Category: Blog posts

How good are our weather/climate models?

On July 14, 2024

Pretty good apparently.

I recently carried out some model experiments using WRF to evaluate how our weather forecasts perform in terms of simulating the diurnal cycle of air temperature and humidity, which are the two key parameters determining heat stress experienced by humans – thanks to our collaborators at National Weather Service (NWS), San Diego.

The NWS provides daily weather forecasts using The Global Forecast System (GFS) for upto 16 days into the future at 0.25km spatial resolution, which can be freely downloaded from the following website:

https://nomads.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/

While the GFS forecast is one key forecast product among several other weather forecasts adopted by the NWS, it is also typically used to drive regional climate models such as WRF at fine resolution using them as initial and boundary conditions. The GFS provides forecast over the entire globe but at a compromised coarse spatial resolution of 25km because of computational constraints. Thankfully, these data allows us to run regional model simulations at fine grid resolution, typically at 1-3km, suitable for making weather forecast and other climate studies on a local scale, which is more relevant to the public. Such fine resolution simulations better resolve the topographic and vegetation details and thus can provide better forecast on a city scale.

So here is what I did. I basically downscaled the GFS forecast (GFS-25km) using my WRF set-up over the Imperial Valley at 1km resolution and compared the downscaled results with the observations for a recent time period.

Fig. 1. (a) WRF model domain configuration showing the region of interest (d03) over the Imperial Valley and (b) the agricultural regions of the Imperial/Coachella valleys.

I also conducted another set of simulations by using ERA5 reanalysis (ERA5-WRF) instead of using GFS forecast (GFS-WRF). ERA5 reanalysis, which is also a global product at 31km resolution, is not a forecast but a hindcast with a 5-day latency. These reanalysis data are nothing but similar model results calibrated using actual observations so they are supposed to be more accurate.

I compared the above two sets of downscaled results from WRF and the original 25km GFS results with the actual observations recorded at four of our recently installed stations in the Imperial/Coachella valleys. Basicallly, the idea was to see if there is any value of running a high-resolution model at 1-km resolution, instead of just using the original forecast at 25km spatial resolution.

Above I show two figures comparing the above four sets of results in terms of 2m air temperature and 2m relative humidity. Here are my key takes from these results:

– The diurnal cycle of air temperature is simulated quite well by the 25km GFS forecast in the Imperial Valley region and WRF downscaling doesn’t seem to add much value.

– The performance of GFS-WRF is comparable to the ERA5 although the latter assimilates observations. The European Centre for Medium-Range Weather Forecasts (ECMWF) also provides similar forecast product at 25-km resolution but they require paid subscription. So, GFS forecast is a clear win here.

– There is some added value of WRF downscaling in the Coachella date palm region, where vegetation is taller. The GFS forecast underestimated the temperature but WRF did a much better job. This makes sense because tall vegetation clearly plays a strong role in this region in modulating the local weather, whose effect becomes more apparent at higher resolution.

– In terms of humidity, it seems to be a major challenge in forecasting. WRF downscaling appears to improve it somewhat but there is a lot to work upon in terms of getting the humidity right.

– Interestingly, the GFS forecast performance does not seem to downgrade with the forecast lead time as one would generally expect. The longer the forecast time into the future, less the reliability of the forecast because the model results depends upon the accuracy of initial/boundary conditions which become more uncertain as we go into the future. As a matter of fact, forecasting diurnal cycle is easier for models because they have repetitive patterns. The main challenge for our weather and climate models is to simulate the non-repeating weather and climate events such as extreme events.

As extreme events (e.g., extreme heat, extreme precipitation, extreme air pollution) are becoming more frequent, prediction of which is much more important to the society, comparisons in terms of extreme climate would be more meaningful. However, such evaluation requires multi-year simulations, and thus requires much more resources, time and effort, which is beyond the scope of this simple investigation.

Thank you for your time.

