ABSTRACT Snow cover trends for Canada over the 1955–2017 period for the daily snow depth–observing network of Environment and Climate Change Canada (ECCC) are presented based on an updated quality-controlled historical daily in situ snow depth dataset. The period since approximately 1995 is characterized by a rapid decline in manual observations (loss of over 800 manual observing sites between 1995

ABSTRACT Most studies of climate change in the Arctic report how much warmer the climate is getting. In this study we use 1950–2020 daily observed minimum temperatures at 34 weather stations in Canada’s north to examine how rapidly the region is losing annual occurrences of cold weather (−30°C or colder). Kendall–Theil trend analysis is used to assess the strength and significance of trends. Twenty-nine

ABSTRACT Based on the daily Japanese 55-year Reanalysis (JRA-55) from 1979 to 2015, this study shows that atmospheric heat sources over the Tibetan Plateau (TP) and its surrounding areas (TPSR) in summer have a significant 10- to 30-day intraseasonal oscillation (ISO). The linkage of the ISO with the amplified precipitation to the south of the middle and lower reaches of the Yangtze River (MLYR) is

ABSTRACT A recent analysis of observed oxygen changes shows a 2% decline in marine oxygen during the 50 years since 1960. However, these oxygen changes vary on time scales related to climate modes and by regions, including areas of increasing oxygen. Hence, any local oxygen change is related to various subsets of these drivers for the different regions and time scales. Here we provide an overview of

(2021). Correction. Atmosphere-Ocean: Vol. 59, No. 2, pp. 133-135.

ABSTRACT Previous studies indicate that the “spring flood” precipitation in northwestern Yunnan is closely related to the movement of the South Asian High (SAH) and the apparent moisture sink (Q2) in the southeastern Tibetan Plateau (TP). In this study, using 38 years of ERA-Interim daily- and monthly-mean grid data along with 35 years of Gongshan daily precipitation data, the correlation between the

ABSTRACT The surface warming of northern continents during the twentieth century is not uniform across seasons. Surface warming is particularly pronounced over northwestern Canada, where winter trends are much larger than summer ones. The upper-air temperature trends over the region are analyzed in three radiosonde datasets from 1958 to 2012 to assess their seasonal structure. The seasonal variation

ABSTRACT Utilizing the Community Atmosphere Model, version 4 (CAM4), the influence of sudden Arctic sea-ice thinning on North Atlantic Oscillation (NAO) events is investigated on a sub-seasonal time scale. First, the control simulation with CAM4 using prescribed daily boundary conditions produces realistic descriptions for the frequency and evolution of NAO events. Second, sensitivity experiments are

ABSTRACT Based on two single-model initial-condition 50-member ensembles of climate simulations conducted with two generations of Canadian Earth System Models (CanESM2 and its successor CanESM5), we analyze the ensemble mean and spread of the projected trends of wintertime North American surface air temperature (SAT) and extreme indices of cold (TX10) and warm (TX90) days over the next half-century

ABSTRACT Utilizing the Community Atmosphere Model, version 4 (CAM4), the influence of sudden Arctic sea-ice thinning on North Atlantic Oscillation (NAO) events is investigated on a sub-seasonal time scale. First, the control simulation with CAM4 using prescribed daily boundary conditions produces realistic descriptions for the frequency and evolution of NAO events. Second, sensitivity experiments are

ABSTRACT The surface warming of northern continents during the twentieth century is not uniform across seasons. Surface warming is particularly pronounced over northwestern Canada, where winter trends are much larger than summer ones. The upper-air temperature trends over the region are analyzed in three radiosonde datasets from 1958 to 2012 to assess their seasonal structure. The seasonal variation

ABSTRACT In the atmosphere, cloud particles have different shapes. The study of cloud particle shapes plays an important role in understanding cloud precipitation processes, radiative transfer, and weather modification. The image resolution and data quality of cloud probes affect the accuracy of the classification of particle shapes. To solve the occlusion of the photosensitive edge of the particle

