# Monitoring and Forecasting the Impact of the 2018 Summer Heatwave on Vegetation
## 1 Introduction
In those studies, analysis impact was successfully evaluated using several datasets such as (i) in situ measurements of soil moisture (ii) agricultural statistics, (iii) river discharge, (iv) independent flux estimates related to vegetation dynamics (evapotranspiration, Sun-Induced Fluorescence (SIF) and Gross Primary Productivity (GPP)). [PERSON] et al. [7] highlighted LDAS-Monde capacity to better characterize agricultural droughts (spatial area and intensity) than an open-loop counterpart (i.e. model without any assimilation of satellite derived measurements) over the continental United States of America. They found that LDAS-Monde can provide improved initial conditions to initialize forecast and that its impacts persist through time. In the above mentioned study, LDAS-Monde satellite-derived surface soil moisture dataset (ESA CCI SSM, [45; 46; 47; 48]) along with satellite derived LAI (GEOV1,[[http://land.copernicus.eu/global/](http://land.copernicus.eu/global/)]([http://land.copernicus.eu/global/](http://land.copernicus.eu/global/)) last access on June 2018), were jointly assimilated leading to a quarter degree spatial resolution reanalysis of the LSVs over 2010-2016. Stemming from previous work [7], the present study investigates the capability of LDAS-Monde to represent the impact of the summer 2018 heatwave in Europe on vegetation. Spring and summer 2018 in Europe were marked by unusually hot weather that had led to record-breaking temperatures in many countries across Northern and Central Europe. According to ECMWF, near-surface air temperature anomaly in Europe in the period of April to August, calculated with respect to the 1981-2010 average for those months, was much larger in 2018 than in any previous year since 1979 [49]. According to the National Oceanic and Atmospheric Administration (NOAA) Europe had its second warmest July on record. It follows its second warmest June on record (behind 2003), its warmest May since continental records began in 1910, surpassing the previous record set in 2003: the whole summer 2018 was above climatology; Europe's warmest summer since continental records began in 1910 at +2.16 \({}^{\circ}\)C (Global Climate Report, [[https://www.ncdc.noaa.gov/sotc/global/](https://www.ncdc.noaa.gov/sotc/global/)]([https://www.ncdc.noaa.gov/sotc/global/](https://www.ncdc.noaa.gov/sotc/global/)) last access October 2018). Northern Hemisphere summer precipitation was generally weaker than normal across central Europe. Such an event is likely to affect land surface conditions. In this study, satellite derived estimates of LAI and SSM as well as LDAS-Monde are used to monitor the impact of the heatwave on vegetation, focusing on July 2018. Firstly, we assess the heatwave impact on satellite derived LAI and SSM, using time-series over 2000 to 2018 and 2008 to 2018, respectively. Secondly, we evaluate the heatwave impact on the simulated LAI from LDAS-Monde forced by ECMWF ERA-5 reanalysis from January 2008 to October 2018 at 0.25\({}^{\circ}\)\(\times\) 0.25\({}^{\circ}\) and by ECMWF Integrated Forecasting System (IFS) high resolution operational analysis (HRES) from April 2016 to December 2018 at 0.10\({}^{\circ}\)\(\times\) 0.10\({}^{\circ}\). The use of both ERA5 and HRES to force LDAS-Monde enable to assess the impact of resolution versus system quality over a common one year period (2017) were ERA5 was downscaled to HRES spatial resolution. Another added value of using HRES consists in its forecast capacity, up to 10 days ahead. Forecast of LAI initialized by LDAS-Monde analysis with a leading time up to 8-days is then investigated in order to assess whether or not the heatwave impact on land surface conditions could have been anticipated. The remainder of this paper is organized as follows: Section 2 describes the LDAS-Monde system, the satellite derived estimates of LAI and SSM and the ECMWF analysis and reanalysis forcing, results are analyzed and discussed in Sections 3 and 4.