Summer is approaching its peak, are you prepared?

By Sagar Parajuli

On June 25, 2024

In Blog posts

I almost dozed off on a red light yesterday. What could be the reason?

*Myself during the installation of heat stress sensors (black globe thermometer, temperature/humidity sensors, and pyranometer) in Imperial Valley, CA in May, 2024.*

I don’t turn on my A/C to save cost, energy, or environment whatever one might think of, unless it is unbearably hot. I only turn on the fan. Yesterday was not an extreme day anyway. Just a normal weather day in the upper 70s. And my car is always parked indoor whether at home or office. And I had enough rest for sure. So what else could be the reason?

May be CO? We know that exposure to carbon monoxide can make us sick and even unconscious depending upon the concentration. Where else can be its greatest risk, other than in a car?

May be Oxygen? We know that low oxygen level can also make us sick. Again, where else can it be lower than in an enclosed box? Oh sorry, I forgot about the high mountains.

May be heat? We all know this is also a possibility. We see more people dozing off in summer everywhere, even in meetings and conferences. :).

May be many of you have also experienced something similar. If it happens during a 15-minute drive, imagine what those long haul drivers have to go through, who have no choice but to drive for more than 12 hours everyday. I am 100% sure, coffee can’t solve this problem, however big your cup may be. This is especially critical in summer.

It could be any or all of the above factors. But summer heat is probably the most likely factor here.

With the above context, the question I would like to ask today is why the heat-related deaths are much higher in the developed countries than in developing regions such as Africa or India? As far as I know, the most intense heatwave in the recent history in India occured in 2015 and only about 2500 people died when the maximum temperature rose close to 50 degree celsius. In contrast, more than 60,000 people died during the heatwaves of 2022 in Europe when the maximum temperature rose to something similar.

Humidity has a role to play on heat stress, and the data from India may not be accurate for various reasons, but these factors can’t explain such an order of magnitude discrepancy.

What could be the main reason?

The answer has to lie in our modern way of life. We are spending most of our times indoor which is interfering with our body’s ability to acclimatize. We, the city dwellers, have become a new species that can only survive within a very narrow range of temperature T±ΔT.

The term acclimatization probably needs to be redefined. Traditionally, it referred to how people adapt to different climate regions based on geography. But now, because of our HVAC way of life, the exposure to high temperature is more based on indoor vs. outdoor temperatures than the temperature in region1 vs. region2.

The way we define heatwaves also needs to be reassessed. Normally, it is defined based on how far is the daily maximum temperature from the historical average value in a given location. But, with our indoor way of life, the average base temperature needs to represent our ‘indoor’ temperature where we spend or live most of our time. Obviously, it is going to be different for different people. It might even be associated with social structure and poverty level—just my naive guess.

It is not only about heat, it is also about oxygen level. Although oxygen is the most vital element of life, it’s study has received the least attention for some unknown reasons. One such eccentric study (I wonder how they received the funding) in a Journal of American Chemical Society, the oxygen level is declining in large cities globally, and that the increase in heatwave occurrence was correlated with reduced oxygen level.

Increasing number of studies are showing that air pollution, oxygen level, extreme weather events, occurrence of heatwaves, energy demand all of these are correlated. Our environmental problems have become much more complex nowadays. We need to rise above our traditional area of expertise and think differently if we want to solve these problems. We have to put all these pieces of the puzzle together to know whether the puzzle is a tiger or an elephant.

Together we can.

A fertile trip through the Central Valley to Sacramento

By Sagar Parajuli

On February 15, 2024

In Blog posts

I have lived in the southern edge of California, but the Central Valley keeps coming on my head. It has remained as a place of wonder in my heart too.

Anything that is at the center has power, it pulls you towards it. Central Valley is California’s center. It is California’s womb. Womb is where creation takes place. It is where growth takes place. No wonder, Central Valley produces more than 2/3 of the fruits and nuts consumed in the entire US.

