 2008–2020 period and indicated an acceleration of OA, reflected by a mean pHin situ decrease of 0.0046 year–1 in the sWEC for that period. Further observations over the 1998–2020 period revealed that the climatic indices North Atlantic Oscillation (NAO) and Atlantic Multidecadal Variability (AMV) were linked to trends of SST, with cooling during 1998–2010 and warming during 2010–2020, which might have impacted OA trends at our coastal stations. These results suggested large temporal variability of OA in coastal ecosystems of the sWEC and underlined the necessity to maintain high-resolution and long-term observations of carbonate parameters in coastal ecosystems.

Evaluation of coastal Antarctic precipitation in LMDz6 global atmospheric model using ground-based radar observations

In the current context of climate change in the poles, one of the objectives of the APRES3 (Antarctic Precipitation Remote Sensing from Surface and Space) project was to characterize the vertical structure of precipitation in order to better simulate it. Precipitation simulated by models in Antarctica is currently very widespread and it overestimates the data. Sensitivity studies have been conducted using a global climate model and compared to the observations obtained at the Dumont d’Urville coast station, obtained by a Micro Rain Radar (MRR). The LMDz/IPSL general circulation model, with zoomed configuration over Dumont d’Urville, has been considered for this study. A sensitivity study was conducted on the physical and numerical parameters of the LMDz model with the aim of estimating their contribution to the precipitation simulation. Sensitivity experiments revealed that changes in the sedimentation and sublimation parameters do not significantly impact precipitation rate. However, dissipation of the LMDz model, which is a numerical process that dissipates spatially excessive energy and keeps the model stable, impacts precipitation indirectly but very strongly. A suitable adjustment of the dissipation reduces significantly precipitation over Antarctic peripheral area, thus providing a simulated profile in better agreement with the MRR observations.

Assessment of ICESat-2 ice surface elevations over the Chinese Antarctic Research Expedition (CHINARE) route, East Antarctica, based on coordinated multi-sensor observations

Abstract. We present the results of an assessment of ice surface elevation measurements from NASA's Ice, Cloud, and land Elevation Satellite-2 (ICESat-2) along the CHINARE (CHINese Antarctic Research Expedition) route near the Amery Ice Shelf in East Antarctica. The validation campaign was designed and implemented in cooperation with the 36th CHINARE Antarctic expedition from December 2019 to February 2020. The assessment of the ICESat-2 geolocated photon product (ATL03) and land ice elevation product (ATL06) was performed based on coordinated multi-sensor observations using two roof-mounted kinematic global navigation satellite system (GNSS) receivers, two line arrays of corner cube retroreflectors (CCRs), two sets of retroreflective target sheets (RTSs), and two unmanned aerial vehicles (UAVs) with cameras. This systematic validation of the ICESat-2 data covered a variety of Antarctic ice surface conditions along the 520 km traverse from the coastal Zhongshan Station to the inland Taishan Station. This comprehensive investigation is complementary to the 750 km traverse validation of flat inland Antarctica containing a 300 km latitude traverse of 88∘ S by the mission team (Brunt et al., 2021). Overall, the validation results show that the elevation of the ATL06 ice surface points is accurate to 1.5 cm with a precision of 9.1 cm along the 520 km CHINARE route. The elevation of the ATL03 photons has an offset of 2.1 cm from a GNSS-surveyed CCR and is accurate to 2.5 cm with a precision of 2.7 cm as estimated by using RTSs. The validation results demonstrate that the estimated ICESat-2 elevations are accurate to 1.5–2.5 cm in this East Antarctic region, which shows the potential of the data products for eliminating mission biases by overcoming the uncertainties in the estimation of mass balance in East Antarctica. It should be emphasized that the results based on the CCR and RTS techniques can be improved by further aggregation of observation opportunities for a more robust assessment. The developed validation methodology and sensor system can be applied for continuous assessment of ICESat-2 data, especially for calibration against potential degradation of the elevation measurements during the later operation period.

U.S. Coast Guard icebreaker operations and science support in Antarctica

ABSTRACT U.S. ships and sailors have contributed significantly to Antarctic exploration and research since the first land sightings of Antarctica in 1820. Since Operation High Jump in 1946–1947, the U.S. Coast Guard and U.S. Navy have operated polar icebreakers in support of United States national interests in Antarctica and the Southern Ocean. In the early years of continuous U.S. presence in Antarctica, they were critical to logistical support in the building of research stations at McMurdo, Wilkes Land, Cape Hallett, Gould Bay (Ellsworth), Marie Byrd Land (Byrd), and Palmer (Antarctic Peninsula). Their icebreaking capabilities have been key to the annual ice escort operations of supply ships in McMurdo Sound and other coastal stations. These icebreakers and their assigned aviation detachments have supported numerous U.S. and international research expeditions and projects in waters that had rarely been previously explored, expanding knowledge in all the natural sciences. U.S. Coast Guard icebreakers supported U.S. State Department Antarctic Treaty inspections for many years. Recently, the role of USCG icebreakers in Antarctic science research has diminished, both in number of projects assigned and areas deployed. A new class of U.S. Coast Guard polar icebreakers is in work, designated as polar security cutters, and it is hoped that these icebreakers will be able to continue supporting Antarctic science activities.

