A simple model of ozone–temperature coupling in the tropical lower stratosphere

Observations show strong correlations between large-scale ozone and temperature variations in the tropical lower stratosphere across a wide range of timescales. We quantify this behavior using monthly records of ozone and temperature data from Southern Hemisphere Additional Ozonesonde (SHADOZ) tropical balloon measurements (1998–2016), along with global satellite data from Aura microwave limb sounder and GPS radio occultation over 2004–2018. The observational data demonstrate strong in-phase ozone–temperature coherence spanning sub-seasonal, annual and interannual timescales, and the slope of the temperature–ozone relationship (T / O3) varies as a function of timescale and altitude. We compare the observations to idealized calculations based on the coupled zonal mean thermodynamic and ozone continuity equations, including ozone radiative feedbacks on temperature, where both temperature and ozone respond in a coupled manner to variations in the tropical upwelling Brewer–Dobson circulation. These calculations can approximately explain the observed (T / O3) amplitude and phase relationships, including sensitivity to timescale and altitude, and highlight distinct balances for “fast” variations (periods < 150 d, controlled by transport across background vertical gradients) and “slow” coupling (seasonal and interannual variations, controlled by radiative balances).

Evapotranspiration Components Dynamic of Highland Barley Using PML ET Product in Tibet

Highland barley is the unique germplasm resource and dominant crop in Tibet with low-level precipitation and a severe shortage of available water resources. Understanding the characteristics and dynamics of evapotranspiration (ET) components (vegetation transpiration (Ec), soil evaporation (Es), and canopy interception evaporation (Ei)) of highland barley can help better optimize water management practices. The seasonal and interannual variations in ET components of highland barley were investigated using the PML-V2 ET product during 2001–2020. The results suggested that Es was the most important ET component and accounted for 77% of total ET for highland barley in Tibet. ET components varied obviously over the altitude, Es, and Es/ET ratio; a decreasing trend was observed with the increase in altitude from 3500 m to 3800 m and then this changed to an increasing trend until reaching the altitude of 4100 m, while Ec, Ei, and their ratios presented an opposite changing pattern to that of Es. Seasonal variation in daily ET components of highland barley displayed a parabolic pattern, peaked in August, while the temporal distributions differed considerably among different ET component ratios. The seasonal variations in ET components were correlated significantly with air temperature, relative humidity, and precipitation, while ET components ratios were more influenced by the environment, irrigation practice, and management rather than meteorological variables. Es and its ratio in highland barley decreased significantly during 2001–2020, while the Ec/ET ratio generally showed an opposite trend to the Es/ET ratio, and Ei and its ratio presented an insignificantly decreasing trend. The interannual variations in ET components were not correlated significantly with meteorological variables, while Ei was more influenced by meteorological variables, especially the precipitation characteristics.

Seasonal and interannual variations of MODIS Aqua chlorophyll-a (2003–2017) in the Upper Gulf of Thailand influenced by Asian monsoons

Seasonal and interannual variations of chlorophyll-a (chl-a) in the upper Gulf of Thailand (uGoT) were obtained using new regionally tuned algorithms applied to Moderate Resolution Imaging Spectroradiometer-Aqua. This long time-series (2003–2017) data were analyzed in the context of variations in environmental conditions associated with the Southeast Asian Monsoon. Chl-a distribution patterns were distinct for the non-monsoon (NOM), southwest-monsoon (SWM), and northeast-monsoon (NEM) seasons. During the SWM/NEM, high/low chl-a concentrations were associated with high/low precipitation and river discharge. During the NOM chl-a concentrations were generally low, because of low precipitation. In general, chl-a variability was tightly coupled to discharge from the Chao Phraya and Tha Chin rivers. Chl-a concentrations were generally higher in the north, but chl-a accumulation in the east/west of the uGoT could be linked to piling of freshwater to the east/west during the SWM/NEM caused by changes in wind direction and the reversal of currents. Interannual changes in chl-a were attributed to El Niño-Southern Oscillation (ENSO) rather than Indian Ocean Dipole (IOD) driven changes in precipitation, river discharge, and wind patterns. During the SWM, positive/negative chl-a anomalies coincided with high/low precipitation and river discharge during La Niña/El Niño. During the NEM, positive/negative chl-a anomaly coincided with high/low river discharge and strong/weak wind during La Niña/El Niño. Meanwhile, during NOM, positive chl-a anomaly could be attributed to anomalous high wind speed and precipitation during El Niño.