When you truly wish for something, the entire universe conspires to make it happen.

I got invited to Sacramento for an event at the California State Capitol. I took this opportunity to steer through the fertile lands of the Central Valley. But something got my plan changed. I blamed the weather. And I decided to fly to Sacramento, instead of driving. I now planned to drive back, through the Central Valley.

The stormy weather this season lasted almost a week in the first week of February 2024 due to multiple atmospheric rivers. The flight took off on time despite the bad weather. Clouds were beautiful on their own but that is not what I had wished to see. Sierra Nevada mountains were fully covered with snow too. That was still not what I had wished to see. I had wished to see the green agricultural fields of the Central Valley from above. I couldn’t see much. Only a part of the green fields was visible near Sacramento, as the plane descended for landing. Those too, were flooded due to the heavy rain.

I atteded a CCST event at the California State Capitol in the afternoon the same day. It was a pleasure presenting my current research in the Imperial Valley to the Assemblymembers Mike Fong and Christopher Ward. There were othere legislative staff, people from California Energy Commission, California Air Resources Board, and also a astrophysics group from University of California (UC), Santa Cruz attending the event. It was specially enlightening to chat with professor Sandra Faber, an astrophysicst at UC, Santa Cruz, who had interesting views on a range of topics from energy and environment to policies. It was quite an experience presenting my research, repeatedly, in an elevator-pitch style, to multiple people from different backgrounds, packed in a small meeting room at the Capitol.

My return trip started from Oroville. Central valley can’t be understood without looking at its water infrastructures. That is why I decided to start my journey from the Oroville dam, the tallest dam in the US, on the Feather River, north of Sacramento. The dam was built between 1957-1968. To highlight the significance of this project to the entire California, a sackful of gravel and sand was used in the first concrete used in this dam.

My first stop was at the Antioch Bridge that lies in the south of the Sacramento County. This is the place where the northward flowing San Joaquin river meets the southward flowing Sacramento river. Such places are considered auspicious — they are, indeed. A short video clip of the area that I took is here. As I stood on the fishing pier, a useful guide to fish eating captured my attention (included below).

View of the Antioch bridge from a distance.

Google map view of the Antioch Bridge. The Sacramento and the San Joaquin rivers can be seen on the left and the right of the bridge.

After seeing the Antioch Bridge area, I headed south through the Byron highway. I stopped near the UC Davis Fish conservation center to see the beginning part of the California Aqueduct in the Sacramento-San Joaquin river delta, which was built to supply water from the northern California to the southern California. This was an engineering masterpiece because it involves pumping of water against gravity by huge pumps and dumping the water to the distribution aqueducts and canals. At the moment, these canals and aqueducts never run to their full capacity because the federal and state regulations now restrict pumping of water from the delta region to protect the endangered delta-smelt and other local fish species.

The green meadows on the little hills seen in the west of the Byron highway were spectacular. The view definitely reminded me of the natural beauty of Switzerland. The US as a country is huge and it indeed has so many beautiful landscapes waiting for us to explore.

I intentionally took California highway 99 avoiding the more usual I-5 route, although it would take much longer time to reach San Diego. As I drove through the Central Valley cities of Modesto, Merced, Fresno, and Tulare, I saw several railway lines that ran through the cropfields. Most of them were part of the Union Pacific railroad, which is the second largest railroad in the US. This centuries-old railroad network which was first built in 1806 made it possible to transport the excess produce of the Central Valley to the rest of the US. There are probably other smaller trolleys as well operated by the individual farm owners in the central valley.

Union Pacific trolley as seen from the Byron highway.

There were crop fields on both sides of the highway. I drove for hours through these fields while stopping occasionally to take some pictures. The almond trees were just beginning to flower. I couldn’t really tell whether they were amond trees or peach (apricot?) trees because I know that both of them look similar. We had a lot of peach trees in our village so I can recognize them. But it is hard to tell what it is in this flowering season.

