scholarly journals Retrieval of Daily Mean VIIRS SST Products in China Seas

2021 ◽  
Vol 13 (24) ◽  
pp. 5158
Author(s):  
Qianmei Li ◽  
Qingyou He ◽  
Chuqun Chen
Keyword(s):  
Diurnal Variation ◽  
Infrared Imaging ◽  
Accurate Estimation ◽  
High Temporal Resolution ◽  
China Seas ◽  
Retrieval Method ◽  
Diurnal Variability ◽  
Satellite Sst ◽  
Sinusoidal Pattern ◽  
Transient Measurements

Sea surface temperature (SST) is one of the most important factors in regulating air-sea heat flux and, thus, climate change. Most of current global daily SST products are derived from one or two transient measurements of polar-orbiting satellites, which are not the same to daily mean SST values. In this study, high-temporal-resolution SST measurements (32–40 snapshots per day) from a geostationary satellite, FengYun-4A (FY–4A), are used to analyze the diurnal variation of SST in China seas. The results present a sinusoidal pattern of the diurnal variability in SST, with the maximum value at 13:00–15:00 CST and the minimum at 06:00–08:00 CST. Based on the diurnal variation of SST, a retrieval method for daily mean SST products from polar-orbiting satellites is established and applied to 7716 visible infrared imaging radiometer (VIIRS) data in China seas. The results suggest that it is feasible and practical for the retrieval of daily mean SST with an average RMSE of 0.133 °C. This retrieval method can also be utilized to other polar-orbiting satellites and obtain more daily mean satellite SST products, which will contribute to more accurate estimation and prediction between atmosphere and ocean in the future.

scholarly journals A Novel Approach to Obtain Diurnal Variation of Bio-Optical Properties in Moving Water Parcel Using Integrated Drifting Buoy and GOCI Data: A Case Study in Yellow and East China Seas

2021 ◽  
Vol 13 (11) ◽  
pp. 2115
Author(s):  
Yuying Xu ◽  
Weibing Guan ◽  
Jianyu Chen ◽  
Zhenyi Cao ◽  
Feng Qiao
Keyword(s):  
Time Series ◽  
Optical Properties ◽  
Diurnal Variation ◽  
Mass Movement ◽  
East China ◽  
China Seas ◽  
Diurnal Variability ◽  
Drifting Buoy ◽  
Novel Approach ◽  
Water Parcel

Ocean processes that can influence rapidly changing ocean color include water-mass movement and bio-optical property changes in the water parcel. Traditionally, diurnal variability of bio-optical properties relies on daily time series at fixed locations by satellite sensors or in situ observations. There is a lack of an effective way to observe diurnal variation of bio-optical properties in a moving water parcel on a large scale. In this paper, we propose a new method to acquire diurnal variation of bio-optical properties in a moving water parcel. The novel approach integrates drifting buoy data and GOCI data. The movement of surface current was tracked by a drifting buoy, and its spatiotemporally matching bio-optical properties were obtained via the GOCI data. The results in the Yellow and East China seas during the summers of 2012 and 2013 show that the variation of time series following the movement of water parcel was obviously different from that obtained at fixed locations. The hourly differences of the former are 15.7% and 16.3% smaller than those of the latter for Chl a and total suspended sediment (TSS), respectively. The value of ag440 was more stable within the moving water parcel than in the fixed location. Our approach provides a simple and feasible way for observing diurnal variability of bio-optical properties in a moving surface water parcel.

scholarly journals Diurnal variability of the atmospheric boundary layer height over a tropical station in the Indian monsoon region

2017 ◽  
Vol 17 (1) ◽  
pp. 531-549 ◽  
Author(s):  
Sanjay Kumar Mehta ◽  
Madineni Venkat Ratnam ◽  
Sukumarapillai V. Sunilkumar ◽  
Daggumati Narayana Rao ◽  
Boddapaty V. Krishna Murthy
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Diurnal Variation ◽  
Indian Monsoon ◽  
Winter Season ◽  
Monsoon Region ◽  
Diurnal Variability ◽  
The Mean ◽  
Indian Monsoon Region ◽  
Tropical Station

