Insider tips to improve your accuracy

Our scientists have decades of combined experience installing sensors in the field, and we’ve learned a lot about what to do and what not to do. Join Dr. Doug Cobos and Chris chambers in live Q&A session where they discuss weather station installation considerations and best practices you don’t want to miss.

Presenters

Dr. Cobos is a Research Scientist and the Director of Research and Development at METER.  He also holds an adjunct appointment in the Department of Crop and Soil Sciences at Washington State University where he co-teaches Environmental Biophysics.  Doug’s Masters Degree from Texas A&M and Ph.D. from the University of Minnesota focused on field-scale fluxes of CO₂ and mercury, respectively.  Doug was hired at METER to be the Lead Engineer in charge of designing the Thermal and Electrical Conductivity Probe (TECP) that flew to Mars aboard NASA’s 2008 Phoenix Scout Lander.  His current research is centered on instrumentation development for soil and plant sciences.

Chris Chambers operates as the Environment Support Manager and the Soil moisture sensor Product Manager at METER Group, the world leader in soil moisture measurement. He specializes in ecology and plant physiology and has over 10 years of experience helping researchers measure the soil-plant-atmosphere continuum.

Questions?

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Next steps

• Related webinar: Which weather station is right for you?
• Related article: Which weather monitoring system is right for you? 
• ATMOS 41 FAQs
• Request a ZENTRA Cloud live demo

Transcript

BRAD NEWBOLD 0:01
Hello everyone and welcome to Office Hours Live with the METER Environment Team. Today’s session will focus on weather data. And we’re shooting for about an hour of live Q&A with our experts here Dr. Doug Cobos and Chris Chambers, whom I’ll introduce in just a moment. But before we start, we’ve got a couple of housekeeping items. First, we want this session to be interactive, of course, so we encourage you to submit any and all questions in the Questions pane. And we will try to get to all of your questions if we don’t, which we more than likely won’t, someone from our science or support team will get back to with an answer via the email you registered with. Second, if you want us to go back or repeat something you missed, don’t worry. We will be emailing you a recording of this session within the next three to five business days.

BRAD NEWBOLD 0:49
All right, with all of that out of the way, let’s get started. Today our panelists here our research scientist Dr. Doug Cobos, and application specialist Chris Chambers. Doug is the Director of Research and Development at METER Environment. He also holds an adjunct appointment in the department of Crop and Soil Sciences at Washington State University, where he co teaches environmental biophysics. His master’s degree from Texas A&M and PhD from the University of Minnesota focused on field scale fluxes of CO2 and Mercury respectively. He was hired here at METER to be the lead engineer in charge of designing the thermal and electrical conductivity probe that flew to Mars aboard NASA’s 2008 Phoenix Scout lander. His current research is centered on instrumentation development for soil and plant sciences. And Chris Chambers operates as the Support Manager here at METER Group. He specializes in ecology and plant physiology and has over 13 years of experience helping researchers measure the soil plant atmosphere continuum.

BRAD NEWBOLD 1:44
Alright, so thanks for joining us, everybody. All right, let’s get started. We’re going to take some questions here. And just remember that you can submit questions at any time, and we will be able to answer them. First come, first serve. So we do have some questions here. First off, we’ve had a bunch of questions about sensor selection. And so maybe we can use some of these first questions to kind of hit that topic. But a lot of people asking how many sensors to use when they’re taking weather data. What are the other types of measurements that they would need to accompany weather data? Whether or not having an all-in-one station is better compared to a station that has several separate sensors? So Chambers and Doug, maybe we could hit that kind of sensor topic first.

CHRIS CHAMBERS 2:45
Good morning, Doug.

DOUG COBOS 2:46
Good morning, Chambers. Oh, sorry, Chris.

CHRIS CHAMBERS 2:50
Um, so let’s go ahead and get started. It’s a pleasure to be with you all this morning. Or whatever time of day it is, wherever you are. So the first question we’ve got queued up here is what are the advantages of using soil moisture as an ancillary measurement, and how many sensors do I need? So if we’re primarily interested in weather, why would we measure soil moisture?

DOUG COBOS 3:13
Well, it’s I mean, the biggest factor there for me, Chambers, is that the soil moisture is a real driver of weather events, and is a forcing factor that actually is one of the controlling factors of the weather. So if you’re operating a big network and you’re trying to do any kind of prediction, then understanding the surface soil moisture especially, and how available that water is to come out into the atmosphere is going to affect things tremendously. So I think the big weather networks are really keying in on this over time,

CHRIS CHAMBERS 3:49
Right. And if you’re doing hydrological modeling, or that storage component for soil moisture, it’s what’s hanging around in your profile.

DOUG COBOS 3:59
Yep.

CHRIS CHAMBERS 4:00
You really need that measurement for a water balance or or hydrological model.

DOUG COBOS 4:07
Yeah. And then getting back to your, you know, plant science roots. I mean, if you’re doing anything, if your network or your observations have anything to do with plants, then you have to know the availability of water for transpiration and photosynthesis,

CHRIS CHAMBERS 4:22
Right. We always needed this type of data. You can’t tell very much about the plant water status unless you know what’s in the soil, unless you know what the inputs are. And frequently those measurements are, especially when I was actively doing research, you know, your weather station could be miles away.

DOUG COBOS 4:42
Yeah.

CHRIS CHAMBERS 4:45
How about, how many sensors do I need specifically for soil moisture?

DOUG COBOS 4:50
Tag, you’re it. It’s an age old question, right.

CHRIS CHAMBERS 4:52
I guess. Yeah. So especially if you’re just measuring up with where you’re measuring weather, you’re probably going to want some kind of profile. And it really depends on the questions that you’re asking or what you intend to do with the data. So a lot of weather networks already have soil moisture data. If you want to make your data available in a national or a statewide network, then look at what is already in the database. There’s probably recommendations for how many sensors you need and at what depths. SNOTEL sites, state mesonets, they all have guidelines, National Soil Moisture network. And if you’re not going to use or don’t want your data to be available in one of those networks, then what kind of question are you asking? Are you trying to validate the data based off of, validate some satellite data? Or do you want to know what’s in the root zone? Do you want to know what’s escaping the root zone? You may or may not need that many sensors. But think about the questions that you’re asking and what you want to do with the data.

