Latest Event Updates
North Eastern Space Applications Centre (NESAC) has been providing thunderstorm nowcasting (forecasting up to 4 hours) services for North Eastern Region (NER) of India since 2015 under the North Eastern Regional node for Disaster Risk Reduction (NER-DRR) initiatives. This was done using the data from satellite imager and sounder onboard INSAT-3D / INSAT-3DR, automatic weather station data, and by analysing numerical weather forecast data. However, it was difficult to detect, track and forecast using this data alone as most of the thunderstorms being a localised event, extending only over a few tens of km and having a lifetime of less than one hour. The availability of DWR data has opened a new window for precise identification of thunderstorm weather systems, track them and forecast the probable areas which may get affected, albeit with lesser lead time.
The first S-band dual-polarimetric Doppler Weather Radar (DWR) was installed at Cherrapunjee, Meghalaya which was dedicated to the nation by Shri Narendra Modi, Hon’ble Prime Minister of India on May 27, 2016. NESAC is operating the DWR continuously since then, and the data is made available in near real-time for the public through the MOSDAC (Meteorological and Oceanographic data archival centre) and IMD websites. The DWR is calibrated at regular intervals and the data and products are being validated. It has unobstructed coverage for the entire state of Meghalaya, Tripura, Southern Assam, and part of Mizoram and Manipur. For the western and central Assam region, the DWR has coverage beyond 3-degree elevation only. The DWR also sees a large part of India’s neighbouring country, Bangladesh. The radar completes one volume scan in 11 minutes, comprising of 360-degree azimuth scan for 10 elevation angles ranging from 0.5 to 21 degrees. It also allows sector scan (in both azimuth and elevation) for high temporal observation of any event. The DWR covers a distance of 250 km (up to 500 km only for Z) with a spatial resolution of 300 m.
A thunderstorm is a pre-monsoon season (April-May) phenomenon over the NER of India. The data collected by the DWR during 2016 was used to understand the thunderstorm and storm signatures and calibrate the nowcasting model. During 2017 the nowcasting service was made operational. Severe thunderstorm nowcasting services for Southern Assam, Meghalaya, and Tripura were done primarily using the DWR data and for the rest of the NER, the earlier methodology was used. In addition to the Z (radar reflectivity), S (spectral width) and V (velocity) data collected by the DWR, extensive use of the polarimetric data like ZDR (differential reflectivity) and ρHV (Correlation coefficient) were also made to differentiate thunderstorm clouds from non-thunderstorm clouds.
The use of the Cherrapunjee DWR data has improved the thunderstorm nowcasting accuracy over Meghalaya, Southern Assam, and Tripura states. Altogether 48 severe and very severe thunderstorms were forecasted in these three states during April 1 to June 15, 2017, period. The accuracy of nowcasting was more than 90% with lead time varying from 30 minutes to more than 2 hours. The nowcasting services were disseminated through NER-DRR website and also through direct communication to the concerned at the state level.
(The DWR, Cherrapunjee coverage for an elevation angle of 3 degrees (left). Calibration of the DWR using metal sphere attached to hydrogen gas-filled balloon & Pisharoty sonde (right))
(Max V (left) and Max S (right) data from DWR, Cherrapunjee. Max V is used to estimate the velocity at which a weather system is moving and Max S gives an idea about the internal turbulence within cloud system)
High-resolution optical imaging Earth Observation Satellite (EOS) systems such as CARTOSAT provide multi-spectral remote sensing data in the visible and near-infrared (VNIR) wavelengths of the order of sub-meter to few-meters. These datasets can be used in a variety of applications, particularly associated with precise mapping, monitoring and change detection of earth’s surface, if top of the atmosphere (TOA) measurements can be properly compensated for atmospheric absorption and scattering effects. Existing physics based atmospheric correction (AC) algorithms for multi/hyperspectral remote sensing data over land involves simultaneous use of visible and short-wave infrared (SWIR) channels to derive aerosol information. Hence, such algorithms cannot be used for AC of data acquired by VNIR sensors to derive “surface reflectance”.
Towards this, Space Applications Centre, Ahmedabad has developed a new algorithm for AC of high-resolution VNIR remote sensing data in which aerosol information is retrieved from sensor measurements in VNIR channels and by selecting appropriate aerosol optical properties from a set of defined aerosol models. The algorithm uses lookup tables generated with vector radiative transfer calculations. Derived aerosol information and pre-computed lookup tables are employed to derive surface reflectance. Good quality surface reflectances have been obtained when this algorithm was applied on Cartosat-2 Series Satellite data. It is found that this algorithm significantly removes the haze from the images, making surface features distinctly visible, and hence more useable for qualitative as well as quantitative analysis and further applications.