Distribution of picoplankton and detritus in the lower course of the Kama River

The distribution of picoplankton and detritus in the lower course of the Kama River in 2009, 2012, 2016 and 2020 was analyzed. The abundance (1.5-6.7 × 106 cells mL−1) and biomass (25-173 ug C L−1) of picoplankton corresponds to the mesotrophic level. The abundance and biomass of the heterotrophic picoplankton increases from spring to autumn, the autotrophic picoplankton has maximum in August. The amount (17-1367 × 103 particles mL−1) and mass (0.1-62 μg C L−1) of picodetritus varies greatly from station to station without clear patterns, but basically its mass is higher at coastal stations. Heterotrophic picoplankton prevails in picoseston structure; the average APP and picodetritis contributions are comparable, with little excess of picodetritus. The structure of the picoseston varies significantly depending on the season and the riverbed or the coastal location of the station. The amount of nanodetritus is very high (up to 229 × 103 particles mL−1 and 662 μg C L−1), and it varies slightly both in space and in time. Its mass is almost always several times higher than the biomass of picoceston Most likely, nanodetritus is one of the main factors affecting the plankton of the lower course of the Kama River.

Early stages of anchovy: abundance, variability and larval condition at the fixed coastal station EPEA between 2000-2017

Densities of eggs and larvae of Engraulis anchoita and the nutritional condition of larvae were analyzed in the fixed sampling station (EPEA) in the period 2000-2017. These variables were analyzed seasonally and trends over time were determined. Ichthyoplankton samples were collected by oblique trawls using Bongo nets with 300 μm of pore mesh and fixed with formaldehyde 5% in seawater. Six morphometric variables were measured to estimate the nutritional condition of larvae. The developmental stage of each specimen was also determined. The highest mean value of egg density was detected in the October-December period, with a secondary mode in August, followed by one in March. Larval density presented a mode in October. Autumn and spring were the most favorable seasons for larval condition while winter proved to be the least favorable one. An increase in food availability during autumn and spring due to primary and secondary production peaks could explain the high nutritional condition and growth values observed in these seasons at the EPEA. No changes in trends of variables over time were detected. The integrated study of density and nutritional condition of E. anchoita larvae allows the determination of favorable breeding periods for the species, while the continuation of the long term study will allow evaluating possible effects of climate change in the early life stages of this species.

Extreme winds and fire weather in coastal Santa Barbara County,CA: An observational analysis

AbstractCoastal Santa Barbara (SB) County in Southern California, characterized by a Mediterranean climate and complex topography, is a region prone to downslope windstorms that create critical fire weather conditions and rapidly spread wildfires. The Santa Ynez Mountains, oriented from east to west, rise abruptly from the coast, separating air masses from the ocean and the Santa Ynez Valley. The juxtaposition of these geographic features generates spatiotemporally variable wind regimes. This study analyzes diurnal‐to‐seasonal wind cycles and extremes in this region using hourly data from eight weather stations and four buoys for the period 1998–2019. Data from a vertical wind profiler at the Santa Barbara airport in Goleta, CA was extracted from August 2016 to September 2020. Air temperature, dew point temperature, and the Fosberg fire weather index are examined at land stations. We show that cycles in wind speed vary spatiotemporally; mountain (valley and coastal) stations exhibit a pronounced semiannual (annual) cycle, and wind maxima is observed during the evening (afternoon) at mountain (valley and coastal) stations. Differences in wind speed percentiles were evident among stations, particularly at and above the 75th percentile. Strong winds recorded at buoys were significantly correlated (betweenr = 0.3–0.5) to land stations. However, cross‐correlational analysis did not reveal any temporal lags between mountain stations and buoys. Distributions of temperature and dew point during extreme winds differed between east and west mountain stations. Significant fire weather conditions were most frequent at mountain stations in Refugio and Montecito, with 5% occurrence in the spring and over 3% occurrence in fall. Weaker summertime winds lowered fire weather conditions at Montecito in the summer.

Sea breeze characteristics over a coastal station in peninsular Malaysia

Sea breeze characteristics over a coastal station in peninsular Malaysia

Spatio‐temporal variability in the stratiform/convective rainfall contribution to the summer monsoon rainfall in India

AbstractSpatio‐temporal variability of contributions of stratiform and convective rainfall to Indian monsoon (June–September) rainfall have been investigated using hourly rainfall data of well distributed 126 stations in India for the period 1969–2015. The criteria used for identifying stratiform rainfall are hourly rainfall ≤5 mm and spatial homogeneity. The study showed that Indian monsoon rainfall exhibits two distinctive features, viz. stratiform component dominating over peninsular (southern) India and convective component dominating over northern India. The diurnal variation shows domination of convective activity in the afternoon hours over the northern parts of India. Intra‐seasonal variability in the stratiform rainfall is the lowest over the West Coast stations through‐out the season. While it shows low values during the onset (June) and withdrawal (September) phases of monsoon and higher values during July–August in Peninsular India. Inter‐annual variations in the convective rainfall are larger than that of stratiform rainfall all over the country. Trend analysis indicates that both stratiform and convective rainfall are decreasing over the central parts of the country and increasing significantly along West Coast and western parts of the country. During excess monsoon year, convective rainfall activity is more than in deficit monsoon year, in Central India. The results brought out in the study will be useful as a proxy for understanding the spatial and temporal variability of the latent heating fields over India in the monsoon season and validation of model simulations of clouds and rainfall types.