A close-up view of an almond tree south of Fresno.

At the end of the crop fields near Bakersfield, the green medows looked spactacular on the west side of highway 99. I also saw a huge water pumping station (visible in the picture below). It was State Water Project’s Wind Gap pumping plant, the last major water lift from the California Aqueduct over the Tehachapi Mountains, which was renamed the Ira J. Chrisman Wind Gap Pumping Plant in his honor.

Vineyards near Bakersfield with the Green meadows in the background. Also seen on the right is the Ira J. Chrisman Wind Gap Pumping Plant.

https://images.nationalgeographic.org/image/upload/v1638892259/EducationHub/photos/replumbing-california.jpg

When I looked on the left, the Sierra Nevada mountain was smiling with considerable amount of snow.

The history of California is so intriguing. The Central Valley was transformed from desert to a rich land producing fruits, nuts, and vegetables some 100 years ago. Engineers built one of the most complex network of Aqueducts to irrigate the Central Valley farmlands. Dams were built, canals were laid, wells were digged. The California Aqueduct that begins at the Sacramento–San Joaquin River Delta was built in 1963. That is well before our era of computer and internet. We are living in the 21st century, but infrastructure-wise, we are only enjoying what our ancestors built. We haven’t built anything such significant in our times. Of course we have done a lot in the IT and computing sector.

The older generation got busy working. They got busy building and growing. They developed and used technologies that defied even the worst droughts. They adapted. They adapted from one crop to another. From rivers to wells. From west to east.

Central Valley farmers used technology as it became available to foster their yields. They knew all the details, when to plant, how to plant, and even how to better pollinate. To them, it didn’t matter, whether water was available or not. It didn’t matter whether soil was good or not. They grew pistachios when the water was saline. When winds didn’t blow, they knew how to pollinate. They knew how to make the fruits puffy too.

I am ever fascinated by its story of transformation. California is a miracle. Not a single person made it. But it has only known growth from the very beginning. It has never remained. And will never stand still.

Many things in California happened more than 200 years ago. California developed, flourished, and a part of it even got perished much before we were even born. California has always been in a rush, from gold rush, to water rush, to now lithium rush.

California still looks beautiful as it moves, and transforms. It is wonderful to live here and be a witness of California’s growth. California is indeed unbeatable.

California is not just about Silicon Valley

By Sagar Parajuli

On January 20, 2024

In Blog posts

California is not just about Silicon Valley; it is the Central Valley and the Imperial Valley (IV) that truly define California’s richness, as they produce more than half of the fruits, vegetables, and nuts consumed in the United States. The Imperial Valley, which lies on the south side of the Salton Sea, alone provides more than 80% of the nation’s fresh winter fruits and vegetables. But have you ever wondered how those succulent oranges, almonds, and lettuces come to your table every day?

WRF modeling domain over the Imperial and Coachella Valleys.

Unfortunately, the farmworkers in the Imperial and Coachella Valleys experience a high number of cardiovascular diseases due to heat stress. Not only this, the IV region is recently going through tremendous environmental stress due to water and air pollution; extreme droughts and flooding; and land use change.

I have built a high-resolution, high-performance weather model set up centered around the Imperial and Coachella Valleys that can be used to address such environmental concerns. As an example, the model can simulate how the microclimate will change when croplands are converted to solar fields. Similarly, the model can be used to forecast of heat stress experienced by farm workers at a specific time and location using Wet Bulb Globe Temperature (WBGT).

What question intrigues you the most about this region?

A short trip to Salton Sea and Imperial Valley

By Sagar Parajuli

On January 3, 2024

In Blog posts

I wanted to end my holidays by paying a visit to my research site, the Salton Sea and the Imperial Valley. The GPS took me through highway 79, which was one of the windiest road I have ever driven in the US.