ABSTRACT This study presents the spatial and temporal features of more than 45 million cloud-to-ground (CG) lightning flashes recorded by the Canadian Lightning Detection Network for the years 1999–2018. Although sensor upgrades have improved the detection efficiency and location accuracy of CG lightning, the large-scale spatial patterns remain about the same as found in a previous study covering the

ABSTRACT Atmosphere–ocean teleconnections influence the accumulation and melt of snow in western Canada and can be useful in seasonal forecasting of snowmelt and runoff. Interannual variation in these atmosphere–ocean modes has been shown to influence the accumulation and melt of snow within British Columbia (BC), Canada. We investigate fall mean sea level pressure (MSLP) globally as a predictor of

ABSTRACT Defining a reference climate for precipitation is an important requirement in the development of climate change scenarios to support climate adaptation strategies. It is also important for many hydrological and water resource applications. This, however, remains a challenge in regions that are poorly covered by meteorological stations, such as northern Canada or mountainous regions. Reanalyses

ABSTRACT An ocean wave model for the northwest Atlantic Ocean based on WAVEWATCH III is used to evaluate four different source term packages (known as ST2, ST3, ST4, and ST6) for the wind input and wave dissipation. The performance of ST2, ST3, ST4, and ST6 is assessed using available measurements from buoy stations and satellite altimeters. The model results for significant wave height ( H s ), mean

ABSTRACT Although it is an important branch of the global overturning circulation, the deep western boundary current (DWBC) in the Pacific was poorly understood because of sparse observations. Six state-of-the-art global ocean model outputs were used herein to evaluate their performance in simulating the DWBC in the Melanesian Basin (MB) and the Central Pacific Basin (CPB). These model outputs were

ABSTRACT Existing scientific literature and international assessments, such as those by the Intergovernmental Panel on Climate Change, provide a wide range of projections for global mean sea level rise (SLR) in the twenty-first century. At the local scale, the ranges or uncertainties of projections are even larger. There is a pressing need to compile plausible local SLR scenarios to aid coastal communities

(2020). A Severe Thunderstorm Outbreak North of 70°N Over the Canadian Arctic Islands with Unusual Lightning Characteristics. Atmosphere-Ocean: Vol. 58, No. 4, pp. 231-242.

ABSTRACT The quality of ensemble forecasts is significantly affected by sample quality. In this paper, the influence of sample quality on simulation results is analyzed by optimizing the distribution of ensemble members. As part of our research, simulated and observed tracks are compared; samples with smaller track errors are retained, and samples with larger track errors are eliminated in order to

ABSTRACT Topographic features, stratification, and barotropic tidal currents are three factors that determine internal tide (IT) generation. However, the mechanism of the impacts of stratification variation on IT generation in Luzon Strait (LS) has not been extensively explored. A three-dimensional high-resolution model is used to simulate the M2 ITs in the northern South China Sea (SCS) under different

ABSTRACT This study modelled physical and biological changes in the Bay of Bengal, the Arabian Sea, and the exclusive economic zone around Sri Lanka by examining the relationships between sea surface temperature (SST) and a range of biological and physical variables allowing prediction of the changes in the variables studied with changing temperature. Datasets were extracted from satellite data from

The Strait of Georgia, British Columbia, Canada, is an important ocean region in which wave and weather conditions can vary rapidly in time and space because of the complex mountain topography that surrounds it. Here we analyze existing observational data and a newly developed near real-time numerical wave model, forced by modelled local winds and ocean currents, to characterize the surface wave conditions

Using the National Centers for Environmental Prediction–Department of Energy Atmospheric Model Intercomparison Project 2 daily reanalysis datasets, the present study reveals that an upper tropospheric vertical thermal contrast (VTC) exists between pressure levels at 100 and 250 hPa over the Mediterranean region (MR) during the midsummer monsoon. An increase and decrease in the tropospheric temperature

