Tag: Temperature (page 1 of 2)

Bangalore’s temperature outliers in February 2015

by Pavan Srinath

In the few months that Bangalore does not get much rainfall, temperature is the most interesting (and useful) thing to look at. I take a quick look at how the temperature is varying across the city, thanks to five Citizen Weather Network stations that regularly report data.

Visually representing the data often throws up insights far better than conventional statistical analysis, and the same is true here.

Looking at the past 10 days of weather in Bangalore, it is immediately apparent that most of them follow trends similar to each other. With variation of less than 1°C, at least four out of five stations are quite similar to each other in both maximum and minimum daily temperatures.


Two outliers stand out. For at least the 10 day period in February, Electronics City’s maximum temperature was consistently and significantly lower than the remaining 4 locations in Bangalore. On February 19, Electronics City recorded a maximum of 35.7 °C, a full 2.5 °C higher than all other locations in town.

Coming to minimum temperatures, GKVK, the agricultural univeristy campus north of town, consistently recorded lower temperatures than the rest of the locations. On February 23, the minimum temperature was 13.7 °C, a full 4 °C lower all other areas.

As the Citizen Weather Network grows, we hope to understand the spatial variation in temperature across the city much better. With more data, we may even be able to attribute causes to temperature variation. We will also be able to tell which temperature effects persist through the year, and perhaps quantify heat island effects on the city of Bangalore.

Pavan Srinath is a weather enthusiast at Know Your Climate, and tweets at @zeusisdead.

Temperature data used for the chart can be downloaded here.

Help us grow the Bangalore Citizen Weather Network

by Saurabh Chandra

An update is due since our last announcement in July. We have been making announcements on twitter and Facebook but here is a brief summary of the progress made till date.

Our technology partner Yuktix has deployed 7 automated weather stations across Bangalore. In the last 6 months or so, the automated weather station (AWS) has been running robustly since the last 4 months or so (except for a DNS issue with Airtel last week). There is a version with solar backup and a version that is directly plugged-in to power too. We have versions with institutional mountings and also with light-weight balcony mounts. Each AWS has:

  1. Temperature, Pressure and Humidity sensors mounted inside a Stevenson Screen
  2. A rain bucket with a tipping bucket sensor
  3. A control unit that beams the data reliably over the mobile network (each station comes with a pre-paid data plan for 3 years

The AWS transmits data continuously every few minutes to the cloud and the data is available in graphs or is downloadable for analysis by anyone. An Android app will be available soon to view the data.

We are excited to announce that our field trial phase is successfully closed and we are now open to taking pre-orders for stations that you can play host to. Our target is to pepper Bangalore with 25+ stations and create an open data network of the same. For this community project we have a special price from Yuktix for personal stations at 35k (without solar) + installation charges if any. The stations will take 4-5 weeks for delivery from the time of pre-order.

Fill this form for your pre-order and join the network.

Saurabh Chandra is a tech entrepreneur in Bangalore and a weather enthusiast at Know Your Climate.

In Citizen Matters: Weather Web around Bangalore

Know Your Climate and the Bangalore Citizen Weather Network is featured in Citizen Matters today.

Two young weather enthusiasts from the city have initiated the Citizen Weather Network that aims to capture real-time weather data from 30 locations in Bengaluru and make it freely available for public view over a web API. With five stations already installed in different parts of the city, they have started tracking Bengaluru’s microclimate. These indigenously developed Automated Weather Stations (AWS) house sensors for recording temperature, pressure, humidity and rainfall. Each weather station costs under Rs 50K.

The initiative, the brainchild of Pavan Srinath, Head of Policy Research at Takshashila Institution in Ulsoor, started in the form of a blog – Know Your Climate. As Srinath puts it, the blog was an attempt to make a serious study on the climate change by analysing the existing data available in the public domain, and placing it before the public in a simpler way. In 2014, Saurabh Chandra, CEO of Razorfish Neev, joined hands with Srinath to bring the idea to fruition.

Srinath says, “We approached Rajeev Jha of Yuktix Technologies to work towards building an indigenous weather station. Jha accepted the challenge and within eight months the first two Automated Weather Stations were ready.” The pilot stations were installed on the rooftop of Srinath’s house in Jayanagar and Saurabh’s house in Hebbal. Each station was developed at a cost of under Rs 50,000, much lower compared to the conventional stations that are built at a cost of Rs 2 lakh.

The modular weather stations are installed with sensors for measuring four factors – temperature, pressure, humidity and rainfall. While temperature, pressure and humidity sensors are housed within a radiation shield, the rain gauge is maintained separately. All these are connected to a main circuit board that logs all the data. The data is updated once in every three minutes which helps gauge the intensity of rain and weather pattern over time.

Jha vouches for the reliability of the data generated using the considerably cheap, but accurate sensors. “The instruments that we use in the station have been chosen after studying the specifications for an Automatic Weather Station published by the Indian Meteorological Department (IMD),” he says.

