# CERRA single-levels: “invalid combination” for evaporation and total\_column\_water\_vapour + requests stuck in “Accepted”

**URL:** <https://forum.ecmwf.int/t/cerra-single-levels-invalid-combination-for-evaporation-and-total-column-water-vapour-requests-stuck-in-accepted/15018>\
**Category:** C3S - Datasets and Usage\
**Tags:** c3s, cerra\
**Created:** [27 May 2026 11:12 UTC](https://forum.ecmwf.int/t/cerra-single-levels-invalid-combination-for-evaporation-and-total-column-water-vapour-requests-stuck-in-accepted/15018 "2026-05-27T11:12:39Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Mikel\_Areso](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/m/cab0a1/32.png) [@Mikel\_Areso](https://forum.ecmwf.int/u/Mikel_Areso)\
**Post date:** [27 May 2026 11:12 UTC](https://forum.ecmwf.int/t/cerra-single-levels-invalid-combination-for-evaporation-and-total-column-water-vapour-requests-stuck-in-accepted/15018/1 "2026-05-27T11:12:39Z")

</div>

Hello,

I am trying to download the `evaporation`, `total_column_water_vapour` and `total_precipitation` variables from the `reanalysis-cerra-single-levels` dataset to use as input for WAM2layers moisture tracking. I am consistently getting `400 Client Error: Bad Request — invalid combination of values` for the first two, and CDS queue is extremely slow for the third (one forecast leadtime request taking ~6.5 hours since 2026-05-26).

The CERRA product user guide ( [Copernicus European Regional ReAnalysis (CERRA): product user guide - Copernicus Knowledge Base - ECMWF Confluence Wiki](https://confluence.ecmwf.int/display/CKB/Copernicus+European+Regional+ReAnalysis+(CERRA)%3A+product+user+guide) ) lists these variables:

- **evaporation** — forecast-only, accumulated, valid leadtimes 1–6 hourly.
- **total column integrated water vapour** — analysis & forecast, instantaneous.
- **total precipitation** — forecast-only, accumulated, valid leadtimes 1–6 hourly.

But I cannot find the exact API slug accepted by CDS for _total column water vapour_. I have tried (all return 400):

- `total_column_water_vapour`
- `total_column_integrated_water_vapour`
- `total_column_water`
- `vertically_integrated_total_water_vapour`

All requests with `product_type: analysis`, `level_type: surface_or_atmosphere`, and a single timestamp.

For `evaporation` with `product_type: forecast`, `leadtime_hour: [3]`, `level_type: surface_or_atmosphere` I also get 400. With `leadtime_hour: [1]` the request was _accepted_ but is still queued after 4+ hours.

## Minimal reproducible example

```python
import cdsapi
c = cdsapi.Client()

# Fails: 400 invalid combination
c.retrieve('reanalysis-cerra-single-levels', {
    'variable': ['total_column_water_vapour'],
    'level_type': 'surface_or_atmosphere',
    'data_type': 'reanalysis',
    'product_type': 'analysis',
    'year': '2014', 'month': '08', 'day': '20',
    'time': ['12:00'],
    'data_format': 'netcdf',
}, 'tcw_test.nc')

# Fails: 400 invalid combination
c.retrieve('reanalysis-cerra-single-levels', {
    'variable': ['evaporation'],
    'level_type': 'surface_or_atmosphere',
    'data_type': 'reanalysis',
    'product_type': 'forecast',
    'year': '2014', 'month': '08', 'day': '20',
    'time': ['09:00'],
    'leadtime_hour': ['3'],
    'data_format': 'netcdf',
}, 'evap_test.nc')

```

## What does work

The same dataset with the following variables and parameters works fine in `analysis`:  
`2m_temperature, 2m_relative_humidity, surface_pressure, 10m_wind_speed, 10m_wind_direction`  
(also with `level_type: surface_or_atmosphere`).

## What I’m asking

1. **What is the exact API slug for “total column integrated water vapour”** in `reanalysis-cerra-single-levels`?
2. **What is the correct parameter combination for `evaporation`** (accumulated, forecast)? Is `leadtime_hour` set correctly?
3. **Is there a known issue with CERRA queue priority since [date]?** Requests appear to remain in “Accepted” indefinitely.

Environment:

- `cdsapi==0.7.4` (latest as of 2026-05)
- `.cdsapirc` URL: [CDSAPI setup - Climate Data Store](https://cds.climate.copernicus.eu/api) , key set without the deprecated UID prefix.

Thank you!