Figure 1
![Distribution of height differences between mean-tide and zero-tide systems in Poland [cm] (own study based on Mäkinen (2008))](https://sciendo-parsed.s3.eu-central-1.amazonaws.com/647361ba4e662f30ba53c232/j_rgg-2020-0001_fig_001.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=ASIA6AP2G7AKOLDSTF5E%2F20251216%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20251216T173851Z&X-Amz-Expires=3600&X-Amz-Security-Token=IQoJb3JpZ2luX2VjEJ7%2F%2F%2F%2F%2F%2F%2F%2F%2F%2FwEaDGV1LWNlbnRyYWwtMSJIMEYCIQCMf%2Bn3%2FKNSdNh4ZdmH6fqRuJLg4auxfkomwzG6WZJJIAIhANLqjs1Na4mtSvfJaHXDICxZLcRbbvKaUaUUZnBs4oILKrwFCGcQAhoMOTYzMTM0Mjg5OTQwIgxegoRVBRZ3blQuV8QqmQVAtOEnv13ZiMUri6xWJ8p3vgLscwVCM55zH0qIdXhNOg%2FIhBT2IWXsP4QF0P60Xt3yPM1Umhi6PEtfmcJ9T4H4dIx01%2Bk%2BPTaAnTF6lRXqfy%2BGzzc0nQuxUhzIOpcbo6VoOYJD%2BEK%2FNXTsbAi8Eobmg8EKg7u9J0KRZcgSS%2FNuwlhX6KzlK8m5vviaMo7UjcvAbqTtHisB5k%2FFAUqoPdbzhto5W%2F89aiYx3YigTv43opbd%2F0WMlg2QTIxVD3uv6l%2BENnjIAts8SAdJeMAN5qftG2ueFajs6fJc%2FuccMnpRrYxGMp9BiK4EUaM3B03NeWzFgv9JIEwujECWgzKd4tN2G%2Fe7isjsA5XjyXJnMehEtcQzm7RNA4pSKdtCa36DpDv5nyfREpovOQMTrfeJ%2Be0yE8TE7YFWpU6tM58Bn0pBojyI59CS177BwOWJudKDY9a6L3l8HMY9OxQP2%2F8K2Au5Xm0xBnWRFjkR%2F6YoPGIrDl7oey5jhKpLZazyjiTvWalkajgjDt7f62Y9JgJx4Tvm9kvQ%2B5EDXNnifQQRZYO%2FGubFTZmnLbH819xJrtpFkVrKb%2F2oBiErtyoa4%2B0sVkqJGFFs4K06BJIBN0ypt5ioBlDZdc8UKQnKew%2FU%2FKHDAsXEqeV05Xqy0Xl%2BBrv7Uk6XD02GrQniGtacpeikfe94ZZCGFb%2BqZPicpfO9xhkUzZBBMqgu6lWEcsWVSHwNxiD6dZNl95HjBwTLwnR7CiNC4MGFhMTFzslqKVN90Tm%2FD2uTLHI4vu%2FCu%2BJfDPNeOrcFoQssH1508i%2BP8qFUP6LIEtz7gjTnZw%2BvAwI0nnOx1EIOiLd4v2dQGfeF0HQbqfT0UEZr9qK3K8tDHlInx0uYJB4FXKbKjmhxajCpwoXKBjqwAezTQOaYiEW302w9F1SO97amT4Jxn1VOujRUIB0nUHAl7XH1R%2B0UyDugRiHLTCo9xEbLKCL4ekU1dyJRoljB8prhsjkTPXA8guGng3fLxk%2Ff5jZLmZNrc75fWI8rBygJAlWrVWeUGLW%2Br3OQs7Gm%2FwhmOTVpWem2mbJcRW1G0OfgCnvBhnIhmwUa7vJoIvxZAyRGGsMmPzMdnVCqUj1%2Fe9f3tjyyhATp66yqfIOKgUXt&X-Amz-Signature=737c15719d04d1d372a97167409e6aa0a0ba2ff2a049a48b9393dbd4e0e1677c&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject)
Figure 2

Figure 3

The assessment of the accuracy of the model ΔHKronstadt′60–KRON86: raw data (the points of the reference network) and after adjustments (the Danish method)
| Parameter | Raw data | The Danish method |
|---|---|---|
| Average [cm] | –8.2 | –8.2 |
| Deviation [cm] | 0.9 | 0.6 |
| Maximum [cm] | –6.4 | –6.9 |
| Minimum [cm] | –10.5 | –9.6 |
| Curtosis | –0.11 | –0.04 |
| Skewness | –0.24 | –0.01 |
The recommendations of the GUGiK concerning the conversion of heights depending on the state of data in districts (Somla, 2018)
| Case | The state of the reference network | Recommended method of height calculation | Gross cost [PLN/point]a |
|---|---|---|---|
| 1 |
| Adjustment in PL-EVRF2007-NH frame | 10 |
| 2 |
| Performing control measurements, data verification and adjustment in the PL-EVRF2007-NH frame | 50 |
| 3 |
| Modernisation of the reference network and adjustment in the PL-EVRF2007-NH frame | 700 |
Characteristics of selected elevation frames in Poland
| The name of elevation frame | Measurement campaign | Average error after adjustment [mm/km] | Characteristics of the frame |
|---|---|---|---|
| Kronstadt’60 (Wyrzykowski, 1993) | 1947–1958 | 0.78 |
|
| Kronstadt’86 (Kowalczyk and Rapinski, 2012; Łyszkowicz, 2012) | 1974–1982 | 0.84 |
|
| Kronstadt’2006a (Gajderowicz, 2007; Kowalczyk and Rapinski, 2012) | 1999–2002b | 0.88 |
|
| PL-KRON86-NH (Somla, 2018) | 1974–1982 | 0.91 |
|
| PL-EVRF2007-NH (Mäkinen, 2008; Somla, 2018) | 1999–2012 | 0.91 |
|