Following figures illustrate the drastically improved quality of the images after applying the AC algorithms, where the contribution of light due to molecular scattering and scattering from thick layer of aerosol to the sensor measurement at the top the of the atmosphere is removed.
(Parts of Ahmedabad as viewed from Cartosat-2 Series Satellite on 03/11/2016)
(Cartosat-2 Series Satellite View of Ahmedabad, Satellite Area on 03/11/2016)
Brandon Jarratt took GIS professionals behind the scenes of animated city creation at the Esri User Conference, being held this week in San Diego. Jarratt served as general technical director for Disney’s Zootopia, which won the 2016 Academy Award for Best Animated Feature Film. Jarrett took the stage during the plenary session to describe how the Zootopia team used Esri CityEngine software to create the complex city that serves as the backdrop for the movie.
Jarratt said Disney animated features need three elements: compelling stories, appealing characters, and believable worlds. That’s believable worlds, not realistic worlds.
In this case, the complex city of Zootopia had to be designed from the ground up as a complex city with various districts designed to accommodate the vast array of animal species. In the world of Zootopia, humans don’t exist. Transportation systems, houses, streets, and services need to accommodate animals as tall as giraffes and as small as a shrew. To meet these challenges, the designers turned to Esri CityEngine and its multi-scaling feature. The Zootopia world also needed to incorporate various habitats, or in this case, districts. At the centre a large complex city dominates.
CityEngine was used in the creation of the city in Big Hero 6 as well. In Big Hero 6, the base city geography used was San Francisco, upon which Japanese-style buildings were placed. In all, 80,000 buildings were incorporated into San Fransokyo.
(San Fransokyo in Big Hero 6. (Image: Disney))
Zootopia, on the other hand, was built from scratch – including the terrain. The team started with research of various landscapes to create a basemap.
(Zootopia concept map. (Photo: T. Cozzens))
At the city-building stage, CityEngine’s custom tool was used to lay down streets. Buildings were designed for each district. The building styles couldn’t be repeated too often, or the city would look unrealistic, Jarratt said. The designers used carefully calibrated mix rules to keep the cities lively.
(The desert area of Sahara Square is made of 61,000 parts, including buildings, wall segments and palm trees. (Image: Disney))
The ability in CityEngine to change the makeup of a city, adjusting the frequency of the various parts, made it easy for the illustration team to meet the art director’s requirements. When he wanted more skyscrapers or buildings of a certain design, the team was able to provide new concept images the same day.
(Zooptopia being built in Esri CityEngine. (Photo: T. Cozzens))
Esri’s CityEngine GIS technology is used by city planners to design our future smart cities. “It’s so similar to how city planners create real cities,” said Esri President Jack Dangermond. He then presented Jarratt with Esri’s first-ever Best Animated Feature Using GIS award.
The new Landsat Explorer web app from Esri enables users to wield Landsat imagery to explore geology, vegetation, agriculture, and cities anywhere in the world. The app, driven by publicly accessible image services, offers a way to better visualize the planet and understand how the earth has changed over time.
(A false color band combination, where vegetation appears in red, delineates the Exumas Islands in the Bahamas. With the Scatter Plot tool, users can select two bands to plot on a graph, with the more frequent occurrences appearing on this graph in red.)
Using the app is simple: Open it in a web browser, search for a location, and apply analysis tools on the fly to get immediate, dynamic results. With no download required, Landsat Explorer users get instant, interactive access to an extensive collection of multispectral, multi temporal Landsat imagery.
Landsat satellites have been collecting information about the earth’s surface for almost 45 years. Each Landsat image contains multiple bands of spectral data gathered at different wavelengths. More than just offering pictures of the planet, Landsat’s different bands can be combined and analyzed to learn about what is happening on the ground, beyond what the eye can see.
Beyond enabling users to instantly view half a million Landsat images using different band combinations or enhancements, Landsat Explorer offers extensive analytical capabilities. The visualization and analysis tools let users do the following, all on the spot:
- Visualize the data using custom indexes and band combinations
- Filter and select specific dates to analyze and compare
- Interactively compare two images using a swipe tool
- Create custom masks
- Perform change detection
- Generate spectral and temporal profiles
- Create scatter plots using spectral bands
- Add data (city roads, for example) from ArcGIS Online
Landsat Explorer joins Esri’s existing suite of Landsat apps, including the Landsat Arctic and Antarctic Apps. Whether users answer their own questions by applying Landsat Explorer’s powerful analysis tools or take the small leap to create their own imagery apps, it’s never been simpler to instantly visualize and dynamically analyze the earth’s surface.
