====== 11.C - Other Natural Sources ======

==== Short description ====

Within **NFR 11.C - Other Natural Sources: Other**, natural activities and resulting emissions other than volcanoes (11.A) and forest fires (11.B) are to be taken into account.

The 2023 EMEP/EEA Guidebook distinguishes the following emission sub-categories of **NFR 11.C - Natural Sources: Other**:

^  NFR 11.C sub-categories                                                ^
| Other natural sources: Non-managed & managed forests                    |
| Other natural sources: Natural grassland and other vegetation           |
| Other natural sources: Wetlands and waters                              |
| Other natural sources: Animals                                          |
| Other natural sources: Geological seepage                               |
| Other natural sources: Forest & grassland soils                         |
| [[#Other natural sources: Lightning]]                                   |
| Other natural sources: Changes in forest and other woody biomass stock  |
| Other natural sources: Forest and grassland conversion                  |
| Other natural sources: Abandonment of managed land                      |
| Other natural sources: CO<sub>2</sub> from or removal into soil          |
| Other natural sources: Other                                            |
\\

However, for the time being, from the natural sources listed above, only emissions from lightning is taken into account in the German emissions inventory.

NOTE: As NFR 11.C is a memo item category, emissions reported here are not accounted for in the National Totals.

===== Other natural sources: Lightning  =====

For the time being, the only natural emission source reported within NFR 11.C is lightning.


^  Category Code                          ^  Method  ^  AD  ^  EF  ^
|  11.C                                   |  T1      |  NS  |  D   |
|  {{page>general:Misc:LegendEIT:start}}                        ||||
\\
^  NO<sub>x</sub>                                                                    |  NMVOC  |  SO<sub>2</sub>  | NH<sub>3</sub>  |  PM<sub>2.5</sub>  |  PM<sub>10</sub>  | TSP  |  BC  |  CO  |  Heavy Metals                                  |||||||||  POPs  |
^  -/-                                                                               |  NA     |  NA              |  NA             |  NA                |  NA               |  NA  |  NA  |  NA  |  NA                                            |||||||||  NA    |
|  //This memo item source category is not included in the key category analysis.//                                                                                                                                                               |||||||||||||||||||
\\

Lightning (and corona discharge) during thunderstorm events cause atmospheric chemical reactions to take place at high voltages and high temperatures. These reactions cause the production of NO<sub>x</sub> in the atmosphere.

====Methodology====

The calculation of NO<sub>x</sub> emissions from lightning uses strike counts from the German weather service and default emission factors from the 2023 EMEP/EEA guidebook [(EMEP2023)].

For the complete time series, the emissions are calculated as follows: 

<WRAP center round info 50%>
**EM** = **AD** (number of lightning strikes) * ** EF** (kg emission per strike)
</WRAP>

===Activity data ===
The number of lightning strikes in Germany is taken from a commercial system called "BLIDS" run by Siemens. The data has been cross-referenced with information from the German weather service. Consistent strike count data is available from 1992 onward and has been back-populated to cover the full time series since 1990. The following table shows the strike figures over time.

__Table 1: Annual number of lightning strikes in Germany, as 1990, in [1,000 strikes]__
^ 1990  ^ 1995  ^  2000   ^  2005  ^  2010  ^  2011  ^  2012  ^  2013  ^  2014  ^  2015  ^  2016  ^  2017  ^  2018  ^  2019  ^  2020  ^  2021  ^  2022  ^  2023  ^
|  443  |  394  |  1,026  |  802   |  589   |  687   |  656   |  542   |  623   |  550   |  432   |  443   |  446   |  329   |  399   |  512   |  242   |  316   |

===Emission factor(s)===

For the calculation of emissions in this category, the Guidebook emission factor of 2.75 kg NO<sub>x</sub> per strike is used.

====Emission Trend====

The emission value is solely dependent on the strike count and varies between 1 to 3 kilotons of NO<sub>x</sub> per year. 

Figure 1: NFR 11.C, NO<sub>x</sub> emissions from lightning

{{ :sector:natural_sources:11c_nox_from_lightning.png?nolink&800 | Annual nitrogen oxides emissions from lightning over Germany.}}

===== Recalculations =====

<WRAP center round info 65%>
With **activity data and emission factors remaining unrevised**, no recalculations were carried out compared to the previous submission.
</WRAP>

==== Uncertainties ====
The AD from BLIDS does have a low uncertainty of ± 3%. The uncertainties for the emission factors are estimated to be relatively high, being a default value. Hence the overall uncertainty for the emission estimation of NO<sub>x</sub> from lightning is qualified estimated by expert judgement to be high (>50%).


====Planned Improvement====

<WRAP center round info 45%>
At the moment, no source-specific improvements are planned.
</WRAP>

[(EMEP2023> EMEP/EEA 2023: EMEP/EEA air pollutant emission inventory guidebook 2023, URL: https://www.eea.europa.eu/publications/emep-eea-guidebook-2023/part-b-sectoral-guidance-chapters/11-natural-sources/11-c-other-natural-sources-6/view, Copenhagen, 2023)]