These sensors collect the sample of the environment every 15 seconds. As many as 12 samples are taken for each transmitted reading. “We provide the data in par with the standards set by the IMD and World Meteorological Organisation. I can assure data accuracy of +/- 0.1 degree,” he affirms.

Read the full article at Citizen Matters

Citizen Weather Network Featured in Bangalore Mirror

Know Your Climate and the Citizen Weather Network are featured in Bangalore Mirror today by Jayanthi Madhukar.

Every Bangalorean has said it at least once in their lifetime — it is getting hotter nowadays. But if one happens to say this to Pavan Srinath, he’ll probably ask, “Where is the data supporting the statement?”

But who needs weather data? Isn’t it better to crib and whine about the weather? Srinath laughs. “It is highly interesting to know about one’s microclimate,” he attempts to explain. “If I get a weather update saying it will start raining here at Ulsoor at 5.30pm, I will plan to leave the office earlier to avoid a traffic jam.” One wishes.

[Full Article – Bangalore Mirror, September 14, 2014]

WeatherWatchers1x WeatherWatchers2x

The Changing Local Climate of Bangalore: Part One

Bangalore is a rapidly changing city, both for the better and for worse. If somebody from the Bangalore of the ’80s or the ’90s were to visit the city today, it would be very difficult for them to recognize the city – and so it is to those who return from elsewhere after decades. The same is said of Bangalore’s weather, of how ‘it isn’t what it used to be‘. Cold winters, warm but never-too-hot summers and an extended season of rains populate the Bangalore weather of our dreams – dreams that appear to be increasingly disconnected from reality.

Many blame global climate change as at least part of the reason for a hotter Bangalore, along with local urbanization and related heat island effects, while others focus only on the latter. What does data from weather stations tell us? This post seeks to find out.

The question of whether Bangalore is heating up can be broken down into four parts. First, is the climate of Bangalore getting hotter in the long run? Second, is the change in temperatures consistent with global climate change? Third, is this warming related to the changes that we might be feeling? And fourth, could there be changes in temperature in the city above and beyond what gets recorded at a weather station?

The long term temperature trends of Bangalore tell an astonishing story.

Changing Local Climate of Bangalore 1901-2000

It turns out that over the last century, between 1901 and 2000, minimum temperatures have been consistently rising in Bangalore at a rapid rate. However, maximum temperatures don’t quite follow the same trend. Instead, it appears that maximum temperatures peaked in the 1920s and 1930s! Since then, they fell sharply by 1940 by about 1.5°C and have been rising steadily ever since.

Why was Bangalore facing such high maximum temperatures in the 1920s and ’30s? The answer is that we simply don’t know. It is important to note while there are prominent global trends at play like anthropogenic climate change, there are often distinct but important local trends in climate that need to be understood and dealt with locally. These trends may be anthropogenic or natural, but their impacts are often quite real. The wind systems around Bangalore could have been different then, or cloud cover was unusually low for a couple of decades, or it could have been entirely something else.

Apart from the mysterious hump in maximum temperatures, it is also pertinent to note that temperatures are rising faster in Bangalore than the global average! Minimum temperatures in the city have increased by about 1.32 degrees Celsius over the last hundred years (± 0.11°C). This is about double the global average. It is equally interesting to note that maximum temperatures are rising even faster since 1940.

Trends in minimum temperatures of individual months also indicate that December, February and March are warming faster than the other months. All months display the same peculiarities in maximum temperatures as seen in the graph above. It is also unfortunate that comparable data is not currently available to examine how temperatures in Bangalore have been in the last decade.

Do these changes confirm our perceptions of the changing climate of Bangalore? The answer to that is both yes and no. Climate data strongly supports the notion that winter nights are getting significantly warmer in the city – with summer nights joining in. Day time temperatures are not increasing (despite what people think!), at least at the century timescale. The difficulty when it comes to understanding perceptions of weather and climate is that people are experiencing weather in the present, and employing memory to remember weather from the past. Both of these are quite flawed, and that is not a slur on anyone’s judgement. Also, it is quite difficult to perceive a 1° change over a century (or even 2 decades!) when temperatures change by about 10°C every day, and an even larger number over the year.

Finally, the faster rise in minimum temperatures in Bangalore could indeed be because of urbanisation, land use change, and heat island effects. But one cannot conclude for certain by looking at this data alone. Also, the built up area near somebody’s home could have increased, with a corresponding loss of trees. Data from a weather station in the central business district of Bangalore can never be able to tell us the effect of that.

How has urbanisation affected ambient climate in Bangalore? Are there other factors that determine whether you feel that a summer is particularly hot? More on these questions in the second part of this article.

Written by Pavan Srinath

The data used in this article is available here from IMD. You can also download the CSV file here. This article is the first in a series being written in the run-up to the Open Data Camp Bangalore 2013 that is happening over the weekend of March 2-3.

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