ISRO’s new communication satellite
- Launched on: June 29 at 2.45 a.m. [IST]
- Mass: 3,477 kg
- Life: 15 years
- Cost: ₹ 1,013 crore, including launch fee
- Launch vehicle: European booster Ariane-5 ECA / VA238
GSAT-17, the country’s newly launched communication satellite, will soon join the fleet of 17 working Indian communication satellites in space and augment their overall capacity to some extent. The 3,477-kg spacecraft was released into a temporary orbit in space as planned at 2.45 a.m. [a.m.] IST on Thursday about 39 minutes after launch from the European spaceport of Kourou in French Guiana. It was dusk at the South American near-equatorial spaceport.
(Image Source: The Hindu (www.thehindu.com)
GSAT-17 was sent up as the second passenger on the European booster, Ariane-5 ECA VA-238, according to ISRO and the European launch company Arianespace. GSAT-17, built mainly for broadcasting, telecommunication and VSAT services, carries over 40 transponders. It also has the equipment to aid Meteorology forecasts and search and rescue operations across the sub-continent.
“GSAT-17 is designed to provide continuity of services of operational satellites in C, extended C and S bands,” ISRO said. The satellite was released into what is called a temporary `geosynchronous transfer orbit’ or GTO, where it started orbiting distant 249 km at the near end to Earth and 35,920 km at the farthest point. Its operations were immediately taken over by the spacecraft command team at the ISRO Master Control Facility in Hassan.
“Preliminary health checks of the satellite revealed its normal functioning. In the coming days, orbit raising manoeuvres will be performed to place GSAT-17 in the geostationary orbit (36,000 km above the equator) by using the satellite’s propulsion system in steps,” ISRO said.
It normally takes around two weeks to reach and settle in its planned slot over India at 93.5° East longitude. Meanwhile, its various functional appendages such as antennas and solar arrays are deployed. The spacecraft was approved in May 2015 with an outlay of ₹1,013 crore, including its launch fee and insurance. Its co-passenger was the 5,700-kg Hellas Sat 3-Inmarsat S EAN shared by two satellite operators.
ISRO Chairman A.S. Kiran Kumar has earlier said they need double the number of communication spacecraft to support various users across the country. ISRO does not yet have a launcher that can lift payloads above 2,000 kg. As such it must hire foreign launch vehicles — mostly of Arianespace — to put its heavier communication spacecraft in orbit. Only this month, it tested its first GSLV-Mark III vehicle which can do this job for it.
“Today, GSAT-17 became India’s third communication satellite to successfully reach orbit in the past two months,” said an official release. It launched GSAT-19 on the new MkIII on June 5 and the 2,230-kg GSAT-9 or the South Asia Satellite on May 5, both from Sriharikota.
Designed and assembled at the ISRO Satellite Centre in Bengaluru, GSAT-17 has been at the Kourou space port since May 15, undergoing pre-launch checks and tests. Project Director Prakash Rao and a rotating team of over 20 ISRO engineers were attending to it during the period, said an ISRO official.
GSAT-17’s co-passenger has two operators. Hellas Sat 3 provides direct to home television and telecom services across Europe, West Asia and South Africa. Global satellite operator Inmarsat will provide in-flight Internet facilities for European airlines, as signified in the satellite’s tag EAN or European Aviation Network.
Classification of UAVs
Classification of Drones by Size
Large Size Drones
These drones are used in the attack, combat and reconnaissance roles. Large size UAVs can fly to a very long distance without recharging or refueling. Large attack systems can carry missiles that can be fired remotely after observing and locking in the target. Reconnaissance UAVs are used to observe and secure a very large area.
Medium Size Drones
This range of drones is generally used in reconnaissance or to gather data. Such units are deployed in military, commercial, industrial and agricultural fields.
Small Size Drones
These drones are the most widely used units. UAVs of this size are used by commercial establishments, government departments, professional photographers and hobbyists.
These units are used for very specific purpose. Miniature drones have been developed for military usage. The device is small enough to fit in the palm. Military personnel use it for spying during a close combat mission. It can be used to view the inside of a standing or damaged building during search and rescue operations.
Classification by Design
This type of UAV has propeller on the tail or nose. Some wing design units have propellers on the wings. Jet propulsion is also used in large UAVs. There are small units that can be launched even from hand but larger units require a small runway to get off the ground. The advantage of this design is that this type of UAV consumes lower amount of energy compared to UAV with tilt rotor design.
Tilt Rotor Design
This type of UAV is also called quadcopter because of use of four rotors for lift and propulsion. It can lift off and land anywhere in the same way as a helicopter. These UAVs are the most widely used units due to ease of launching and landing. There is no need of runway or catapult to launch the aircraft.
Classification by Usage
UAVs have been used widely in attack and combat roles. Military use of drones includes reconnaissance and observation from the sky. Cargo drones are used to supply weapons and cargo to the military units.
There are a wide range of commercial applications of drones. A camera equipped drone is used to map an area. It helps know if the proposed construction site is suitable for construction of a particular structure. UAV is used in commercial sector to take photos and videos of buildings, construction sites and ground areas. Real estate developers use such photos and videos to advertise their building projects.