Abstract. The diurnal variation of atmospheric boundary layer (ABL) height is studied using high-resolution radiosonde observations available at 3 h intervals for 3 days continuously from 34 intensive campaigns conducted during the period December 2010–March 2014 over a tropical station Gadanki (13.5° N, 79.2° E; 375 m), in the Indian monsoon region. The heights of the ABL during the different stages of its diurnal evolution, namely, the convective boundary layer (CBL), the stable boundary layer (SBL), and the residual layer (RL) are obtained to study the diurnal variabilities. A clear diurnal variation is observed in 9 campaigns out of the 34 campaigns. In 7 campaigns the SBL did not form in the entire day and in the remaining 18 campaigns the SBL formed intermittently. The SBL forms for 33–55 % of the time during nighttime and 9 and 25 % during the evening and morning hours, respectively. The mean SBL height is within 0.3 km above the surface which increases slightly just after midnight (02:00 IST) and remains almost constant until the morning. The mean CBL height is within 3.0 km above the surface, which generally increases from morning to evening. The mean RL height is within 2 km above the surface which generally decreases slowly as the night progresses. The diurnal variation of the ABL height over the Indian region is stronger during the pre-monsoon and weaker during winter season. The CBL is higher during the summer monsoon and lower during the winter season while the RL is higher during the winter season and lower during the summer season. During all the seasons, the ABL height peaks during the afternoon (∼ 14:00 IST) and remains elevated until evening (∼ 17:00 IST). The ABL suddenly collapses at 20:00 IST and increases slightly in the night. Interestingly, it is found that the low level clouds have an effect on the ABL height variability, but the deep convective clouds do not. The lifting condensation level (LCL) is generally found to occur below the ABL for the majority of the database and they are randomly related.

scholarly journals Characterizing the diurnal cycle of South Atlantic stratocumulus cloud properties from satellite retrievals

2018 ◽  
Author(s):  
Chellappan Seethala ◽  
Jan Fokke Meirink ◽  
Ákos Horváth ◽  
Ralf Bennartz ◽  
Rob Roebeling
Keyword(s):  
Diurnal Variation ◽  
Biomass Burning ◽  
Diurnal Cycle ◽  
Near Infrared ◽  
South Atlantic ◽  
Radiation Budget ◽  
Ozone Monitoring Instrument ◽  
Liquid Water Path ◽  
Diurnal Variability ◽  
Late Afternoon

Abstract. Marine stratocumulus (Sc) clouds play an essential role in the earth radiation budget. Here, we compare liquid water path (LWP), optical thickness (COT), and effective radius (CER) retrievals from two years of collocated Spinning Enhanced Visible and InfraRed Imager (SEVIRI), MODerate resolution Imaging Spectroradiometer (MODIS), and Tropical Rainfall Measuring Mission Microwave Imager (TMI) observations, estimate the effect of biomass burning smoke on passive imager retrievals, as well as evaluate the diurnal cycle of South Atlantic marine Sc clouds. The effect of absorbing aerosols from biomass burning on the retrievals was investigated using aerosol index (AI) obtained from the Ozone Monitoring Instrument (OMI). SEVIRI and MODIS LWPs were found to decrease with increasing AI relative to TMI LWP, consistent with well-known negative visible/near-infrared retrieval biases in COT and CER. In the aerosol-affected months of July–August–September, SEVIRI LWP – based on the 1.6-µm CER – was biased low by 14 g m−2 (~ 16 %) compared to TMI in overcast scenes, while MODIS LWP showed a smaller low bias of 4 g m−2 (~ 5 %) for the 1.6-µm channel and a high bias of 8 g m−2 (~ 10 %) for the 3.7-µm channel compared to TMI. Neglecting aerosol-affected pixels reduced the mean SEVIRI-TMI LWP bias considerably. On a two-year data base, SEVIRI LWP had a correlation with TMI and MODIS LWP of about 0.86 and 0.94, respectively, and biases of only 4–8 g m−2 (5–10 %) for overcast cases. The SEVIRI LWP diurnal cycle was in good overall agreement with TMI except in the aerosol-affected months. Both TMI and SEVIRI LWP decreased from morning to late afternoon, after which a slight increase was observed. Terra and Aqua MODIS mean LWPs also suggested a similar diurnal variation. The relative amplitude of the two-year mean and seasonal mean LWP diurnal cycle varied between 35–40 % from morning to late afternoon for overcast cases. The diurnal variation in SEVIRI LWP was mainly due to changes in COT, while CER showed only little diurnal variability.