Review of the Barents sea hydrological conditions

Based on more than 50 works published during the period 1946−2019, the chapter gives an overview of current ideas about bottom topography, large-scale circulation, currents and tides, water flows across borders, temperature and salinity distribution, water masses, frontal zones, seasonal and interannual variations in hydrological characteristics, stratification and ice conditions of the Barents Sea. Among the many classifications of water masses of the sea, the review gives preference to the most consistent and reasonable classification proposed by V. Ozhigin and V. Ivshin in 1999.

A simple model of ozone-temperature coupling in the tropical lower stratosphere

Observations show strong correlations between large-scale ozone and temperature variations in the tropical lower stratosphere across a wide range of time scales. We quantify this behavior using monthly records of ozone and temperature data from SHADOZ tropical balloon measurements (1998–2016), along with global satellite data from Aura MLS and GPS radio occultation over 2004–2018. The observational data demonstrate strong in-phase ozone-temperature coherence spanning sub-seasonal, annual and interannual time scales, and the slope of the ozone-temperature relationship (O3/T) varies as a function of time scale and altitude. We compare the observations to idealized calculations based on the coupled zonal mean thermodynamic and ozone continuity equations, including ozone radiative feedbacks on temperature, where both temperature and ozone respond in a coupled manner to variations in the tropical upwelling Brewer-Dobson circulation. These calculations can approximately explain the observed (O3/T) amplitude and phase relationships, including sensitivity to time scale and altitude, and highlight distinct balances for ‘fast’ variations (periods < 150 days, controlled by transport across background vertical gradients) and ‘slow’ coupling (seasonal and interannual variations, controlled by radiative balances).

Diurnal and seasonal amplitude and phase variations of the radio signals of RSDN-20 transmitters and the intensity of radio noise (11.9 kHz) registered in Yakutsk during 2009-2017

В работе проводится анализ суточных, сезонных и межгодовых вариаций интенсивности радиошума, а также амплитуды и фазы сигналов радиотехнической системы дальней навигации РСДН-20 по данным регистрации на частоте 11.904 кГц в г. Якутске в периоды нарастания, максимума и спада в 24-м цикле солнечной активности (2009-2017 годы). Наиболее ярко выражены сезонные дневные вариации амплитуды. Зарегистрировано увеличение фазовой задержки радиосигнала от дня к ночи, что характерно для увеличения эффективной высоты волновода Земля – ионосфера. Наблюдаемое уменьшение фазовой задержки в ночное зимнее время на радиотрассе малой протяженности Хабаровск-Якутск возможно объясняется интерференцией мод высших порядков. Наблюдается асимметрия дневных сезонных вариаций амплитуды ОНЧ радиосигналов (11.904 кГц). Амплитуда сигнала в период осеннего равноденствия ближе к летнему солнцестоянию, а амплитуда весеннего равноденствия — к зимнему солнцестоянию. В дневные часы сезонные вариации амплитуды и фазы относительно стабильны год от года. В периоды нарастания, максимума и спада в 24-м цикле солнечной активности отмечены большие изменения амплитуды ОНЧ-сигнала, зарегистрированные зимой, по сравнению с летом. На фоне повышения солнечной активности в зимний период ночью регистрируется повышение фазовой задержки на радиотрассе меньшей протяженности Хабаровск-Якутск (1400 км) на 23 ± 6°. The daily, seasonal and interannual variations of the radio noise intensity, the amplitude and phase of signals from the long-range navigation radio system RSDN-20 are analyzed based on the registration at a frequency of 11.904 kHz in Yakutsk during increase, maximum and decrease periods in the 24th solar cycle activity (2009-2017). The most pronounced seasonal daytime amplitude variations. The signal phase delay increase from day to night was recorded, which is characteristic of an increase in the effective height of the Earthionosphere waveguide. The observed phase delay decrease in the winter night time on the short radio propagation path Khabarovsk-Yakutsk can be explained by the interference of higher-order modes. There is an asymmetry of the daytime seasonal variations of the amplitude of VLF radio signals (11.904 kHz). During daytime, seasonal variations in amplitude and phase are relatively stable from year to year. Against the background of an increase in solar activity in winter, at night, the phase delay increase is recorded by 23 ± 6°on a shorter radio path Khabarovsk-Yakutsk (1400 km).

