Latitude Angle Research Articles

Determination of optimum tilt and azimuth angle of BiSPVT system along with its performance due to shadow of adjacent buildings

Development of a BIPV system with appropriate azimuth and tilt angle on top of a suitable existing or new building in urban areas is a possible option to generate both electrical and thermal energies and also to create an additional living space. These azimuth and tilt angles are significantly influenced by the shadow of the neighborhood’s buildings. The relative height, plan orientation, plan area, position, and horizontal distance of the neighborhood’s buildings are critical parameters for determining optimum azimuth and tilt angle to receive maximum insolation. Present proposed model accurately calculates these angels and the energy, and the model also works well when water flows over the BIPV panel from an overhead tank through gravity with an aim to increase the efficiency of PV panel. The periodic nature of relevant parameters is considered in the thermal modeling of the BiSPVT system. Results indicate that the optimum azimuth angle from south-facing increases with a rise in the latitude angle of the place. The optimum tilt angle depends on the corresponding latitude and the different contributing parts of total insolation. The electrical output of a south-facing BiSPVT system with a tilt angle equal to latitude is increased by 3.7% when BiSPVT system is installed at optimum azimuth and tilt angle. The output is further enhanced by 4.3% when water is flown at the rate of 1.1 kgs−1 over the PV panel.

Linear Regression Algorithm Results for a PV Dual-Axis Tracking-Type System

A photovoltaic (PV) module converts solar energy into electrical energy. In order to increase the output power of any PV module, several factors including tilt angle, orientation angle, load profile, environmental condition, latitude of the location site, and energy management techniques should be considered. It is essential to continuously deliver the highest possible power to a load for a given day, which may be achieved by using a tracking-type system as compared to a fixed-type system. The purpose of this paper is to present the results of an algorithm that may be applied to a dual-axis system located in an elevated plateau of the interior of South Africa in order to sustain a high output power. Two identical 310W PV modules were used for a fixed-type and tracking-type system. The fixed-type system was installed at a tilt angle of Latitude minus 10° serving as a baseline to the tracking-type system. A LabView user interface was developed to record and display the voltage and current measurements from the PV modules. Results indicate that the dual-axis tracking-type system extracted more power (on average 39.32% more power) as compared to the fixed-type system. A key recommendation is to use a linear regression algorithm with a tracking-type system to enable a higher output energy yield for a given day.

Comparison of Thermal Performance Analysis for Single-Slope Solar Stills Using Three Different Depths of Seawater

In this study an attempt was done to compare the thermal performance for the three identical single-slope solar stills using three different depths of seawater (1, 2, and 3 cm). It was executed under the climatic conditions of Mansoura University (31.045°N latitude angle, and 31.352°E longitude angle, and 6.72 m above the sea level). The experimental work was carried out form the 1st of January until the 19th of April 2020. Different of climatic factors and solar still measurements were monitored, measured and recorded. The hourly average solar energy available inside the solar still wind speed and ambient air temperature during the daylight-time, respectively, was 461.4 W, 1.3 m/s and 21.4oC. The thermal efficiency for the lowest depth of seawater was higher than that of the other two depths by 22.44% and 49.03%, respectively. The distillation efficiency of the lowest depth of seawater was higher than that of the other depths by 13.34% and 20.15%, respectively. The lowest depth of seawater augmented the productivity rate of freshwater by 42.04% and 77.27% as compared with the other two depths, respectively. The estimated costs of distilled one litre of freshwater from the three different depths of seawater, respectively, were approximately 0.68, 0.96, and 1.20 EGP.