scholarly journals Comparison of Different Rainfall Erosion Estimation Methods for the Island of Crete

Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 67 ◽  
Author(s):  
Dimitrios D. Alexakis ◽  
Manolis Grillakis
Keyword(s):  
Temporal Resolution ◽  
Total Duration ◽  
Power Estimation ◽  
Monthly Rainfall ◽  
Rainfall Data ◽  
Estimation Methods ◽  
Accurate Estimation ◽  
High Temporal Resolution ◽  
Rainfall Erosivity ◽  
Daily Data

Interactions between soil and rainfall plays a vital role in ecological, hydrological and biogeochemical cycles of land. Among those interactions, the phenomenon of rainfall induced soil erosion is crucial to the soil functions, as it affects the soil structure and organic matter content that subsequently affects soil ability to hold moisture and nutrients. The erosive power of a specific rainfall event is regulated by its intensity and total duration. Various methodologies have been developed and tested to estimate the rainfall erosivity in different hydroclimatic regions and using different rainfall measuring timescales. Studies have shown that high temporal resolution measurements provide a more robust erosivity estimation. Nonetheless the sparsity and scarcity of such high temporal resolution data make the accurate estimation of rainfall erosivity difficult. Here, we compare different erosion power estimation methods based on different rainfall timescales for the island of Crete. Sub-daily (30-min) rainfall data based estimation is used as the basis for the assessment of a daily data based estimation methodology and two different methods that use monthly rainfall data. Modified Fournier Index (MFI) is incorporated in the study through different literature approaches and a regression equation is developed between rainfall erosivity power and MFI index for Crete. Results indicate that the use of daily data in the rainfall erosive power estimation is a good approximation of the sub-daily estimation, while formulas based on monthly rainfall data tend to exhibit larger deviations.

scholarly journals Impact of More Frequent Observations on the Understanding of Tasmanian Fire Danger

2011 ◽  
Vol 50 (8) ◽  
pp. 1617-1626 ◽  
Author(s):  
Paul Fox-Hughes
Keyword(s):  
Fire Danger ◽  
Weather Data ◽  
High Temporal Resolution ◽  
Fire Weather ◽  
Fire Weather Index ◽  
Diurnal Variability ◽  
Weather Events ◽  
Forest Fire Danger ◽  
Synoptic Observations ◽  
Climate Studies

AbstractHalf-hourly airport weather observations have been used to construct high-temporal-resolution datasets of McArthur Mark V forest fire danger index (FFDI) values for three locations in Tasmania, Australia, enabling a more complete understanding of the range and diurnal variability of fire weather. Such an understanding is important for fire management and planning to account for the possibility of weather-related fire flare ups—in particular, early in a day and during rapidly changing situations. In addition, climate studies have hitherto generally been able to access only daily or at best 3-hourly weather data to generate fire-weather index values. Comparison of FFDI values calculated from frequent (subhourly) observations with those derived from 3-hourly synoptic observations suggests that large numbers of significant fire-weather events are missed, even by a synoptic observation schedule, and, in particular, by observations made at 1500 LT only, suggesting that many climate studies may underestimate the frequencies of occurrence of fire-weather events. At Hobart, in southeastern Tasmania, only one-half of diurnal FFDI peaks over a critical warning level occur at 1500 LT, with the remainder occurring across a broad range of times. The study reinforces a perception of pronounced differences in the character of fire weather across Tasmania, with differences in diurnal patterns of variability evident between locations, in addition to well-known differences in the ranges of peak values observed.

scholarly journals Evaluation and application of a semi-continuous chemical characterization system for water soluble inorganic PM<sub>2.5</sub> and associated precursor gases