DOUG COBOS 6:10
Yeah, and all those things you touched on, you know, would determine if you want to scatter your sensors spatially, or if you want to go vertical for a profile or some combination of both. So I mean, there’s a lot of different options there. So really, I mean, actually, with any environmental measurement, the take home is, make sure you you understand what you’re trying to measure and what the data products are that you’re trying to get first and then set up your installation with that.

CHRIS CHAMBERS 6:41
Exactly. All right. Shall we move on?

BRAD NEWBOLD 6:46
Yeah, I was just wondering, so all-in-one versus separate?

DOUG COBOS 6:50
We can touch on that a little bit, if you want, Brad. That’s actually a good question. So recently, a lot of all-in-one weather stations have come on the market. And they certainly have their advantages, but they also have their disadvantages.

DOUG COBOS 7:05
Many of the weather standards including World Meteorological Organization call for measurements at different heights, right. So your rain measurement needs to be close to the surface and shielded from the wind, your wind speed measurements need to be higher up. And so you cannot accomplish that with an all-in-one. That is really the biggest drawback of the all-in-one. However, the all-in-one stations are extremely convenient and are what WMO would call fit for purpose, right, that for a lot of weather networks and a lot of microenvironment monitoring, and a lot of field scale measurements or plot scale measurements, they’re a really, really nice option. It just depends on you know, if you need to adhere to a certain standard and in some ways, the quality of the data or the accuracy. So you’re not going to find an all-in-one that has a Class A pyranometer. So if you need you know, stuff like that,

CHRIS CHAMBERS 8:03
or net radiation, or something like that,

DOUG COBOS 8:06
Exactly.

CHRIS CHAMBERS 8:07
But in the defense, in the bonus column of all-in-one weather stations, then they are really simple to put together. Basically, you’re just mounting one unit on the top of the pole, maybe with a data logger, And data management as well, having just all of those measurements come into one port of your data logger really lets you do a lot more with your data logger.

DOUG COBOS 8:36
True. Yep.

BRAD NEWBOLD 8:40
All right. Let’s see. We do have several questions asking about installation. So maybe we could cover this topic next. Just number one, is there a general guide for installation of weather stations? And then there’s some other specific questions that we can get to but first, yeah, kind of overall general guideline for installation.

CHRIS CHAMBERS 9:04
You brought up the World Meteorological Organization or WMO.

DOUG COBOS 9:08
Yep. They have extensive guidelines on siting for measuring the weather, the bulk weather parameters, most accurately. And many other standards organizations, the Association of State Climatologists, NOAA, you know, all of these organizations have really solid recommendations on how to get the best weather data possible. But those recommendations really are tailor-made for meteorological and climatological and weather observations. But if you get into some specialty networks and some specialty uses, like maybe urban networks, then those recommendations aren’t going to serve those needs very well.

CHRIS CHAMBERS 9:53
Right. And, you know, it depends what you’re measuring too. For weather especially, your location is going to be very important. Because you could wind up measuring a microclimate.

DOUG COBOS 10:07
Yep, yep.

CHRIS CHAMBERS 10:08
Which if you want weather, that’s not going to be really what you want to be measuring,

DOUG COBOS 10:13
Yeah, that I mean, that brings up an anecdote that the microclimates are extremely important. We had a situation here where we have a testbed on on our rooftop, which is not a valid meteorological observation, but it is a handy place for us to be able to test all our instrumentation, and about 200 meters away, down the hill a little bit toward the creek, we also have some instrumentation deployed. And on clear nights when we get inversion conditions and cold air drainage, the low temperature can be different by as much as 10 degrees C. So we’re talking about tremendous differences in weather variables do just to siting. So you do need to pay attention to this. It’s a big deal.

BRAD NEWBOLD 11:01
All right. We did have a new question pop in here. And we’ll come back to installation stuff in a second. Do you have any specific sensors for profiling wind as regards to wind shear or microburst in accordance to WMO standards? Do you know of any?

DOUG COBOS 11:18
Yeah, I think that you would just need to do that with individual sensors, that you’d have to create a profile with multiple sensors at the different heights to be able to try and capture those. And I’m not sure what they do at airports in terms of of looking at wind shear and things like that. That’s a little bit outside my knowledge zone.

BRAD NEWBOLD 11:41
All right. Okay. A couple more installation questions. One was just asking about enclosures. So are there good ways to enclose your station that would be acceptable?

CHRIS CHAMBERS 11:56
Like if you’ve got it in the middle of some range land and want to keep cattle from completely tearing it down?

DOUG COBOS 12:02
Yep, you better do it. Because they will.

CHRIS CHAMBERS 12:06
That’s right. And we’ve seen this frequently with, you can put some chain link fences around it, you do want to be careful that you’re not biasing the reading or impacting the reading and — I don’t know off the top of my head what the what the safest distance is. Definitely below your station, right?

DOUG COBOS 12:26
Yeah, so if you’re using a kind of a — not really a standard, but a lot of people make their their measurements at two meters height. WMO calls out 10 meters for wind speed and some other things. But you definitely want to keep your fence, your chain link or whatever kind of fence it is, below that level so you’re not influencing the wind field, but I mean, it would be a pretty tall fence to go two meters anyway. So it’s not really a big deal. I think that most installations will have some type of fencing to keep the animals out because animals are really difficult on instrumentation. Pretty indiscriminate.

CHRIS CHAMBERS 13:06
They can discriminate sometimes.

DOUG COBOS 13:07
Maybe they can — shiny and well, they also would tend to chew on your wires and knock stuff down. So yeah, I would definitely recommend that you put some kind of exclosure around that.

BRAD NEWBOLD 13:18
Alright. Okay. We’ve got a big, we’ve got a big question here that just popped in. Alright, so this one, they’re asking about gap filling. And we’re gonna read through this, we’re gonna see if we can work through this. Their main question here at the end, is there a good procedure on how to gap fill in weather data? Those kinds of things. But here’s their question here, saying that they’ve got two weather stations about 800 meters apart at their experimental site. Part of the applications for the weather data is to be used as input for crop simulation. So we do have a lot of other crop related questions that maybe we can touch on later as well. It’s a rain fed cropping system. We typically use the weather data, so solar radiation, et cetera, we have listed a whole bunch here, and daily timesteps. The data needs to be complete. If a day is missing, the model doesn’t run. So therefore we need to do some gap filling in the weather station data so it can be useful. So far, we mutually fill the missing data in these two stations because we see the variable measurements except for rain are very close to each other. But then we still have the remaining gaps. So for now, the best idea was to fill it in with a nearby weather station about nine kilometers away. So is there a good procedure again on gap filling weather data? We know rainfall very spacially, but then what’s best. Do we use the weather station from nine kilometers away or do you have any other suggestions?