Optimum Tilt Angles of Solar Panels: A Case Study for Gansu Province, Northwest China

The article deals with optimizing tilt angles of photovoltaic panels for fixed and manually adjusted solar photovoltaic system with due south-facing orientation to maximize the output of solar electricity in Gansu province, northwest China. There are three models by Liu and Jordan, Hay and Kliein and Theilacker selected to calculate the seasonal and yearly optimum tilt angles of solar panels through Matlab programs on seven sites in Gansu province. Meanwhile, the outdoor experiment was conducted to measure the yearly sum of global solar irradiance at different tilt angles. The study found that (1) the calculated yearly optimum tilt angles by three models are close among each other especially between Liu and Jordan’s and Klein and Theilacker’s models; (2) the annual optimum tilt angles of solar panels for fixed installation could be set at model’s angle for higher latitude sites with most-rich solar energy, and latitude angle for lower latitude sites with medium-rich and less-rich solar resources; (3) the seasonal optimum tilt angles should be set at average models’ angle for manual adjustment of photovoltaic system across a year; (4) for all sites, the model’s angle could be selected for a photovoltaic system when considering limitation of land-use area.

The Assessment of Pad-Fan Evaporative Cooling System in Broiler Housing تقدیر معاییر نظام وسادة – مروحة للتبرید بالتبخیر فى مساکن دجاج التسمین

An investigation was executed to study the impact of using different thicknesses for pad cooling and various airflow rates on the cooling system effectiveness inside the house of broilers and on its performance in the summer of 2019, Egypt (latitude angle of 30.42°N and longitude angle of 30.59°E). The trial was done using 20, 30, 40, and 50 m3 /s. airflow rates, As well as using ten and fifteen cm pad thickness. The experimental work results' pointed to using a pad cooling system with fifteen cm pad thickness with 20, 30, 40, and 50 m3 /s airflow rates increase the temperature cooling effect by 25.54, 30.89, 13.36, and 44.63 % comparing with using ten cm pad thickness for the same previous flow rates, respectively. Cooling efficiency increased by 24.73, 29.5, 12.17, and 44.46% when using a cooling system with fifteen cm pad thickness comparing with using a cooling system with ten cm pad thickness for 20, 30, 40, and 50 m3/s airflow rates, respectively. The average value of pad water consumption decreased by 57 % when using a fifteen cm pad cooling system compared to a 10 cm pad cooling system. The lowest mean value for T.H.I. was 25.4°C at an airflow rate of 50 m3/s for fifteen cm pad thickness. Reared birds in the house with fifteen cm pad cooling thickness were not stressed, according to T.H.I. Value and thus lead to increasing the production Efficiency factor by 17.91% comparing with using a ten cm pad cooling system.

Telemedicine system using mobile internet communication

Purpose Telemedicine is delivered to patient anywhere during emergency treatment care, and medical information is transferred from one site of patient to another site of specialist doctors by using mobile internet communication. Some rural areas have slow internet speed because of weak internet signal propagation from mobile towers. A good design of antenna is needed to improve mobile internet speed for big medial data transmission in telemedicine application. Hence, this paper aims to propose economically low-cost design of antenna. Design/methodology/approach Telemedicine recommended to design the satellite frequency modulation dish (SAT FMD) antenna ( where in FM radio antenna, dish antenna are combined ) to improve the internet speed at Telemedicine system and Hospitals for purpose of Telemedicine communication and information for emergency treatment. Findings In the proposed system, designed SAT FMD satellite-based antenna improved internet speed is achieved at 90.6% accuracy in this research method. Finding latitude and longitude angles to identify the patient location, nearest hospitals location and finding distance, shortest path routing between patient and hospital. Finding elevation, Azimuth, latitude, longitude, skew for alignment dish to focus satellite and mobile cell tower to improve internet speed at telemedicine area and hospitals and reduced transmission delay and nodal delay of big medical data. Social implications The social awareness among people can be shared information of accident patient to communicate Hospital and Ambulance driver by internet mobile app tools and help find nearest hospitals to emergency treatment for accident people. Originality/value This paper presents SAT FMD antenna model based on satellite dish antenna consisting of FM radio receiver antenna and dish antenna for telemedicine communication.