A quick video of Lake Cuyamaca

One of the main attraction en route was the Lake Cuyamaca Recreation park. People were fishing and having fun at the park. It was chilling cold though for me having come from Santee. It is indeed one of the best camping site, which I will consider for the future. Borrego springs and Anza-Borrego Desert State Park are two other attractions en route which are a few miles west and east of the highway.

After the winding road ended, there comes the flat land of Ocotillo Wells State Vehicular Recreation Area, which is a popular camping site. Before I reached the site, I saw dozens of RVs coming from the opposite direction and I was wondering from where they were coming. Then I passed through the Ocotollio Wells camping area and realized those were the people who camped in the area and were returning home after celebrating the new year outdoor. It was January 2 so it made perfect sense.

One of the bizarre site I came across while heading to Westmoreland was the Republic of Slowjamastan. I became so curious after I saw a big signboard with such a name because of the key words ‘republic’ and ‘slojamastan’, which sounds a bit russian. The board clearly seemed eccentric to the California land. I googled about it later and knew that it was a micronation declared by an individual, which has become a humorous and symbolic attraction at least if not more.

Then I headed to the Salton Sea near the Salton City. I was determined to touch the water of Salton Sea today so I explored several off roads going to the Salton Sea and I finally found a dirt road which went straight to the sea through the marshlands. I stopped my car some 100 feet away from the sea shore and headed to the Sea. A few birds were the only living creatures other than myself around. The water was somewhat clean, not what I had expected at the least. It probably gets dirter in summer and the foul smell would also be more severe by then. In this winter time, the Salton Sea looked quite nice and clean. It was not a beach so I had hard time walking on the spongy land but I was able to touch its water, which was warm, a peculiar characterstics of the Salton Sea.

A close-up view of the Salton Sea Shore

Upon my return, I visited a few farms such as Bee Sweet Citrus and Three Flags Ranch. They were mostly growing Lemon, Pomelo, and Date Palms. I was so curious to see these farmlands that I didn’t care the signs ‘no trespassing’ at all and kept driving through these orchards.

A view of Lemon orchard east of highway 86 near naval base.

Then I came across the famous Alfalfa fields, as I passed through the Forrester Road S30 towards the south. Alfalfa is the protein-rich plant used to produce hay for the cattles. The hay gets exported to the dairy farms across California and as far as Japan and Saudi Arabia. I was seeing these fields for the first time. Most of the Alfalfa was already harvested and stacked ready to be transported. But some nearby fields were already growing another round of Alfalfa. When I entered the fresh young Alfalfa fields, it was very muddy because Alfalfa is often flood irrigated. As a matter of fact, Alfalfa is one of the most water-intensive plant. The farmers were using the water from the nearby canals.

Harvested Alfalfa ready to be transported.

Other than Alfalfa, I mostly saw spinach and turnips growing there.

I enjoyed chicken tacos (always corn option for me) in a local Chevron store in Westmoreland.

Upon my return, I passed through a solar field, the Tenaska Imperial Solar Energy Center South, a 130 MW solar field, developed by the Tenaska Energy company in 2013. It begins right after the Alfalfa crop fields after the Foxglove canal and extends on both sides of the I-8 commonly called as the Kumayaya highway.

There are several other solar fields in the region. Another big solar farm is the Mount Signal Solar farm (794 MW) which is located right next to the US-Mexico border, west of Calexico, which was developed by 8minute Solar Energy, an American photovoltaic (PV) developer. It was built in 3 phases between 2014-2018. This solar farm is clearly visible in the high-resolution Leaf Area Index (LAI) data (Figure below, marked with red circle) that I am using in my WRF model to simulate the effect of land use changes on the microclimate of the Imperial Valley region.

I took a different route for my return along I-8, which was a beautiful scenic drive through rocky hills. I also went to Lake Morena which was some 5 miles off the highway. This site is linked to the famous rainmaker of the 20th century Charles Hatfield, who was known to make rain by mixing and burning various chemicals into the air. His recipe was top-secret, only known by him and he took it to the grave. Charles and his brother set up their rainmaking tower beside the Morena Reservoir and supposedly got to work in 1916.