This study investigates the possible reasons for the cold events over central and eastern China (CEC) in early 2008 and 2016. The Arctic is dramatically warming, in particular over the Barents–Kara Seas region and notable cold events were observed over CEC although La Niña and El Niño events occurred in early 2008 and 2016, respectively. At the same time, the westerlies decelerated at middle latitudes

The El Niño–Southern Oscillation (ENSO) plays an important role in pre-flood season (PFS) precipitation over South China. In this work, the analysis of observational and reanalysis data shows that PFS precipitation is closely related to the onset time of El Niño events. The PFS precipitation tended to be higher (lower) than normal for spring (summer) El Niño events during the 1979–2016 period. Our

ABSTRACT This study presents the development of a new dataset of homogenized temperature for use in trend analysis and monitoring climate change in Canada. This dataset contains daily data for 780 locations across the country: 508 locations with an active station (current observations) and long record (starting prior to 1990); 53 locations with an active station and short record (starting after 1990);

The El Niño–Southern Oscillation (ENSO) plays an important role in pre-flood season (PFS) precipitation over South China. In this work, the analysis of observational and reanalysis data shows that PFS precipitation is closely related to the onset time of El Niño events. The PFS precipitation tended to be higher (lower) than normal for spring (summer) El Niño events during the 1979–2016 period. Our

This study investigates the possible reasons for the cold events over central and eastern China (CEC) in early 2008 and 2016. The Arctic is dramatically warming, in particular over the Barents–Kara Seas region and notable cold events were observed over CEC although La Niña and El Niño events occurred in early 2008 and 2016, respectively. At the same time, the westerlies decelerated at middle latitudes

Using the National Centers for Environmental Prediction–Department of Energy Atmospheric Model Intercomparison Project 2 daily reanalysis datasets, the present study reveals that an upper tropospheric vertical thermal contrast (VTC) exists between pressure levels at 100 and 250 hPa over the Mediterranean region (MR) during the midsummer monsoon. An increase and decrease in the tropospheric temperature

A three-dimensional regional circulation model is used to investigate the internal M2 tide structure in the Strait of Canso located in eastern Nova Scotia, Canada. The embayment, an active shipping port, was found to have M2 baroclinic velocities occasionally reaching 0.15 m s−1 and typically faster than the barotropic tide. An internal tide spatial structure develops, characterized by the first vertical

In the present work, sensitivity experiments for two parameter schemes are conducted using the Regional Climate Model System, version 4.6, to improve the model capability for reproducing rainfall over the Maritime Continent (MC). One parameter is the warm cloud auto-conversion threshold in the Emanuel convective scheme, and the other parameter is the relative humidity threshold of cloudiness in the

The interannual variability of the summertime Northwest Pacific (NWP) subtropical anticyclone (NWPSA) has been widely investigated for its important role in the variability and predictability of the East Asian summer monsoon. A preceding El Niño–Southern Oscillation (ENSO) event influences the NWPSA by anchoring ocean memory in the North Indian Ocean, NWP region, etc. This study reveals a discontinuity

Based on the daily Japanese 55-year Reanalysis data, the characteristics of the summer (June–July–August) quasi-biweekly oscillation (QBWO) of atmospheric apparent heat sources over the Tibetan Plateau (TP) and its surrounding areas (TPSR) are investigated. The first three leading modes of the atmospheric intraseasonal heat source over the TPSR reflect two independent propagation features of the QBWO

Cyclone Nilofar was the third-strongest cyclone in the Arabian Sea. It was a category 4 cyclone that arrived in last week of October 2014. It lingered in the Arabian Sea for 10 days and caused a significant phytoplankton bloom that was detected by satellite observation. In this study, the authors investigated the ocean biological and physical responses to cyclone Nilofar using chlorophyll a (chl a)