The Impact of PV Panel Positioning and Degradation on the PV Inverter Lifetime and Reliability

The photovoltaic (PV) inverter lifetime is affected by mission profiles, which include the solar irradiance and ambient temperature of the installation site. In previous research, the design for reliability approach has been used to evaluate the reliability of the PV inverter, where the solar irradiances have been measured on a fixed tilt and orientation angle. In most cases, the tilt is chosen to be the latitude angle and the orientation is facing south for maximum energy production throughout the year. However, the impact of the tilt and orientation of the PV array on the inverter lifetime has not been considered so far. The tradeoff between the PV energy yield and the inverter lifetime can be analyzed for different PV array positioning. This article thus evaluates the lifetime of the PV inverter with varying the tilt and orientation angle of PV panels, where the PV panel degradation rate is also taken into account. The evaluation is based on the mission profiles of Algiers, Algeria. The results reveal that orientation has a strong impact on the PV inverter loading and certain orientations result in high PV energy production and long lifetime of the PV inverter. It is also shown that the PV panel aging in Algeria has a significant impact on the lifetime estimation of the PV inverter for different orientations.

Estimation and validation of a clear sky hourly global solar radiation in Beni-Suef, Egypt

The availability of hourly and daily solar radiation data is considered one of the important design tools for several solar energy applications. The objective of this work is to develop a model to calculate the hourly solar radiation falling on a horizontal surface in Beni-Suef city, Egypt via a validated simulation model. This model will help the researches in upper Egypt universities along with the designing of solar energy projects in the Beni-Suef city residential and industrial zones. The average solar radiation is calculated daily on hourly basis throughout the year, then the monthly average solar radiation is estimated. The results indicate the maximum value of average solar radiation is in June as 8.1 kWh/m2/day. Solar radiation is also calculated with several tilt angles to find out the optimum tilt angle that enable the surface to receive maximum solar radiation. The calculations focused on empirical equations of solar radiation and the experimental measurements obtained from the nearest station to the location. The model describes solar equations and it can be used to estimate global irradiance. Also, it shows the parameters of the system and climate change of the specific site (Beni-Suef city). Results are validated by comparison between the measured, calculated, and published reference data for the specific site and obtained good agreement with each other. It is found also that the optimal tilt angle that receives maximum solar radiation is 29 deg. which comply with the latitude angle of Beni-Suef city.

Effect of design parameters on performance of passive basin solar stills considering instantaneous ambient conditions: A transient CFD modeling

A transient CFD model is developed to investigate the parameters affecting the productivity of a solar still. Instantaneous weather data is accounted as boundary conditions while the absorption of solar irradiance, as well as radiative heat transfer is considered by DO equation. Evaporation and condensation rates are evaluated by solving species transport equation for water vapor and application of Fick’s law. Latent heats are added to the energy equation as sink and source terms by considering a coefficient that accounts for the latent heat shared between neighboring bodies. Effects of wind speed, glass cover thickness, water depth, water to cover distance and cover inclination on performance of a passive solar still are investigated. Stepped solar stills are also modeled and effects of number of steps and water to cover distance are discussed. Results show that a 14.4% increase in the productivity is observed when the wind speed increases from 1 m/s to 6 m/s, and a 3.5% improvement occurs by decreasing the glass thickness from 4 mm to 2 mm. The optimum values of water depth and water to cover distance are found to be 2 and 8 cm respectively, with the cover tilt equal to the local latitude angle. Moreover, by converting the basin solar still to the appropriate stepped solar still, the productivity increases about 17.4%.

Optimizing the inclined field for solar photovoltaic arrays

Existing studies are focused on maximizing the solar energy collection by photovoltaic modules installed on a flat (horizontal) field. This paper presents an analytical model, which considers the tilt angle of the field along with the modules and evaluates the direct solar energy accumulation within a given time period. Validation of the model is performed by comparing the results with measurements obtained from a computer-aided 3D model. Then, various applications of the model are demonstrated for optimizing field and module tilt angles. The simulations were performed at a virtual site in Auckland (New Zealand; latitude: ∼36.86⁰S). For the given dimensions of the field and the modules, the results showed that nearly horizontal modules collect 35% more energy than when they are at the latitude angle. If they are tilted at the latitude angle, increasing the inclination angle of the field above 16⁰ increases energy collection by 48%. A contour plot of energy collection over the specified ranges of tilt angles was developed to help designers choose the best possible combinations. Finally, the monthly and seasonal energy collections are also presented for modules fixed on an inclined field, tilted at latitude angle.