CHRIS CHAMBERS 14:51
Oh, that’s a really tricky one.

DOUG COBOS 14:52
Yeah, it is. When I first heard gap filling, I thought you were talking about spatial gap filling, but this is temporal gap filling, and that is the the most difficult one of course.

CHRIS CHAMBERS 15:03
Which, if you’re using, you know, you don’t have data where you are then it becomes a spatial problem, too because nine kilometers is a long way away to infer your precipitation in many cases.

DOUG COBOS 15:15
Yeah. So for the weather data that they listed, it sounds like they may be calculating reference evapotranspiration from those measurements. And so I think that when both stations are out, and you’re stuck, then using the nearest weather station, you know, is probably the best way to do it. If you had a data scientist on your staff or wanted to do a little bit of data science work, you could probably determine the bias between that station that’s nine kilometers away and your two stations that are in the location that you care about. I don’t know if that’s really you know,

CHRIS CHAMBERS 15:58
You put an asterisk by those data points or some kind of class variable so you can separate them out in the analysis later or see if they pop out as an outlier or something.

DOUG COBOS 16:07
Yeah. But if you’re just calculating ETO, then that station nine kilometers away, if you just have limited data gaps, then the accumulation of error in your evapotranspiration should be relatively small. So if you’re only looking at a few hours here, a few hours there, then it shouldn’t jack your ET measurements up too badly to do that. But the rainfall one is, the statement that rainfall is inherently variable over space is a really good one. And that’s one that’s often overlooked in the literature, in people’s thinking, but rainfall is highly variable spatially, and that’s probably the biggest potential error that you’re going to have.

CHRIS CHAMBERS 16:50
Comes up in support all the time, too, it’s like oh, this rain, you know, this precipitation gauge three miles away got just a deluge and then the station here didn’t get any precipitation. What’s wrong with —

DOUG COBOS 17:05
Yeah, what’s going on? The station out at the airport that NOAA uses, you know, said that I got three centimeters of rain, and I’m still dry out here, what’s going on? Well, you know, it’s highly variable, so there’s not really a great way to fill the gap there unless you had maybe access to some radar models. So I think that the radar estimates of rainfall at a particular location are getting better and better. And so you might be able to feed those in. I don’t know where those data are available publicly, though.

BRAD NEWBOLD 17:43
All right. Good job you guys. Let’s see. So that question was covering tangentially some issues with installation in farmland or dealing with crops and those kinds of things. Is there anything different — there’s one question here that pops up as well saying, is there any different guidelines for installing weather stations in agricultural research or with growers or consultants of growers, those kinds of things?

DOUG COBOS 18:14
Yeah, well, the rule of thumb there is place it where you where you want the measurements to be made. So you know if you’re doing, if you’re worried about frost, then you need to put it right in your orchard. If you’re worried about rainfall in a particular field, then definitely put it in that field. I mean, you want it to be as close as possible to the environment that you’re trying to measure.

CHRIS CHAMBERS 18:37
If you’re measuring ET?

DOUG COBOS 18:38
If you’re measuring ET? Yep, you better get some fetch and you better get it close to the crops of interest.

CHRIS CHAMBERS 18:44
Now in that case, would you rather have it like in a crop that you use for a reference or maybe in a meadow right next door, something well watered? You know, some of the models assume a well watered lawn.

DOUG COBOS 18:56
The ET, yeah, the Penman Monteith does assume a well watered reference crop, either alfalfa or grass. And so putting that, getting it in a representative location that represents those conditions would be a good idea.

BRAD NEWBOLD 19:15
I was gonna say there’s a couple, you were talking about ET. There’s a couple questions in here asking about calculating ET. And this particular question is asking for grapes and other high value crops. Do you have any other, but in general, do you have any other suggestions for generating ET within these specific crops?

CHRIS CHAMBERS 19:39
Well, one of the nice things about the Penman Montieth model that you suggested is that you can calculate an ET based off of standard weather readings. You don’t need super specialized equipment, your radiation, your temperature, your relative humidity, wind speed, if you have those things, then you can get an estimate of ET. There are more precise ways to do it. But those can run pretty expensive by the time you put a full, a flux tower or something.

DOUG COBOS 20:12
Sure, yeah. And if you rely on the crop coefficients, if you have a pretty good handle on what your crop coefficients are, then you can get at the actual ET. I see in this question, though, that they’re also asking about using soil moisture to back check that evapotranspiration, and that is actually a really good idea because any kind of bias that you have either in your location of your weather station or in the weather measurements will create a systematic over or under estimation in the calculated evapotranspiration. Or any error in your crop coefficient will lead to a bias that accumulates over time. And so having a ground check to check that — it’s almost a pun —to check the soil moisture. It’ll tell you how much.

CHRIS CHAMBERS 21:05
Should look at your storage.

DOUG COBOS 21:06
Yeah, yep. And that that is, I mean, soil moisture is a really nice integrator of what has happened above, you know, in terms of evapotranspiration, in terms of precipitation. So if you have that information on the soil moisture, it really helps you do that ground truth and maybe adjust your measurements to account for any of that bias over time.

BRAD NEWBOLD 21:30
All right. Um, let’s talk about some maintenance questions here. Just in general, I mean, we’ve got a lot of questions about just general maintenance, about calibration, recalibration, support services, other things like that. Just in general, how about how about this one here, just what is the recommended maintenance for your weather station or in particular for METER’s ATMOS 41?

DOUG COBOS 21:57
Yeah, so that’s a really good question. And this is something that is pretty important. Some of the sensors that you’re going to find on pretty much any weather set up have some drift over time. And so we try and quantify that and give some recommendations as to when things need to be recalibrated or need to be switched out. So specifically, in terms of the ATMOS 41, which is our little all-in-one, there is a small daughterboard that houses the relative humidity, vapor pressure, and barometric pressure chips, and so the calibration is stored on those. And so we recommend that you change those out every year, or every two years, at the worst. And so this is something that takes about, oh, I don’t know, six, seven minutes. You can do it in the field, all you need to do is get another one of those daughter boards from us, and you can change it in the field and get your measurement spot on.