I wanted to drive all around the Salton Sea and the Imperial Valley to see all the interesting land use changes happening there but time was not enough in this trip. That will be the plan for my next trip to the region.

Useful links

By Sagar Parajuli

On November 20, 2023

In Blog posts

Learn about Multilevel Models

How weather models work?

A good discussion forum focused on the issues of climate

Know some limitations of weather prediction models

what a Nobel Prize winner has to say on climate change

A cool animation of global wind patterns

Visualize present and future weather data at Ventusky

Live animation of true color GOES image over California

Some cool videos in science

Some climate change lessons and videos from Pacific Institute for Climate Solutions

Know about climate model resolution from this GFDL page

Visualize vectors and mathematical function

Learn about Navier-Stokes Equations

Some interesting papers in Climate:

Global climate model violate scaling of the observed atmospheric variability

Research resources:

How to write a great research article? Tips from this Nature page

Data analysis and visualization:

Data visualization with NASA/Giovanni tool for several available model and reanalysis datasets

Latest data visualization tool, similar to Giovanni but more powerful: Climate Engine

Cloud seeding and weather modification

By Sagar Parajuli

On January 25, 2023

In Blog posts

Imagine a world without rainfall. We call it droughts. Or imagine a situation of torrential rainfall and flooding, like in Pakistan last year.

And imagine a world where all our groundwater reserves have dried up. This is not too hypothetical a scenario — the world’s groundwater reserves are already declining. Groundwater is no different from fossil fuels – it is going to deplete one day if we continue to extract without allowing it to recharge.

A drought does not kill in hundreds – when it happens, it kills millions. China, India, Bangladesh, Africa, and even Russia and USA have faced such droughts in their history. And flooding has similar consequences – it causes extensive loss of lives and properties.

So what can we do to prepare ourselves for such adverse scenarios or natural calamities? How can we make sure that we have enough freshwater resources to meet the demand of an ever-increasing population which is already 7 billion?

Cloud seeding is one potential solution. Cloud seeding can be used both to suppress or enhance rainfall. If used appropriately, the application of cloud seeding technology has many possibilities — from enhancing rainfall, snow packs, and groundwater reserves — to suppressing hails, the great enemy of farmers, which can destroy large crop fields in minutes. Cloud seeding is relatively a mature technology used since the 1950s when scientists first discovered the seeding ability of dry ice and silver iodide. It was extensively applied in the late 20th century but it slowly lost momentum afterward for various reasons. Its exploration is again gaining attention as we face prolonged droughts, heatwaves, flooding, and fires worldwide.

This week, scientists and policymakers from around the world working in the field of cloud seeding and rain enhancement are meeting in Abu Dhabi to discuss these and other related issues aiming to find water solutions for the future.

On the first day of #IREF organized by The UAE Research Program for Rain Enhancement Science (UAEREP), we saw several interesting new approaches in cloud seeding works, from the use of electrical charge to acoustic methods for rain enhancement. Today was another engaging day discussing the process-level understanding of aerosol-cloud interactions and the adoption of cloud seeding technology by countries such as Ethiopia and Thailand for tackling their water problems. For anyone interested in understanding rain enhancement technologies, below is the link to today’s program.

PhD: concluding remarks

By Sagar Parajuli

On May 18, 2022

In Blog posts

When I was a kid, I never dreamed of earning a PhD. All I wanted was to study more and more. So I just followed the course of the river. I didn’t know or care whether the destination is ocean or something else.

When I became an adult, I knew that the society where I was brought up highly revered a PhD. So I had thought that I will also some day do a PhD.