Analysis of Ionospheric Scintillations of NavIC L5 and S -band Signals over Low Latitude Indian Region

Abstract The NavIC (Navigation with Indian Constellation) system’s performance degrades significantly in equatorial low latitude region due to ionospheric effects. Ionospheric scintillation (IS) is one of the major problems to NavIC system. IS occurs due to the random fluctuations in amplitude and phase of the signal. It also depends on solar cycle, latitude, seasons, time and elevation angle of the satellite. Not much significant amount of work is reported on ionospheric scintillation effects on NavIC signals. In this paper, ionospheric scintillation effects on NavIC L5 band (1176.42 MHz) and S1 band (2492.08 MHz) signals due to (1B,1C,1D,1E,1F,1G) are investigated. Amplitude scintillation index S4 is computed based on Carrier to Noise ratio (C/N0) measurements from ISRO IGS (IRNSS/GPS/SBAS) receiver for Kurnool station (Lat:15°47′49″N, Lon:78°4′39″E) and Hyderabad (Lat:17°23′31″N, Long: 78°19′10″E) station. The analysis is carried out for Kurnool station (June and September months) and Hyderabad station for Equinox Months (March & September) and Solstice Months (June & December) for the year 2017. IS effects of L5 and S1 band signals are analysed. It is observed that scintillation effects are severe for L5 band compared to S1 band signals. This work will be helpful to improve the user position accuracy.

COOLING GREENHOUSES BY USING SOLAR ENERGY

Two experimental greenhouses were used in this study, (G1) a greenhouse was ventilated naturally (as control) and (G2) another greenhouse was cooled by using solar energy, it contains: principally of the units: regeneration heat source (solar collector), the rotary wheel dehumidifier (The first part was the regeneration part that equals 50% of the total surface area). Two pad materials were used as pads for cooling, the used materials were cellulose and palm fiber. Three different air velocities of 1,2and 3 m/s were used with each pad material. Three water flow rats of 10, 15 and 20 L/min were used on each pad. The experiments were carried out in the premises of an open roof (third floor) of a Faculty of Agriculture Engineering, Al- Azhar University, Nasr City, Cairo Egypt (Latitude angle of 30° 02’ 30” N, Longitude angle of 31° 14’ 07” E, and mean altitude above sea level of 18 m). The experiments were carried out on April to July2018. The obtained results indicated that the average temperature of 31.0 °C was outside the greenhouse through all the experiments while the average temperatures of 36.4, 24.5 °C were inside the greenhouses (G1), (G2), respectively. The average temperature reduction of 6.6 °C was outside and inside the cooling greenhouse by using solar energy, while the average temperature reduction of 11.9 °C was in the un cooled greenhouse. The highest cooling efficiency of 79.5% was recorded when the outside temperature of 30.6 °C and relative humidity of 41.2%, the previous highest cooling efficiency was when the cellulose pad material was used at water flow rate of 20L/min and wheal face air velocity of 2 m/s.

Optical and thermal performance analysis of a micro parabolic trough collector for building integration

Medium temperature thermal energy (100–400 °C) is widely used in industrial processes and in large buildings. The presented work investigated the feasibility of a new solar collector which was designed to harvest solar energy from factory rooftops for industrial process heat applications. The proposed solar collector was comprised of parallel micro-parabolic troughs, vacuum tube receivers, and an internal tracking mechanical contained in a glazed box which can be easily mounted on large buildings. The system does not require external rotational tracking and achieves a concentration ratio of ~4.2 in a ~150 mm height, so it can be easily integrated with buildings. The optical performance of the presented collector is analysed and modelled theoretically and numerically, considering the effect of shading, inclination, and orientation. Furthermore, a transient thermodynamic model is developed to calculate its thermal efficiency and stagnation temperature, along with the effect of vacuum pressure, beam radiation, and emissivity of selective coatings. The theoretical analysis, verified by TRNSYS simulations and an outdoor experiment, revealed that the annual optical efficiency of the system was about 66.7% and the thermal efficiency was about 59.3% at 200 °C, if the collector was inclined to local latitude angle. These results reveal that the proposed design is competitive with evacuated flat plates (i.e., the TVP collector which has a thermal efficiency of ~36% at a normalized temperature difference of 0.2). Further, if the collector were to be installed on the vertical façade of a building, the theoretical model estimated that the optical and thermal efficiencies would be 44.1% and 37.5%, respectively. An economic analysis indicated that a levelized cost of heat energy of 0.51 $/kWh can be obtained. Overall, since the proposed collector has a simple structure and a low-profile, this study indicates it is promising for medium temperature solar thermal heat production for industrial processes and/or for multi-effect absorption chillers.