CHRIS CHAMBERS 22:53
But it’s a weather station. Even if you have cloud access and can keep your eyes on the data all the time, you still need to put some thought into maintenance.

DOUG COBOS 23:03
You bet.

CHRIS CHAMBERS 23:04
Precipitation, rain gauges, rain funnels get clogged up,

DOUG COBOS 23:07
Nobody has figured out how to keep that rain gauges from getting clogged.

CHRIS CHAMBERS 23:10
No one that we know of anyway.

DOUG COBOS 23:13
Weighing gauges, I suppose, but of course those are accumulating, you know, bird poop.

CHRIS CHAMBERS 23:18
It gets right in there. You still need to get in there and check it out. So yeah, every two years with the ATMOS 41s. You can send it in, we’ll do a full calibration service, do a new calibration certificate for you, check all the measurements, make sure they’re okay. If you want to keep your device in the field, the ones the measurements that tend to drift like Doug said, we have field replaceable components.

DOUG COBOS 23:46
That includes the solar radiation as well. You can switch the

CHRIS CHAMBERS 23:48
Solar radiation and relative humidity.

DOUG COBOS 23:50
Yeah, those are really the two big ones. But, you know, aside from just the calibration, the maintenance issues that Chambers talked about, going out there, clean out your rain gauge, make sure it’s clean, get the cobwebs out of your sonic anemometer path, make sure that there’s no ants or wasps trying to nest in it. So regular site visits are always a bonus, okay. Not always necessary until things happen, but you’re going to be better off if you send a student out or a technician occasionally.

CHRIS CHAMBERS 24:22
And if you see something in the data, then definitely go out and check, especially the precipitation. The ATMOS 41 has accelerometers on it that can give you some information about what’s happening out there. If you see something odd, maybe it’s fallen over or got hit by operations or something like that.

DOUG COBOS 24:43
So just another anecdote, I have a buddy here is a local farmer that they’ve let us do a whole lot of testing on some of their alfalfa, and so we got them an ATMOS 41, and he was complaining, oh man you know, we got, again that same precipitation thing. Oh, they got half an inch of rain, and I only measured a 10th of an inch. What’s going on? And so I walked over to his weather station and pop the funnel off and it was about, I don’t know, two centimeters thick bird poo and just completely plugged so.

CHRIS CHAMBERS 25:13
Great.

DOUG COBOS 25:13
Yeah. So make sure you, if you see an anomaly and you have questions, get out there and check it out.

CHRIS CHAMBERS 25:18
We’ve got the hawks out here that build nests right next to it, and they love to perch on the rain gauges, and so do mice, so you go to your rain gauge and you find a happy mouse inside there.

DOUG COBOS 25:29
That’s not going to help your measurements.

CHRIS CHAMBERS 25:30
Never good for your data.

BRAD NEWBOLD 25:34
Lovely, thank you. How about this, how about the importance of support. So I mean, this comment here is, you know, very important value is support. Many, many purchases that you make, you know, on Amazon or other places, there’s no support associated. Can you guys just talk about the importance of support in maintaining your weather station or other other sensors?

DOUG COBOS 26:01
Things are gonna go wrong.

CHRIS CHAMBERS 26:03
Eventually.

DOUG COBOS 26:04
Invariably things are going to go wrong, it will happen at some point. And if you have a whole weather setup, then you’ve got a whole bunch of sensors out there, and at some point, you’re gonna get some questionable data, and if you don’t have somebody who’s a domain expert to help you either interpret that or tell you how to fix it, then you’re kind of stuck.

CHRIS CHAMBERS 26:27
To check out your data, see if it’s, if the sensor looks like it’s working within specification, it might be something like clean out the funnels or, you know, sometimes instrumentation does have a problem and needs to come in for service. And you look at these all-in-one weather stations, it’s easy to look at them as well, it’s just one instrument, right? Well, it’s actually got nine different sensors on there, any of which, you know, can encounter problems over the life of a sensor suite.

DOUG COBOS 27:00
You bet. You bet. And there are some things that, that people like Chambers and Jeff Ritter and that support team here, they see time and time again. And so they can really save you a lot of time and heartache if you’ll just send an email or break off a call and say, Hey, something funny is happening. Well, yeah, if you’re seeing your rainfall trickle through at one millimeter per hour, you know, for several days after your rainfall event, that means you have a plugged funnel.

CHRIS CHAMBERS 27:29
And we have some recommendations on how to check your funnel, how to check the precipitation, so that you can have a quantitative test and see if your instrument is actually measuring in the field. And if you do the test, and it’s fine, then you have some other variable that’s affecting your data and not the instrument and then you can eliminate that as the source of error.

BRAD NEWBOLD 27:56
All right. There was another question just came in, kind of piggybacking off of previous discussions regarding soil moisture, getting soil moisture readings with your weather data. And they were just asking, what tools do you recommend for installing sensors, including our TEROS sensors? Are there any special requirements, especially when we’re dealing with soil moisture in conjunction with your weather station?

CHRIS CHAMBERS 28:21
We could do a whole seminar on this.

DOUG COBOS 28:22
Yeah, have we? Have we not?

CHRIS CHAMBERS 28:24
I think we have at various stages. Just in the short version, making sure that you get good contact with soil is generally the single most important thing that you can do to get good soil moisture data. And know something about your soil. If you’re doing water content, take a soil sample, because interpreting soil moisture generally needs that soil type information as well.

DOUG COBOS 28:54
Yep.

CHRIS CHAMBERS 28:55
So determining what depths, how many sensors you want to get out. And then having the smallest possible impact on your site while getting the best contact with the soil you have sensors is is where you want to focus your efforts.

DOUG COBOS 29:13
We have spent, well, as you know, we’ve spent a lot of time trying to come up with installation techniques that do both of those things, that make sure that the sensor is installed into undisturbed soil, and you have the least site disturbance as possible. And so I mean, if you guys are interested, get on the website and look up our borehole installation tool.

CHRIS CHAMBERS 29:35
We’re still working on that.

DOUG COBOS 29:36
Yeah, we’ve got iteration number two.

CHRIS CHAMBERS 29:38
Better, better, cheaper installation tools.

DOUG COBOS 29:41
Yes. Very low disturbance, perfect installation down several meters. It’s I mean, this may not be so important for a lot of the weather related soil moisture measurements because most of those would be at shallower depths, but

CHRIS CHAMBERS 29:57
Down to about a meter is generally the deepest.