Global Solar Radiation Transfer and Its Loss in the Atmosphere

Based on the analysis of solar radiation and meteorological parameters measured at a subtropical forest in China during 2013–2016, a new empirical model of global solar irradiance has been developed. It can calculate global solar irradiance at the ground and at the top of the atmosphere (TOA); both are in agreement with the observations. This model is used to calculate the extinction of global solar irradiance in the atmosphere and the contributions from absorbing and scattering substances. The loss of global solar irradiance is dominated by absorbing and absorbing substances. The results show clear seasonal and interannual variations during the observation period. Sensitivity analysis indicates that global solar irradiance is more sensitive to changes in scattering, quantified by the S/G factor (S and G are diffuse and global solar radiation, respectively), than to changes in absorption. The relationships between the extinction factor (AF) of G and S/G and between the AF and the aerosol optical depth (AOD) are determined and used to estimate S/G and the AOD from the measured AF. This empirical model is applied to calculate the albedos at the TOA and the ground. This empirical model is useful to study global solar radiation and the energy–atmosphere interactions.

Temporal-Spatial Variations of Atmospheric Static Stability: A Comparison of the Influences from Temperature and Its Vertical Difference

The temporal-spatial variations of the static stability of dry air and the relative importance of their influencing quantities are explored. Derivation shows that while it links to the vertical difference of temperature, static stability also relates to the temperature itself. The static stability is expressed as a nonlinear function of temperature and the vertical difference of temperature. The relative importance of the two influencing quantities is assessed with the linear regression. Tests show that the linear fitting method is robust. The results of the dominance rely on the data examined, which include an interannual variation, a seasonal variation, and a spatial variation that consists of the grid points over the globe. It is revealed that in lower troposphere, while the temporal variations of static stability are dominated by the vertical difference of temperature, the temperature itself may also have considerable influence, especially over the high latitudes of the two hemispheres. In stratosphere, temperature tends to have more contributions. Over Antarctic, temperature dominates the seasonal and interannual variations of the static stability. The spatial variation of the static stability of July is influenced by both temperature and its vertical difference before 1980, but after that it is dominated by temperature.

Global Dust Optical Depth Climatology Derived from CALIOP and MODIS Aerosol Retrievals on Decadal Time Scales: Regional and Interannual Variability

We present a satellite-derived global dust climatological record over the last two decades, including the monthly mean visible dust optical depth (DAOD) and vertical distribution of dust extinction coefficient at a 2º (latitude) × 5º (longitude) spatial resolution derived from CALIOP and MODIS. Dust is distinguished from non-dust aerosols based on particle shape information (e.g., lidar depolarization ratio) for CALIOP, and on dust size and absorption information (e.g., fine-mode fraction, Angstrom exponent, and single-scattering albedo) for MODIS, respectively. On multi-year average basis, the global (60° S–60° N) and annual mean DAOD is 0.029 and 0.063 derived from CALIOP and MODIS retrievals, respectively. In most dust active regions, CALIOP DAOD generally correlates well with the MODIS DAOD, with CALIOP DAOD being significantly smaller. CALIOP DAOD is 18 %, 34 %, 54 % and 31 % smaller than MODIS DAOD over Sahara Deserts, the tropical Atlantic Ocean, the Caribbean Sea, and the Arabian Sea, respectively. Over East Asia and the northwestern Pacific Ocean (NWP), however, the two datasets show weak correlation. Despite these discrepancies, CALIOP and MODIS show similar seasonal and interannual variations in regional DAOD. For dust aerosol over NWP, both CALIOP and MODIS show a declining trend of DAOD at a rate of about 2 % yr−1. This decreasing trend is consistent with the observed declining trend of DAOD in the southern Gobi Desert at a rate of −3 % yr−1 and −5 % yr−1 according to CALIOP and MODIS, respectively. The decreasing trend of DAOD in the southern Gobi Desert is in turn found to be significantly correlated with an increasing trend of vegetation and a decreasing trend of surface wind speed in the area.