Study of Exospheric Neutral Composition of Mars observed from Indian Mars Orbiter Mission

The exospheric composition data of Mars for the period 2014–15 has been extracted and analysed using the observations carried out by the MENCA (Mars Exospheric Neutral Composition Analyser) payload on-board the Mars Orbiter Mission (MOM) launched by India. The latitude, longitude, altitude and solar zenith angle coverage of the partial pressure values of different exospheric constituents are determined and assigned to create a new data-set with orbit-wise data assimilation particularly between 260 and 600 km altitude range. Apart from getting the results on mean individual orbits’ partial pressure profiles, the variations of the total as well as partial pressures are studied with respect to the distribution of the major atmospheric constituents and their dependence on solar activity. In particular, CO2 and O variations are considered together for any differential effects due to photolysis and photo-ionisation. The results on the gradual reduction in densities due to decreasing daily mean sunspot numbers and strong response of CO2 and O pressures to solar energetic particle events like that of 24 December 2014 are presented.

Improving the energy production of roof-top solar PV systems through roof design

Australia is receiving an average of 58 million PJ of solar radiation per year, which is about 1000 times larger than its total energy generation. Roof-top solar photovoltaic (PV) systems alone can supply a phenomenal fraction of the nation’s total energy. The architectural design and orientation of roofs have considerable impacts on the energy efficiency of roof-top solar PV systems. These aspects, however, have received scant academic attention within the literature. To address this knowledge gap, this research seeks to increase the energy production of roof-top solar PV systems through roof design. The energy generation of roof-top solar PV systems is modelled using Helioscope software, and then validated using real-time monitored data. Based on the verified model, the impact of different tilt angles and shading from surrounding obstructions upon energy generation are analyzed in detail. To ground the research in practical terms, the aesthetic design of five typical roof design patterns (including flat, shed, gable, hip, and butterfly roof) are explored to compare the energy generated from solar PV systems fitted to each design. Findings indicate that: (1) the simulated energy generation from the solar PV system is close to the monitored data, with equal annual generation; (2) the shading of surrounding obstructions can reduce the energy generation of roof-top solar PV systems considerably, where up to 24% energy loss is reported; (3) the optimal tilt angle is about 35°, which is close to the latitude angle of the studied location; and (4) the shed roof design provides the maximum potential for solar energy generation when compared to that of other roof design patterns. The energy generation variation of other aesthetic roof patterns is also presented, providing support for informed decision making on the roof design. This study contributes to the field through improving the energy production of roof-top solar PV systems based on roof design along with considering aesthetic concerns. Novel insights generated will be beneficial for researchers and government policy makers alike; the work also introduces simulation-based methodological approaches for practitioners who seek to improve the energy generation of roof-top solar PV systems.

Optimization of Sun Tracking Data Handling to Improve Efficiency of PV Module

The procedure of tracking the sun depends on azimuth, altitude and declination angle of sun, latitude and longitude of a location and others. The orientation of sun around the earth can be tracked by using sun tracking mechanisms to collect the maximum percentage of incidents sun ray normal to the panel. This study is conducted to meet objective i.e. optimizing data handling. Three case studies have been implemented. In the first case, a computerized sun tracking device is assumed to rotate the photovoltaic panel as per the sun movement. The output is accurate, but it is expensive as typical multiple sensors, mechanical drive and microcontroller are used. In the second scenario, the solar panel is fixed at sun azimuth (ɸ) 180° and altitude 58° angle which causes more variations in the percentage of incident sun ray normal to the panel throughout the day. Whereas, in the third case, the panel is supposed to change its direction according to the 12 paths (trajectory) of sun instead of 365 paths and each path is comprised with the monthly average of the sun azimuth and altitude angle. This procedure will reduce data handling/ sun tracking cost as compared to the first case. How to cite this article: Taheem A, Sachdeva A, Sharma VS. Optimization of Sun Tracking Data Handling to Improve Efficiency of PV Module. J Adv Res Alt Energ Env Eco 2019; 6(1&2): 1-15. DOI: https://doi.org/10.24321/2455.3093.201901

