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Overview

TRACER Campaign

Atmospheric Radiation Measurement user facility (ARM)

TRacking Aerosol Convection interations ExpeRiment (TRACER)

Notebook for learning the basics of ACT with TRACER data
Corresponding Author: Adam Theisen (atheisen@anl.gov)

Overview

The ARM TRACER campaign collected a lot of very interesting data in Houston, TX from October 1, 2021 to September 30, 2022. One event that stands out is a dust event that occurred from July 16 to July 19, 2022. This notebook will give an introduction to basic features in ACT, using one of the datastreams from this event

  1. Intro to ACT

  2. Instrument Overview

  3. Downloading and Reading in PSAP Data

  4. Quality Controlling Data

  5. Visualizing Data

  6. Questions for the User to Explore

Prerequisites

This notebook will rely heavily on Python and the Atmospheric data Community Toolkit (ACT). Don’t worry if you don’t have experience with either, this notebook will walk you though what you need to know.

You will also need an account and token to download data using the ARM Live webservice. Navigate to the webservice information page and log in to get your token. Your account username will be your ARM username.

ConceptsImportanceNotes
ACTHelpful
  • Time to learn: 60 Minutes

  • System requirements:

    • Python 3.11 or latest

    • ACT v1.5.0 or latest

    • numpy

    • xarray

    • matplotlib


Intro to ACT

The Atmospheric data Community Toolkit (ACT) is an open-source Python toolkit for exploring and analyzing atmospheric time-series datasets. Examples can be found in the ACT Example Gallery. The toolkit has modules for many different parts of the scientific process, including:

Enhanced Skew-T plot from ARM’s Southern Great Plains Site (SGP)

Data Discovery (act.discovery)

The discovery module houses functions to download or access data from different groups. Currently it includes function to get data for ARM, NOAA, EPA, NEON, and more!

Input/Output (act.io)

io contains functions for reading and writing data from various sources and formats.

Visualization (act.plotting)

plotting contains various routines, built on matplotlib, to help visualize and explore data. These include

  1. Time-series plots

  2. Distribution plots like histograms and heatmaps

  3. Geographic plots for moving systems like radiosondes or aircraft

  4. Skew-T plots for radiosonde data, built off MetPy

  5. Wind rose plots for wind and data roses

  6. Cross-section plots for working with 3-dimensional data

Corrections (act.corrections)

corrections apply different corrections to data based on need. A majority of the existing corrections are for lidar data.

Quality Control (act.qc)

The qc module has a lot of functions for working with quality control information, apply new tests, or filtering data based on existing tests. We will explore some of that functionality in this notebook.

Retrievals (act.retrievals)

There are many cases in which some additional calculations are necessary to get more value from the instrument data. The retrievals module houses some functions for performing these advanced calculations.

Utilities (act.utils)

The utils module has a lot of general utilities to help with the data. Some of these include adding in a solar variable to indicate day/night (useful in filtering data), unit conversions, decoding WMO weather codes, performing weighted averaging, etc...

NEON-ARM

ARM and NEON data from Utquivaik, AK

SONDE

Instrument Overview

Single Particle Soot Photometer

MPL

Micropulse Lidar

Particle Soot Absorption Photometer (PSAP)

The particle soot absorption photometer collects aerosol particles on a substrate (filter) and measurements the change in light transmission relative to a reference filter. Bulk particle absorption is derived after correcting for scattering effects. Lean more

Single Particle Soot Photometer (SP2)

The single-particle soot photometer (SP2) measures the soot (black carbon) mass of individual aerosol particles by laser-induced incandescence down to concentrations as low as ng/m^3. Learn more

Aerodynamic Particle Sizer (APS)

The aerodynamic particle sizer (APS) is a particle size spectrometer that measures both the particle aerodynamic diameter based on particle time of flight and optical diameter based on scattered light intensity. The APS provides the number size distribution for particles with aerodynamic diameters from 0.5 to 20 micrometers and with optical diameters from 0.3 to 20 micrometers. Learn more