BRAD NEWBOLD 30:02
All right. Okay, we’re gonna switch gears. And there’s some questions regarding data in general. So let’s see, let’s do this one first. How do we correct overestimates of air temperature due to the instruments heating due to sunshine?

DOUG COBOS 30:19
Well, I can tell you for sure that we’ve done a webinar on that one. So if you know the solar radiation load on your sensor, and if you know the wind speed, and also well, you need to know the reflectivity and the size of the sensor, but you can use first principles energy balance to understand how much your air temperature would heat up over ambient temperature, if it’s sitting in the sunshine.

DOUG COBOS 30:49
And this is where all-in-ones really shine. Because,

DOUG COBOS 30:52
Yeah, because you have that information. And well, if your all-in-one has a solar radiation sensor, most don’t, but the ones that do have a solar radiation sensor, you could correct that. You’re going to be better off though, typically, making sure that you have a radiation shield and keeping the sun off it, but even then you can get some pretty substantial errors under low wind speed and high radiation.

CHRIS CHAMBERS 31:14
That’s right. Comparison models with the ATMOS 41s correction generally do better than non aspirated shields.

CHRIS CHAMBERS 31:20
Absolutely do better than non aspirated shields. I mean, you can get a couple of degree temperature difference between air temperature and your sensor temperature, even if it’s in a radiation shield if that radiation shield is un aspirated. So the precipitation variability, and then air temperature measurement are the two that I think that most people take for granted and overlook the errors that can accumulate there, if you’re not careful.

CHRIS CHAMBERS 31:45
Lots of ins and outs to the measurement unit that we try to make easy and so that you don’t have to worry about that.

DOUG COBOS 31:49
That’s right. Yep. It’s our job.

BRAD NEWBOLD 31:53
All right. And this next one is asking, how important is metadata for the representivity of the data series and model calculations?

CHRIS CHAMBERS 32:02
What’s metadata again?

DOUG COBOS 32:03
Metadata, yeah metadata, the higher data, the supporting data,

CHRIS CHAMBERS 32:07
Alright, yeah.

DOUG COBOS 32:09
So I think that this is another one that’s often overlooked. I mean, if you don’t have the supporting data to tell you where your measurement is, the height of the measurement, what the vegetation is near near the site, then your data often lose a lot of meaning. And so.

CHRIS CHAMBERS 32:29
And this is where you might not be able to use your data to infer what you’re hoping to infer. If you’ve got features nearby, you may be measuring microclimate instead of weather. And your data may be just specific to that spot. And you can’t make larger inferences about the weather at that area.

DOUG COBOS 32:50
Right. So we’ve done a lot, well, we have a lot of ideas, and we’ve enacted about half of them in our ZENTRA system to allow the metadata to be stored along with the data records. So you’re able to input the height or depth of your measurement, the GPS coordinates of the measurement are automatically stored there. And then we’ve spent quite a bit of time recently having all of our sensors be smart sensors. So the sensors themselves will tell you if there’s a problem with your calibration, they’ll tell you if there’s a problem with the measurement, they’ll tell you if maybe a sensor has broken and they’ve had to revert to a subsensor that’s less accurate. So all of those data come through in the data stream. And I think that that is pretty helpful for some of the big network operators, especially to be able to have some automated QA QC on the data stream when the sensor in the system reports and says, Hey, I’ve got a problem. Yeah.

CHRIS CHAMBERS 33:50
Right.

BRAD NEWBOLD 33:52
All right. Let’s see. I think we’re going to come back. We have had, coming back to installation, we have had a lot of questions, people concerned about leveling sensors. Is there any little insights you can give about, we’ve got people talking about weather stations, PAR sensors, anemometers, other things like that. Any insights there?

DOUG COBOS 34:15
Yeah, level is good. Okay, next question, Brad.

CHRIS CHAMBERS 34:21
Do you remember the spec, how far out of level is it before you run into a problem?

DOUG COBOS 34:24
Well, so I can speak specifically for the ATMOS 41 with our rainfall measurement. Some drops have to hit a couple of electrodes and it’s about three degrees off level that you start missing those. We tell everybody to don’t touch to try and give a little bit of safety factor there. But also your wind speed, your precipitation, catch, wind direction, your solar radiation, all of those things are going to accumulate errors if you’re not perfectly level. So it’s a pretty good idea to look at your bubble level, or actually in our instruments, yeah, get your pole level, look at the bubble level on the instrument or in the ATMOS line, we have accelerometers level sensors in there that, so you will see your level data come through in the data stream. And you know, if you set a flag or if you look at that, you can tell if you have a problem and get back out and re level your sensor.

CHRIS CHAMBERS 35:23
Yep.

DOUG COBOS 35:23
Yeah, but that is important, Brad.

BRAD NEWBOLD 35:26
All right. I’m glad I asked it then. All right. Um, another maintenance question. Our battery levels are giving us a lot of issues. Any tricks to keeping stations running that are dropping below 50% battery power.

CHRIS CHAMBERS 35:40
So this crosses over into data logging and data management and as a system with the ATMOS 41 and the ZL6, power management is critical. We try to make that as behind the scenes as possible with solar panels and the recharging and rechargeable batteries and all that, but again, you are in the field, and you’re transmitting to a cell tower. And in most cases, your cell reception is going to determine what your power budget is.

DOUG COBOS 36:20
That’s right.

CHRIS CHAMBERS 36:21
And so if you’ve got a device that’s out just on the edge of cell service, and it’s trying and trying to get signals, and then it has to do a bunch of retries because it’s got a poor signal, and then there’s a lot of things going on behind the scenes with cell signal strength too. And it can vary at a site between 25 and 50% in any given case. So definitely managing your cell transmissions is one of the tricky parts about that.

DOUG COBOS 36:54
Yep.

CHRIS CHAMBERS 36:56
We also have some good tools. Sometimes the sensor is the problem, and it’s drawing more current, and we have some tools on how to actually measure if the sensor is operating within specification, and that’s the ZSC Bluetooth reader.

DOUG COBOS 37:11
Yep, so we put that functionality in. One other that just came up recently had a cosmic ray neutron sensor that was running on a ZL6 and the batteries were going down. There’s no reason that the batteries should have been going down on this and so. I will make the statement that birds are pretty indiscriminate with where they poop. It’s not just rain gauges where they like to go but that the solar panels can get pretty gummed up with bird poo too, if you’re not careful. So

CHRIS CHAMBERS 37:40
And we’ve had canopies grow up over, I put this thing out.