Effect of solar cell efficiency and flight condition on optimal flight control and energy performance for Z-shaped wing stratospheric solar aircraft

The parameters of solar cell efficiency, flight date of year, latitude and sun elevation angle are important to energy conversion of solar cells, which affect optimal flight control and energy performance of Z-shaped solar aircraft. This work is mainly focusing on studying the effect of varying these parameters on optimum attitude planning, optimum wing morphing control and maximum net energy input for Z-shaped solar aircraft. This study shows that, with higher solar cell efficiency, the solar aircraft prefers to more daylight hours configured as Z-shaped wing, larger morphing angle and larger angle between projection of sunlight and wingspan axis, which enhances to achieve more net power input. For the middle and high latitudes in winter with low sun elevation angles, the Z-shaped solar aircraft tends to large morphing angles and small angles between projection of sunlight and wingspan axis. For the low and middle latitudes of the other seasons with high sun elevation angles, it prefers to small morphing angles to make its central wing totally expose to the sunlight, and orient flight attitude to make the projection of sunlight coincide with wingspan axis. Moreover, the research on the impact of solar cell efficiency shows that, compared with the planar wing, the optimal Z-shaped wing is more effective to improve energy margin and extend perpetual flight days with the same increase of solar cell efficiency. The results can provide valuable engineering reference on optimum wing morphing control and optimum attitude planning for Z-shaped stratospheric solar aircraft.

Dawn/Dusk Asymmetry of the Martian UltraViolet Terminator Observed Through Suprathermal Electron Depletions

AbstractSuprathermal electron depletions are structures of the nightside ionosphere of Mars resulting from an equilibrium between electron loss and creation processes. Photoionization of oxygen and carbon dioxide by UV and EUV photons is the main ionization process of the Martian atmosphere. The observation of suprathermal electron depletions is strongly unexpected in the portion of the Martian environment where photoionization can occur. This region is delimited by the UltraViolet (UV) terminator, behind which no UV ionizing photons are detected. In this study suprathermal electron depletions are used to determine the position of the UV terminator thanks to MAVEN observations. The MAVEN spacecraft is now in its fourth year of data recording and has already covered more than one Martian year, a large range of latitude, local time, and solar zenith angle in the nightside down to 110‐km altitude. This coverage enables us to determine the approximate position of the UV terminator over one Martian year. We then investigate the variation of its position on the dawnside and duskside and depending on seasons. Our results are compared with models of the Martian atmosphere and in situ data of the atmospheric composition which all highlight an asymmetry between the duskside and the dawnside at equinox. However, models show an inversion in the position of the dusk and the dawn UV terminator at perihelion and aphelion, which cannot yet be confirmed or disproved by the data.

