---
jupytext:
  formats: md:myst
  text_representation:
    extension: .md
    format_name: myst
kernelspec:
  display_name: Python 3
  language: python
  name: python3
---

# Parsivel2

The OTT Parsivel2 is a laser-based disdrometer for comprehensive measurement of all types of precipitation. There are currently 3 such disdrometers in operation at the BCO. The longest running disdrometer (451995) was in operation since 2023-05-14, was decommissioned 2025-10-14 due to hardware issues, and was reinstalled 2026-01-22. The other two, 451996 and 451997, were added 2025-09-22. Below we provide the locations of the three parsivels accompanied by their serial numbers.

![Locations of 3 parsivels](3parsivels_locs.png)

![Parsivel2 @ BCO](parsivel2_bco.jpg)

The device works on the extinction principle and measures precipitation particles using the shadowing effects they cause when they pass through a laser band.

Parsivels 451995 and 451997 (1 and 3) are oriented facing east, while 451996 (2) is facing north.

The Parsivel2 captures both the size and the rate of fall in detail of the individual hydrometeors and classifies them into a range of 32 classes each.
The temporal resolution covers between 10 seconds and one hour.
The raw data is used to calculate for example precipitation type, amount and intensity.

## The measurement principle

OTT Parsivel2 uses a laser-optical sensor to measure precipitation. The transmitter unit of the sensor generates a flat, horizontal beam of light that the receiver unit converts to an electrical signal. This signal changes whenever a hydrometeor falls through the beam anywhere within the measuring area (54 cm2). The degree of dimming is a measure of the size of the hydrometeor and the fall velocity is derived from the extinction signal duration.

```{admonition} Uh oh!
:class: warning

Comparison with other precipitation measurements corroborates findings from the literature that the parsivel does not accurately capture rain events surpassing 20 mm h-1 in intensity.
```

## Data Availability

The data from the first parsivel is available as `BCO.disdrometer_PARSIVEL451995_c1` in the catalog.

The next two are published under the keys `BCO.disdrometer_PARSIVEL451996_c1_v2` and `BCO.disdrometer_PARSIVEL451997_c1_v2`.

## Versions

The dataset from the first parsivel is available in multiple versions.

* Version 1: first version of the dataset
* Version 2: firmware revision is time-dependent, firmware was upgraded during the measurement period on 2025-08-31 (before installation of second and third parsivels.)

## Sample Plot

The plot shows rain rate and particle size distribution during September 2024 (the period where the [ORCESTRA Campaign](https://orcestra-campaign.org) visited the BCO).

```{code-cell} python
import intake
import matplotlib.pylab as plt
cat = intake.open_catalog("https://tcodata.mpimet.mpg.de/catalog.yaml")
ds = cat.BCO.disdrometer_PARSIVEL451995_c1.to_dask()
subset = ds.sel(time="2024-09")
fix, (ax1, ax2) = plt.subplots(1, 2, figsize=(12, 4))
subset["rain_rate"].plot(ax=ax1)
subset["raw"].mean("time").plot(cmap="Blues", ax=ax2);
```

The full dataset:

```{code-cell} python
ds
```