DOUG COBOS 37:44
Oh, yeah. Somebody in the tropics. Yeah.

CHRIS CHAMBERS 37:47
Two months later, the solar panel is completely blocked by solar radiation.

BRAD NEWBOLD 37:56
All right. This next one is a suggestion or feedback or something that this commenter has seen. They say that it seems that all-in-one systems like the ATMOS 41 can be teamed with ancillary powered heated rain gauges or unpowered chemical snow melting gauges to get four season performance. Can you guys talk a little bit about that potential?

DOUG COBOS 38:18
Yeah, I mean, that that is a really good strategy to extend your precipitation measurement, which is the primary reason that the ATMOS 41 wouldn’t be called a four season measurement, that it really, under frozen precipitation conditions, it’s not going to get you any information. So if you have a secondary measurement to measure the rain or the snow, then that is a really great idea. May not get all the way there because your wind path can get gummed up with snow and filled with snow under some conditions. And that’s a really tricky one. Because even you know, your anemometers, they claim to be four season, you know, your cup anemometers or propeller anemometers. Those also struggle a lot when you have blowing snow and accumulating ice. Those can give you also no information when they get frozen. And so.

CHRIS CHAMBERS 39:15
We skied the SNOTEL backcountry skiing one day, and just that cup anemometer — wind was howling and that cup anemometer was just an unbroken, just a solid block of ice.

DOUG COBOS 39:28
Yeah, it’s a it’s a tough thing to do.

CHRIS CHAMBERS 39:29
Unfortunately it is, it’s very tricky.

DOUG COBOS 39:32
Yeah.

BRAD NEWBOLD 39:35
All right. Let’s shift gears to talk about some urban weather data here. So just in general, so we’ve talked about installations in other places, in farmland and elsewhere. How about weather stations to study urban weather?

DOUG COBOS 39:56
Yeah the urban environment.

CHRIS CHAMBERS 39:57
Is urban weather a thing? Are we looking at weather or are we looking at microclimate?

DOUG COBOS 40:01
Well, I think that I think that you’re hitting on exactly the right topic there, Chambers, is that you are looking at microclimate, and the microclimate variability in an urban setting is just tremendous. So yeah, I mean, you better say,

CHRIS CHAMBERS 40:13
Where do you put your weather station? At the top of the building? Is it going to give you similar conditions to what’s happening on the streets?

DOUG COBOS 40:20
Likely not.

CHRIS CHAMBERS 40:21
In a park?

DOUG COBOS 40:22
Yeah. I mean, where do you care, where are people hanging out? Are they hanging out on roof?

DOUG COBOS 40:26
Right.

DOUG COBOS 40:27
Probably not.

CHRIS CHAMBERS 40:28
Probably not.

DOUG COBOS 40:28
Probably, hopefully hanging out in the park, but they might be hanging out on the street. I mean, this is kind of the tricky part. If you site this thing in the park, then it’s going to probably read a little bit higher vapor pressure and relative humidity. If you site it on your roof, it’s probably going to read a little bit higher temperature, especially in sunlight.

CHRIS CHAMBERS 40:46
Well, part of the problem with early climate change warnings was that the argument was that well all of these temperature measurements are biased towards urban or near urban areas that have heat island effects.

DOUG COBOS 41:00
Yeah.

CHRIS CHAMBERS 41:00
So that was back — what’s my timeline like — in the 90s, earlier than that, 80s somewhere?

DOUG COBOS 41:06
People started studying that.

CHRIS CHAMBERS 41:07
Where there was a lot of concern about the bias and where weather stations were being measured. So it’s, I don’t know if we have all the answers to this question.

DOUG COBOS 41:21
I mean,

CHRIS CHAMBERS 41:21
Do we have just more questions?

DOUG COBOS 41:22
I don’t, we have, yeah, a lot of questions. That’s for the urban weather folks to answer those questions. I mean, typically an urban environment, you’re going to have some network. You’re going to have multiple locations where you’re making these measurements. And so if some of the measurements are in parks, if some of the measurements are in a more, you know, kind of asphalt type setting, if some are closer to buildings, then maybe you get a better integrated idea of what’s going on and what the conditions, the felt conditions, are in that environment.

BRAD NEWBOLD 41:36
So would that include one of these other questions, so you talked, you’re hinting a lot about temperature, and, you know, with heat islands and other things like that, would this also impact wind speed data and

DOUG COBOS 42:07
Oh for sure.

BRAD NEWBOLD 42:07
things like if you’re on a roof or being blocked by some other obstacle?

DOUG COBOS 42:11
That’s probably the most variable one. If you’re sitting right next to a building and the wind is coming from the building direction, you’re going to get obviously the wrong answer. From that standpoint, having it up above the buildings would would be best, but then, you know, are you — it just depends on if you’re wanting to understand how humans feel, what the operative temperature or the felt temperature is at a certain location, then you’re going to get the wrong answer if you put that up where there’s a lot more wind speed. You’re gonna get the right answer if you put it down where the humans are hanging out.

DOUG COBOS 42:47
And then if you want to know whether there’s an inversion going on, then you’re looking at a completely different set of data.

DOUG COBOS 42:51
Yep. Yeah, tricky stuff. This is why I have a weather station that’s at my house. So I know exactly what’s going on all the time. Kind of a weather junkie, though, I mean, I pull out my phone every day and look and see what’s going on outside and what happened, you know, the day before.

BRAD NEWBOLD 43:12
All right. Let’s see. This one, I don’t know if we’ve we’ve hit this one specifically. But talking about comparing results between standard rain gauges with a read switch against all-in-one rain gauges. Can you talk a little bit about comparing the two when necessary?

DOUG COBOS 43:32
That’s exactly right.

CHRIS CHAMBERS 43:32
I don’t really see a dominant — it’s kind of how you get to the measurement isn’t quite as important as the other variables

CHRIS CHAMBERS 43:43
that are in there, I think.