2009 ◽  
Vol 2 (1) ◽  
pp. 65-80 ◽  
Author(s):  
K. J. Godri ◽  
G. J. Evans ◽  
J. Slowik ◽  
A. Knox ◽  
J. Abbatt ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Chemical Characterization ◽  
Water Soluble ◽  
High Temporal Resolution ◽  
Field Sampling ◽  
Inorganic Particles ◽  
Regional Sources ◽  
Inorganic Species ◽  
Seasonal And Diurnal Variations ◽  
Continuous Chemical

Abstract. Water soluble inorganic particles components (Cl−, SO42−, NO3−, and NH4+) and concentrations of their associated precursor gases (HCl, SO2, HNO3, NH3) were semi-continuously measured using the Dionex Gas Particle Ion Chromatography (GPIC) system. Sampling was conducted adjacent to a high traffic street in downtown Toronto, Canada from June 2006 to March 2007. This study evaluated the precision and accuracy of field sampling measurements with the GPIC both relative to filter based measurements and other co-located semi-continuous instruments (R&amp;P 8400N Nitrate Monitor, API Fluorescent SO2 Gas Analyzer, and Aerodyne C-ToF-AMS). High temporal resolution PM2.5 mass reconstruction is presented by combining GPIC measured inorganic species concentrations and Sunset Laboratory OCEC Analyzer determined organics concentrations. Field sampling results were also examined for seasonal and diurnal variations. HNO3 and particulate nitrate exhibited diurnal variation and strong partitioning to the gas phase was observed during the summer. Ammonia and particulate ammonium also demonstrated seasonal differences in their diurnal profiles. However, particulate sulphate and SO2 showed no diurnal variation regardless of season suggesting dominant transport from regional sources throughout the year.

scholarly journals Gaseous (DMS, MSA, SO<sub>2</sub>, H<sub>2</sub>SO<sub>4</sub> and DMSO) and particulate (sulfate and methanesulfonate) sulfur species over the northeastern coast of Crete

2003 ◽  
Vol 3 (5) ◽  
pp. 1871-1886 ◽  
Author(s):  
H. Bardouki ◽  
H. Berresheim ◽  
M. Vrekoussis ◽  
J. Sciare ◽  
G. Kouvarakis ◽  
...  
Keyword(s):  
Detection Limit ◽  
Diurnal Variation ◽  
Eastern Mediterranean ◽  
Mean Value ◽  
Sulfur Cycle ◽  
Heterogeneous Reactions ◽  
Sticking Coefficient ◽  
Sulfur Species ◽  
Diurnal Variability ◽  
Northeastern Coast

Abstract. A detailed study of the levels, the temporal and diurnal variability of the main compounds involved in the biogenic sulfur cycle was carried out in Crete (Eastern Mediterranean) during the Mediterranean Intensive Oxidant Study (MINOS) field experiment in July-August 2001. Intensive measurements of gaseous dimethylsulfide (DMS), dimethylsulfoxide (DMSO), sulfur dioxide (SO2), sulfuric (H2SO4) and methanesulfonic acids (MSA) and particulate sulfate (SO42-) and methanesulfonate (MS-) have been performed during the campaign. Dimethylsulfide (DMS) levels ranged from 2.9 to 136 pmol·mol-1 (mean value of 21.7 pmol·mol-1) and showed a clear diurnal variation with daytime maximum. During nighttime DMS levels fall close or below the detection limit of 2 pmol·mol-1. Concurrent measurements of OH and NO3 radicals during the campaign indicate that NO3 levels can explain most of the observed diurnal variation of DMS. Dimethylsulfoxide (DMSO) ranged between 0.02 and 10.1 pmol·mol-1 (mean value of 1.7 pmol·mol-1) and presents a diurnal variation similar to that of DMS. SO2 levels ranged from 220 to 2970 pmol·mol-1 (mean value of 1030 pmol·mol-1), while nss-SO42- and MS- ranged from 330 to 7100 pmol·mol-1, (mean value of 1440 pmol·mol-1) and 1.1 to 37.5 pmol·mol-1 (mean value of 11.5 pmol·mol-1) respectively. Of particular interest are the measurements of gaseous MSA and H2SO4. MSA ranged from below the detection limit (3x104) to 3.7x107 molecules cm-3, whereas H2SO4 ranged between 1x105 and 9.0x107 molecules cm-3. The measured H2SO4 maxima are among the highest reported in literature and can be attributed to high insolation, absence of precipitation and increased SO2 levels in the area. From the concurrent SO2, OH, and H2SO4 measurements a sticking coefficient of 0.52±0.28 was calculated for H2SO4. From the concurrent MSA, OH, and DMS measurements the yield of gaseous MSA from the OH-initiated oxidation of DMS was calculated to range between 0.1-0.4%. This low MSA yield implies that gaseous MSA levels can not account for the observed MS- levels. Heterogeneous reactions of DMSO on aerosols should be considered to explain the observed levels of MS-.