Aerosol Chemical Speciation Monitor (ACSM)

The aerosol chemical speciation monitor is a thermal vaporization, electron impact, ionization mass spectrometer that measures bulk chemical composition of the rapidly evaporating component of sub-micron aerosol particles in real time. Standard measurements include mass concentrations of organics, sulfate, nitrate, ammonium, and chloride. Learn more

Micropulse Lidar (MPL)

The micropulse lidar (MPL) is a ground-based, optical, remote-sensing system designed primarily to determine the altitude of clouds; however, it is also used for detection of atmospheric aerosols. Learn more

PSAP

Particle Soot Absorption Photometer

SP2

Imports

Let’s get started with some data! But first, we need to import some libraries.

Downloading and Reading ARM’s NetCDF Data

ARM’s standard file format is NetCDF (network Common Data Form) which makes it very easy to work with in Python! ARM data are available through a data portal called Data Discovery or through a webservice. If you didn’t get your username and token earlier, please go back and see the Prerequisites!

Let’s download some of the PSAP data first but let’s just start with one day.

Quality Controlling Data

ARM has multiple methods that it uses to communicate data quality information out to the users. One of these methods is through “embedded QC” variables. These are variables within the file that have information on automated tests that have been applied. Many times, they include Min, Max, and Delta tests but as is the case with the AOS instruments, there can be more complicated tests that are applied.

The results from all these different tests are stored in a single variable using bit-packed QC. We won’t get into the full details here, but it’s a way to communicate the results of multiple tests in a single integer value by utilizing binary and bits! You can learn more about bit-packed QC here but ACT also has many of the tools for working with ARM QC.

Other Sources of Quality Control

ARM also communicates problems with the data quality through Data Quality Reports (DQR). These reports are normally submitted by the instrument mentor when there’s been a problem with the instrument. The categories include:

  • Data Quality Report Categories

    • Missing: Data are not available or set to -9999

    • Suspect: The data are not fully incorrect but there are problems that increases the uncertainty of the values. Data should be used with caution.

    • Bad: The data are incorrect and should not be used.

    • Note: Data notes are a way to communicate information that would be useful to the end user but does not rise to the level of suspect or bad data

Additionally, data quality information can be found in the Instrument Handbooks, which are included on most instrument pages. Here is an example of the PSAP handbook.

What do you observe?

There are 5 tests being applied to the data. The main ones that are flagged are tests 1, 4, and 5. Tests 4 and 1 are tripped at the same time and if we look at the description for 4, when that test fails, it sets the data to missing_value for us. That leaves test 5 which is suspect data so let’s try and filter that data out as well to see what it looks like

ARM Data Quality Reports (DQR)!

ARM’s DQRs can be easily pulled in and added to the QC variables using ACT. We can do that with the below one line command. However, for this case, there won’t be any DQRs on the data but let’s visualize it just in case!

Visualizing Data

We’ve already worked with visualizing the data in basic ways but what other options are there in ACT? This section will show you how to create a variety of different plots. More plotting examples can be found in ACT’s Documentation.


Questions for the User to Explore

  1. What does the data look like for the full month of July? Do we have to do more to properly visualize the data?

  2. What do the scatter plots look like when plotted against the red channel absorption coefficient vs the transmittance?

  3. Can you change the groupby plot to be for each day instead of by hour?


Next Steps

The next notebook in this series will help the users explore other datasets that can be utilized to analyze this dust event. These include using data from the instruments previously noted here.

Data Used in this Notebook

Ermold, B., & Flynn, C. Particle Soot Absorption Photometer (AOSPSAP3W1M). Atmospheric Radiation Measurement (ARM) User Facility. Sedlacek et al. (2011)

References
  1. Sedlacek, A., Smith, S., Ermold, B., Flynn, C., Trojanowski, R., Andrews, E., Hayes, C., Salwen, C., & Flynn, C. (2011). aospsap3w1m.b1. Atmospheric Radiation Measurement User Facility. 10.5439/1225037