DOUG COBOS 43:45
If the rain gauge is reading right, which you would assume that they all have been calibrated and can measure the amount of water that’s come through them accurately. And I would make the statement that that’s generally going to be true no matter if it’s a tipping bucket or tipping spoon gauge with the read switch or, you know, any accumulating rain gauge, really, your bigger errors and your bigger differences are going to come from things like the radius of your intake, right. So rain gauges with a smaller intake will miss more rain if you have higher wind speeds, and the differences are going to come from the location, the height that you mount the rain gauge at, so the higher your wind speed, the less rain you’re gonna get. If you mount this thing at the ground surface or rain shield it, those are going to be much bigger effects than the accuracy of the rain gauge itself.

CHRIS CHAMBERS 44:40
Although it does affect the specs. I’m thinking about the resolution of a drip counter, like in the ATMOS 41.

DOUG COBOS 44:46
That’s true.

CHRIS CHAMBERS 44:46
And because that gets point 0.017, I think is our smallest resolution.

CHRIS CHAMBERS 44:51
Yeah, 0.017 mm.

CHRIS CHAMBERS 44:52
I’ve never seen a tipping bucket or a read switch that gets that kind of resolution. As we were, gosh I remember chatting with a client and luckily they had leaf wetness sensors out there because, like we’re getting precipitation,

DOUG COBOS 45:04
We’re seeing precipitation!

CHRIS CHAMBERS 45:05
It has not rained. There’s no precipitation gauge that is logging this. And they were they were seeing dew, they were seeing condensation in the funnel, and then it was dripping, and it would just make a few drips like one every 15 minutes or something like that, until it dried out. And that data was corroborated exactly by their leaf wetness sensors. Yeah, that was, those are the fun ones where, hey, this is what’s happening.

DOUG COBOS 45:30
That’s when support is fun?

BRAD NEWBOLD 45:35
When everything works, right?

DOUG COBOS 45:36
Yep.

CHRIS CHAMBERS 45:36
Or at least when you can figure out what’s going on.

BRAD NEWBOLD 45:40
Let’s see. How about, here is a fun one. What kind of weather equipment would be considered appropriate for a utility scale solar installation?

DOUG COBOS 45:52
Yeah, this is a really interesting one. Been learning more about the renewables area and about the solar installations. And by far the number one most important, is that class A pyranometer. I mean, you’ve got to know what solar radiation is coming in if you’re going to determine any kind of efficiency from your solars.

CHRIS CHAMBERS 46:12
Measure it down to the joule.

DOUG COBOS 46:13
Yeah, exactly. And then a lot of people actually are adopting all-in-one weather stations to monitor the rest of the weather parameters. So none of the all-in-ones have that class A pyranometer. You’d have to measure that separately. But an all-in-one is typically going to be adequate to measure the rest of the environmental parameters. Except of course soiling. That’s the other big one. You’ve got to somehow measure how much dust is accumulating on your solar panels, which that’s kind of a tricky one at this point.

CHRIS CHAMBERS 46:50
Right.

BRAD NEWBOLD 46:52
All right. Let’s see. We’ve got a few minutes left. We’ll hit some of these next ones here. I’ll get to this one in a second. There are a couple of questions asking about, in general, just again, we’ve talked about ET already a little bit, but specifically about how does ET work with METER’s weather stations and within ZENTRA Cloud and those models and just can you talk a little bit about how those work specifically within ZENTRA Cloud?

CHRIS CHAMBERS 47:27
Yeah, basically, we implement FAO 56, right?

DOUG COBOS 47:31
Exactly.

CHRIS CHAMBERS 47:31
And so if you want to learn the nuts and bolts about it, it’s in FAO. You’re going to look for FAO 56. Based off of Penman Montieth equation.

DOUG COBOS 47:44
And actually, I think that Colin Campbell and Dirk Baker did a webinar, yeah, joint webinar with Campbell Scientific about measuring evapotranspiration, and so that’s a pretty good reference. And they reference some literature that helps with that as well. Brad, were you asking about, were they asking about ZENTRA Cloud as well?

BRAD NEWBOLD 48:07
Yeah, yeah. So they’re asking about how does that work in ZENTRA Cloud right now?

DOUG COBOS 48:10
So it’s super easy in ZENTRA Cloud. All you have to do is apply one of the, what do we call them, scientific models?

CHRIS CHAMBERS 48:17
Yep, one of the models.

DOUG COBOS 48:17
And say give me ETO or ETR. You can have the alfalfa reference or the grass reference,

CHRIS CHAMBERS 48:25
Wait, which is which?

DOUG COBOS 48:25
And it will do all the calculations.

CHRIS CHAMBERS 48:28
I always get those confused.

DOUG COBOS 48:28
I have a percent chance of getting it right, yeah.

CHRIS CHAMBERS 48:30
And then it just asks you which sensor you want to use for the measurements, and then the timescale. And then on a daily, it’s a daily model, so that throws people off sometimes. It sums the ET at the end of the day.

DOUG COBOS 48:46
Yeah, I mean, but that’s FAO 56. That’s the way that it’s recommended. So that’s the way that we have to do it. Yeah, super simple, though. It’s way easier than calculating it yourself, I can tell you that.

CHRIS CHAMBERS 48:57
Or putting a $10,000 eddy covariance station out there.

DOUG COBOS 49:00
Right.

BRAD NEWBOLD 49:03
All right, along with ZENTRA Cloud, again, this individual is asking, will ZENTRA Cloud eventually facilitate additional metadata? We talked about metadata. So having additional sight pictures, maintenance, all within your account there.

DOUG COBOS 49:17
Pictures are on the list. It’s just, we’re not there yet.

CHRIS CHAMBERS 49:21
Yeah, it’s balancing that ease of use versus utility. But we know how important it is to be able to see what’s happening at your site. So yeah, ZENTRA Cloud is a living, breathing, developing software that we’re actively investing effort into, and I am excited to see how it grows over the coming years.

DOUG COBOS 49:46
Yep. And so I mean, the question was asking about facilitating additional metadata. It said site, you know, pictures and things, but I did mention earlier that our metadata feed has come a long way. So there is a lot of self diagnostics. And when you’re asking about maintenance, like you did, then those self-diagnosing measurements are pretty helpful with that. It will tell you immediately, hey, something’s going on. Time for maintenance.

CHRIS CHAMBERS 50:15
Oh, I love this question. I don’t know if I have all the answer is for it. To what extent does the soil life, such as Mycorrhizae fungi affect the amount of water the soil can hold, and how do you include this variable in your measurements? That’s great. We don’t really include things like that in the research on Mycorrhizae are in kind of a fantastic stage right now where there’s a lot of new things coming out every day. So we know they affect the amount of water that the soil can hold, and not so much that, how much the plants can take up. Yeah. And how much sharing happens between plants. I don’t know. I’m going to keep my eye on the research over the next few years, I hope and see how that develops.