Urban areas are large sources of greenhouse gases (GHGs) to the atmosphere. Measurements of atmospheric GHGs in urban areas provide information on these emissions, which can complement bottom-up estimates. Here, we present an Open-Path Fourier Transform Infrared (OP-FTIR) spectroscopy system for GHG monitoring in Toronto, Canada. We describe the installation of the OP-FTIR and retrieval of CO2, CO

Atmospheric response to mid-latitude sea surface temperature (SST) anomalies is a long-standing and perplexing problem. There have been extensive studies on the issue of atmospheric response to mid-latitude SST anomalies from observational, theoretical, and modelling perspectives. This paper serves as a brief review focusing on large-scale SST anomalies. Here, convincing new observational evidence

A pan-Arctic sea-ice–ocean prediction system is assessed in terms of its ability to predict sea-ice velocity. This system is based on the Regional Ice Ocean Prediction System running operationally at the Canadian Centre for Meteorological and Environmental Prediction. A form drag parameterization is implemented in the system to allow spatially and temporally varying neutral drag coefficients depending

The components, sources, and seasonal and spatial changes of fluorescent dissolved organic matter (FDOM) in the continental shelf area of the East China Sea (ECS), were determined by excitation and emission matrices (EEM) spectroscopy and parallel factor analysis (PARAFAC). The PARAFAC model identified four FDOM components from 234 samples in June and October 2014. The four components consisted of

We assess how weather events on the Canadian Prairies during the 2012 growing season were temporally and spatially represented by a high-resolution, non-World Meteorological Organization (WMO) standard private provider network, Earth Networks (EN), relative to the WMO standard climate stations operated by federal and provincial governments. We found that there was a large amount of missing station

This study reveals the spatial and temporal variations of summer extreme heat (EH) distribution in China under the background of anthropogenic climate change. Using data from 1542 meteorological stations in China during the 1961–2018 period, both the interannual and interdecadal variations of the frequency and intensity of EH are analyzed. Variations in the temporal and spatial distribution of EH in

Summer precipitation in the northern China monsoon region (NCMR; 35°–55°N, 108°–135°E) shows significant intraseasonal variability. The early-summer (June) and late-summer (July–August) precipitation patterns show clear differences in their formation mechanisms and the systems that affect them. We used empirical orthogonal function (EOF) analysis to investigate the two leading modes of July–August

The science of understanding severe thunderstorms and developing techniques for their prediction is relatively young, with most fundamental research having been carried out only during the last 75 years. Though it is not widely known, Canada has played an important role in such research and development, and some of Canada’s atmospheric scientists have been pioneers globally in a number of areas. This

This study investigates the response of the subtropical gyre circulation in the North Pacific Ocean to quadrupled CO2 using the Community Earth System Model, version 1 (CESM1). In particular, an overriding technique is applied to isolate and quantify the effects of wind stress and thermal warming caused by CO2 emissions. Results show that, in response to the increase in CO2, the total mass transport

(2019). V. Fortin, G. Roy, T. Stadnyk, K. Koenig, N. Gasset, and A. Mahidjiba. Ten Years of Science Based on the Canadian Precipitation Analysis: A CaPA System Overview and Literature Review. Atmosphere-Ocean: Vol. 57, No. 4, pp. 318-318.

(2019). Introduction to the Special Issue on the Year of Tropics–Midlatitude Interactions and Teleconnections (YTMIT) Atmosphere-Ocean: Vol. 57, No. 3, pp. 157-160.