A study on harmonizing total ozone assimilation with multiple sensors

Abstract. Bias estimations and corrections of total column measurements are applied and evaluated with ozone data from satellite instruments providing near-real-time products during summer 2014 and 2015 and winter 2015. The developed standalone bias-correction system can be applied in near-real-time chemical data assimilation and long-term reanalysis. The instruments to which these bias corrections were applied include the Global Ozone Monitoring Experiment-2 instruments on the MetOp-A and MetOp-B satellites (GOME-2A and GOME-2B), the total column ozone mapping instrument of the Ozone Mapping Profiler Suite (OMPS-NM) on the Suomi National Polar-orbiting Partnership (S-NPP) satellite, and the Ozone Monitoring Instrument (OMI) instrument on the Aura research satellite. The OMI data set based on the TOMS version 8.5 retrieval algorithm was chosen as the reference used in the bias correction of the other satellite-based total column ozone data sets. OMI data were chosen for this purpose instead of ground-based observations due to OMI's significantly better spatial and temporal coverage, as well as interest in near-real-time assimilation. Ground-based Brewer and Dobson spectrophotometers, and filter ozonometers, as well as the Solar Backscatter Ultraviolet satellite instrument (SBUV/2), served as independent validation sources of total column ozone data. Regional and global mean differences of the OMI-TOMS data with measurements from the three ground-based instrument types for the three evaluated 2-month periods were found to be within 1 %, except for the polar regions, where the largest differences from the comparatively small data set in Antarctica exceeded 3 %. Values from SBUV/2 summed partial columns were typically larger than OMI-TOMS on average by 0.6 % to 1.2 %, with smaller differences than with ground-based observations over Antarctica. Bias corrections as a function of latitude and solar zenith angle were performed for GOME-2A/B and OMPS-NM using colocation with OMI-TOMS and three variants of differences with short-term model forecasts. These approaches were shown to yield residual biases of less than 1 %, with the rare exceptions associated with bins with less data. These results were compared to a time-independent bias-correction estimation that used colocations as a function of ozone effective temperature and solar zenith angle which, for the time period examined, resulted in larger residual biases for bins whose bias varies more in time. The impact of assimilating total column ozone data from single and multiple satellite data sources with and without bias correction was examined with a version of the Environment and Climate Change Canada variational assimilation and forecasting system. Assimilation experiments for July–August 2014 show a reduction of global mean biases for short-term forecasts relative to ground-based Brewer and Dobson observations from a maximum of about 2.3 % in the absence of bias correction to less than 0.3 % in size when bias correction is included. Both temporally averaged and time-varying mean differences of forecasts with OMI-TOMS were reduced to within 1 % for nearly all cases when bias-corrected observations are assimilated for the latitudes where satellite data are present.

Retrieval of Total Precipitable Water from Himawari-8 AHI Data: A Comparison of Random Forest, Extreme Gradient Boosting, and Deep Neural Network

Total precipitable water (TPW), a column of water vapor content in the atmosphere, provides information on the spatial distribution of moisture. The high-resolution TPW, together with atmospheric stability indices such as convective available potential energy (CAPE), is an effective indicator of severe weather phenomena in the pre-convective atmospheric condition. With the advent of high performing imaging instrument onboard geostationary satellites such as Advanced Himawari Imager (AHI) onboard Himawari-8 of Japan and Advanced Meteorological Imager (AMI) onboard GeoKompsat-2A of Korea, it is expected that unprecedented spatiotemporal resolution data (e.g., AMI plans to provide 2 km resolution data at every 2 min over the northeast part of East Asia) will be provided. To derive TPW from such high-resolution data in a timely fashion, an efficient algorithm is highly required. Here, machine learning approaches—random forest (RF), extreme gradient boosting (XGB), and deep neural network (DNN)—are assessed for the TPW retrieved from AHI over the clear sky in Northeast Asia area. For the training dataset, the nine infrared brightness temperatures (BT) of AHI (BT8 to 16 centered at 6.2, 6.9, 7.3, 8.6, 9.6, 10.4, 11.2, 12.4, and 13.3 μ m , respectively), six dual channel differences and observation conditions such as time, latitude, longitude, and satellite zenith angle for two years (September 2016 to August 2018) are used. The corresponding TPW is prepared by integrating the water vapor profiles from InterimEuropean Centre for Medium-Range Weather Forecasts Re-Analysis data (ERA-Interim). The algorithm performances are assessed using the ERA-Interim and radiosonde observations (RAOB) as the reference data. The results show that the DNN model performs better than RF and XGB with a correlation coefficient of 0.96, a mean bias of 0.90 mm, and a root mean square error (RMSE) of 4.65 mm when compared to the ERA-Interim. Similarly, DNN results in a correlation coefficient of 0.95, a mean bias of 1.25 mm, and an RMSE of 5.03 mm when compared to RAOB. Contributing variables to retrieve the TPW in each model and the spatial and temporal analysis of the retrieved TPW are carefully examined and discussed.