DOUG COBOS 51:05
I mean, when you’re talking about those fungal interactions, often you’re talking about the soil structure, right, and water holding capacity, which, if you’re measuring just water content, that doesn’t get you all the way. I mean, it tells you about the water balance, but if you’re talking about you know, plants or microbes, then your water potential measurement is going to be a more important one. And so at that point, you maybe don’t care as much about how much water is there and what the fungal effects are. But you can

CHRIS CHAMBERS 51:39
What the availability,

DOUG COBOS 51:40
Yeah, you can actually nail the availability, and that’s the key bit.

CHRIS CHAMBERS 51:43
How much energy needs to be exerted to extract that water, and then the effects, like you mentioned, the effects that they have on the soil in terms of soil structure and soil microbial activity. Those are the fun questions to answer.

DOUG COBOS 51:56
Well, you know, it’s interesting that people now are starting to colocate water content and water potential sensors in the soil, and then you can actually derive the moisture characteristic curve. And that moisture characteristic curve, or the relationship between water content and water potential for a given soil, will evolve over time. And I think that’s what this question is really getting at is, you know, the water holding capacity is determined by that moisture characteristic curve. So yeah, people are measuring those in situ.

BRAD NEWBOLD 52:28
Alright, okay. I think maybe we’ll do two more questions here. This one, I know, we touched on installation, they’re just wondering, do they have to use METER gauge augers with TEROS installations?

DOUG COBOS 52:48
No.

BRAD NEWBOLD 52:48
Okay.

DOUG COBOS 52:49
No, I mean, you can install the sensors in many different ways. The old tried and true is, you know, dig a big trench down to the depth you want to,

CHRIS CHAMBERS 52:58
and some people still really like that, because they get to see the soil profile, you get to get soil samples exactly at the depth. And all of that is important, especially within water content.

DOUG COBOS 53:09
And you can tell, you know, when you insert it if you’ve hit a rock or hit a root, or you know, or if you have some type of problems. So no, you don’t have to use the borehole installation tool, it’s just a really handy way to get a good quality installation.

CHRIS CHAMBERS 53:23
And focus on soil to sensor contact. If you do nothing else in installing your soil moisture sensors, make sure you get good contact with the soil.

BRAD NEWBOLD 53:33
All right, and we did get some information from our friend and colleague, Leo Rivera. That auger in question is specific to the TEROS 6.

DOUG COBOS 53:42
Yhat yeah, that’s the soil temperature profile sensor. That’s a whole different beast from the water content sensors.

CHRIS CHAMBERS 53:48
And the answer is still no, you don’t have to use that. It is recommended because it’s the same size as the thing.

DOUG COBOS 53:55
Hey, we answered the wrong question. But we had a lot of fun answering the question.

CHRIS CHAMBERS 53:58
I answered the question I wanted to answer. Sue me.

BRAD NEWBOLD 54:03
That’s right. What we learned is the friends along the way. All right. Um, let’s see. Final question here, I think, and we’re going to combine these two, and this is just about dealing with some fun and exotic installations. One is asking about installing on a glacier surface, and the other is in active volcanic areas. So any insights in those two?

DOUG COBOS 54:27
Are these coming from somebody in Iceland that would be on a glacier in a

CHRIS CHAMBERS 54:32
in a volcano?

DOUG COBOS 54:33
Yeah. Well, the active volcanic areas, that one’s going to be a tough one, just from the standpoint of measuring rainfall. I mean, any type of ash fall or dust accumulation is certainly going to gum up your rain gauge. And even if you’re using a weighing rain gauge, it’s going to give you some accumulation that’s not actually rain. It would be solid material that’s accumulating, so that’s going to be pretty tough one. The rest of the measurements ought to be okay if you clean your pyranometer pretty often. I mean, yeah, your solar radiation is

CHRIS CHAMBERS 55:06
Dust covering solar radiation is going to be a problem.

DOUG COBOS 55:11
Yeah, tough one. But I mean, anytime you’re doing research or monitoring anything in a volcanic area, that’s kind of a special case, and you better be prepared to do a little bit of extra work I think. What about the glacier?

CHRIS CHAMBERS 55:22
The glacier? Watch your metadata. The ATMOS 41 has accelerometers on it. So you’ll know if you get some movement and it comes out of level.

DOUG COBOS 55:34
Yeah, exactly.

CHRIS CHAMBERS 55:35
And you need truck back on there.

DOUG COBOS 55:36
Differential melting and you’re at a tilt.

CHRIS CHAMBERS 55:39
You know, that’s something where cloud access is so helpful for keeping an eye on your site, knowing when there’s a problem for troubleshooting. You know, and then if you run into a problem, and you see it in the cloud, then you have just truck right out there and fix it with a minimal loss of data. You know, but sometimes those are, your cell signal is focused on areas where people are.

DOUG COBOS 56:04
Yeah.

CHRIS CHAMBERS 56:05
You know, so it just might not be an option on the surface of a glacier, depending on where it is.

DOUG COBOS 56:10
In that case, you better get out there pretty often.

CHRIS CHAMBERS 56:13
Yeah.

BRAD NEWBOLD 56:15
All right. I think we have come up to the end of the hour here. So that’s gonna wrap it up for us. And, yeah, we just want to say thank you for joining us today. We hope you enjoyed this discussion.

DOUG COBOS 56:29
We did.

BRAD NEWBOLD 56:29
Thanks again.

CHRIS CHAMBERS 56:31
Yeah. Had a good time.

BRAD NEWBOLD 56:32
It was fun. Yeah, thanks again for all the great questions. We had a bunch that were submitted. We got through almost all of them. So that was great. Good job. Good job, Chris. Good job, Doug. Props to you guys. For those in the audience, please consider answering the short survey that will appear after we close here just to let us know what types of Q&A themes you’d like to see in the future. And for more information, definitely on what you’ve heard today, please visit us at metergroup.com. Finally, look for the recording of today’s presentation in your email. And stay tuned for future METER Office Hours events. Thanks again. Stay safe, and have a great day.

CHRIS CHAMBERS 57:12
Ciao.

DOUG COBOS 57:12
Bye bye.