The authors propose a modified complementary method to estimate regional evapotranspiration (ET) under different climatic and physical conditions using only meteorological data. The purpose of this study is to investigate the applicability of the modified complementary method for estimating global ET distribution and corresponding water balance. Gridded data from the Climate Research Unit, University

Intervention experiments using the Coupled Forecast System model, version 2 (CFSv2), have been performed in which various Madden-Julian Oscillation (MJO) evolutions were added to the model’s internally generated heating: Slow Repeated Cycles, Slow Single Cycle, Fast Repeated Cycles, and Fast Single Cycle. In each experiment, one of these specified MJO evolutions of tropical diabatic heating was added

This study evaluates the 1981–2010 spatiotemporal differences in six available climate datasets (daily total precipitation and mean air temperature) over the Lower Nelson River Basin (LNRB) in ten of its sub-watersheds at seasonal and annual time scales. We find that the Australian National University spline interpolation (ANUSPLIN), and inverse distance weighted (IDW) interpolated observations from

Offshore wind energy has the potential to ease energy and environmental crises, improve people’s living standards on remote islands, and, finally, make contributions to sustainable development. Accurate energy evaluations should be performed before the exploitation of offshore wind energy; this includes not only assessments of the resource’s historical characteristics but also a focused effort on understanding

A detailed analysis is performed on an inland-penetrating atmospheric river (AR) driven by and coupled to a Colorado cyclone in the first week of February 2016. This winter weather system was initiated by a trough of low pressure moving across the Rocky Mountains from the California coast. The low-level jet ahead of the trough was capable of extracting water vapour from the Gulf of Mexico to feed a

The impact of cloud representation on the simulation of mid-latitude recurrent large-scale flows and forecast skill of mid-latitude atmospheric teleconnections is evaluated using the Community Climate System Model, version 4 (CCSM4), and the super-parameterized CCSM4 (SP-CCSM4). Patterns of low-level atmospheric circulation anomalies and convection associated with the Madden–Julian oscillation (MJO)

Sea surface temperature (SST) from four Nucleus for European Modelling of the Ocean (NEMO) model simulations is analyzed to study the bulk flux parameterization to compute SST over the Hudson Bay Complex (HBC) for the summer months (August and September) from 2002 to 2009. The NEMO simulation was forced with two atmospheric forcing sets with different resolutions: the Coordinated Ocean-ice Reference

Abstract The developmental stages of Sargassum along with physicochemical factors affect the Sargassum biomass and, thus, affect the size of the habitat used by various fauna and flora. In this study, Sargassum spp. were collected from four stations in Kuwait coastal waters that are mainly distinguished by their levels of turbidity. Investigations revealed that the effects of season (i.e., temperature

In situ observations of snow water equivalent (SWE) from manual snow surveys and automated sensors are made at approximately 1000 sites across Canada in support of water resource planning for flood control and hydroelectricity production. These data represent an important source of information for research (e.g., validation of hydrological and climate models), for applied studies (e.g., ground snow

The North Open Water polynya is a recurring polynya and is a significant feature of northern Baffin Bay in the winter. An area of open water remains as the sea ice grows around it in the fall, and in the spring the polynya gradually expands as the thinner ice surrounding it melts. It is an important overwintering area for various bird and animal species. With climate change affecting the Arctic in

(2019). Introduction to the Special Section on the Aquatic Climate Change Adaptation Services Program. Atmosphere-Ocean: Vol. 57, No. 1, pp. 1-2.

The potential influence of a developing La Niña on Arctic sea-ice annual variability is investigated using both observational data and an atmospheric general circulation model. It is found that during the developing phase of an eastern Pacific (EP) La Niña event in June, July, and August (JJA) and September, October, and November (SON), the sea-ice concentration (SIC) over the Barents–Kara Seas declines

Freezing rain occurs in complex atmospheric conditions when the temperature is close to 0°C. To better understand how its occurrence will change in the future, there is a need to assess how well regional climate models can reproduce those conditions. The goal of the present study is to investigate the influence of horizontal resolution on the simulation of freezing rain using the fifth generation of

Weather and climate are major factors influencing worldwide wildfire activity. This study assesses surface and atmospheric conditions associated with the 2014 extreme wildfires in the Northwest Territories (NWT) of Canada. Hot and dry conditions led to the NWT experiencing the most severe wildfire season in its recorded history. The season included a record number of cloud-to-ground lightning flashes