Farmers use drones to spray pesticides, fertilizers and other chemicals. Special camera and sensors are used to spot problems in the crops. Diseased parts of the crop can be spotted early. Different types of data related to the farm, crop, land and atmospheric conditions can be collected. This data is used to ensure healthy crop and successful harvest.
Law enforcement agencies use drones to fight crimes. They use it for surveillance of a suspected target. Real time surveillance is useful during active crime scenes where sending the police personnel without knowing the ground situation can be dangerous.
Advance 3D imaging equipment installed in a drone is used to survey landscape. Thousands of high quality images are stitched together to create precise and high definition 3D map of a ground area. It gives a better understanding of the geographical features of the area.
It is difficult to know the magnitude of destruction immediately after a disaster. There is urgent need to find the ground information quickly. Sending search and rescue teams to such an area without prior knowledge of ground conditions may result in waste of precious time. A UAV helps know exact locations where help is needed.
Drones equipped with scientific equipment are used to observe storms and other natural disasters. The data collected and analyzed from such operations are used to develop predictive models that help predict an impending disaster with better accuracy.
This type of commercial venture is yet to take off due to regulatory constraints. However, many companies are working actively in this field. It is going to be a lucrative field for the sellers of products.
Research and Development
Scientists use drones to gather different types of data related to the ground, sea and air. They can find useful data without sending several teams to the target locations. Accurate scientific data from various locations can be collected quickly and easily.
UAVs are now used widely to protect border areas from intruders. It helps gather intelligence information in the battlefield. The information proves useful in protecting borders, combat units and security installations. Military personnel can avoid high risk missions or go to such missions with better information of the ground situation
Hobbyists use small size drones for recreational purposes. These units are used to enjoy the thrill of flying an aircraft. Now many UAVs made for general users have camera to take photos and videos. Some new UAV models can follow the moving drone pilot. There are strict drone flying rules and regulations that hobbyist drone operators must know.
There are various problems, issues and challenges associated with UAVs. It is difficult to regulate flying of small drones. Thousands of small drones are sold every year. These products are available easily online and offline. A small drone can be built even by a novice using easily available parts from the Internet. Even a small drone poses high safety risks to large planes and ground installations like fuel depots. There are occasional instances where operators lose control of their UAV during the flight. There have been no serious accidents so far but there are many reports of criminals using drones to supply illegal and banned items into prisons. The insurance aspect is not fully defined and developed. There are privacy risks to people. Drones can fly high and record visible parts of a private property. It can be used to look inside homes through windows.
Government authorities have been trying to overcome these challenges with proper regulations. There are many rules and regulations for UAV ownership and operations and law enforcement agencies are already using different technologies to stop rogue UAVs. The options include signal jamming as well as capturing and attacking to bring down the rogue UAVs.
The drone industry is also advancing at a rapid pace. Large numbers of UAVs are being sold and used all around the world, and the market for military drones is expected to exceed $10 billion by 2017. Private UAV sales are expected to cross $82 billion in the first 10 years. At the same time, the drone industry is expected to generate more than 100,000 jobs. Use of such technologies help improve living conditions. There are benefits and challenges in use of UAVs. Governments are trying to keep pace with these developments by framing proper rules and regulations.
Computation of solar energy potential is essential to select the locations for solar photovoltaic (PV) thermal power plants. The use of remote sensing observations from geostationary satellite sensors is ideal to capture space-time variability of surface insolation. An android App for the computation of solar energy potential has been developed by Space Applications Centre (SAC), ISRO, Ahmedabad at the behest of Ministry of New and Renewable Energy, Govt. of India. It is a very useful tool for installation of PV solar panels for tapping solar energy.
The App provides monthly/yearly solar potential (in kWh/m2) and minimum/maximum temperature at any location. It also displays the location on the satellite image and provides azimuth/elevation angles as well as day length over different time periods in a year.
Following are the major features of the App:
- The App provides solar energy potential (in kWh/m2) at any given location.
- The required location can be keyed in or can be obtained through GPS.
- It gives monthly and yearly solar potential processed using Indian Geostationary Satellite data (Kalpana-1, INSAT-3D, and INSAT-3DR). It also offers monthly minimum and maximum temperature to calculate realistic solar potential.
- The location is displayed on the image with satellite data in the background.
- It also provides azimuth and elevation angles, and day length over different time periods in a year.
- Obstruction of sunlight due to terrain is also calculated using Digital Elevation Model (DEM).
- It also suggests optimum tilt angle for solar PV installation.
- This App needs an internet connection to calculate the results.
- The complete report can be saved as a PDF file.
The App can be downloaded from “New and Renewable Energy” section at vedas.sac.gov.in