We can plan something but not everything. That is what I have experienced. PhD thought came into my mind when my supervisor at Masdar Institute came to my desk one day. He showed a small ad in an AGU newsletter about a PhD position at UT Austin. I didn’t want to let down my supervisor so I applied. In fact, that was the only place where I applied. Until then, I had only thought of returning back to Nepal and rejoining my low-paid but highly revered ‘engineer’ position. I was not sure about it even after I got the offer. I really didn’t know that UT-Austin was a good ranking Tier 1 university until I posted about this offer in my Facebook page. The comments reflected that UT Austin is a great place. My perceptions got changed. I decided to pursue.

I was about to give up soon after I started my research at UT Austin. I was hit really hard in one of the group meeting. Not only by my supervisor but also by my colleagues. I felt the lowest of my life on that day. But soon I realized that it was because the standard and quality of research was much higher than I expected.

I was very busy taking 3 courses at that time and it was very hard to manage time for research. A few colleagues had already failed in their qualifying exams. So I many times felt that it was a wrong decision to pursue a PhD. My health was also not favoring me; I had been diagnosed with celiac disease (allergic to gluten). I very much regretted for leaving my government job of an Engineer back in Nepal.

So there were only two options. Do or die. It is the same thing but a different tone is used in research: publish or perish. But as I interacted more and more with my colleagues and knew about research, I realized that we all were on the same boat. So I decided to continue. I worked harder. Time was not a problem for me because I was married single at that time. Weekends and holidays then meant more research. No wonder, my eye power kept on increasing at a rate of 0.25 per year.

Things started getting better. Qualifying exam was a great success.

I was still not comfortable in the world of research. I tried to avoid people who criticized my work. But later I realized that I can’t escape anywhere in research. You can’t escape your peers. You can’t escape your experts in your field. Most importantly you can’t escape the reviewers of you papers. It took little longer for me to realize that such interactions, feedback, comments, etc. are actually good things.

I never thought that I would be able to graduate in three and half years. But it happened. I worked hard and it got reflected. One of the reason for this success is also that I didn’t waste any of my work at UT Austin, not even the class projects. I always kept the main research topic in my mind before I started any class projects. So all of those activities later became part of my dissertation.

My daughter was born in the last year of my PhD. And the degree of ‘father’ means no less than PhD to me. Indeed, graduate study is when many people get engaged, married, or have their first kids.

With my adviser(to my right), co-adviser(to my left), and examination committee members after the defense on April 15, 2016.

The most important thing that I realized during my PhD study is that learning is a never-ending process. Initially, I really thought that research is or has to be flawless. But I was totally wrong on that. There can be many flaws in your research. That is exactly why we discuss the limitation in the end of a research paper. PhD makes us understand this reality in depth.

I also realized that we can’t be successful in PhD just by gaining knowledge. We have to develop some conscience too. Knowledge without conscience is indeed dangerous.

When I was a child, I believed that if something is written in a text book, it must be true. I believed everything I read in a book. But now, I trust nothing other than my conscience. I now not only buy the conclusions of a research but the wholeness of it, with its limitations and assumptions. After all, a theory is only true until the assumptions are true.

In our research, we try to model the earth system. Modeling the earth system is indeed overwhelmingly complex. Even a grain of sand is very much complex to model, let alone the whole Earth. We must simplify many physical processes. We have to make many assumptions. So sometimes it can be frustrating too. But the beauty of research is that we understand little more everyday than yesterday. The beauty of research is in seeking, not in gaining something.

With my wife Sirjana and daughter Nova on graduation day, May 21, 2016.

As I look at my Tam hanging on the wall, my heart leaps up with pride realizing that I received the highest degree possible in an academic world. But as I look out of the window and see the wonders of the nature, my heart bows down realizing that there is so much more to explore. I am still not sure how much knowledge I gained during my PhD but I know with certainty that I know very little.

Finally, what does this degree really mean? This degree reflects the knowledge of many people, knowledge that is passed down through generations. I am merely a carrier of this knowledge. It also reflects the aspirations of many people; my family, my teachers, my friends, and many anonymous others. It is an outcome of their good wishes.