scholarly journals Tracking isotopic signatures of CO<sub>2</sub> at the high altitude site Jungfraujoch with laser spectroscopy: analytical improvements and representative results

2013 ◽  
Vol 6 (7) ◽  
pp. 1659-1671 ◽  
Author(s):  
P. Sturm ◽  
B. Tuzson ◽  
S. Henne ◽  
L. Emmenegger
Keyword(s):  
High Altitude ◽  
Isotope Ratios ◽  
Particle Dispersion ◽  
High Temporal Resolution ◽  
Research Station ◽  
Close Link ◽  
Diurnal Variability ◽  
Air Masses ◽  
The Mean ◽  
Δ13c And Δ18o

Abstract. We present the continuous data record of atmospheric CO2 isotopes measured by laser absorption spectroscopy for an almost four year period at the High Altitude Research Station Jungfraujoch (3580 m a.s.l.), Switzerland. The mean annual cycles derived from data of December 2008 to September 2012 exhibit peak-to-peak amplitudes of 11.0 μmol mol−1 for CO2, 0.60‰ for δ13C and 0.81‰ for δ18O. The high temporal resolution of the measurements also allow us to capture variations on hourly and diurnal timescales. For CO2 the mean diurnal peak-to-peak amplitude is about 1 μmol mol−1 in spring, autumn and winter and about 2 μmol mol−1 in summer. The mean diurnal variability in the isotope ratios is largest during the summer months too, with an amplitude of about 0.1‰ both in the δ13C and δ18O, and a smaller or no discernible diurnal cycle during the other seasons. The day-to-day variability, however, is much larger and depends on the origin of the air masses arriving at Jungfraujoch. Backward Lagrangian particle dispersion model simulations revealed a close link between air composition and prevailing transport regimes and could be used to explain part of the observed variability in terms of transport history and influence region. A footprint clustering showed significantly different wintertime CO2, δ13C and δ18O values depending on the origin and surface residence times of the air masses. Several major updates on the instrument and the calibration procedures were performed in order to further improve the data quality. We describe the new measurement and calibration setup in detail and demonstrate the enhanced performance of the analyzer. A measurement precision of about 0.02‰ for both isotope ratios has been obtained for an averaging time of 10 min, while the accuracy was estimated to be 0.1‰, including the uncertainty of the calibration gases.

scholarly journals Gaseous (DMS, MSA, SO<sub>2</sub>, H<sub>2</sub>SO<sub>4</sub> and DMSO) and particulate (sulfate and methanesulfonate) sulfur species over the northeastern coast of Crete

2003 ◽  
Vol 3 (4) ◽  
pp. 3869-3906 ◽  
Author(s):  
H. Bardouki ◽  
H. Berresheim ◽  
M. Vrekoussis ◽  
J. Sciare ◽  
G. Kouvarakis ◽  
...  
Keyword(s):  
Detection Limit ◽  
Diurnal Variation ◽  
Eastern Mediterranean ◽  
Mean Value ◽  
Sulfur Cycle ◽  
Heterogeneous Reactions ◽  
Sticking Coefficient ◽  
Sulfur Species ◽  
Diurnal Variability ◽  
Northeastern Coast