Post originally posted on May 23, 2016.

Satellite data: an overly underused resource

By Sagar Parajuli

On May 18, 2022

In Blog posts

Satellite data have greatly contributed in improving our understanding of Earth’s climate. We have several climate models but, without satellite data, we don’t know how they are performing. Without the satellite data, we don’t know how far is our imagination from reality. Satellite data provide us the realistic boundary conditions. Without the boundaries, our theory may easily turn into a fiction.

Several satellites fly above us everyday. They are watching us. They are recording our behavior. They are indeed CCTV in large scale. They are recording human activities. We have done many things unconsciously in the past. We have emitted environmental pollutants. We have polluted ocean and water bodies. We have cut down trees. But now it is all documented. If you emit pollution or exploit natural resource, you may have to appear in the court one day.

A lot of data has been generated by various satellites. There is a lot of data. Tremendous amount of data. But, unfortunately, only a fraction of this data has been really used, for some useful purpose.

Take an example of surface reflectance data which are available from MODIS and other satellites. Reflectance basically measures how the surface properties change over time. In fact, Earth’s surface records a lot of things, much more things than what you think right now. When it rains, it gets recorded. When the surface gets dried, it is recorded. When it is very cold, it is recorded. When it is very hot, it is recorded. When a hurricane happens, it is of course recorded. When there is flooding, it is indeed recorded. When an asteroid falls, why would it not record it? Deforestation is surely recorded. Even information about day, night, and Earth’s rotation all are recorded. What is not recorded? Everything. Just everything. In a single reflectance data, you will find everything you need. You just need to change your perspective. You will see a lot of information hiding in the data set.

It is only because of our poor creativity that we are sending satellites one after another. Otherwise, we can extract myriad of useful information that we need just from a single data set. We just need some skill to decode that information. We just need a creatively advanced algorithm to extract the required signal from the data. We will benefit more from our satellite data if we spend more time developing algorithms that can extract the various useful signals in a data set.

The possibilities of using satellite data are endless. We just need to be creative. Do not search in Google Scholar for what others have already done with the data. If you do so, you will only reproduce what others have already done. Ask yourself. How can you use the data to manifest your inner passion? Think differently. Creativity will emerge, from within you.

Who said that vegetation data can’t be used to study the fires? We just need to understand the connection. Creativity is within us. To be creative, we have to believe in our own capacity first. The only difference between we and Einstein is that Einstein believed in himself but we didn’t. The exact same intelligence resides within each of us. It is only a question of how much we allow it to come out. To the one who believes in himself/herself, possibilities are endless.

Why air quality matters?

By Sagar Parajuli

On July 14, 2021

In Blog posts

The air we breathe today is no longer the same when we were child. The rapidly increasing industrialization and urbanization has made it increasingly difficult to find fresh air in the cities we live. Even the remote villages are affected because the pollutants are transported downwind within a matter of hours when the meteorology is favorable.

Air pollution is one of the main thing to worry about at the moment globally. Air pollution is what is really killing people. Millions of people are dying every year from respiratory diseases related to air pollution. A research paper published in 2020 in Cardiovascular Research journal estimates about 8.8 million people die prematurely every year around the globe due to outdoor and indoor air pollution. Even in the current context of COVID-19 pandemic, It is a well known fact that more people are dying by COVID-19 because of preexisting conditions related to lung health.

Air quality is a common agenda of all lives including us the human beings. Who would not agree on a policy to reduce air pollution? Who would disagree if we say that we need to curb pollutant emissions to improve the quality of air that we and our children will breathe? We all are affected by air pollution without exceptions. It is our common problem that we must solve together. And fortunately, if we take care of air pollution, we will also solve most of the problems related to global warming and climate change.

So why not focus our attention in solving the problems of air quality? It is indeed the most sensible thing to do. Isn’t it so?

Thank you!