Abstract. A detailed study of the levels, the temporal and diurnal variability of the main compounds involved in the biogenic sulfur cycle was carried out in Crete (Eastern Mediterranean) during the Mediterranean Intensive Oxidant Study (MINOS) field experiment in July-August 2001. Intensive measurements of gaseous dimethylsulfide (DMS), dimethylsulfoxide (DMSO), sulfur dioxide (SO2), sulfuric (H2SO4) and methanesulfonic acids (MSA) and particulate sulfate (SO42−) and methanesulfonate (MS−) have been performed during the campaign. Dimethylsulfide (DMS) levels ranged from 2.9 to 136 pmol · mol-1 (mean value of 21.7 pmol · mol−1) and showed a clear diurnal variation with daytime maximum. During nighttime DMS levels fall close or below the detection limit of 2 pmol ·mol−1. Concurrent measurements of OH and NO3 radicals during the campaign indicate that NO3 levels can explain most of the observed diurnal variation of DMS. Dimethylsulfoxide (DMSO) ranged between 0.02 and 10.1 pmol · mol−1 (mean value of 1.7 pmol · mol−1) and presents a diurnal variation similar to that of DMS. SO2 levels ranged from 220 to 2970 pmol · mol−1 (mean value of 1030 pmol · mol−1), while nss-SO42− and MS− ranged from 330 to 7100 pmol · mol−1, (mean value of 1440 pmol · mol−1) and 1.1 to 37.5 pmol · mol− (mean value of 11.5 pmol · mol−1) respectively. Of particular interest are the measurements of gaseous MSA and H2SO4. MSA ranged from below the detection limit (3×104) to 3.7×107 molecules cm−3, whereas H2SO4 ranged between 1×105 and 9.0×107 molecules cm−3. The measured H2SO4 maxima are among the highest reported in literature and can be attributed to high insolation, absence of precipitation and increased SO2 levels in the area. From the concurrent SO2, OH, and H2SO4 measurements a sticking coefficient of 0.52±0.28 was calculated for H2SO4. From the concurrent MSA, OH, and DMS measurements the yield of gaseous MSA from the OH-initiated oxidation of DMS was calculated to range between 0.1–0.4%. This low MSA yield implies that gaseous MSA levels can not account for the observed MS− levels. Heterogeneous reactions of DMSO on aerosols should be considered to explain the observed levels of MS−.

scholarly journals Diurnal variability of the Atmospheric Boundary Layer height over a tropical station in the Indian Monsoon Region

2016 ◽  
Author(s):  
Sanjay Kumar Mehta ◽  
Madineni Venkat Ratnam ◽  
Sukumarapillai V. Sunilkumar ◽  
Daggumati Narayana Rao ◽  
Boddapati V. Krishna Murthy
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Diurnal Variation ◽  
Indian Monsoon ◽  
Winter Season ◽  
Monsoon Region ◽  
Diurnal Variability ◽  
The Mean ◽  
Indian Monsoon Region ◽  
Tropical Station

Abstract. The diurnal variation of atmospheric boundary layer (ABL) height is studied using high resolutions radiosonde observations available every 3-h intervals for 3 days continuously from 34 intensive campaigns conducted during the period December 2010–March 2014 over a tropical station Gadanki (13.5° N, 79.2° E), in the Indian monsoon region. The heights of the ABL during the different stages of its diurnal evolution, namely, the convective boundary layer (CBL), the stable boundary layer (SBL), and the residual layer (RL) are obtained to study the diurnal variability. A clear diurnal variability in 9 campaigns is observed while in 7 campaigns the SBL does not form for the entire day and in the remaining 18 campaigns the SBL form intermittently. The SBL forms 33 %–55 % during nighttime and 9 % and 25 % during the evening and morning hours, respectively. The mean SBL height is within 0.3 km above the surface which increases slightly just after midnight (0200 IST) and remain almost steady till morning. The mean CBL height is within 3.0 km above the surface which generally increases from morning to evening. The mean RL height is within 2 km above the surface which generally decreases slowly as the night progresses. Diurnal variation of the ABL height over the Indian region is stronger during the pre-monsoon and weaker during winter season. The CBL is higher during the summer monsoon and lower during the winter season while the RL is higher during winter season and lower during summer season. During all the seasons, the ABL height peaks during the afternoon (~ 1400 IST) and remains elevated till evening (~ 1700 IST). The ABL suddenly collapses at 2000 IST due to cooling after the sunset and increases slightly over night. Interestingly, it is found that the low level clouds have an effect on the ABL height variability, but not the deep convective clouds.

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